JP7560974B2 - Laser confocal microscope - Google Patents

Description

The technology disclosed herein relates to a laser confocal microscope.

For example, Patent Document 1 discloses a confocal microscope that uses the principle of laser confocal. Specifically, the confocal microscope disclosed in Patent Document 1 includes a laser light source that irradiates laser light through an objective lens, and a light receiving unit (light receiving element) that receives reflected light of the laser light through an optical system consisting of a pinhole (pinhole member) and the like, and generates a light receiving signal according to the intensity of the received light.

On the other hand, Patent Document 2 discloses a film thickness measurement device (film thickness measurement device inside a cell) that uses spectral interference. Specifically, the film thickness measurement device in Patent Document 2 is configured as a dedicated machine specialized for a specific measurement target, such as the film thickness of a colored film patterned on a substrate, and can measure film thickness using the principle of spectral interference.

JP 2009-258186 A JP 2007-205791 A

The confocal microscope described in Patent Document 1 can measure film thickness using the principle of laser confocal. However, this conventional confocal microscope has the problem that it cannot measure film thickness with the same high accuracy as film thickness measurement using spectral interferometry.

The technology disclosed here has been developed in light of these issues, and its purpose is to achieve film thickness measurement using spectroscopic interferometry in a laser confocal microscope.

The first aspect of the present disclosure relates to a laser confocal microscope including a stage for placing a measurement object, a laser light source that irradiates a laser light through an objective lens onto the measurement object placed on the stage, a light receiving unit that receives the reflected light of the laser light from the measurement object through a confocal optical system having the objective lens and generates a light receiving signal according to the light receiving intensity of the reflected light, a measurement unit that measures the surface shape of the measurement object based on the light receiving signal generated by the light receiving unit, a white light source that irradiates the measurement object placed on the stage with white light through an objective lens, a camera that receives the white light reflected from the measurement object and generates a camera image of the measurement object based on the white light reflected, a spectroscope that generates a light receiving signal according to the light receiving intensity for each wavelength, and an optical branching unit that branches the white light reflected from the measurement object into light directed to the camera and light directed to the spectroscope.

And, according to the first aspect of the present disclosure, the measurement unit measures the surface shape of the measurement object based on the light receiving signal generated by the light receiving unit, and also measures the film thickness of the measurement object based on the light receiving signal generated by the spectrometer.

According to the first aspect, the laser confocal microscope can generate a camera image using white light, and can also measure an object based on the confocal principle using laser light (laser confocal method).

According to the first aspect, the laser confocal microscope can measure film thickness based on the principle of spectral interference (spectral interferometry) by splitting the reflected light of white light. By reusing the white light and camera for the camera, it is possible to perform film thickness measurement on general measurement objects that can be placed on a stage while minimizing the number of parts required to realize spectral interferometry, particularly the introduction of dedicated parts for film thickness measurement using spectral interferometry.

According to a second aspect of the present disclosure, the laser confocal microscope includes a drive unit that changes the height position of the stage relative to the objective lens, an attachment/detachment mechanism configured to attach/detach the objective lens, a calculation unit that calculates a focal position where the focal position of the objective lens coincides with the surface of the measurement object based on a light receiving signal generated by the light receiving unit at each height position of the stage or the objective lens, and a focus adjustment unit that operates the drive unit to relatively adjust the height position of the stage or the objective lens to coincide with the focal position calculated by the calculation unit, and the confocal optical system is configured to be able to change the magnification of the measurement object by replacing the objective lens attached to the attachment/detachment mechanism, and the measurement unit measures the film thickness of the measurement object at each magnification of the measurement object.

In the case of dedicated machines such as conventional film thickness measurement devices, it was possible to measure film thickness even if the objective lens was slightly out of focus. Furthermore, such dedicated machines use a low-magnification objective lens with a deep depth of field, so the field of view is wide and it is relatively easy for users to adjust the observation position.

However, in the case of a general-purpose machine such as the laser confocal microscope, it is expected that the film thickness will be measured at a higher magnification than the dedicated machine described above. Therefore, the depth of field will be shallower than the dedicated machine described above. Furthermore, the field of view will be narrow, making it difficult for the user to grasp the observation position.

In contrast, according to the second aspect, the laser confocal microscope is configured to be able to perform measurements at high magnification using a detachable mechanism, but the calculation unit and focus adjustment unit are configured to automatically perform focusing. Therefore, good measurements can be achieved even when measuring film thickness at high magnification.

Furthermore, according to a third aspect of the present disclosure, the laser confocal microscope may include a junction section that coaxially couples the white light emitted from the white light source and the laser light emitted from the laser light source, and the optical branch section may be disposed on the optical path between the junction section and the objective lens.

According to the third aspect, the optical branching section is disposed closer to the objective lens than the merging section. In this way, by disposing the optical branching section near the objective lens, a configuration in which the optical branching section can be freely attached and detached can be easily realized. As a result, it becomes easy to distinguish between film thickness measurement and measurement by the laser confocal method.

According to a fourth aspect of the present disclosure, the laser confocal microscope may include a detachable mechanism configured to detachably attach the objective lens, and an adapter incorporating the optical branching unit, and the confocal optical system may be configured to change the magnification of the object to be measured by replacing the objective lens attached to the detachable mechanism, and the adapter may be configured to be detachable from the detachable mechanism.

According to the fourth aspect, after removing the objective lens suitable for the laser confocal method from the attachment/detachment mechanism, an adapter with a built-in optical branching unit can be attached to the attachment/detachment mechanism. This allows the adapter to be attached and detached together with the optical branching unit with the same feel as an objective lens. This means that it is possible to easily switch between two different measurement principles, the laser confocal method and the spectral interferometry, which contributes to improving usability.

Furthermore, according to a fifth aspect of the present disclosure, the adapter may be configured to allow the objective lens, which is separate from the adapter, to be detachably attached, and the objective lens may be configured to be attachable to the attachment/detachment mechanism via the adapter.

According to the fifth aspect, among the objective lenses, the objective lens used for film thickness measurement by the spectral interferometry in particular can be attached to the attachment/detachment mechanism via an adapter. This is effective in improving the usability of the adapter.

Furthermore, according to a sixth aspect of the present disclosure, the attachment/detachment mechanism may be configured as a revolver that rotates around a predetermined central axis, and the revolver may be configured to be capable of attaching the objective lens and the adapter so as to surround the central axis.

According to the sixth aspect, the laser confocal microscope can switch measurement principles by performing the relatively simple operation of removing the objective lens from the revolver and replacing it with an adapter. Since the measurement principle can be switched with the same feel as changing the objective lens, the usability of the device can be improved.

According to a seventh aspect of the present disclosure, the laser confocal microscope may include a branching optical system that branches the white light emitted from the white light source into a reference light directed toward a predetermined reference surface and a measurement light directed toward the measurement object, and an imaging unit that receives the reference light reflected by the reference surface and the measurement light reflected by the measurement object to capture an interference image, and the measurement unit may measure the surface shape of the measurement object based on a plurality of interference images captured by the imaging unit at a plurality of height positions defined within a height range including the focal position.

According to the seventh aspect, the laser confocal microscope can measure the surface shape based on the principle of white light interference (white light interferometry) by capturing an interference image that reflects the interference phenomenon between the measurement light and the reference light.

Here, the "imaging unit" may be configured by the camera. In that case, the interference image corresponds to the camera image captured under specific conditions.

Incidentally, in order to measure the surface shape with high accuracy, it is necessary to search in advance for the focal position where the interference objective lens or the like is focused, but there is still room for improvement in terms of usability in conventionally known methods.

The white light interference microscope according to the seventh aspect uses the principle of confocal laser light (laser confocal method) rather than white light interference method when searching for the focal position.

When using the laser light confocal method, a relatively high light receiving intensity is achieved at the focused position, while the light receiving intensity is significantly reduced at the unfocused position. This makes it possible to sufficiently increase the gain of the light receiving element without starting the search from a relatively focused state. This is advantageous in terms of effort and time, and ultimately makes it possible to improve usability when adjusting the focus.

Furthermore, according to an eighth aspect of the present disclosure, the laser confocal microscope may be provided with a mode switching unit that executes one of a group of modes including at least a first mode for measuring the surface shape of the measurement object and a second mode for measuring the film thickness of the measurement object.

According to the eighth aspect, the laser confocal microscope can selectively use at least the first mode and the second mode as its main function. This allows the laser confocal microscope to be used for various purposes.

Furthermore, according to a ninth aspect of the present disclosure, the laser confocal microscope may be configured such that the measurement unit measures the film thickness of the measurement object based on the light receiving signal generated by the light receiving unit, and when the second mode is selected, the mode switching unit executes one of a first submode in which the film thickness is measured based on the light receiving signal generated by the spectrometer and a second submode in which the film thickness is measured based on the light receiving signal generated by the light receiving unit.

In general, film thickness measurements based on laser confocal techniques are more suitable for thicker objects than measurements based on spectroscopic interferometry.

According to the ninth aspect, the laser confocal microscope can selectively use either the film thickness measurement based on the spectroscopic interferometry method or the film thickness measurement based on the laser confocal method. This makes it possible to perform appropriate measurements each time depending on the thickness of the object.

According to a tenth aspect of the present disclosure, the laser confocal microscope may include an attachment/detachment mechanism configured to attach and detach the objective lens, an adapter incorporating the optical branching unit, and a mode switching unit that executes one of a group of modes including at least a first mode for measuring the surface shape of the measurement object and a second mode for measuring the film thickness of the measurement object, the adapter configured to be attachable to the attachment/detachment mechanism, the attachment/detachment mechanism configured as a revolver that rotates around a predetermined central axis, the revolver configured to be able to attach the objective lens and the adapter so as to surround the central axis, and the mode switching unit may not allow the revolver to rotate when the second mode is selected.

The adapter may have a larger diameter than the objective lens because it contains an optical branching section. In that case, there is a risk of the adapter colliding with the stage when the adapter is rotated through the revolver.

On the other hand, according to the tenth aspect, when the second mode is selected, that is, when the adapter (and the optical branching unit) is placed facing the object to be measured, the revolver and the adapter are not allowed to rotate in that position. By configuring it in this way, it is possible to prevent a collision between the adapter and the stage.

As described above, according to the present disclosure, film thickness measurement using spectroscopic interferometry can be achieved in a laser confocal microscope.

FIG. 1A is a schematic diagram illustrating the system configuration of a laser confocal microscope. FIG. 1B is a schematic diagram illustrating a system configuration of a laser confocal microscope during film thickness measurement. FIG. 2 is a perspective view of the observation unit. FIG. 3A is a schematic diagram illustrating a white light optical system of the observation unit. FIG. 3B is a schematic diagram illustrating a laser optical system of the observation unit. FIG. 3C is a schematic diagram illustrating a white light optical system during film thickness measurement. FIG. 4 is a block diagram illustrating the configuration of a laser confocal microscope. FIG. 5 is a block diagram illustrating the configuration of a unit control system. FIG. 6A is a diagram illustrating an example of the relationship between the relative position of the sample in the Z direction and the received light intensity caused by the interference light of white light in one pixel. FIG. 6B is a diagram illustrating an example of the relationship between the relative position of the sample in the Z direction and the received light intensity caused by reflected light of the laser light in one pixel. FIG. 6C is a diagram illustrating the magnitude of the second pitch. FIG. 6D is a diagram comparing the magnitude of the fourth pitch and the first pitch. FIG. 6E is a diagram comparing the magnitude of the third pitch and the fourth pitch. FIG. 6F is a diagram comparing the magnitude of the third pitch and the fourth pitch. FIG. 7 is a diagram for explaining a procedure for setting a height range. FIG. 8 is a perspective view of the spectroscopic unit. FIG. 9 is an exploded perspective view of the spectroscopic unit. FIG. 10A is a diagram illustrating the relationship between the reflectance for each wavelength of white light and the film thickness of a sample. FIG. 10B is a diagram illustrating an example of the relationship between the received light intensity caused by the reflected light of the laser light and the film thickness of the sample. FIG. 11 is a side view of the electric revolver. FIG. 12 is a flow chart illustrating a basic procedure for using a laser confocal microscope. FIG. 13 is a flowchart illustrating a procedure for setting parameters using a laser confocal microscope. FIG. 14 is a flowchart illustrating an example of an execution procedure of autofocus by a laser confocal microscope. FIG. 15 is a flowchart illustrating a procedure for measuring the surface shape using a laser confocal microscope. FIG. 16 is a flow chart illustrating a procedure for measuring the film thickness of a sample using a laser confocal microscope. FIG. 17 is a diagram showing an example of a display screen during simple setting. FIG. 18 is a diagram illustrating a display screen during measurement by white light interferometry. FIG. 19 is a diagram showing an example of a display screen at the time of basic setting. FIG. 20 is a diagram illustrating an example of a display screen during film thickness measurement.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that the following description is merely an example.

<Laser confocal microscope 1>
Fig. 1A is a schematic diagram illustrating a system configuration of a laser confocal microscope 1 according to an embodiment of the present disclosure. The laser confocal microscope 1 illustrated in Fig. 1 is a device for magnifying and observing a sample SP as an observation object and a measurement object, and for measuring the surface shape (three-dimensional shape) of the sample SP.

When measuring the surface shape of the sample SP, the laser confocal microscope 1 can perform the laser confocal method using a confocal optical system having a pinhole or the like. On the other hand, the laser confocal microscope 1 according to this embodiment uses white light as coaxial epi-illumination, and receives the reflected light with the imaging unit 58 (camera), so that the sample SP can be observed based on the image (interference image) generated by the camera.

The laser confocal microscope 1 is also configured as a two-beam interferometer using white light. In other words, the laser confocal microscope 1 can also perform white light interferometry, which utilizes the interference of two beams of white light, when measuring the surface shape of the sample SP.

Here, FIG. 1B is a schematic diagram illustrating the system configuration of the laser confocal microscope 1 when measuring film thickness. As illustrated in FIG. 1B, the laser confocal microscope 1 can also measure the film thickness of the sample SP by replacing the existing objective lens 54 with a spectroscopic unit Os and using the spectral interference of white light.

When measuring film thickness, the laser confocal microscope 1 can selectively use either measurement based on the principle of spectral interference or measurement using the laser confocal method.

When focusing on its observation function, the laser confocal microscope 1 can be called a magnifying observation device, simply a microscope, or a digital microscope, while when focusing on its measurement function, it can be called a three-dimensional shape measuring device, a surface shape measuring device, or a film thickness measuring device. When focusing on its measurement principle, the laser confocal microscope 1 can also be called a white light interferometer or a white light interference microscope.

As shown in FIG. 1A, the laser confocal microscope 1 according to this embodiment includes an observation unit 2 and an external unit 3. The observation unit 2 is a unit made up of optical components for performing observation and measurement using white light interference. Meanwhile, the external unit 3 is a unit for realizing communication functions, power supply functions, and the like. The external unit 3 can also be incorporated into the observation unit 2 for integration. As shown in the figure, when the laser confocal microscope 1 is configured with the observation unit 2 and the external unit 3, a power supply device 3a that supplies power to the observation unit 2 can be provided in the external unit 3. The observation unit 2 and the external unit 3 are connected by wiring 2a.

The laser confocal microscope 1 can also be connected to an operation terminal 4. The operation terminal 4 can be connected by a communication section 3b (see FIG. 4) built into the external unit 3. Instead of connecting the operation terminal 4 to the external unit 3, or in addition to connecting the operation terminal 4 to the external unit 3, the operation terminal 4 can also be connected to the observation unit 2. In that case, the observation unit 2 will have a built-in device equivalent to the communication section 3b.

As shown in FIG. 1A, the operation terminal 4 according to this embodiment has a display unit 41, a keyboard 42, a mouse 43, and a storage device 44. The operation terminal 4 can be incorporated into the observation unit 2 or the external unit 3 to be integrated as a component of the laser confocal microscope 1. In this case, the operation terminal 4 can be called a control unit or the like rather than an "operation terminal", but this embodiment illustrates a case where it is separate from the observation unit 2 and the external unit 3.

