JP7636906B2 - MEASUREMENT APPARATUS, LITHOGRAPHIC APPARATUS, AND METHOD FOR MANUFACTURING ARTICLE - Patent application - Google Patents

Description

The present invention relates to a measurement apparatus, a lithography apparatus, and a method for manufacturing an article.

Lithography apparatuses that transfer the pattern of an original onto a substrate include, for example, exposure apparatuses and imprinting apparatuses. Exposure apparatuses project the pattern of an original onto a substrate coated with a photosensitive material via a projection optical system, thereby forming a latent image pattern corresponding to the pattern of the original in the photosensitive material on the substrate. Imprinting apparatuses form a pattern of the imprinting material corresponding to the pattern of the original on the substrate by bringing the original (mold) into contact with the imprinting material supplied onto the substrate and curing the imprinting material. In such lithography apparatuses, alignment between the original and the substrate is important. Patent Document 1 describes a method in which an imprinting apparatus brings the original (mold) and the substrate into contact with each other via the imprinting material, and aligns the original and the substrate in this state.

JP 2011-181944 A

When aligning an original and a substrate in a lithography apparatus, a measurement device is used that measures the relative positions of the original and the substrate by detecting multiple types of marks provided on the original and the substrate. However, the multiple types of marks may differ from each other, for example, in terms of the material (quality) that constitutes the mark, the shape of the mark, the thickness of the mark, etc. Also, among the multiple types of marks, there may be marks on which a film is deposited. In this case, the light reflectance of the multiple types of marks may differ from each other, resulting in differences in the amount of light detected by the measurement device for the multiple types of marks, and depending on these differences, it may be difficult to accurately measure the relative positions of the original and the substrate.

Therefore, the present invention aims to provide an advantageous technology for measuring the relative position between the original and the substrate with high accuracy.

In order to achieve the above object, a measurement device as one aspect of the present invention is a measurement device that measures a relative position between a first member and a second member, and includes an imaging unit that images a first mark provided on the first member and a second mark provided on the second member while the first mark and the second mark are within an imaging field of view, and a processing unit that determines the relative position between the first member and the second member, wherein the imaging unit images the first mark and the second mark using a plurality of types of imaging conditions in which the intensities of illumination light that illuminates the marks are different, thereby obtaining images under each imaging condition, and the processing unit obtains images under the plurality of types of imaging conditions in which the brightness of the first mark and the brightness of the second mark in the images are within an allowable range. and when there is a common imaging condition in which the brightness of the first mark in the image falls within the tolerance range, the relative position of the first member and the second member is calculated based on the position of the first mark and the position of the second mark in an image obtained under the common imaging condition, and when there is no common imaging condition among the plurality of types of imaging conditions, the relative position of the first member and the second member is calculated based on the position of the first mark in a first image obtained under a first imaging condition among the plurality of types of imaging conditions in which the brightness of the first mark in the image falls within the tolerance range and the position of the second mark in a second image obtained under a second imaging condition among the plurality of types of imaging conditions in which the brightness of the second mark in the image falls within the tolerance range.

Further objects and other aspects of the present invention will become apparent from the following description of preferred embodiments thereof with reference to the accompanying drawings.

The present invention can provide, for example, an advantageous technique for measuring the relative position between an original and a substrate with high accuracy.

1 is a schematic diagram illustrating a configuration of an imprint apparatus; FIG. 1 is a diagram showing an example of the configuration of a measurement unit. FIG. 1 is a diagram showing an example of the configuration of a measurement unit. FIG. 1 shows an example of the configuration of a light source unit. FIG. 1 is a diagram showing the relationship between the light intensity distribution on the pupil plane and the detection aperture. Diagram for explaining interference fringes FIG. 1 shows an example of a diffraction grating configuration. FIG. 2 is a diagram showing a schematic view of a mold mark and a substrate mark within an imaging field of view; A diagram showing the brightness (ideal characteristics) of each mark in an image obtained when the master-side mark, the substrate-side mark, and the interference fringes are captured under common imaging conditions. FIG. 1 shows the brightness (actual characteristics) of each mark in an image obtained when an original-side mark, a substrate-side mark, and interference fringes are captured under common imaging conditions. Flowchart showing alignment of a mold and a substrate FIG. 1 is a diagram for explaining a method for determining the position of a mark from an image obtained by an imaging unit. FIG. 13 is a diagram showing images of the original-side mark and the substrate-side mark with respect to the intensity of the illumination light. FIG. 1 is a diagram for explaining a method for manufacturing an article.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

In the following embodiment, an imprinting apparatus that uses an original (mold) to form a pattern of an imprint material on a substrate is described as an example of a lithography apparatus, but the present invention is not limited to this. For example, the present invention can also be applied to other lithography apparatuses, such as a planarization apparatus that uses an original (member) to planarize a composition on a substrate, and an exposure apparatus that exposes a substrate to light and transfers a pattern of an original (mask) onto the substrate.