In addition, one or more of the display unit 41, keyboard 42, mouse 43, and storage device 44 can be incorporated and integrated into the observation unit 2, external unit 3, etc., to form components of the laser confocal microscope 1. In other words, the entire operation terminal 4, or each component of the operation terminal 4, can be made part of the laser confocal microscope 1. For example, the laser confocal microscope 1 can be equipped with a display unit 41, and with a keyboard 42 and mouse 43 (operation unit).

The keyboard 42 and mouse 43 are well-known devices for operating a computer, and form an operation unit for operating the operation terminal 4. These accept operation input by the user, and by inputting a signal corresponding to the operation input to the operation terminal 4, the laser confocal microscope 1 can be operated via the operation terminal 4. Specifically, by operating the keyboard 42 and mouse 43, it is possible to input various types of information, perform selection operations, select images, specify areas, specify positions, etc.

Note that the keyboard 42 and the mouse 43 are merely examples of an operation unit. Instead of the keyboard 42 and the mouse 43, or in addition to the keyboard 42 and the mouse 43, various devices such as pointing devices, voice input devices, and touch panels can also be used.

The display unit 41 is configured, for example, by a liquid crystal display or an organic EL panel. This display unit 41 can display information to the user, such as the contents stored in the storage device 44. Note that a touch panel may be incorporated into the display unit 41 as an operation unit.

In addition, the components, means, elements, units, etc. described below may be provided in either the observation unit 2, the external unit 3, or the operation terminal 4.

In addition to the above-mentioned devices and equipment, the laser confocal microscope 1 can also be connected, by wire or wirelessly, to devices for performing various operations and controls, printers, computers for performing various other processes, storage devices, peripheral devices, etc.

For example, when measuring the film thickness of the sample SP, a spectrometer 12 is connected to the observation unit 2. As shown in FIG. 1B, the spectrometer 12 is connected to the spectroscopic unit Oc via an optical cable 11. The spectrometer 12 can be connected to the unit control system 8 built into the observation unit 2, the external unit 3, the operation terminal 4, etc., by wire or wirelessly.

<Overall configuration of observation unit 2>
Fig. 2 is a perspective view of the observation unit 2. The external shape of the observation unit 2 is as shown in Fig. 2. This observation unit 2 includes a base 20 placed on a workbench or the like, a support part 21 extending upward from the back part of the base 20, a head part 22 provided on the upper part of the support part 21, and a stage 23 on which a sample SP as a measurement object is placed.

The front side of the observation unit 2 refers to the side closest to the user when the user faces the observation unit 2 in a normal operating position. On the other hand, the back side of the observation unit 2 refers to the other side away from the user when the user faces the observation unit 2 in a normal operating position. These definitions are merely for the convenience of explanation and do not limit the actual usage state.

In the following description, the depth direction connecting the front and back sides of the observation unit 2 (the long direction of the head part 22) is referred to as the "X direction", and the left-right direction of the observation unit 2 (the short direction of the head part 22) is referred to as the "Y direction". The direction along both the X direction and the Y direction is referred to as the "horizontal direction", and the plane along the horizontal direction is referred to as the "horizontal plane".

Furthermore, the height direction of the observation unit 2 is referred to as the "Z direction." This Z direction is perpendicular to both the X direction and the Y direction. In the following description, the "height position" refers to the position when viewed along the coordinate axis (Z axis) along the Z direction. The height position is sometimes referred to as the "Z position."

Of course, this disclosure is not limited to these definitions, and the definitions of the X direction, Y direction, Z direction, etc. can be changed as desired.

Of the components that make up the observation unit 2, the stage 23 is configured as an electrically operated mounting base. The stage 23 can be moved in the Z direction by rotating the elevation dial 23a shown in Figures 1 and 2, etc.

In addition to components related to the external shape of the observation unit 2, such as the base 20, the observation unit 2 includes a white optical system 5, which is a collection of parts related to observation and measurement using white light, a laser optical system 6, which is a collection of parts related to measurement using laser light, a unit drive system 7 that drives the stage 23, etc., and a unit control system 8 that executes various processes via the white optical system 5, the laser optical system 6, and the unit drive system 7.

The white light optical system 5 is an observation optical system (non-confocal observation optical system) that uses white light as illumination for observation or as a source for generating interference light, and is an optical system for observing a sample SP illuminated by white light and generating an interference image that characterizes the surface shape of the sample SP. Note that the term "optical system" is used in a broad sense here. In other words, the white light optical system 5 is defined as a system that includes a light source, an imaging element, etc. in addition to optical components such as lenses. The same applies to the laser optical system 6.

The laser optical system 6 is an observation optical system (confocal observation optical system) that uses the so-called laser confocal method, and is a system for two-dimensionally scanning the laser light and irradiating the laser light in a focused state to generate an image based on the reflected light of the laser light (hereinafter referred to as a "laser image").

The unit drive system 7 is composed of a Z-direction drive unit 71 that operates the stage 23, an electric revolver (electric variable magnification mechanism) 74 that switches the objective lenses in the first and laser optical systems 5 and 6, etc. The unit drive system 7 operates various components that make up the laser confocal microscope 1 based on electrical signals input from the unit control system 8.

The unit control system 8 is connected to the white optical system 5, the laser optical system 6, and the unit drive system 7 so as to be able to send and receive electrical signals, and is configured to be able to display interference images, laser images, etc. on the display unit 41, to perform autofocusing of the laser confocal microscope 1 based on the laser image, and to measure the surface shape of the sample SP based on at least one of the interference image and the laser image.

Specifically, the unit control system 8 according to this embodiment has as its main components a scan control unit 8a that controls two-dimensional scanning of the laser light, and a first surface shape measuring unit 8j and a second surface shape measuring unit 8k that measure the surface shape of the sample SP based on the interference image generated by the white optical system 5 or the laser image generated by the laser optical system 6. Here, the first surface shape measuring unit 8j is an example of a "measuring unit" in this embodiment. These will be described in detail later.

As shown in FIG. 4, the unit control system 8 according to this embodiment is configured to be shared by the white optical system 5, the laser optical system 6, and the unit drive system 7, but is not limited to this configuration. For example, a dedicated control system may be connected to each of the white optical system 5, the laser optical system 6, and the unit drive system 7.

The classification of the white optical system 5, the laser optical system 6, the unit drive system 7, and the unit control system 8 is merely a convenient classification for providing a systematic explanation, and does not limit the configuration of the present disclosure. The laser confocal microscope 1 according to this embodiment has parts shared between the white optical system 5 and the laser optical system 6, such as the first beam splitter 57.

(White Optical System 5)
3A is a schematic diagram illustrating the optical system of the observation unit 2, particularly the white optical system 5. The white optical system 5 of the observation unit 2 can be configured similarly to an optical system conventionally used in a white interferometer, and uses a white light source 51, which will be described later, as a light source for observation and measurement. This white optical system 5 is configured to irradiate the sample SP with white light emitted from the white light source 51, and to collect the reflected light on the imaging section 58.

Specifically, the white optical system 5 includes a white light source 51, a first mirror 52, a first half mirror 53, an objective lens 54, a branching optical system 55 that constitutes an interference objective lens Oc together with the objective lens 54, a first lens 56, a first beam splitter 57, and an imaging unit 58 having an image sensor 58a. The imaging unit 58 is electrically connected to a first surface shape measuring unit 8j, which is an element of the unit control system 8. In the example shown in FIG. 3A, the branching optical system 55 is configured to be built into the interference objective lens Oc, but the present disclosure is not limited to such a configuration. As described later, the branching optical system 55 and the objective lens 54 can be laid out as independent components, and the branching optical system 55 can be configured to operate as necessary.

--White light source 51--
The white light source 51 irradiates the sample SP placed on the stage 23 with white light via an objective lens 54 (interference objective lens Oc when white light interferometry is used) (see reference symbol L1 in FIG. 3A ). When used as illumination for observation, the white light source 51 functions as a coaxial epi-illumination system that is coaxial with the optical axis of the imaging unit 58 (particularly, the optical axis of the imaging element 58a).

Specifically, the white light source 51 according to this embodiment has a light emitter 51a that can be configured, for example, by a halogen lamp or a white LED (Light Emitting Diode), and an optical component (not shown) into which the white light emitted from the light emitter 51a is incident.

The white light emitted from the white light source 51 is reflected by the first mirror 52 and the first half mirror 53, and then irradiated onto the sample SP via the objective lens 54 and the branching optical system 55.

--First mirror 52--
The first mirror 52 is disposed so as to face an illuminant (not shown) of the white light source 51 with the mirror surface of the first mirror 52 tilted. The first mirror 52 reflects the white light emitted from the white light source 51 and causes the white light to enter the first half mirror 53.

--First half mirror 53--
The first half mirror 53 is disposed on the optical axis of the image sensor 58a. The first half mirror 53 reflects the white light reflected by the first mirror 52 again, thereby coaxializing the optical axis of the white light with the optical axis of the image sensor 58a. The coaxial white light is irradiated onto the sample SP via the objective lens 54. The first half mirror 53 is an example of a "junction" in this embodiment.

The white light reflected by the sample SP returns to the first half mirror 53 via the objective lens 54. The first half mirror 53 transmits the reflected white light and guides it to the imaging unit 58 via the first lens 56 and the first beam splitter 57.

--Objective lens 54 and branching optical system 55--
The objective lens 54 is configured as an interference objective lens Oc integrated with the branching optical system 55. This interference objective lens Oc can be configured as an objective lens for two-beam interference.

That is, the interference objective lens Oc includes a focusing objective lens 54 and a branching optical system 55 that splits the light (white light or laser light) that passes through the objective lens 54 into two beams (reference light and measurement light) and overlaps the two beams with different optical path lengths.

In particular, the interference objective lens Oc according to this embodiment can be configured as a Mirau-type interference objective lens Oc, as illustrated in FIG. 3A, among objective lenses classified as objective lenses for two-beam interference.

More specifically, the branching optical system 55 has an interference beam splitter 55a and a reference mirror 55b. When configured as a Mirau-type interference objective lens Oc, the interference beam splitter 55a and the reference mirror 55b are both arranged coaxially with respect to the optical axis of the objective lens 54, as illustrated in FIG. 3A.

More specifically, the interference beam splitter 55a splits the white light emitted from the white light source 51 and passed through the objective lens 54 into a reference light (see symbol Lr in FIG. 3A) directed toward a predetermined reference surface (in this embodiment, the mirror surface of the reference mirror 55b) and a measurement light directed toward the sample SP as the measurement object. After being reflected by the sample SP, the latter measurement light reenters the interference beam splitter 55a (see symbol L2 in FIG. 3A). Meanwhile, the reference mirror 55b reflects the reference light generated by the interference beam splitter 55a and propagates it toward the interference beam splitter 55a.

Therefore, the reflected light of the measurement light (measurement light reflected by the sample SP) merges with the reference light reflected by the reference mirror 55b, and the two propagate in an overlapping state. Hereinafter, the reflected light of the reference light and measurement light propagating in an overlapping state may be collectively referred to as "interference light." The interference light thus formed passes through the objective lens 54, the first half mirror 53, the first lens 56, and the first beam splitter 57 in sequence, and reaches the imaging unit 58.

The interference objective lens Oc is not limited to the Mirau type as described above. For example, a Michelson type interference objective lens can also be used. In that case, the reference mirror 55b is placed at a position off the optical axis of the objective lens 54 (a position that is non-coaxial with respect to the optical axis of the objective lens 54).

The interference objective lens Oc is not essential when the white light source 51 is used simply as illumination. In that case, instead of the interference objective lens Oc having the branching optical system 55, the objective lens 54 can be used alone, as illustrated in FIG. 3. Hereinafter, the objective lens 54 not having the branching optical system 55 may be referred to as a "normal objective lens."

The interference objective lens Oc is also not required when using laser light for various processes. In such cases, a normal objective lens 54 is basically used, but the interference objective lens Oc can be used even for processes that use laser light, such as autofocus, which will be described later.

Although details are omitted, as shown in FIG. 3B, a ring light 54a can be attached to the objective lens 54 and used as illumination for observation (non-coaxial epi-illumination).

--First lens 56--
The first lens 56 is disposed so as to be coaxial with the optical axis of the image sensor 58 a. The first lens 56 collects the white light reflected by the sample SP and makes the white light enter the image sensor 58 a via the first beam splitter 57.

--First beam splitter 57--
The first beam splitter 57 is disposed on the optical axis of the image sensor 58a. The first beam splitter 57 is configured as, for example, a cube mirror, and reflects light falling within a specific wavelength range, in particular, the laser light used in the laser optical system 6.

As illustrated in FIG. 3A, the first beam splitter 57 transmits the white light etc. collected by the first lens 56 and guides it to the imaging unit 58. As illustrated in FIG. 3B, the first beam splitter 57 also reflects the laser light emitted from the laser light source 61 (see reference character L3 in FIG. 3B) and the reflected light of the laser light from the sample SP (see reference character L4 in FIG. 3B).

--Image capture unit 58--
The imaging unit 58 receives the reference light reflected by the mirror surface (reference surface) of the reference mirror 55b and the measurement light reflected by the sample SP as the measurement object, and captures an interference image reflecting the interference between the reference light and the measurement light. When the white light source 51 is used simply as illumination, the imaging unit 58 also functions as a camera for capturing an image of the surface of the sample SP. That is, the imaging unit 58 is an example of the "camera" in this embodiment.

More specifically, the imaging unit 58 has an imaging element 58a for receiving light, such as white light, focused by the first lens 56. This imaging element 58a photoelectrically converts the light incident through the first lens 56, etc., using a plurality of pixels arranged on its light receiving surface, and converts it into an electrical signal corresponding to the optical image of the subject.

The imaging element 58a may be a plurality of light receiving elements arranged along the light receiving surface. In this case, each light receiving element corresponds to a pixel. Specifically, the imaging element 58a according to this embodiment is configured with an image sensor made of a CMOS (Complementary Metal Oxide Semiconductor), but is not limited to this configuration. For example, an image sensor made of a CCD (Charged-Coupled Device) may also be used as the imaging element 58a.

Then, the imaging unit 58 generates an image corresponding to the optical image of the subject based on the electrical signal converted by the imaging element 58a, and inputs this to the unit control system 8, etc. Among the images (camera images) generated by the imaging unit 58, the image of the interference fringes used in white light interferometry corresponds to the aforementioned "interference image." Of course, the images generated by the imaging unit 58 also include images for observing the surface of the sample SP.

- Basic principles of white light interferometry -
As described above, the imaging unit 58 receives the reference light reflected by the mirror surface (reference surface) of the reference mirror 55b and the measurement light reflected by the sample SP as the measurement object. Here, the reference light and the reflected measurement light propagate through the same optical path after being emitted from the interference objective lens Oc, but a difference occurs in the optical path length when passing through the branching optical system 55, so that interference occurs when the two lights overlap each other.

Here, if the reference light and the measurement light are in phase, they will reinforce each other through interference. In this case, the amount of light received by the image sensor 58a (amount of received light) will be greater than when the phases are not in phase, and the intensity of the received light, i.e., the brightness value detected at each pixel, will be greater.

On the other hand, if the reference light and the measurement light do not match in phase, particularly if they are shifted by half a wavelength, they will weaken each other due to interference. In this case, the amount of light received by the image sensor 58a will be smaller than when the phases match, and the intensity of the received light, i.e., the brightness value detected at each pixel, will be smaller.

Therefore, in the area illuminated by the white light through the interference objective lens Oc, the areas where the phases of the reference light and the measurement light match are bright, and the areas where they do not are dark, forming a light and dark striped pattern (interference fringes). The imaging unit 58 captures the interference fringes to capture an interference image that reflects the light and dark.