<Embodiments of Imprint Apparatus>
An embodiment of an imprinting apparatus according to the present invention will be described. The imprinting apparatus is an apparatus that brings an imprinting material supplied onto a substrate into contact with a mold, and applies energy for hardening to the imprinting material to form a pattern of a cured material to which a concave-convex pattern of the mold has been transferred. For example, the imprinting apparatus supplies an imprinting material onto a substrate, and hardens the imprinting material while a mold (mold) on which a concave-convex pattern has been formed is brought into contact with the imprinting material on the substrate. Then, the distance between the mold and the substrate is widened, and the mold is peeled off (released) from the hardened imprinting material, thereby forming a pattern of the imprinting material on the substrate. This series of processes is called an "imprinting process", and is performed for each of a plurality of shot regions on the substrate.

The imprint material is a curable composition (sometimes called uncured resin) that hardens when curing energy is applied. The curing energy may be electromagnetic waves, heat, or the like. The electromagnetic waves may be, for example, infrared light, visible light, ultraviolet light, or other light with a wavelength selected from the range of 10 nm to 1 mm.

A curable composition is a composition that is cured by irradiation with light or by heating. Among these, a photocurable composition that is cured by light contains at least a polymerizable compound and a photopolymerization initiator, and may contain a non-polymerizable compound or a solvent as necessary. The non-polymerizable compound is at least one selected from the group consisting of sensitizers, hydrogen donors, internal mold release agents, surfactants, antioxidants, polymer components, etc.

The imprint material is applied in the form of a film on the substrate using a spin coater or a slit coater. Alternatively, the imprint material may be applied in the form of droplets, or in the form of islands or a film formed by connecting multiple droplets, on the substrate using a liquid ejection head. The viscosity of the imprint material (viscosity at 25°C) is, for example, 1 mPa·s or more and 100 mPa·s or less.

[Imprinting device]
FIG. 1 is a schematic diagram showing the configuration of an imprinting apparatus 1 of this embodiment. The imprinting apparatus 1 may include a mold holding unit 4 that holds a mold 7 (mold) and a stage 5 that can hold a substrate 8 and move. The imprinting apparatus 1 may also include an irradiation unit 2, a measurement unit 3 (measurement device), a supply unit 6, and a control unit 12. The imprinting apparatus 1 of this embodiment employs a photocuring method in which the imprinting material is cured by irradiating the imprinting material with light. In FIG. 1, the directions perpendicular to each other in a plane parallel to the surface of the substrate 8 are the X-axis direction and the Y-axis direction, and the direction perpendicular to the X-axis direction and the Y-axis direction is the Z-axis direction. In the following description, when the term "X-axis direction" is used, it may be defined as including the +X direction and the -X direction. The same applies to the "Y-axis direction" and the "Z-axis direction".

The mold 7 is usually made of a material that can transmit ultraviolet light, such as quartz, and a concave-convex pattern to be transferred to the imprint material on the substrate is formed in a portion of the surface on the substrate side that protrudes toward the substrate (pattern area 7a). The substrate 8 is made of glass, ceramics, metal, semiconductor, resin, etc., and a member made of a material different from the substrate may be formed on the surface as needed. Specific examples of the substrate 8 include silicon wafers, compound semiconductor wafers, and quartz glass. Before applying the imprint material, an adhesion layer may be provided as needed to improve adhesion between the imprint material and the substrate.

The mold holding unit 4 is an original plate holding unit that holds the mold 7 by vacuum suction force, electrostatic force, or the like. The mold holding unit 4 may include a mold chuck that holds the mold 7, and a mold driving mechanism that drives the mold chuck in the Z-axis direction to drive the mold 7 in the Z-axis direction. The mold driving mechanism drives the mold 7 in the Z-axis direction to change the distance between the mold 7 and the substrate 8, for example, in a contact process that brings the mold 3 into contact with the imprint material on the substrate, and/or in a release process that peels the mold 3 from the hardened imprint material. The contact process may be understood as a pressing process that presses the mold 7 against the imprint material on the substrate. The mold holding unit 4 may also include a deformation mechanism that deforms the mold 7 to reduce the difference in shape between the pattern region 7a of the mold 7 and the shot region of the substrate 8, a tilt mechanism that tilts the mold 7, a drive mechanism that drives the mold 7 in the X-axis direction and the Y-axis direction, and the like.

The stage 5 is a substrate holder that holds the substrate 8 by vacuum suction force, electrostatic force, or the like, and is configured to be movable in the X-axis and Y-axis directions. The stage 5 may include, for example, a substrate chuck that holds the substrate 8, and a substrate drive mechanism that drives the substrate chuck to drive the substrate 8 in the X-axis and Y-axis directions. The stage 5 may also include a drive mechanism that drives the substrate 8 in the Z-axis and θ-directions (rotational directions around the Z-axis), a tilt drive mechanism that tilts the substrate 8, and the like.

Here, in the imprinting apparatus 1 of this embodiment, the operation of changing the distance between the mold 7 and the substrate 8 in the contact process and/or the release process can be performed by driving the mold 3 in the Z-axis direction by the mold holding unit 4, but is not limited thereto. For example, the operation can be performed by driving the substrate 8 in the Z-axis direction by the stage 5, or by driving the mold 7 and the substrate 8 relatively in the Z-axis direction by both the mold holding unit 4 and the stage 5. Also, in the imprinting apparatus 1 of this embodiment, the alignment between the mold 7 and the substrate 8 can be performed by driving the substrate 8 in the X-axis direction and the Y-axis direction by the stage 5, but is not limited thereto. For example, the alignment can be performed by driving the mold 7 in the X-axis direction and the Y-axis direction by the mold driving unit 4, or by driving the mold 7 and the substrate 8 relatively in the X-axis direction and the Y-axis direction by both the mold holding unit 4 and the stage 5.

During the imprinting process, the irradiation unit 2 (curing unit) irradiates the imprinting material on the substrate 8 with light (e.g., ultraviolet light) through the mold 7 while the mold 7 and the imprinting material on the substrate 8 are in contact with each other, thereby curing the imprinting material. The irradiation unit 2 may have a light source that emits light (ultraviolet light) and a plurality of optical elements for uniformly irradiating the light emitted from the light source to the imprinting material on the substrate in a predetermined shape. For example, the irradiation area (irradiation range) of the light by the irradiation unit 2 may be approximately the same as the area of the pattern area 7a of the mold 7, or an area slightly larger than the area of the pattern area 7a. This is to prevent the mold 7 or the substrate 8 from expanding due to heat generated by the irradiation of light, thereby causing misalignment or distortion of the pattern of the imprinting material, by keeping the irradiation area to a minimum. In addition, this is also to prevent abnormalities in the subsequent operation of the supply unit 6 due to the ultraviolet light reflected by the substrate 8 or the like reaching the supply unit 6 and curing the imprinting material remaining in the supply unit 6. Examples of light sources that can be used include high-pressure mercury lamps, various excimer lamps, excimer lasers, and light-emitting diodes. The type, number, and wavelength of the light source can be selected appropriately depending on the characteristics of the imprint material that is the light receiving body.

The measurement unit 3 (measurement device) measures the relative position between the first member and the second member by optically detecting the first mark provided on the first member (mold 7 or mold holding unit 4) and the second mark provided on the second member (substrate 8 or stage 5). In the case of this embodiment, the measurement unit 3 includes an imaging unit 25 (image sensor) that captures the first mark and the second mark while they are within the imaging field of view, and measures the relative position between the first member and the second member based on the image obtained by the imaging unit 25. The measurement unit 3 may also capture interference fringes generated by the overlapping of a third mark provided on the first member and a fourth mark provided on the second member with the imaging unit 25, and measure the relative position between the first member and the second member based on the image obtained thereby.

In this embodiment, the mold 7 is described as the first member, the mark 10 on the mold 7 as the first mark and/or the third mark, the substrate 8 as the second member, and the mark 11 on the substrate 8 (shot area) as the second mark and/or the fourth mark. The configuration of the measurement unit 3 and the configuration/arrangement of each mark will be described in detail later. The imprint apparatus 1 may also include a drive mechanism that drives the measurement unit 3 in the X-axis direction and the Y-axis direction according to the positions of the mark 10 on the mold 7 and the mark 11 on the substrate 8 so that the mark 10 and the mark 11 fall within the imaging field of view. The drive mechanism may be configured to drive the measurement unit 3 in the Z-axis direction to adjust the focus of the measurement unit 3 to the position of the mark.