Here, the phase difference between the reference light and the measurement light is due to the difference in the optical path length between the two. Therefore, the contrast of the interference fringes and the arrangement of light and dark will change depending on the distance between the sample SP and the interference objective lens Oc.

Therefore, by changing the relative height position of the interference objective lens Oc with respect to the sample SP, capturing interference images at each height position, and analyzing how the interference fringes change between each interference image, it is possible to measure the surface shape of the sample SP, such as the uneven shape.

To perform such measurements, the imaging unit 58 inputs electrical signals representing the interference images captured at each height position to the first surface shape measuring unit 8j described above. The first surface shape measuring unit 8j is configured to measure the surface shape of the sample SP based on the multiple interference images corresponding to the input electrical signals.

In this way, the white light optical system 5 is an optical system capable of performing shape measurement using white light interferometry. The intervals between the bright and dark parts of the interference fringes and the peak widths of the received light intensity corresponding to each bright and dark part are narrowed to the order of nanometers, let alone micrometers. Furthermore, the size of these intervals and peak widths is derived solely from the difference in optical path length, and is constant and does not depend on the magnification of the objective lens 54, etc. Therefore, this method can perform measurements on the order of several nanometers in height, regardless of the performance of the objective lens 54, etc., and can perform extremely excellent measurements in terms of accuracy in the height direction (Z direction) and resolution in the same direction, compared to methods such as focus synthesis and laser confocal.

(Laser optical system 6)
3B is a schematic diagram illustrating a laser optical system of the observation unit 2. The laser optical system 6 can be configured similarly to an optical system conventionally used in a confocal microscope, and uses a laser light source 61, which will be described later, as a light source for measurement. The laser optical system 6 is configured to irradiate the sample SP with laser light emitted from the laser light source 61, and to collect the reflected light on a light receiving unit 66.

Specifically, the laser optical system 6 includes a laser light source 61, a second beam splitter 62, a laser light scanning unit 63, a first beam splitter 57, a first lens 56, a first half mirror 53, an objective lens 54 or an interference objective lens Oc, a second lens 64, a pinhole plate 65 with a pinhole 65a formed therein, and a light receiving unit 66 having a light receiving element 66a. Of these, the light receiving unit 66 is electrically connected to a second surface shape measuring unit 8k, which is an element of the unit control system 8. The laser optical system 6 is an example of a "confocal optical system" in this embodiment.

In other words, the laser optical system 6, which serves as a confocal optical system, is laid out so that when the laser light is focused on the surface of the sample SP, the reflected light of the laser light is focused near the pinhole 65a or the light receiving element 66a (more specifically, the pinhole 65a is laid out at a position that is "conjugate" with the focal plane of the objective lens 54).

--Laser light source 61--
The laser light source 61 irradiates the sample SP placed on the stage 23 with laser light through an objective lens 54 that is the same as or different from the interference objective lens Oc. That is, as illustrated in FIG. 3AA, the laser light may be irradiated through the objective lens 54 and the branching optical system 55, or as illustrated in FIG. 3B, the laser light may be irradiated only through the objective lens 54 without the branching optical system 55. In the following description, for simplicity, a case where the laser light is irradiated without the branching optical system 55 will be described. This laser light source 61 functions as a so-called point light source.

As the laser light source 61, for example, a He-Ne gas laser or a semiconductor laser can be used. In place of the laser light source 61, various light sources capable of generating a point light source can be used, in which case, for example, a combination of a high-intensity lamp and a slit can be used.

The laser light output from the laser light source 61 passes through the second beam splitter 62 and reaches the laser light scanning unit 63, from which it is irradiated onto the sample SP via the first beam splitter 57, the first lens 56, the first half mirror 53 and the objective lens 54.

--Second beam splitter 62--
The second beam splitter 62 is disposed on the optical axis of the laser light source 61, and is located between the laser light source 61 and the laser light scanning unit 63. The second beam splitter 62 transmits the laser light output from the laser light source 61 and guides it to the laser light scanning unit 63. The second beam splitter 62 also reflects the laser light reflected by the sample SP and guides it to the light receiving unit 66. As the second beam splitter 62, a well-known beam splitter can be used.

--Laser light scanning unit 63--
The laser light scanning unit 63 can perform two-dimensional scanning on the surface of the sample SP with the laser light irradiated from the laser light source 61. Note that the "two-dimensional scanning" here refers to a two-dimensional operation of scanning the irradiation position of the laser light on the surface of the sample SP.

As shown in FIG. 3B, the laser light scanning unit 63 is configured as a so-called two-axis galvanometer scanner and is disposed between the second beam splitter 62 and the first beam splitter 57.

The laser light scanning unit 63 can scan the laser light along at least one of a predetermined first direction and a second direction perpendicular to the first direction (both in the illustrated example). Specifically, the laser light scanning unit 63 according to this embodiment has a first scanner 63a for scanning the laser light incident from the second beam splitter 62 in the first direction, and a second scanner 63b for reflecting the laser light scanned by the first scanner 63a toward the first beam splitter 57 while scanning it in the second direction.

In this embodiment, the "first direction" corresponds to the X direction defined as described above. The "second direction" corresponds to the Y direction defined in the same manner as the X direction. Of course, the definitions are not limited to these, and the definitions of the first direction and the second direction can be changed as desired.

The laser light scanning unit 63 may be any unit configured to perform two-dimensional scanning of the laser light on the surface of the sample SP, and is not limited to the two-axis galvano scanner described above. For example, a photoacoustic element method (resonant method) may be used in which a piezoelectric element is attached to an acousto-optical medium made of glass, and an electric signal is input to the piezoelectric element to generate ultrasonic waves, thereby diffracting the laser light passing through the acousto-optical medium and deflecting the light, or a Nipkow disk method may be used in which a disk having one or multiple rows of pinholes in a spiral shape is rotated, and the light passing through the pinholes scans the surface of the sample SP two-dimensionally.

The laser light that passes through the laser light scanning unit 63 is reflected by the first beam splitter 57 and is irradiated onto the sample SP via the first lens 56, the first half mirror 53, and the objective lens 54.

The laser light irradiated to the sample SP is reflected by the sample SP and returns to the observation unit 2. Specifically, the reflected laser light from the sample SP passes through the objective lens 54, the first half mirror 53, the first lens 56, and the laser light scanning unit 63, and is then reflected by the second beam splitter 62 and reaches the second lens 64.

The laser light scanning unit 63 is operated by the scanning control unit 8a described above. More specifically, the laser light scanning unit 63 is electrically connected to the scanning control unit 8a and is configured to operate upon receiving an electrical signal input from the scanning control unit 8a.

--Second lens 64--
The second lens 64 is disposed so as to be coaxial with the optical axis of the light receiving element 66a in the light receiving section 66, and is located between the second beam splitter 62 and the pinhole plate 65. The second lens 64 collects the reflected light of the laser light from the second beam splitter 62, and makes the light enter the light receiving element 66a via the pinhole plate 65.

-Pinhole plate 65-
The pinhole plate 65 is a plate-like member arranged perpendicular to the optical axis of the light receiving element 66a, and has a pinhole 65a penetrating the plate-like member in the plate thickness direction. The pinhole plate 65 is arranged between the second lens 64 and the light receiving unit 66. The reflected light of the laser light focused by the second lens 64 passes through the pinhole 65a and enters the light receiving element 66a.

As mentioned above, the pinhole 65a is positioned conjugate with the focal plane of the objective lens 54, allowing the laser optical system 6 to function as a confocal optical system.

--Light receiving unit 66--
The light receiving section 66 receives the reflected light of the laser light from the sample SP via a pinhole 65a in the confocal optical system (laser optical system 6), and generates a light receiving signal according to the received intensity of the reflected light.

More specifically, the light receiving unit 66 has a light receiving element 66a for receiving the reflected light collected by the second lens 64. This light receiving element 66a photoelectrically converts the light incident through the pinhole 65a by using a photoelectric surface formed in its entrance window, and converts it into an electrical signal corresponding to the intensity of the received light.

It is preferable that the light receiving element 66a has a higher frame rate than the imaging element 58a. More preferably, the light receiving element 66a has a higher sensitivity than the imaging element 58a. Specifically, the light receiving element 66a according to this embodiment is configured with an optical sensor made of a PMT (PhotoMultiplier Tube), but is not limited to this configuration. As the light receiving element 66a, the imaging element 58a described above can be used, or, for example, a photodetector such as an HPD (Hybrid Photo Detector) using an avalanche diode or an MPPC (Multi-Pixel Photon Counter) can be used.

The light receiving unit 66 then generates an image corresponding to the optical image of the subject by associating the electrical signal converted by the light receiving element 66a with the irradiation position of the laser light, and inputs this to the unit control system 8, etc. The image (laser image) generated by the light receiving unit 66 can be used for shape measurement by the laser confocal method, or for observing the surface of the sample SP.

- Basic principles of laser confocal imaging -
As described above, the pinhole 65a is disposed at a position conjugate with the focal plane of the objective lens 54. Therefore, when the laser light emitted from the laser light source 61 is focused on the surface of the sample SP, the reflected light from the surface converges near the pinhole 65a and is focused on the light receiving element 66a. In this case (when in focus), the amount of light received by the light receiving element 66a (amount of received light) is significantly larger than when not in focus, and therefore the intensity of the received light, i.e., the luminance value detected at each pixel, is increased.

On the other hand, when the laser light is not focused on the sample SP (out of focus), the light reflected from the surface of the sample SP diffuses rather than converges near the pinhole 65a, and most of the light is blocked by the pinhole plate 65. In this case, the amount of light received by the light receiving element 66a (amount of received light) is significantly smaller than when in focus, and the intensity of the received light, i.e., the brightness value detected at each pixel, becomes smaller.

Therefore, in the scanning area of the laser light realized by the scanning control unit 8a operating the laser light scanning unit 63, the part where the focus is on the surface of the sample SP is bright, while other heights are dark. Therefore, it is possible to measure the surface shape of the sample SP (in particular, information that characterizes the height of the sample SP) based on the brightness of the reflected light of the laser light.

To perform such measurements, the light receiving unit 66 inputs an electrical signal indicating the received light intensity of the reflected light of the laser light scanned two-dimensionally by the scanning control unit 8a and the laser light scanning unit 63 to the second surface shape measuring unit 8k described above. The second surface shape measuring unit 8k measures the surface shape of the sample SP based on the received light intensity (specifically, the brightness or darkness of the reflected light) indicated by the input electrical signal.

In this way, the laser optical system 6 is an optical system capable of performing shape measurement using the laser confocal method, and since it detects only substantially focused light, it is not as good as white light interferometry, but it can provide brightness information with superior accuracy in the height direction (Z direction) and resolution in the same direction compared to other methods such as focus synthesis.

In addition, shape measurement using the laser confocal method involves two-dimensional scanning of a spot of laser light, so it can provide brightness information with superior horizontal resolution compared to white light interferometry.

(White light optical system 5 as an optical system for spectral interference)
3C is a schematic diagram illustrating a laser optical system of the observation unit 2. The white light emitted from the white light source 51 can be used for film thickness measurement by spectral interference. In that case, the white optical system 5 can be reused simply by replacing the objective interference lens Oc with the spectroscopic unit Os.

Specifically, the white light optical system 5 as an optical system for spectral interference includes a white light source 51, a first mirror 52, a first half mirror 53, a spectroscopic unit Os, an optical cable 11, and a spectrometer 12.

The configurations of the white light source 51, the first mirror 52, and the first half mirror 53 have already been described. The white light emitted from the white light source 51 (see L5 in FIG. 3C) is reflected by the first mirror 52 and the first half mirror 53 and reaches the spectroscopic unit Os.

-Spectroscopic unit Os-
Fig. 8 is a perspective view illustrating the configuration of the spectroscopic unit Os. Fig. 9 is an exploded perspective view illustrating the configuration of the spectroscopic unit Os. As illustrated in Figs. 8 and 9, the spectroscopic unit Os according to this embodiment has a unit body 9 including an adaptor 91 and a bracket 92, and an objective lens 54 attached to the unit body 9.

The adapter 91 is configured so that the objective lens 54, which is separate from the adapter 91, can be attached and detached. Specifically, the adapter 91 according to this embodiment is configured to be approximately cylindrical, and a bracket 92 can be attached to its upper end, while the objective lens 54 can be attached to its lower end. When measuring film thickness, the objective lens 54 is attached to the electric revolver 74 via the adapter 91 and bracket 92. Note that instead of configuring the adapter 91 so that the objective lens 54 is attached, the adapter 91 and the objective lens 54 may be configured as one unit.

The adapter 91 is configured to be detachably attached to the electric revolver 74, which is configured to detachably attach the objective lens 54. In other words, the adapter 91 according to this embodiment is configured to be attachable to the electric revolver 74 in place of the objective lens 54 (by replacing the objective lens 54). The adapter 91 is attached to the electric revolver 74 via a bracket 92.

The bracket 92 is formed in a roughly ring shape and has a shape that corresponds to the through hole 74a provided on the underside of the electric revolver 74. By replacing the bracket 92, it becomes possible to attach the adapter 91 to a wide variety of laser confocal microscopes 1 without changing the design of the adapter 91 itself.

As illustrated in FIG. 3C, the adapter 91 has a built-in optical branching unit 91a that branches the reflected white light from the sample SP (see L6 in FIG. 3C) into light directed toward the imaging unit 58 as a camera and light directed toward the spectrometer 12. The optical branching unit 91a according to this embodiment is configured with a half mirror that transmits approximately 100% of the light on one side and reflects at least a portion of the light on the other side. The optical branching unit 91a is disposed on the optical path between the first half mirror 53 as a junction and the objective lens 54. Note that the adapter 91 according to this embodiment is configured to have a larger diameter than the objective lens 54 due to the built-in optical branching unit 91a.

The optical branching unit 91a, which is made of a half mirror, transmits (by the one side) the white light emitted from the white light source 51 and incident on the bracket 92, while reflecting (by the other side) a portion of the reflected light from the sample SP reflected through the objective lens 54 and transmitting the other portion. The reflected light reflected by the optical branching unit 91a is guided to the spectroscope 12, while the reflected light transmitted through the optical branching unit 91a reaches the imaging unit 58 as a camera. An optical cable 11 leading to the spectroscope 12 is connected to the outer surface of the adapter 91, and the white light reflected by the optical branching unit 91a is input to the spectroscope 12 via this optical cable 11.

The optical branching unit 91a may be configured with an optical element that is movable relative to the objective lens 54. In this case, the optical branching unit 91a can be inserted into or removed from the optical path connecting the objective lens 54 and the first half mirror 53 according to the operating mode of the laser confocal microscope 1 by receiving an electrical signal input from the outside and operating.

The spectroscope 12 generates a light receiving signal according to the light receiving intensity for each wavelength contained in the reflected light based on the reflected light branched by the optical branching unit 91a. This spectroscope 12 generates an optical spectrum of the reflected light, and can detect the light receiving intensity for each wavelength of the reflected light and generate a light receiving signal indicating the detection result. The light receiving signal generated by the spectroscope 12 is input to the first film thickness measurement unit 8l described below.

- Basic principles of film thickness measurement using spectroscopic interferometry -
10A is a diagram illustrating the relationship between the reflectance of each wavelength of white light and the film thickness of the sample SP. In general, when a film exists on the surface of a substrate, light is reflected from both the surface of the film and the surface of the substrate (the interface between the substrate and the film). The reflected light received by the spectroscope 12 is the sum of the light reflected from the surface of the film and the surface of the substrate, but these lights interfere with each other and strengthen or weaken each other.

This interference phenomenon changes depending on the relationship between the wavelength of light, the film thickness, and the refractive index. The reflected light is detected by the spectrometer 12, and the film thickness can be measured by generating its spectrum. Specifically, as shown in FIG. 10A, the behavior of the reflectance versus wavelength is graphed. This reflectance depends on the refractive index of the substrate and the film, so by specifying the respective materials in advance, fitting can be performed with the film thickness as an undetermined parameter.