The supply unit 6 (discharge unit, dispenser) supplies the imprint material 9 (e.g., uncured resin) onto the substrate 8. In this embodiment, the imprint material 9 is a photocurable imprint material that is cured by irradiation with ultraviolet light, but the imprint material 9 can be appropriately selected depending on the type of semiconductor device. In FIG. 1, the supply unit 6 is inside the imprint device 1, but the supply unit 6 may be provided outside the imprint device 1 instead of inside the imprint device 1. When the supply unit 6 is provided outside, the substrate 8 to which the imprint material 9 has been previously supplied by the supply unit 6 is introduced into the imprint device 1. This configuration eliminates the process of supplying the imprint material onto the substrate 8 inside the imprint device 1, which can be advantageous in terms of throughput of the imprint device 1.

The control unit 12 is configured by a computer having, for example, a CPU (processor) and a memory, and controls each part of the imprinting apparatus 1 to control the imprinting process. Specifically, the control unit 12 is electrically connected to the irradiation unit 2, the measurement unit 3, the mold holding unit 4, the stage 5, and the supply unit 6, and can control the imprinting process by sending control commands to each part and acquiring information from each part. For example, the control unit 12 acquires information on the relative positions of the mold 7 and the substrate 8 measured by the measurement unit 3, and aligns the mold 7 and the substrate 8 by controlling the mold holding unit 4 and/or the stage 5 based on the information. Note that an apparatus including a drive mechanism (the mold holding unit 4 and/or the stage 5) that drives the mold 7 and the substrate 8 relatively in the X-axis direction and the Y-axis direction, the measurement unit 3, and the control unit 12 may be understood as an alignment apparatus for the mold 7 and the substrate 8.

Next, the imprint process by the imprint apparatus 1 will be described. The imprint process is performed on each of the multiple shot areas on the substrate 8 held by the stage 5, and may include, for example, a supply process, a contact process, an alignment process, a curing process, and a demolding process. In the supply process, the stage 5 is moved so that the target shot area to be imprinted is positioned below the supply unit 6, and the supply unit 6 supplies the imprint material 9 onto the target shot area. In the contact process, the stage 5 is moved so that the target shot area is positioned below the mold 7, and then the mold holding unit 4 drives the mold 7 to narrow the gap between the mold 7 and the substrate 8, thereby bringing the mold 7 into contact with the imprint material 9 on the substrate. In the alignment process, the measurement unit 3 measures the relative position between the mold 7 and the substrate 8, and aligns the mold 3 and the substrate 8 in the X-axis direction and the Y-axis direction based on the measurement result (information on the relative position). In the alignment process, the mold 7 may be deformed using the above-mentioned deformation mechanism so as to reduce the difference in shape between the pattern area 7a of the mold 7 and the shot area of the substrate 8 based on the measurement results of the measurement unit 3. In the curing process, the irradiation unit 2 irradiates the imprint material 9 on the substrate with light (ultraviolet light) to cure the imprint material 9. In the mold release process, the mold holding unit 4 drives the mold M to widen the gap between the mold 7 and the substrate 8, thereby peeling the mold 7 from the cured imprint 9. By performing such an imprint process on each of the multiple shot areas, a pattern of the cured imprint material 9 can be formed on each shot area.

[Example of measurement unit configuration]
An example of the configuration of the measurement unit 3 (measurement device) will be described. Fig. 2 is a diagram showing an example of the configuration of the measurement unit 3 of this embodiment. The measurement unit 3 can have a detection optical system 21 (detection unit), an illumination optical system 22 (illumination unit), a processing unit 26, and a light source control unit 28.

The illumination optical system 22 converts the light emitted from the light source unit 23 into parallel light using the lens 27a, and then guides the light to the same optical axis as the detection optical system 21 using the prism 24 or the like, and illuminates the marks 10 and 11 in the imaging field of view via the lens 27b. The light source unit 23 may include, for example, a halogen lamp, an LED, a semiconductor laser (LD), a high-pressure mercury lamp, a metal halide lamp, or the like, and may be configured to emit light (for example, visible light, infrared light) that does not include the wavelength of the light (ultraviolet light) that hardens the imprint material 9. The light source control unit 28 controls the light source unit 23. In this embodiment, the detection optical system 21 and the illumination optical system 22 are configured to share some of the optical members that constitute them (specifically, the prism 24 and the lens 27b). The prism 24 is also arranged on the pupil plane of the detection optical system 21 and the illumination optical system 22 or in the vicinity thereof.