To perform such fitting, the spectrometer 12 inputs a light receiving signal generated based on the reflected light of the white light to a first film thickness measurement unit 8l described below. The first film thickness measurement unit 8l is configured to perform the above-mentioned fitting based on the light receiving signal generated by the spectrometer 12 and measure the film thickness of the sample SP.

In addition, as shown in graphs G1, G2, and G3 in FIG. 10A, when the film thickness of sample SP is thin, the reflectance changes more slowly than when it is thick. In other words, the shape of the reflectance graph changes depending on the film thickness of sample SP, so by tracing this relationship in reverse, the film thickness of sample SP can be determined based on the reflectance.

In this way, the white light optical system 5 is an optical system that can perform film thickness measurement using spectroscopic interferometry by replacing the objective lens 54 with the spectroscopic unit Os. Film thickness measurement using spectroscopic interferometry can measure smaller film thicknesses than film thickness measurement using the laser confocal method.

(Basic principles of film thickness measurement using the laser confocal method)
FIG. 10B is a diagram illustrating the relationship between the light receiving intensity caused by the reflected light of the laser light and the film thickness of the sample SP. The film thickness of the sample SP can also be measured using a laser confocal method. For example, when a sample SP formed of a film on a substrate is irradiated with laser light and the reflected light is received through a confocal optical system, the light receiving intensity detected by the light receiving element 66a includes a peak caused by the reflected light from the surface of the film and a peak caused by the reflected light from the surface of the substrate. In this case, the film thickness can be measured by measuring the distance between the peaks. The film thickness measurement using the laser confocal method is configured to be performed by the second film thickness measurement unit 8m described later.

Also, as shown in graphs G4 and G5 in Figure 10B, when the film thickness of sample SP is thick, the distance between the peaks is longer than when the film thickness is thin. At this time, the distance between the peaks, and therefore the film thickness, can be measured with high accuracy. Therefore, film thickness measurement using the laser confocal method is more suitable for thick film thicknesses than film thickness measurement using the spectral interferometry method.

On the other hand, when the film thickness is relatively thin, the distance between the peaks becomes shorter than when the film thickness is thick, making it difficult to distinguish between the two peaks. Therefore, film thickness measurement using the laser confocal method is less suitable for thin film thicknesses than film thickness measurement using the spectral interferometry method.

(Unit drive system 7)
4 is a block diagram illustrating the configuration of the laser confocal microscope 1. The unit drive system 7 drives each part of the laser confocal microscope 1, and is configured as a system that changes the objective lens 54, adjusts the height position of the stage 23 relative to the objective lens 54, and moves the stage 23 in the horizontal direction. Each component of the unit drive system 7 is electrically connected to a unit control system 8, and operates upon receiving an electrical signal input from the unit control system 8.

Specifically, as illustrated in Figures 1, 2, 4, etc., the unit drive system 7 includes a Z-direction drive unit 71, a height position detection unit 72, an XY-direction drive unit 73, and an electric revolver 74. The Z-direction drive unit 71 is an example of the "drive unit" in this embodiment.

-Z direction drive unit 71-
The Z-direction driving unit 71 changes the height position of the stage 23 relative to the objective lens 54. Specifically, the Z-direction driving unit 71 has, for example, a stepping motor and a motion conversion mechanism that converts the rotational motion of the output shaft of the stepping motor into linear motion in the up and down direction (Z direction). The Z-direction driving unit 71 is built into the head unit 22.

By rotating the stepping motor of the Z-direction drive unit 71, the electric revolver 74 and the objective lens 54 attached to the electric revolver 74 move together in the Z direction.

For example, by moving the objective lens 54 in the Z direction while the stage 23 is fixed, the height position of the stage 23 relative to the objective lens 54 can be changed. Note that the stage 23 may be configured to move in the Z direction while the objective lens 54 is fixed.

The Z-direction drive unit 71 can adjust the relative height position of the stage 23 with respect to the objective lens 54 (hereinafter referred to as the "relative distance" or simply as the "height position") with a minimum pitch size of about 1 nm.

Height position detector 72
The height position detector 72 detects the relative distance between the objective lens 54 and the stage 23, and outputs an electrical signal corresponding to the relative distance. This electrical signal is input to the unit control system 8.

Specifically, the height position detection unit 72 can be configured with, for example, a linear scale (linear encoder) or the like. The height position detection unit 72 can detect even a change in the relative distance between the objective lens 54 and the stage 23 of about 1 nm.

In this embodiment, the above-mentioned relative distance is changed by moving the objective lens 54 in the Z direction while the stage 23 is fixed. The amount of movement at that time is detected using a linear scale, so that the relative height position of the stage 23 with respect to the objective lens 54 can be detected. Similarly, even when the stage 23 is moved in the Z direction while the objective lens 54 is fixed, the height position can be detected in the same way.

-XY direction driving unit 73-
The XY direction driving unit 73 is a mechanism for horizontally moving the stage 23. That is, the stage 23 is separate from the stage support member 24 illustrated in Fig. 1, and is supported by the stage support member 24 so as to be horizontally movable.

Specifically, the XY direction drive unit 73 can be configured with an actuator such as a linear motor. This actuator can move the position of the stage 23 relative to the stage support member 24 within a predetermined range along the X and Y directions.

- Electric revolver 74 -
11 is a side view of the electric revolver 74. The electric revolver 74 is configured as an electric variable magnification mechanism, and rotates around a predetermined central axis C. The electric revolver 74 is an example of the "revolver" in this embodiment.

The motorized revolver 74 is configured to allow multiple objective lenses 54 and a spectroscopic unit Os (adapter 91) to be attached to it so as to surround the central axis C. To allow the multiple objective lenses 54 to be attached and detached, the underside of the motorized revolver 74 is provided with multiple through holes 74a arranged to surround the central axis C. The white optical system 5 and the laser optical system 6 are configured to allow the magnification of each of the sample SP to be changed by rotating the motorized revolver 74 around the central axis C or by replacing the objective lenses 54 attached to the through holes 74a.

The objective lenses 54 that can be attached to the electric revolver 74 include an objective lens 54 with a ring illumination 54a attached, an objective lens 54 without a ring illumination 54a attached, and an objective lens 54 that is integrated with the branching optical system 55 to form an interference objective lens Oc.

The above-mentioned spectroscopic unit Os (adapter 91) can also be attached to the motorized revolver 74. Therefore, by performing the relatively simple task of removing the objective lens 54 or interference objective lens Oc attached to the motorized revolver 74 and replacing it with the spectroscopic unit Os, it is possible to switch the optical system for performing measurements using the laser confocal method or white light interferometry (the optical system exemplified in Figures 3A and 3B) to an optical system for performing film thickness measurements using spectroscopic interferometry, as exemplified in Figure 3C.

Similarly, by simply removing the spectroscopic unit Os attached to the motorized revolver 74 and replacing it with the objective lens 54 or the interference objective lens Oc, the optical system for performing film thickness measurement using the spectroscopic interferometry can be switched to an optical system for performing measurement using the laser confocal method or the white light interferometry.

Furthermore, with the spectroscopic unit Os attached to the electric revolver 74, the film thickness of the sample SP can be measured while changing the magnification by simply removing the objective lens 54 attached to the adapter 91 and replacing it with another objective lens 54 with a different magnification.

By rotating the electric revolver 74, one of the objective lenses 54 can be selected and placed opposite the sample SP placed on the stage 23. Information indicating which of the objective lenses 54 is selected is stored in the storage device 82 of the unit control system 8.

By controlling the motorized revolver 74, it is possible to change the magnification of the white light optical system 5 and the laser optical system 6, and to position the interference objective lens Oc required for white light interferometry facing the sample SP. In addition to or instead of the motorized revolver 74, a single-lens objective lens (not shown) consisting of a motorized zoom lens may be used.

The electric revolver 74 can be operated via a screen displayed on the display unit 41 (see Figures 16 to 18 described below), or via a switch provided on the observation unit 2, etc.

(Unit control system 8)
5 is a block diagram illustrating the configuration of the unit control system 8. The unit control system 8 outputs control signals to each part of the white optical system 5, the laser optical system 6, and the unit drive system 7 in the observation unit 2 to control their operations, and receives detection signals from each part to measure the surface shape and film thickness of the sample SP.

The unit control system 8 is also electrically connected to the observation unit 2 as well as the operation terminal 4, and displays the surface shape measurement results on the display unit 41, while also generating control signals to be input to each part of the observation unit 2 based on operational input to the keyboard 42, mouse 43, etc.

In the example shown in FIG. 4, the unit control system 8 is provided in the observation unit 2, but is not limited to this configuration. The unit control system 8 may be provided in the external unit 3 or in the operation terminal 4.

Specifically, the unit control system 8 according to this embodiment has a processing device 81 consisting of a CPU, a system LSI, a DSP, etc., a storage device 82 consisting of a volatile memory, a non-volatile memory, etc., and an input/output bus 83. In addition, the unit control system 8 may be realized by a logic circuit, or may be realized by executing software.

More specifically, as illustrated in FIG. 4, the unit control system 8 is electrically connected to at least the white light source 51, the ring illumination 54a, the image sensor 58a, the laser light source 61, the laser light scanning unit 63, the light receiving element 66a, the Z direction drive unit 71, the height position detection unit 72, the XY direction drive unit 73, and the electric revolver 74. The unit control system 8 controls the white light source 51, the ring illumination 54a, the laser light source 61, the laser light scanning unit 63, the Z direction drive unit 71, the XY direction drive unit 73, and the electric revolver 74. In addition, the output signals of the image sensor 58a, the light receiving element 66a, the height position detection unit 72, and the spectrometer 12 are input to the unit control system 8.

Specifically, as illustrated in FIG. 5, the unit control system 8 according to this embodiment has as its main components a scan control unit 8a, a drive control unit 8b, a display control unit 8c, a mode switching unit 8d, a focus calculation unit 8e, a focus adjustment unit 8f, a brightness adjustment unit 8g, a tilt adjustment unit 8h, a measurement range setting unit 8i, a first surface shape measurement unit 8j, a second surface shape measurement unit 8k, a first film thickness measurement unit 8l, and a second film thickness measurement unit 8m. The first surface shape measurement unit 8i, the second surface shape measurement unit 8k, the first film thickness measurement unit 8l, and the second film thickness measurement unit 8m constitute the measurement unit 80 according to this embodiment. This measurement unit 80 can perform various measurements, such as measurement of the surface shape of the sample SP based on the laser confocal method.

-Scanning control unit 8a-
As described above, the scanning control unit 8a is electrically connected to the laser light scanning unit 63 and controls its operation. The laser light scanning unit 63 can two-dimensionally or one-dimensionally scan within a scanning range defined on the surface of the sample SP according to a control signal input from the scanning control unit 8a. The setting of the scanning range can be appropriately changed depending on the function performed by the laser confocal microscope 1.

- Drive control unit 8b -
The drive control unit 8b controls each part of the unit drive system 7. Specifically, the drive control unit 8b can change the height position of the stage 23 by controlling the Z-direction drive unit 71, can change the horizontal position of the stage 23 by controlling the XY-direction drive unit 73, and can switch the objective lens 54 by controlling the electric revolver 74.

-Display control unit 8c-
The display control unit 8c is electrically connected to the display unit 41 of the operation terminal 4, and controls the display mode on the display unit 41. Specifically, the display control unit 8c according to this embodiment can display the measurement results by the first surface shape measuring unit 8j, the second surface shape measuring unit 8k, etc., can display the camera image generated by the imaging unit 58, and can display various other interfaces.

--Mode switching section 8d--
As described above, the main functions of the laser confocal microscope 1 include observing a sample SP using laser light or white light as a light source, and measuring the sample SP using the laser confocal method or the white light interferometry.

The mode switching unit 8d can use these functions selectively based on the user's operational input via the keyboard 42 and the mouse 43. Specifically, the mode switching unit 8d according to this embodiment can select and execute one mode from a group of modes including, for example, a first mode for measuring the surface shape of the sample SP, a second mode for measuring the film thickness of the sample SP, and a third mode for observing the sample SP, based on the user's operational input. As described later, the user's operational input is performed via an interface displayed on the display unit 41. Of the three operating modes, the third mode is not essential. The laser confocal microscope 1 only needs to be configured to be able to execute at least the first and second modes.

As described above, the thickness measurement of the sample SP can be performed using either the spectroscopic interferometry or the laser confocal method. Therefore, when the third mode is selected, the mode switching unit 8d according to this embodiment can execute either the first submode in which the first thickness measurement unit 8l measures the thickness based on the spectroscopic interferometry, or the second submode in which the second thickness measurement unit 8m measures the thickness based on the laser confocal method, based on the user's operational input.

--Focus calculation unit 8e--
The focusing calculation unit 8e uses the laser confocal method with the laser optical system 6 to make the focus of the objective lens 54 coincide with the surface of the sample SP (in other words, executes "autofocus" using the laser confocal method). The focus adjusted by the laser confocal method is used for both the measurement of the surface shape using the laser confocal method and the measurement of the surface shape using the white light interference method.

That is, as shown in FIG. 8, the laser confocal microscope 1 according to this embodiment is configured to adjust the focus using the laser confocal method, even when the surface shape of the sample SP is measured using the white light interferometry.

When adjusting the focus, the objective lens 54 may be an interference objective lens Oc (first objective lens) for white light interference, or a non-white light interference objective lens 54 different from the interference objective lens Oc may be used.

Specifically, the focusing calculation unit 8e according to this embodiment calculates the focusing position where the focus of the objective lens 54 coincides with the surface of the sample SP based on the light receiving signal generated by the light receiving unit 66 of the laser optical system 6 at each height position of the stage 23 or the objective lens 54. The focusing calculation unit 8e is an example of the "calculation unit" in this embodiment.

Here, "each height position of the stage 23 or the objective lens 54" refers to the relative height position of the stage 23 with respect to the objective lens 54, which can be detected by the height position detection unit 72. This height position can be the distance between the tip surface (tip surface in the Z direction) of the objective lens 54 and the upper surface of the stage 23, but is not limited to this, and can be the distance in the Z direction between a specified part of the objective lens 54 and a specified part of the stage 23. As mentioned above, the height position is also called the "Z position".

In the following description, the "distance between height positions (Z pitch)" refers to the distance between height positions (the movement distance of the objective lens 54 or stage 23 in the Z direction) when generating an interference image in the white optical system 5, when performing autofocus, brightness adjustment, setting the height range (measurement range) during measurement, measuring the surface shape, etc., and when receiving laser light in the laser optical system 6.

Furthermore, in the following description, "moving the Z position upward" means moving the objective lens 54 upward relative to the stage 23 and sample SP, or moving the stage 23 and sample SP downward relative to the objective lens 54, i.e., moving the stage 23 and sample SP away from the objective lens 54 in the Z direction.

Similarly, "moving the Z position downward" means moving the objective lens 54 downward relative to the stage 23 and sample SP, or moving the stage 23 and sample SP upward relative to the objective lens 54, i.e., moving the stage 23 and sample SP closer to the objective lens 54 in the Z direction.

In detail, the focusing calculation unit 8e changes the height position via the drive control unit 8b, irradiates the laser light at each height position, and acquires a light receiving signal. As described above, when the laser light is focused on the surface of the sample SP, the amount of light received by the light receiving element 66a (amount of light received) becomes significantly larger than when it is not focused, and the intensity of the received light becomes relatively large.

Therefore, as shown in FIG. 6B, the focus calculation unit 8e monitors a curve (hereinafter referred to as the "Z-I curve") showing the change in the received light intensity with respect to the height position (Z position), and searches for the height position where the received light intensity peaks. The height position thus searched for is determined as the focus position Zp. This focus position Zp is temporarily or continuously stored in the storage device 82 and input to the focus adjustment unit 8f.

The height positions used to search for the focal position Zp are discrete. The interval between these height positions (Z pitch) is set according to the half-width of the Z-I curve. Specifically, when the half-width of the Z-I curve is assumed to be narrow, the Z pitch is set narrower than when it is assumed to be wide. Here, when the numerical aperture of the objective lens 54 is large, the half-width of the Z-I curve is narrower than when it is small. The numerical aperture of the objective lens 54 generally increases as the lens magnification increases.

Based on the above findings, the focusing calculation unit 8e according to this embodiment is configured to set the Z pitch defined as above to a narrower value as the magnification of the objective lens 54 increases. Specifically, when adjusting the height position of the stage or the objective lens 54 by operating the Z direction drive unit 71 via the drive control unit 8b, the focusing calculation unit 8e changes the height position at a narrower Z pitch and acquires a light receiving signal at each height position. In this way, the Z pitch at which the light receiving signal is acquired can be changed according to the magnification of the objective lens 54.

As a result of further investigation into the Z pitch, the inventors of the present application have newly discovered that the size of the Z pitch can be adjusted depending on the function being performed by the laser confocal microscope 1.

Specifically, in this embodiment, the distance (Z pitch) between each height position of the stage 23 is set to be wider when the focusing calculation unit 8e calculates the focusing position Zp than when the second surface shape measurement unit 8k measures the surface shape of the sample SP using the laser confocal method.

In other words, when the focusing calculation unit 8e searches for the focusing position Zp, the measurement accuracy of the received light intensity is not required as much as when the second surface shape measurement unit 8k measures the surface shape. Therefore, as illustrated in FIG. 6D, when the focusing position Zp is searched for (when the focusing calculation unit 8e searches for the focusing position Zp), the Z pitch can be set coarser than when the surface shape is measured (when the measurement unit 80 measures the surface shape of the sample SP). Hereinafter, the Z pitch used when searching for the focusing position Zp may be referred to as the "first pitch".

For example, in FIG. 6D, the solid black plots indicate the height positions used when searching for the focal position Zp (during autofocus), and the cross plots indicate the height positions used when measuring the surface shape. As shown in FIG. 6D, the first pitch according to this embodiment can be set coarser (wider) than the Z pitch used when measuring the surface shape, which will be described later.

The search for the focal position Zp can be performed by fitting the received light intensity measured at each height position to a parabola, Gaussian function, etc. Details of the fitting are omitted.

As described above, when searching for the focal position Zp, the laser light is emitted at each height position. The scanning range of the laser light at that time can be set to a range suitable for searching for the focal position Zp.

Specifically, the scanning control unit 8a operates the laser light scanning unit 63 at each height position of the stage 23, thereby scanning the laser light when the focusing calculation unit 8e calculates the focusing position Zp. At that time, when the focusing calculation unit 8e calculates the focusing position Zp, the scanning range of the laser light can be set narrower than when the second surface shape measurement unit 8k measures the surface shape based on the laser confocal method (see FIG. 6D).

In more detail, when the focusing calculation unit 8e calculates the focusing position Zp, the scanning range of the laser light can be set to a smaller dimension in one of the first and second directions compared to when the second surface shape measurement unit 8k measures the surface shape.

More specifically, in this embodiment, when the focusing calculation unit 8e calculates the focusing position Zp, the scanning control unit 8a scans the laser light in a line shape along the X direction as the first direction. In this case, the scanning range is set so that the dimension in the Y direction as the second direction is short. Here, the laser light may be scanned over several rows arranged parallel to each other.

Alternatively, instead of implementing the above-mentioned configuration, the scanning interval of the laser light (the interval between the irradiation positions Ps of the laser light) can be set to be wider when the focusing calculation unit 8e calculates the focusing position Zp compared to when the second measurement unit 8l measures the surface shape (thinning-out scan). This allows autofocus to be performed at high speed.

-Focus adjustment unit 8f-
The focus adjustment unit 8f operates the Z-direction drive unit 71 via the drive control unit 8b to adjust the height position of the stage 23 or the objective lens 54, thereby matching the height position with the focus position Zp calculated by the focus calculation unit 8e.

By adjusting the height position using the focus adjustment unit 8f, the focus of the objective lens 54 can be adjusted onto the sample SP, achieving a state suitable for measuring the sample SP.

The adjustment of the height position by the focus adjustment unit 8f is performed not only when the surface shape is measured by the first surface shape measurement unit 8j or the second surface shape measurement unit 8k, but also when observing using a laser image or a camera image, when adjusting brightness by the brightness adjustment unit 8g described below, when adjusting tilt by the tilt adjustment unit 8h, and when setting the height range by the measurement range setting unit 8i. This allows various processes to be started from a focused state, which can be performed at high speed.

- Brightness adjustment section 8g -
Since the processing by the focusing calculation unit 8e and the focus adjustment unit 8f is processing using laser light, the settings of the white light, such as an appropriate exposure time, are unknown at the time when the focus adjustment unit 8f adjusts the focus. In order to smoothly combine autofocusing using the laser confocal method and shape measurement using the white light interferometry, it is necessary to set the white light after autofocusing.

The brightness adjustment unit 8g then starts adjusting the brightness of the white light emitted from the white light source 51, with the height position adjusted by the focus adjustment unit 8f. The adjustment targets here include the control parameters of the white light source 51 itself, as well as parameters that characterize the image sensor 58a for receiving the white light. For example, the brightness adjustment unit 8g can adjust at least one of the exposure time and gain of the image sensor 58a to adjust the brightness of the white light.

Specifically, the brightness adjustment unit 8g according to this embodiment sets a starting position based on the focal position Zp calculated by the focusing calculation unit 8e, and changes the height position of the stage 23 or the objective lens 54 upward or downward from the starting position at a predetermined Z pitch (second pitch). The brightness adjustment unit 8g irradiates white light from the white light source 51 at each height position changed at the second pitch. The magnitude of the second pitch at this time is determined based on the wavelength of the white light, independent of the numerical aperture of the objective lens 54, etc.

For example, in FIG. 6C, the plots filled in black indicate the height positions used when the brightness adjustment unit 8g adjusts the brightness of the white light (during brightness adjustment). As shown in FIG. 6C, the height positions used during brightness adjustment can be set within a predetermined range that includes the focal position Zp.

Note that, although the brightness adjustment unit 8g according to this embodiment is configured to set the focal position Zp as the starting position, this configuration is not limited to this. For example, the height position displaced upward or downward from the focal position Zp along the Z direction may be set as the starting position, and the height position may be changed by moving the stage 23 or the objective lens 54 downward or upward from the starting position at a second pitch.

The brightness adjustment unit 8g adjusts the brightness of the white light based on multiple interference images generated at different height positions. Specifically, the brightness adjustment unit 8g selects an interference image that includes relatively bright pixels (particularly, the brightest pixels in this embodiment) from among the interference images generated via the imaging unit 58. The selection of the interference image can be performed, for example, by comparing the received light intensity used to generate each interference image for each pixel.

The brightness adjustment unit 8g adjusts the brightness of the white light source 51 within a range in which each pixel in the selected interference image (the brightest interference image) is not saturated. In detail, the brightness adjustment unit 8g adjusts the exposure time and gain of the image sensor 58a so that the interference image is as bright as possible within a range in which each pixel in the selected interference image is below a predetermined upper limit value, and determines optimal parameters. The determined parameters are input to a storage device 82 or the like and stored temporarily or continuously.

-Tilt adjustment section 8h-
The tilt adjustment unit 8h calculates and corrects the tilt of the stage 23. Although details are omitted, any method can be used to correct the tilt, such as automatic adjustment using an electric stage.

Tilt correction can preferably be performed during observation or measurement using white light.

--Measurement range setting unit 8i--
FIG. 7 is a schematic diagram showing the relationship between the focal position Zp, the procedure for setting a height range using a starting position set based on the focal position Zp, and the fourth pitch obtained by dividing the height range thus set.

The surface shape can be measured by changing the height position of the stage 23 or the objective lens 54 around the focal position Zp. The range of height positions used in this case (hereinafter referred to as the "height range") can be set using either white light interferometry or laser confocal.

The laser confocal microscope 1 according to this embodiment includes a measurement range setting unit 8i that sets a height range using white light interference. In addition to the measurement range setting unit 8i, or instead of the measurement range setting unit 8i, a second measurement range setting unit that can set a height range using the laser confocal method may be provided.

Here, as shown in FIG. 7, the height range set by the measurement range setting unit 8i is set to include at least the focal position Zp. In other words, the height range is set as a range defined by an upper limit position set to be equal to or higher than the focal position Zp, and a lower limit position set to be equal to or lower than the focal position Zp.

In this embodiment, the measurement range setting unit 8i sets the upper limit position after setting the lower limit position, but is not limited to this setting. The lower limit position may be set after the upper limit position is set.

Furthermore, the measurement range setting unit 8i according to this embodiment divides the distance between the upper limit position and the lower limit position at equal intervals when the upper limit position and the lower limit position are set, thereby setting each height position of the stage 23 when the first surface shape measuring unit 8j or the second surface shape measuring unit 8k measures the surface shape of the sample SP.

Specifically, after the focal position Zp is calculated by the focusing calculation unit 8e, the measurement range setting unit 8i starts setting the height range based on the interference image captured by the imaging unit 58 in a state in which the relative height position of the stage 23 is adjusted by the focus adjustment unit 8f (in a state in which the height position is adjusted to the focal position Zp).

The measurement range setting unit 8i generates an interference image via the imaging unit 58 while changing the height position of the stage 23 or the objective lens 54, calculates the peak position of the interference fringes from the interference image generated at each height position, and determines whether the number of pixels that successfully calculate the peak position exceeds a predetermined first threshold value within the screen. Then, the first measurement range setting unit 8i sets a height range as a range that exceeds the first threshold value (particularly, a range along the Z direction).

In other words, even if interference fringes are found in the interference image, if the peak position of the interference fringes occupies only a small part of the screen, it is considered inconvenient to perform measurements using white light interferometry. Therefore, by setting the height range based on the number of pixels that successfully calculate the peak position of the interference fringes, it becomes possible to set the height range more appropriately.

When setting the height range, the number of pixels constituting the interference image may be reduced compared to when measuring the surface shape. This allows the height range to be set quickly. In addition, the first threshold value, which serves as an index for judgment, is basically stored in the storage device 82, but can be changed as appropriate based on external operational input, etc.

Also, as shown in FIG. 7, when the measurement range setting unit 8i changes the height position of the stage 23 or the objective lens 54 to set the height range, it sets a starting position based on the focusing position Zp calculated by the focusing calculation unit 8e, and moves the stage 23 or the objective lens 54 upward or downward from the starting position at a predetermined Z pitch (third pitch).

As shown in the center diagram of FIG. 7, the measurement range setting unit 8i according to this embodiment is configured to set the focal position Zp as the start position. However, the present disclosure is not limited to such a configuration. For example, the height position displaced upward or downward from the focal position Zp along the Z direction may be set as the start position (in this case, the start position ≠ the focal position Zp), and the height position may be changed by moving the stage 23 or the objective lens 54 downward or upward from the start position at a third pitch.

In addition, when the measurement range setting unit 8i sets the height range, the interval between each height position of the stage 23 can be set to be wider than when the first surface shape measuring unit 8j measures the surface shape of the sample SP. That is, as shown in FIG. 7, when the height range is set (when the measurement range setting unit 8i sets the height range), the Z pitch (third pitch) is allowed to be set coarser than when the surface shape is measured (when the measuring unit 80 measures the surface shape of the sample SP). The third pitch, which is the Z pitch used when setting the height range, can be set coarsely, like the first pitch.

For example, in FIG. 6E, the open circle plots indicate the height positions used when setting the height range, and the cross plots indicate the height positions used when measuring the surface shape as described above. As shown in FIG. 6E, the third pitch according to this embodiment can be set coarser (wider) than the Z pitch (fourth pitch) used when measuring the surface shape, similar to the first pitch described above.

The height range set by the measurement range setting unit 8i and each height position obtained by dividing the height range are input to the first surface shape measuring unit 8j or the second surface shape measuring unit 8k.

-Measuring unit 80-
As shown in FIG. 5, the measurement unit 80 has a first surface shape measurement unit 8j, a second surface shape measurement unit 8k, a first film thickness measurement unit 8l, and a second film thickness measurement unit 8m.

The measurement unit 80 is configured to measure the surface shape of the sample SP based on the light receiving signal generated by the light receiving unit 66 by using the first surface shape measurement unit 8j or the second surface shape measurement unit 8k, and to measure the film thickness of the sample SP based on the light receiving signal generated by the spectrometer 12 by using the first film thickness measurement unit 8l or the second film thickness measurement unit 8m.

As described below, the first surface shape measuring unit 8j measures the surface shape using white light interferometry, and the second surface shape measuring unit 8k measures the surface shape using laser confocal imaging. The first film thickness measuring unit 8l measures the film thickness using spectroscopic interferometry, and the second film thickness measuring unit 8m measures the film thickness using laser confocal imaging. In this way, the measuring unit 80 according to this embodiment can measure two types of measurement objects using two different measurement principles.

As described above, the magnification of the sample SP can be changed by replacing the objective lens 54 to be attached to the adapter 91 of the spectroscopic unit Os. Therefore, the measurement unit 80 can measure the film thickness of the sample SP at each magnification of the sample SP. In other words, the measurement unit 80 is configured to be able to measure the film thickness while changing the magnification.

-First surface shape measuring section 8j-
6A is a diagram illustrating the relationship between the relative position of the sample SP in the Z direction and the intensity of received light caused by the interference light of white light in one pixel. Specifically, the first surface shape measuring unit 8j measures the surface shape of the sample SP by using the white light interferometry. The surface shape of the sample SP is measured based on a plurality of interference images captured by the imaging unit 58 at the position.

The surface shape of the sample SP can also be called the three-dimensional shape or texture of the sample SP. This also applies to the surface shape measured by the second surface shape measuring unit 8k.

More specifically, the first surface shape measuring unit 8j uses the principle of white light interference to obtain an interference image (first image data) that can grasp the surface shape of the sample SP. This first image data is obtained for each imaging range by the imaging unit 58. This imaging range is determined according to the magnification ratio of the objective lens 54, etc.

First, white light is irradiated within the imaging range while the height positions of the stage 23 and thus the sample SP are fixed. This white light is branched by the branching optical system 55 provided in the interference objective lens Oc into reference light reflected by the reference mirror 55b and measurement light reflected by the sample SP. Of these, the reflected measurement light is irradiated to the imaging unit 58 together with the reference light and is received by the imaging element 58a. The measurement light and reference light received by the imaging element 58a overlap each other to generate an interference image. At this time, the received light intensity corresponding to the interference image is acquired, and the received light intensity is acquired for each pixel of the interference image.

Next, the height position of the interference objective lens Oc is changed by the Z-direction drive unit 71 at a predetermined fourth pitch. This changes the height position of the interference objective lens Oc from the previous time, and white light is irradiated onto the sample SP at this different height position. This generates an interference image with different height positions. The received light intensity is monitored for each pixel of this interference image. This is repeated for each height position.

At this time, the movement range of the interference objective lens Oc in the Z direction is equal to the height range set by the measurement range setting unit 8i, and the fourth pitch, which is the range of change in the height position, is equal to the height range divided at equal intervals (see FIG. 7). As explained using FIG. 6D and FIG. 6E, the fourth pitch can be set finer (narrower) than both the first pitch, which is the Z pitch used during autofocusing, and the third pitch, which is the Z pitch used when setting the height range.

The number of pixels in the interference image is determined by the number of pixels arranged on the light receiving surface of the image sensor 58a, but the two numbers do not need to be the same. From the perspective of whether digital zoom is available or not, reduction in data capacity, etc., some of the pixels constituting the image sensor 58a may be used to generate the interference image.

If an interference image captured over a wider range than the angle of view of the imaging unit 58 is desired, the drive control unit 8b controls the XY direction drive unit 73 to move the stage 23 in the X direction or Y direction. Then, white light is irradiated onto an imaging range different from the previous imaging range, and an interference image corresponding to that imaging range is captured. This process is performed at each height position, and the obtained interference images are stitched together to generate integrated first image data.

As shown in FIG. 6A, when the surface of the sample SP coincides with the focal point of the interference objective lens Oc (when it is at the focal position Zp), the measurement light reflected by the surface and the reference light reflected by the reference mirror 55b are incident on the image sensor 58a in a mutually reinforcing state. As a result, the received light intensity at the image sensor 58a is maximized.

On the other hand, when the surface of the sample SP does not coincide with the focus of the interference objective lens Oc (when it is in a non-focused position), the received light intensity at the image sensor 58a increases and decreases repeatedly, but gradually attenuates as it moves away from the focused position Zp. As a result, the light and dark pattern indicating the interference fringes disappears from the interference image. In other words, interference fringes appear in the interference image only near the focused position Zp.

In this way, when the surface of the sample SP coincides with the focus of the interference objective lens Oc, the light receiving intensity distribution of the image sensor 58a reaches a peak (see intensity Ip in FIG. 6A). The light receiving intensity distribution also converges to a value caused by the reference light as a flare component as it moves away from the focal position (see intensity Ib in FIG. 6A). Based on the interference image as the second image data, a curve (Z-I curve) showing the change in light receiving intensity in the Z direction can be obtained for each pixel.

By acquiring data indicating the peak position (position in the Z direction, Z coordinate) of the received light intensity for each pixel, it becomes possible to acquire information (height information) indicating the distance between the surface of the sample SP and the interference objective lens Oc for each pixel. Based on this height information, the surface shape of the sample SP can be measured.

Here, "when the focus is not aligned" means that there is no luminance difference between adjacent pixels (the luminance ratio approaches 1), and conversely, "when the focus is aligned" can be said to be a state in which the luminance difference (luminance ratio) between adjacent pixels is greater than when the focus is not aligned.

During actual measurements, the interference objective lens Oc is moved in the Z direction, and the contrast and phase changes of the interference fringes that appear are analyzed to obtain data showing the unevenness of the surface of the sample SP.

The first image data generated by the first surface shape measuring unit 8j is displayed on the display unit 41 by the display control unit 8c. The user can grasp the surface shape of the sample SP by visually checking the displayed first image data.

-Second surface shape measuring section 8k-
6B is a diagram illustrating an example of the relationship between the relative position of the sample SP in the Z direction and the intensity of the received light resulting from the reflected light of the laser light in one pixel. Specifically, the second surface shape measuring unit 8k is scanned by the scanning control unit 8a controlling the laser beam scanning unit 63. The surface shape of the sample SP is measured based on the received intensity of the reflected light of the laser beam.

More specifically, the second surface shape measuring unit 8k uses the principle of laser confocality to obtain a laser image (second image data) that can grasp the surface shape of the sample SP. This second image data is obtained for each unit area on the sample SP. This unit area is determined according to the magnification of the objective lens 54, etc. The second image data for each unit area is generated based on pixel data, which will be described later.

First, with the height position of the stage 23 and therefore the sample SP fixed, the laser light scanning unit 63 scans the laser light in the X direction within the unit area. When scanning in the X direction is completed, the laser light irradiation position is moved a fixed distance in the Y direction by the laser light scanning unit 63. After this movement, the laser light is scanned in the X direction. By repeating the scanning of the laser light in the X direction and the movement in the Y direction within the unit area, scanning of the unit area in the X and Y directions is completed.

At this time, the reflected light of the two-dimensionally scanned laser light is irradiated onto the light receiving unit 66 via a confocal optical system (laser optical system 6) consisting of a pinhole 65a etc., and is received by the light receiving element 66a.

Next, the height position of the objective lens 54 is changed by the Z-direction drive unit 71. This changes the height position of the objective lens 54 from the previous time, and the unit area is scanned in the X and Y directions with the objective lens 54 at the different height position. After that, the height position of the objective lens 54 is moved by a predetermined pitch (fourth pitch) to scan the unit area in the X and Y directions. This is repeated for each unit area. As already explained, the fourth pitch can be set finer (narrower) than the Z pitch (first pitch) used during autofocus and the Z pitch (third pitch) used when setting the height range (see Figures 6D to 6E).

The number of pixels in the X direction of the second image data is determined by the scanning speed of the laser light by the laser light scanning unit 63 in the X direction and the sampling period. The number of samples in one X direction scan (one scan line) is the number of pixels in the X direction. The number of pixels in the Y direction is determined by the amount of displacement of the laser light by the laser light scanning unit 63 in the Y direction at the end of each X direction scan. The number of scan lines in the Y direction is the number of pixels in the Y direction.

When scanning of the unit area in the X and Y directions is completed, the drive control unit 8b controls the XY direction drive unit 73 to move the stage 23 in the X or Y direction. Then, scanning in the X and Y directions is performed in a similar manner in another unit area different from the previous time. This is repeated to scan multiple unit areas in the X and Y directions. The obtained second image data for each unit area can be linked to create integrated second image data.

As described with reference to FIG. 6B, when the surface of the sample SP coincides with the focal point of the objective lens 54 (when it is at the focal position Zp), the reflected light reflected by the surface is incident on the light receiving element 66a in a state where it is converged near the pinhole 65a. As a result, the intensity of the received light at the light receiving element 66a becomes maximum.

On the other hand, when the surface of the sample SP does not coincide with the focus of the objective lens 54 (when it is in a non-focused position), the light reflected by the surface is incident on the light receiving element 66a with most of it blocked by the pinhole 65a. As a result, the intensity of the light received by the light receiving element 66a is significantly smaller than that at the focused position Zp.

In this way, when the surface of the sample SP coincides with the focus of the objective lens 54, a sharp peak appears in the light receiving intensity distribution of the light receiving element 66a (see intensity Ip in Figure 6B). Based on the first image data in each unit area, a curve (Z-I curve) showing the change in light receiving intensity in the Z direction can be obtained for each pixel.

By acquiring data indicating the peak position (position in the Z direction, Z coordinate) of the received light intensity for each pixel, it becomes possible to acquire information (height information) indicating the distance between the surface of the sample SP and the objective lens 54 for each pixel. By arranging the height information according to the arrangement of each pixel, second image data is generated that can grasp the surface shape of the sample SP.

The second image data generated by the second surface shape measuring unit 8k is displayed on the display unit 41 by the display control unit 8c. The user can grasp the surface shape of the sample SP by visually checking the displayed second image data.

-First film thickness measuring unit 8l-
The first film thickness measuring unit 8l measures the film thickness of the sample SP using spectroscopic interferometry based on the light receiving signal generated by the above-mentioned spectroscope 12.

The spectrometer 12 according to this embodiment generates a light receiving signal corresponding to the light receiving intensity for each wavelength contained in the reflected light of white light. However, the reflectance of the sample SP cannot be determined from the light receiving intensity alone. If the reflectance of the sample SP cannot be determined, it will be difficult to measure the film thickness using spectral interferometry.

Therefore, before or after receiving a light reception signal corresponding to the reflected light from the sample SP from the spectrometer 12, the first film thickness measurement unit 8l irradiates white light onto an index having a known reflectance, and receives a light reception signal corresponding to the reflected light from the spectrometer 12.

The first film thickness measurement unit 8l calculates the reflectance of the sample SP based on the received light intensity corresponding to the reflectance of the index and the received light intensity of the reflected light from the sample SP, and measures the film thickness of the sample SP based on the calculation result.

In more detail, the first film thickness measurement unit 8l uses a reference mirror whose reflectance is substantially 100% and a dark reference whose reflectance is substantially 0% as indicators with known reflectance.

More specifically, the first film thickness measuring unit 8l performs the autofocus configured as described above before irradiating the sample SP and the indicator with white light. When a reference mirror and a dark reference are used as indicators, the autofocus is performed at least three times. The film thickness measured by the first film thickness measuring unit 8l can be displayed on the display unit 41 by the display control unit 8c controlling the display unit 41.

-Second thickness measuring section 8m-
The second film thickness measuring section 8m measures the film thickness of the sample SP based on the light receiving signal generated by the light receiving section 66 using a laser confocal method.

Specifically, the second film thickness measurement unit 8m irradiates the sample SP with laser light and receives reflected light via a confocal optical system consisting of a pinhole 65a etc. The laser light is irradiated while changing the Z position at a predetermined Z pitch, and a laser image is generated at each Z position.

For example, when a sample SP consisting of a film formed on a substrate is used, as described with reference to FIG. 10B, a peak due to light reflected from the surface of the film and a peak due to light reflected from the surface of the substrate appear in each pixel of each laser image. The second film thickness measuring unit 8m calculates the distance between the peaks (relative distance in the Z direction) based on the Z position of each peak.

Meanwhile, the memory device 82 stores in advance the correspondence between the distance between the peaks and the film thickness. The second film thickness measurement unit 8m checks the correspondence stored in the memory device 82 and calculates the film thickness corresponding to the calculated distance between the peaks.

The film thickness measured by the second film thickness measuring unit 8m can be displayed on the display unit 41 by the display control unit 8c controlling the display unit 41.

<Specific example of measurement procedure>
- Basic flow -
12 is a flow chart illustrating a procedure for measuring a sample SP by the laser confocal microscope 1. First, when the laser confocal microscope 1 is started, in step S1, the operation content (operation mode) of the laser confocal microscope 1 and the operating principle to be used during the operation are selected.

As described above, the operation modes correspond to the first mode for measuring the surface shape of the sample SP, the second mode for measuring the film thickness of the sample SP, and the third mode for observing the sample SP. The user selects the operation to be performed by the laser confocal microscope 1 by performing a click operation or the like on the screen displayed on the display unit 41. The mode switching unit 8d displays a screen corresponding to the operation selected by the user on the display unit 41.

As described below, the screen displayed on the display unit 41 conveys various information to the user, such as laser images, interference images, and surface shape measurement results, while also functioning as a user interface (UI) that accepts operational input from the keyboard 42, mouse 43, etc. This UI will be described later.

The principles of use that can be selected in step S1 include at least white light interferometry and laser confocal imaging. In addition, the user may be allowed to select other principles, such as focus synthesis.

In the next step S2, the user operates the above-mentioned screen to select a parameter setting mode to be used in each operation mode. The laser confocal microscope 1 according to this embodiment can execute two parameter setting modes: an automatic setting mode (also called "easy setting") in which the unit control system 8 automatically sets parameters, and a manual setting mode (also called "basic setting") in which the user sets parameters by operating the keyboard 42 or the like. The mode switching unit 8d causes information corresponding to the setting mode selected by the user to be displayed on the display unit 41.

In the next step S3, the objective lens 54 with the lowest magnification is selected from among the multiple objective lenses 54 attached to the electric revolver 74. This switching may be performed automatically by the drive control unit 8b as soon as the setting mode is selected, or may be performed manually by the user.

In the following step S4, the sample SP is placed on the stage 23.

The order of steps S1 to S4 is not limited to the flow described above. For example, the order of steps S1 and S2 may be reversed, or step S4 may be executed earlier than step S1. The flow shown in FIG. 11 is merely an example.

In the next step S5, a measurement location on the sample SP is searched for, and the focus is roughly adjusted to the measurement location (rough focusing). This focusing may be performed manually by the user, or automatically by the focus adjustment unit 8f or the like.

In the next step S6, the objective lens 54 to be used for the measurement is selected. This selection is performed manually by the user via the UI displayed on the display unit 41.

Here, if white light interferometry is selected in step S1, an interference objective lens Oc formed by combining an objective lens 54 and a branching optical system 55 is selected as the objective lens 54. However, the present disclosure is not limited to such a configuration. As described above, even when a measurement is performed using white light interferometry, autofocus using a laser confocal method is performed prior to the measurement. Therefore, even when white light interferometry is selected, a normal objective lens 54 not equipped with a branching optical system 55 may be temporarily selected.

On the other hand, if the laser confocal method is selected in step S1, a normal objective lens 54 not equipped with a branching optical system 55 is selected as the objective lens 54 in step S6.

When the objective lens 54 is selected in step S6, the drive control unit 8b operates the electric revolver 74 to bring the tip surface of the selected objective lens 54 into opposition to the measurement location on the sample SP.

In the next step S7, the unit control system 8 determines whether or not white light interferometry has been selected as the principle of use. If it is determined that white light interferometry has been selected (step S7: YES), the control process proceeds to step S8, where the tilt adjustment unit 8h adjusts the tilt of the sample SP. On the other hand, if it is determined that the laser confocal method has been selected (step S7: NO), the control process skips step S8 and proceeds to step S9. Note that even if the laser confocal method is selected, the tilt adjustment unit 8h may perform tilt adjustment.

In the next step S8, the mode switching unit 8d determines whether the third mode (observation mode) is selected as the operation mode, and if it determines that the third mode is selected (step S8: YES), the process proceeds to step S9. In this case, a camera image illuminated by the white light source 51 is displayed on the display unit 41, and the control process ends.

On the other hand, if it is determined in step S8 that the third mode has not been selected (step S8: NO), the control process proceeds to step S10. In this step S10, the mode switching unit 8d determines whether or not the first mode (surface shape measurement mode) has been selected as the operation mode, and if it is determined that the first mode has been selected (step S10: YES), the process proceeds to step S11. In this case, various parameters are set, the surface shape of the sample SP is measured, etc., based on the selections made in steps S1 and S2.

On the other hand, if it is determined in step S10 that the first mode has not been selected (step S10: NO), the control process proceeds to step S12. In this step S12, it is assumed that the second mode (the mode for measuring film thickness) has been selected as the operating mode, and processing related to measuring the film thickness of the sample is executed.

-Examples of user interfaces-
17 to 20 are diagrams showing specific examples of UIs displayed on the display unit 41. FIG.

Specifically, FIG. 17 is a diagram illustrating an example of the display screen when various parameters are set simply. Also, FIG. 18 is a diagram illustrating an example of the display screen when measuring using white light interferometry, FIG. 19 is a diagram illustrating an example of the display screen when various parameters are set to basic settings, and FIG. 20 is a diagram illustrating an example of the display screen when measuring film thickness.

Here, the first display area R1 is an area for displaying an enlarged portion of the surface (observation surface) of the sample SP, and the second display area R2 is an area for displaying an overview of the entire surface of the sample SP.

The rectangular frame Rg displayed in the second display region R2 is a frame for indicating the area enlarged and displayed as the first display region R1. In the example shown in FIG. 17, etc., a portion of the marking pattern Pt (particularly the corners of the rectangular portion) is displayed within the first display region R1.

Here, button B2 is a UI for selecting the means of acquiring the image displayed on the screen. By clicking this button B2, a camera image captured by the imaging unit 58 can be displayed in the first and second display areas R1 and R2 (camera), or a laser image generated by scanning a laser beam over the surface of the sample SP can be displayed in the first and second display areas R1 and R2 (laser). In the illustrated example, the former "camera" is displayed.

Also, around button B2, a UI is displayed that allows the user to select whether to use the white light emitted from the white light source 51 or the light emitted from the ring illumination 54a described above when generating a camera image, and a UI is displayed for adjusting the brightness of each light source. In the illustrated example, the former, the white light source 51, is selected (shown as "coaxial" in the figure).

When the laser confocal microscope 1 is started and the second mode is selected as the operating mode, the screen shown in FIG. 17 is displayed. Here, tabs T1 to T3 are a UI for switching the operating mode of the laser confocal microscope 1.

For example, clicking tab T1 selects the third mode (operation mode for observing the sample SP), clicking tab T2 selects the first mode, and clicking tab T3 selects the second mode (operation mode for measuring the film thickness of the sample SP). In all of Figures 16 to 18, the first mode is selected.

Button B3 is a UI for selecting the setting mode for various parameters. In the illustrated example, clicking button B3 allows the user to select either the automatic setting mode (simple setting) or the manual setting mode (basic setting). Note that in FIG. 16, the automatic setting mode is selected, and in FIG. 19, the manual setting mode is selected.

Button B1 is a UI for selecting the principle to be used in the measurement. As can be seen from a comparison between FIG. 17 and FIG. 19, button B1 is displayed both when the automatic setting mode is selected and when the manual setting mode is selected. By clicking this button B1, one of the laser confocal method and the white light interferometry can be selected. If other principles, such as focus synthesis, are configured to be executable, additional buttons for selecting the other principles are displayed around button B1. In the illustrated example, white light interferometry is selected.

Button B4 is a UI for selecting an objective lens 54 to be opposed to the sample SP from among multiple objective lenses 54. In the illustrated example, five objective lenses 54 suitable for laser confocal imaging and one interference objective lens Oc suitable for white light interferometry are displayed side by side. Clicking on any one of these objective lenses 54 selects the objective lens 54. In Figures 17 to 19, the interference objective lens Oc is in the selected state.

In addition, when the automatic setting mode is selected, a button B5 for guiding the user in aligning the field of view and a button B6 for guiding the user in adjusting the tilt are displayed on the screen, and when the manual setting mode is selected, a group of buttons B8 for manually adjusting various parameters are displayed on the screen.

When the measurement start button Bs located at the bottom right of the screens in Figures 17 to 19 is pressed, measurement of the surface shape of the sample SP begins. The timing for pressing the measurement start button Bs will be described later.

On the other hand, when tab T3 is clicked as described above, the second mode (operation mode for measuring the film thickness of sample SP) is selected. In this case, the screen shown in FIG. 17 or FIG. 19 transitions to the screen shown in FIG. 20.

The configuration of the screen shown in FIG. 20 is the same as that shown in FIG. 19, except for a pair of buttons B9 that allows the user to select either film thickness measurement using the laser confocal method or film thickness measurement using the spectroscopic interferometry. For example, when one of the pair of buttons B9 labeled "Spectroscopic Film Thickness" is pressed, the device is set to a first submode configured to measure film thickness using the spectroscopic interferometry, and when the button labeled "Laser Film Thickness" is pressed, the device is set to a second submode configured to measure film thickness using the laser confocal method.

The screen shown in FIG. 20, like FIG. 17, displays a button B4 for selecting an objective lens 54 to be opposed to the sample SP from among the multiple objective lenses 54. However, the unit control system 8 (particularly the mode switching unit 8d) according to this embodiment does not allow the rotation of the motorized revolver 74 when the second mode is selected as the operating mode of the laser confocal microscope 1.

More specifically, the mode switching unit 8d according to this embodiment does not allow the rotation of the motorized revolver 74 when the first submode, which is one of the two submodes constituting the second mode and which uses spectroscopic interferometry, is selected as the operating mode of the laser confocal microscope 1. In this case, switching of the objective lens 54 is prohibited.

-Specific examples of various processes-
The process for setting various parameters and the process for measurement based on the set parameters will be described below in order. Fig. 13 is a flow chart illustrating the procedure for setting parameters using a white light interference microscope. Steps S21 to S28 shown in Fig. 13 illustrate the details of the process shown in step S11 in Fig. 12.

First, in step S21 of FIG. 13, it is determined whether the automatic setting mode is selected as the parameter setting mode. This determination is made, for example, by the mode switching unit 8d.

If it is determined that the automatic setting mode has been selected (step S21: YES), the control process proceeds from step S21 to step S22. In this case, as soon as the measurement start button Bs illustrated in FIG. 17 etc. is pressed, the unit control system 8 automatically sets various parameters and then performs measurements based on the automatically set parameters.

On the other hand, if it is determined that the automatic setting mode has not been selected (step S21: NO), the control process proceeds from step S21 to step S27. In this case, in step S27, the user operates the button group B8 illustrated in FIG. 19 to manually set various parameters. Subsequently, when the measurement start button Bs is pressed in step S28, surface shape measurement is performed using white light interferometry or laser confocal method in step S26, and the process returns.

Returning to step S22, when the measurement start button Bs is pressed in this step, the control process proceeds from step S22 to step S23. In step S23, autofocus (automatic focusing) is performed using the laser confocal method, regardless of the principle used to measure the surface shape.

Figure 14 is a diagram illustrating the specific processing performed in step S23 of Figure 13. That is, Figure 14 is a flowchart illustrating the procedure for performing autofocus by the laser confocal microscope 1.

First, in step S31 of FIG. 14, the gain of the light receiving element 66a is temporarily increased. This makes it possible to more reliably capture the reflected light corresponding to the focal position Zp when the laser light is irradiated onto the sample SP. In the case of autofocus using the laser confocal method, it is permissible to significantly increase the gain of the light receiving element 66a even when the focal position Zp is not reached.

In the following step S32, the drive control unit 8b controls the Z direction drive unit 71 to change the relative height position (Z position) of the stage 23 with respect to the objective lens 54 at a predetermined first pitch. Then, the unit control system 8 controls the laser light source 61 to irradiate the sample SP with laser light at each Z position. As described above, this first pitch is set coarser than the Z pitch (fourth pitch) used during measurement by the laser confocal method (see FIG. 6D).

In the next step S33, the scanning control unit 8a controls the laser light scanning unit 63 to linearly scan the laser light for several rows along the X direction. In other words, the entire area is scanned in the X direction, while only a few pixels are scanned in the Y direction. The reflected light of the scanned laser light travels toward the light receiving element 66a via the laser optical system 6 (confocal optical system) consisting of the pinhole 65a and the like. As described above, when the focus of the objective lens 54 coincides with the surface of the sample SP, the light reaches the light receiving element 66a, but when it does not coincide, it is blocked by the pinhole 65a.

In the next step S34, the storage device 82 stores the received light intensity for each Z position.

In the next step S35, the focusing calculation unit 8e searches for the Z position (focusing position Zp) where the light receiving intensity is maximum from among the multiple Z positions. As already explained, the search for the focusing position Zp can be performed by fitting the light receiving intensity stored in association with each Z position using a parabola, Gaussian function, etc.

In the next step S36, the focus adjustment unit 8f controls the Z-direction drive unit 71 to adjust the height position of the stage 23 or the objective lens 54 so as to achieve the focal position Zp found in step S35. This completes the focusing of the objective lens 54 (autofocus is completed).

In the case of known configurations, autofocus using the laser confocal method is assumed to be performed using a normal objective lens 54. However, as described above, the laser confocal microscope 1 according to this embodiment can also perform autofocus with the interference objective lens Oc selected instead of the normal objective lens 54. There is a deviation between the focal position Zp obtained using the normal objective lens 54 and the focal position Zp obtained using the interference objective lens Oc, which is caused by a combination of the optical characteristics (specifically, chromatic aberration) of optical components such as lenses and the wavelength of light passing through each optical component.

In other words, the deviation of the focal position Zp does not change with each measurement due to the laser characteristics, the layout of the scanning area, the unevenness of the sample SP, etc., but only depends on the optical characteristics of the lens. Therefore, the deviation of the focal position Zp can be measured in advance and stored in the storage device 82, etc. The laser confocal microscope 1 according to this embodiment is configured to correct the deviation of the focal position Zp based on the contents stored in the storage device 82 when the focal position Zp is measured using the interference objective lens Oc.

Specifically, in step S37 following step S36, the unit control system 8 determines whether or not the interference objective lens Oc was used when the focusing calculation unit 8e calculated the focusing position Zp. If it is determined that the interference objective lens Oc was used (step S37: YES), the control process proceeds to step S38. In this case, the focusing position Zp is corrected by the amount of the deviation stored in the storage device 82. On the other hand, if it is determined that the interference objective lens Oc was not used (step S37: NO), the control process skips step S38 and returns.

When the flow shown in FIG. 14 ends, the control process proceeds from step S23 to step S24 in FIG. 13. In step S24, the brightness of the white light source 51 is automatically adjusted as a preparation for shape measurement using white light interferometry. Step S24 is performed by the brightness adjustment unit 8g described above using white light interferometry. When measuring the surface shape using the laser confocal method, step S24 can be skipped. The adjustment by the brightness adjustment unit 8g may be performed by adjusting the control parameters of the white light source 51 itself, or by adjusting the exposure time of the imaging unit 58 as a camera.

In the next step S25, the height range to be used when measuring the surface shape is set using white light interferometry. Step S25 is executed by the measurement range setting unit i described above using white light interferometry or laser confocal method.

Once the height range is set, the control process proceeds from step S25 to step S26. FIG. 15 is a diagram illustrating the specific processing performed in step S26 of FIG. 13. That is, FIG. 15 is a flow chart illustrating the procedure for measuring the surface shape using the laser confocal microscope 1.

First, in step S41 of FIG. 15, the drive control unit 8b controls the Z-direction drive unit 71 to move the relative height position (Z position) of the stage 23 with respect to the objective lens 54 within the height range set by the measurement range setting unit 8i.

In the next step S42, the unit control system 8 determines whether or not white light interferometry has been selected as the principle of use for measuring the surface shape. If it is determined that white light interferometry has been selected (step S42: YES), the control process proceeds from step S42 to step S43. In this case, measurement is performed using white light interferometry.

On the other hand, if it is determined in step S42 that the white light interferometry has not been selected and, for example, the laser confocal method has been selected (step S42: NO), the control process proceeds from step S42 to step S48. In this case, in the illustrated example, measurement is performed using the laser confocal method.

When proceeding from step S42 to step S43, the first surface shape measuring unit 8j operates the Z direction driving unit 71 via the driving control unit 8b to change the Z position by the aforementioned fourth pitch. Then, the first surface shape measuring unit 8j irradiates white light from the white light source 51 at each Z position moved by the fourth pitch.

In the next step S44, interference light formed by interference between the reflected measurement light and the reference light is irradiated onto the image sensor 58a, and a signal indicating the received light intensity for each pixel is input to the first surface shape measurement unit 8j.

In the following step S45, an interference image is generated for each Z position based on the signal input in step S44. In this case, as shown in FIG. 18, interference fringes S1, S2, and S3 appear in the interference image. In the following step S46, the first surface shape measuring unit 8j measures the surface shape of the sample SP based on multiple interference images with different Z positions.

On the other hand, when the process proceeds from step S42 to step S48, the second surface shape measuring unit 8k operates the Z direction driving unit 71 via the driving control unit 8b to change the Z position by the fourth pitch. Then, the second surface shape measuring unit 8k irradiates the laser light from the laser light source 61 at each Z position to which the second surface shape measuring unit 8k has been moved by the fourth pitch.

In the next step S49, the laser light is two-dimensionally scanned for each unit area as described above, and the reflected light of the laser light is received through the pinhole 65a that constitutes the confocal optical system. As a result, the reflected light of the laser light is irradiated onto the light receiving element 66a, and a signal indicating the received light intensity for each pixel is input to the second surface shape measuring unit 8k.

In the next step S50, a laser image is generated for each Z position based on the signal input in step S49. In the following step S51, the second surface shape measuring unit 8k measures the surface shape of the sample SP based on multiple laser images with different Z positions.

Finally, in step S47, which follows step S46 or step S51, the display control unit 8c controls the display unit 41 to display the surface shape measurement results obtained by the first surface shape measuring unit 8j or the second surface shape measuring unit 8k on the display unit 41.

-Specific examples of film thickness measurement-
Returning to the explanation of step S12 in Fig. 12, the process performed in this step will be described in detail below. Fig. 16 is a diagram illustrating a specific process performed in step S12 in Fig. 12, and is a flow chart illustrating a procedure for measuring the film thickness of the sample SP by the laser confocal microscope 1.

First, in step S61 of FIG. 16, the unit control system 8 determines whether or not spectroscopic interferometry has been selected as the principle of use for measuring the film thickness of the sample SP. If it is determined that spectroscopic interferometry has been selected (step S61: YES), the control process proceeds from step S61 to step S62. In this case, film thickness measurement using spectroscopic interferometry is performed.

On the other hand, if it is determined in step S61 that the spectroscopic interferometry has not been selected and, for example, the laser confocal method has been selected (step S61: NO), the control process proceeds from step S61 to step S72. In this case, in the illustrated example, film thickness measurement is performed using the laser confocal method.

When the process proceeds from step S61 to step S62, as illustrated in FIG. 1B, the spectroscopic unit Os is attached to the electric revolver 74. This attachment is performed, for example, by the user.

In the next step S63, the sample SP placed on the stage 23 is replaced with the aforementioned reference mirror (an index with a reflectance of substantially 100%), and autofocus is performed to focus on the surface of the reference mirror. The details of autofocus have already been described.

In the next step S64, white light is irradiated onto the reference mirror, and the amount of reflected light (received light intensity of the reflected light) is measured by the spectroscope 12. The spectroscope 12 measures the received light intensity for each wavelength.

In the next step S65, the reference mirror placed on the stage 23 is replaced with the aforementioned dark reference (an index with a reflectance of substantially 0%), and autofocus is performed to focus on the surface of the dark reference.

In the next step S66, white light is irradiated onto the dark reference, and the amount of reflected light (received light intensity of the reflected light) is measured by the spectroscope 12. The spectroscope 12 measures the received light intensity for each wavelength.

In the next step S67, the dark reference placed on the stage 23 is replaced with the sample SP, and autofocus is performed to focus on the surface of the sample SP.

In the next step S68, white light is irradiated onto the sample SP, and the amount of reflected light (received light intensity of the reflected light) is measured by the spectroscope 12. The spectroscope 12 measures the received light intensity for each wavelength.

In the following step S69, the first film thickness measurement unit 8l calculates the reflectance of the sample SP based on the amount of reflected light measured in step S64, the amount of reflected light measured in step S66, and the amount of reflected light measured in step S68.

In the next step S70, the first film thickness measurement unit 8l calculates the film thickness of the sample SP based on the reflectance of the sample SP calculated in step S68 and the change in reflectance with respect to wavelength. Prior to this calculation, the film material, refractive index, etc. are input in advance, and the first film thickness measurement unit 8l calculates the film thickness based on the information input in advance.

On the other hand, if the process proceeds from step S61 to step S72, the second film thickness measurement unit 8m performs autofocus via the focus adjustment unit 8f, etc., to focus on the sample SP.

In the next step S73, the second film thickness measurement unit 8m changes the aforementioned Z position at a predetermined pitch by the drive control unit 8b controlling the Z direction drive unit 71, and irradiates the laser light onto the sample SP at each Z position.

In the next step S74, the reflected light of the laser light irradiated in step S72 is received through a pinhole 65a such as a pinhole 65b. As a result, the reflected light of the laser light is irradiated onto the light receiving element 66a, and a signal indicating the intensity of the received light corresponding to the reflected light is input to the second film thickness measurement unit 8m.

In the next step S75, the received light intensity is stored for each Z position based on the signal input in step S74. In the following step S76, the second film thickness measurement unit 8m searches for two peak positions where the received light intensity is at its maximum value.

In the following step S77, the second film thickness measurement unit 8m calculates the difference (peak-to-peak distance) between the two peak positions found in step S76, and calculates the film thickness of the sample SP based on the peak-to-peak distance and the correspondence stored in the memory device 82.

Finally, in step S71, which follows step S70 or step S77, the display control unit 8c controls the display unit 41 to display the film thickness measurement results obtained by the first film thickness measurement unit 8l or the second film thickness measurement unit 8m on the display unit 41.

<Thickness measurement using laser confocal microscope 1>
As described above, the laser confocal microscope 1 according to this embodiment can measure film thickness based on the principle of spectral interference (spectral interferometry) by splitting the reflected light of white light as illustrated in Fig. 3C. By reusing the white light for the image capturing unit 58 functioning as a camera and the image capturing unit 58, it is possible to perform film thickness measurement on a general sample SP that can be placed on the stage 23 while minimizing the number of parts required to realize the spectral interferometry, particularly the introduction of dedicated parts for film thickness measurement by the spectral interferometry.

In addition, in the case of dedicated machines such as conventional film thickness measurement devices, it was possible to measure film thickness even if the objective lens was slightly out of focus. Furthermore, in the case of such dedicated machines, a low-magnification objective lens with a deep depth of field was used, so the field of view was wide and it was relatively easy for the user to adjust the observation position.

However, in the case of a general-purpose machine such as the laser confocal microscope 1 according to this embodiment, it is expected that the film thickness will be measured at a magnification ratio set to a higher value than that of the dedicated machine described above. Therefore, the depth of field will be shallower than that of the dedicated machine described above. Furthermore, the field of view will also be narrow, making it difficult for the user to grasp the observation position.

In contrast, the laser confocal microscope 1 according to this embodiment is configured to be able to perform measurements at high magnification, but as explained with reference to FIG. 14, the focusing calculation unit 8e and the focus adjustment unit 8f are configured to automatically perform focusing. Therefore, good measurements can be achieved even when measuring film thickness at high magnification.

Also, as shown in FIG. 3C, the optical branching section 91a according to this embodiment is disposed closer to the objective lens 54 than the first half mirror 53, which serves as a merging section. In this way, by disposing the optical branching section 91a near the objective lens 54, a configuration in which the optical branching section 91a can be easily detached can be easily realized. As a result, it becomes possible to easily distinguish between film thickness measurement and measurement by the laser confocal method.

As described with reference to Figures 1B, 3C, 11, etc., the objective lens 54 suitable for the laser confocal method can be removed from the motorized revolver 74 as a detachable mechanism, and then an adapter 91 with a built-in optical branching unit 91a can be attached to the detachable mechanism. This allows the adapter 91 to be attached and detached together with the optical branching unit 91a with the same feel as the objective lens 54. This means that it is possible to easily switch between two different measurement principles, the laser confocal method and the spectral interferometry, which contributes to improving usability.

As shown in FIG. 3C and other figures, among the multiple objective lenses 54, the objective lens 54 used in particular for film thickness measurement using spectral interferometry can be attached to the motorized revolver 74 via an adapter 91. This is effective in improving the usability of the adapter 91.

In addition, in general, the adapter 91 may have a larger diameter than the objective lens 54 because it contains the optical branching section 91a. In that case, there is a risk that the adapter 91 may collide with the stage 23 when the adapter 91 is rotated via the electric revolver 74.

On the other hand, when the second mode described above is selected, that is, when the spectroscopic unit Os is placed facing the sample SP, the motorized revolver 74 and, by extension, the adapter 91 are not allowed to rotate in that position. By configuring it in this way, it is possible to prevent a collision between the adapter 91 and the stage 23.

In addition, as illustrated in FIG. 13, the laser confocal microscope 1 according to this embodiment uses the principle of confocal laser light (laser confocal method) rather than white light interference method when searching for the focal position Zp. This makes it possible to sufficiently increase the gain of the image sensor 58a without having to search for the focal position Zp from a state where the image is focused to a certain extent. This is advantageous in terms of effort and time, and ultimately makes it possible to improve usability when adjusting the focus.

In addition, as explained using Figures 10A and 10B, film thickness measurements based on the laser confocal method are more suitable for thicker objects than measurements based on spectroscopic interferometry.

As a result, the laser confocal microscope 1 according to this embodiment can selectively use measurements by the first film thickness measuring unit 8l based on the spectroscopic interferometry and measurements by the second film thickness measuring unit 8m based on the laser confocal method, as shown in FIG. 16. This makes it possible to perform appropriate measurements each time depending on the thickness of the sample SP.

Other Embodiments
In the above embodiment, the adapter 91 and the objective lens 54 are configured separately, but the present disclosure is not limited to such a configuration. The adapter 91 and the objective lens 54 may be configured integrally. Similarly, the adapter 91 and the bracket 92 may be configured integrally, or the adapter 91, the bracket 92, and the objective lens 54 may be configured integrally.

The configuration of various flowcharts such as FIG. 12 can be changed as appropriate. For example, the order of steps S1 and S2 in FIG. 12 can be swapped, or the order of steps S2 and S3 can be swapped, or the order of steps S24 and S25 in FIG. 13 can be swapped.

-- Modifications to height range settings --
In the embodiment, the measurement range setting unit 8i is configured to set the height range shown in Fig. 7 using white light interference, but the present disclosure is not limited to such a configuration. The measurement range setting unit 8i can also set the height range using a laser confocal method instead of or in addition to using white light interference.

In this case, the measurement range setting unit 8i generates a laser image via the light receiving unit 66 while changing the height position of the stage 23 or the objective lens 54. Next, the measurement range setting unit 8i generates pixel data corresponding to the light receiving signal generated by the light receiving unit 66 for multiple pixels in the laser image generated at each height position on a pixel-by-pixel basis. Then, the measurement range setting unit 8i sets a height range as a range in which all values of the multiple pixel data are below a predetermined second threshold value.

Here, the pixel data is a digital signal obtained by A/D converting the output signal (received light signal) of the light receiving unit 66. Therefore, the value of the pixel data is larger as the gain of the light receiving element 66a is larger, and is smaller as the gain of the light receiving element 66a is smaller. In addition, the pixel data is output from an A/D converter (not shown).

The second threshold value can be, for example, the upper limit of the output range of the A/D converter (hereinafter also referred to as the "output upper limit value"). If the peak value of the pixel data is smaller than the output upper limit value, the pixel data does not saturate at the output upper limit value. Therefore, by making a judgment based on the output upper limit value as the second threshold value, the peak value of the pixel data can be easily detected.

In this case, when the measurement range setting unit 8i sets the height range, the interval between each height position of the stage 23 is set to be wider than when the first surface shape measuring unit 8j measures the surface shape of the sample SP. That is, as illustrated in FIG. 7, when the height range is set, the Z pitch (third pitch) is allowed to be set coarser than when the surface shape is measured.

For example, in FIG. 6F, the open circle plots indicate the height positions used when setting the height range, and the cross plots indicate the height positions used when measuring the surface shape, as described above. As shown in FIG. 6F, the third pitch according to this embodiment can be set coarser (wider) than the Z pitch (fourth pitch) used when measuring the surface shape, similar to the first pitch described above.

The "third pitch" in this modified example has been given the same name as the "third pitch" in the above embodiment in order to clarify its technical significance, but this name is merely set for convenience. In other words, the "third pitch" in the white light interferometry and the "third pitch" in the laser confocal method do not need to be set to the same length and can be different from each other. The same applies to the fourth pitch.

--Modifications of the branching optical system 55--
In addition, in the above embodiment, a configuration in which the branching optical system 55 is built into the interference objective lens Oc has been exemplified, but the present disclosure is not limited to such a configuration. Instead of being disposed in the interference objective lens Oc, the branching optical system 55 may be disposed in the observation unit 2. In such a case, the branching optical system 55 can be configured as an optical element that can be inserted into and removed from the optical path connecting the optical components of the observation unit 2.

When a removable optical element is used as described above, the optical element is inserted into the optical path when a measurement using white light interferometry is performed, and is removed from the optical path when a measurement using laser confocal measurement is performed. Furthermore, this optical element can be inserted and removed as necessary, not limited to when a measurement is performed, when the white light source 51 is used simply as illumination, when various processes using laser light are performed, etc.

1 Laser confocal microscope 23 Stage 5 White light optical system 51 White light source 53 First half mirror (confluence part)
54 Objective lens 55 Branching optical system 55b Reference mirror 58 Imaging unit (camera)
6 Laser optical system (confocal optical system)
61 Laser light source 63 Laser light scanning unit 65a Pinhole 66 Light receiving unit 7 Unit drive system 71 Z direction drive unit (drive unit)
74 Electric revolver (detachable mechanism, revolver)
8 Unit control system 8d Mode switching unit 8e Focusing calculation unit (calculation unit)
8f Focus adjustment unit 80 Measurement unit 8j First surface shape measurement unit 8k Second surface shape measurement unit 8l First film thickness measurement unit 8m Second film thickness measurement unit 9 Unit body 91 Adapter 91a Optical branching unit 11 Optical cable 12 Spectrometer C Central axis Oc Interference objective lens Os Spectroscopic unit SP Sample (measurement object)
Zp Focus position

Claims (11)

A stage for placing an object to be measured;
a laser light source that irradiates a laser light via an objective lens onto a measurement object placed on the stage;
a light receiving unit that receives reflected light of the laser light from the measurement object via a confocal optical system having the objective lens and generates a light receiving signal according to a light receiving intensity of the reflected light;
a measurement unit that measures a surface shape of the measurement object based on a light receiving signal generated by the light receiving unit;
a white light source that irradiates the measurement object placed on the stage with white light via an objective lens;
a camera that receives white light reflected from the measurement object and generates a camera image of the measurement object based on the white light reflected;
a spectroscope that generates a light receiving signal according to the light receiving intensity for each wavelength;
a confluence section for coaxially guiding the white light emitted from the white light source and the laser light emitted from the laser light source;
a light branching unit that is disposed on an optical path between the junction unit and the objective lens and that branches the reflected white light from the measurement object into light directed toward the camera and light directed toward the spectroscope;
A laser confocal microscope characterized in that the measurement unit measures the surface shape of the object to be measured based on the light receiving signal generated by the light receiving unit, and also measures the film thickness of the object to be measured based on the light receiving signal generated by the spectrometer. 2. The laser confocal microscope according to claim 1,
a drive unit that changes a height position of the stage relative to the objective lens;
an attachment/detachment mechanism configured to be able to attach and detach the objective lens;
a calculation unit that calculates a focal position where a focal point of the objective lens coincides with a surface of the measurement target object based on a light receiving signal generated by the light receiving unit at each height position of the stage or the objective lens;
a focus adjustment unit that operates the drive unit to relatively adjust a height position of the stage or the objective lens, thereby making the height position coincide with a focus position calculated by the calculation unit;
the confocal optical system is configured to be able to change a magnification of the measurement object by replacing the objective lens attached to the attachment/detachment mechanism,
A laser confocal microscope, characterized in that the measurement unit measures a film thickness of the measurement object at each magnification factor of the measurement object. A stage for placing an object to be measured;
a laser light source that irradiates a laser light via an objective lens onto a measurement object placed on the stage;
a light receiving unit that receives reflected light of the laser light from the measurement object via a confocal optical system having the objective lens and generates a light receiving signal according to a light receiving intensity of the reflected light;
a measurement unit that measures a surface shape of the measurement object based on a light receiving signal generated by the light receiving unit;
a white light source that irradiates the measurement object placed on the stage with white light via an objective lens;
a camera that receives white light reflected from the measurement object and generates a camera image of the measurement object based on the white light reflected;
a spectroscope that generates a light receiving signal according to the light receiving intensity for each wavelength;
a light branching unit that branches the white light reflected from the object to be measured into light directed toward the camera and light directed toward the spectroscope;
an adapter including the optical branching unit and configured to allow the objective lens to be attached/detached;
an attachment/detachment mechanism configured to be able to attach or detach the objective lens or the adapter;
The measurement unit measures the surface shape of the measurement object based on the light receiving signal generated by the light receiving unit, and also measures the film thickness of the measurement object based on the light receiving signal generated by the spectroscope.
A laser confocal microscope. 4. The laser confocal microscope according to claim 3 ,
The confocal optical system is configured to be able to change the magnification of the measurement object by replacing the objective lens attached to the attachment/detachment mechanism.
A laser confocal microscope. 5. The laser confocal microscope according to claim 3 ,
the adapter is configured to allow the objective lens, which is separate from the adapter, to be detachably attached thereto;
The objective lens is configured to be attachable to the attachment/detachment mechanism via the adapter. 6. The laser confocal microscope according to claim 3 ,
the attachment/detachment mechanism is configured as a revolver that rotates around a predetermined central axis,
The laser confocal microscope is characterized in that the revolver is configured so that the objective lens and the adapter can be attached to the revolver so as to surround the central axis. 3. The laser confocal microscope according to claim 2,
a branching optical system that branches the white light emitted from the white light source into a reference light directed toward a predetermined reference surface and a measurement light directed toward the measurement object;
an imaging unit that receives the reference light reflected by the reference surface and the measurement light reflected by the measurement object and captures an interference image;
A laser confocal microscope characterized in that the measurement unit measures the surface shape of the object to be measured based on a plurality of interference images captured by the imaging unit at a plurality of height positions defined within a height range including the focal position. A stage for placing an object to be measured;
a laser light source that irradiates a laser light via an objective lens onto a measurement object placed on the stage;
a light receiving unit that receives reflected light of the laser light from the measurement object via a confocal optical system having the objective lens and generates a light receiving signal according to a light receiving intensity of the reflected light;
a white light source that irradiates the measurement object placed on the stage with white light via an objective lens;
a camera that receives white light reflected from the measurement object and generates a camera image of the measurement object based on the white light reflected;
a spectroscope that generates a light receiving signal according to the light receiving intensity for each wavelength;
a light branching unit that branches the white light reflected from the object to be measured into light directed toward the camera and light directed toward the spectroscope;
a measurement unit that measures a surface shape of the measurement object based on the light receiving signal generated by the light receiving unit, and also measures a film thickness of the measurement object based on the light receiving signal generated by the spectroscope;
at least,
a first mode for measuring a surface shape of the measurement object;
a second mode for measuring a film thickness of the measurement object;
and a mode switching unit that executes one of a group of modes including the above. 9. The laser confocal microscope according to claim 8,
The measurement unit measures a film thickness of the measurement object based on a light receiving signal generated by the light receiving unit,
When the second mode is selected, the mode switching unit
a first sub-mode for measuring a film thickness based on a light receiving signal generated by the spectrometer;
a second sub-mode for measuring a film thickness based on a light receiving signal generated by the light receiving unit;
A laser confocal microscope characterized by performing one of the above. 2. The laser confocal microscope according to claim 1,
an attachment/detachment mechanism configured to be able to attach and detach the objective lens;
an adapter having the optical branching unit built therein;
a mode switching unit that executes one of a group of modes including at least a first mode for measuring a surface shape of the measurement object and a second mode for measuring a film thickness of the measurement object,
The adapter is configured to be attachable to the attachment/detachment mechanism,
the attachment/detachment mechanism is configured as a revolver that rotates around a predetermined central axis,
the revolver is configured so that the objective lens and the adapter can be attached to the revolver so as to surround the central axis,
The laser confocal microscope, wherein the mode switching unit does not allow rotation of the revolver when the second mode is selected. A stage for placing an object to be measured;
a laser light source that irradiates a laser light via an objective lens onto a measurement object placed on the stage ;
a light receiving unit that receives reflected light of the laser light from the measurement object via a confocal optical system having the objective lens and generates a light receiving signal according to a light receiving intensity of the reflected light;
a measurement unit that measures a surface shape of the measurement object based on a light receiving signal generated by the light receiving unit;
a white light source that irradiates the measurement object placed on the stage with white light via an objective lens;
a camera that receives white light reflected from the measurement object and generates a camera image of the measurement object based on the white light reflected;
a beam splitter that guides the reflected light of the white light from the object to be measured to the camera and guides the reflected light of the laser light from the object to the light receiving unit;
a spectroscope that generates a light receiving signal according to the light receiving intensity for each wavelength;
a light branching unit that is disposed on an optical path between the beam splitter and the objective lens and that branches the reflected white light from the measurement object into light directed toward the camera and light directed toward the spectroscope;
The measurement unit measures the surface shape of the measurement object based on the light receiving signal generated by the light receiving unit, and also measures the film thickness of the measurement object based on the light receiving signal generated by the spectroscope.
A laser confocal microscope.

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