The detection optical system 21 forms (images) the images of the mark 10 of the mold 7 and the mark 11 of the substrate 8 illuminated by the illumination optical system 22 on the imaging surface of the imaging unit 25 (imaging element) via the lens 27b, the prism 24, and the lens 27c. In addition, when the marks 10 and 11 each have a diffraction grating, the detection optical system 21 forms (images) an interference fringe (moiré fringe) generated by the overlapping of the diffraction gratings and the interference of the diffracted light on the imaging surface of the imaging unit 25. The light intensity of the interference fringe (moiré fringe) depends on the diffraction efficiency of the mold 7 (mark 10) and the substrate 8 (mark 11). In addition, the diffraction efficiency changes periodically according to the wavelength of the illumination light. Therefore, there are wavelengths of illumination light that can efficiently form interference fringes on the imaging surface and wavelengths that make it difficult to form interference fringes on the imaging surface. Illumination light with a wavelength that makes it difficult to form interference fringes can become noise in the image obtained by the imaging unit 25. The imaging element of the imaging unit 25 may be a CCD sensor or a CMOS sensor.

The processing unit 26 is configured with a computer having, for example, a CPU, a memory, and the like. The processing unit 26 acquires an image (image data) obtained by the imaging unit 25 by imaging the marks 10 and 11 included in the imaging field of view, and determines the relative position between the mold 7 (mark 10) and the substrate 8 (mark 11) based on the image. This allows the control unit 12 of the imprinting apparatus 1 to control the alignment between the mold 7 and the substrate 8 based on information indicating the relative positions between the mold 7 and the substrate 8 measured by the measurement unit 3 (processing unit 26). Note that the processing unit 26 may be configured as part of the control unit 12 of the imprinting apparatus 1.

Here, the prism 24 is constructed by bonding two optical members together, and has a reflective film 24a on the bonding surface for reflecting light from the peripheral portion on the pupil plane of the illumination optical system 22. This reflective film 24a can also function as an aperture stop that determines the size of the pupil of the detection optical system 21 or the detection NA. The prism 24 may be a half prism having a semi-transparent film on the bonding surface. Alternatively, instead of the prism 24, a plate-shaped optical element having a reflective film on its surface may be used. Furthermore, the reflective film 24a may be configured to reflect light from the central region on the pupil of the illumination optical system 22 and transmit light from the peripheral region, and the positions of the light source unit 23 and the imaging unit 25 may be interchanged.

The position that determines the light intensity distribution on the pupil plane of the illumination optical system 22 and the detection NA of the detection optical system 21 does not have to be the position of the prism 24. For example, as shown in FIG. 3, the detection optical system 21 and the illumination optical system 22 may each be provided with separate aperture stops 29a-29b. In this configuration, the detection NA of the detection optical system 21 is determined by the aperture shape of the aperture stop 29a, and the light intensity distribution on the pupil plane of the illumination optical system 22 is determined by the aperture shape of the aperture stop 29b. The prism 24 in this configuration may be a half prism having a semi-transparent film on the bonding surfaces of the two optical members.

Next, a configuration example of the light source unit 23 will be described. FIG. 4 is a diagram showing a configuration example of the light source unit 23. The light source unit 23 may include a plurality of light sources 30a to 30d. For each of the plurality of light sources 30a to 30d, for example, a semiconductor laser (LD) may be used, but an LED, a halogen lamp, a metal halide lamp, a high-pressure mercury lamp, a sodium lamp, or a combination of these may be used. In addition, the plurality of light sources 30a to 30d may be configured so that the wavelengths of light emitted from each light source are different from each other. For example, the first light source 30a emits light of a first wavelength, and the second light source 30b emits light of a second wavelength different from the first wavelength. It may be understood that the first light source 30a emits light of a first wavelength band, and the second light source 30b emits light of a second wavelength band different from the first wavelength band. In addition, in order to increase the light intensity at a specific wavelength (band), it may be configured so that a specific plurality of light sources emit the same wavelength (band). Additionally, the number of light sources and wavelengths (bands) is not limited to four.

The optical systems 31a to 31d are, for example, lenses, and are provided corresponding to each of the multiple light sources 30a to 30d. Each of the optical systems 31a to 31d shapes the light emitted from each of the multiple light sources 30a to 30d into a desired state (shape). The light that passes through the optical systems 31a to 31d is reflected or transmitted by the optical elements 32a to 32d and combined into one light beam. A dichroic mirror, a half mirror, or the like can be used as each of the optical elements 32a to 32d. When the wavelength bands of the light emitted from each of the light sources 30a to 30d differ from each other by, for example, about 50 nm or more between the light sources, a dichroic mirror can be used as each of the optical elements 32a to 32d that combines the light from each of the light sources 30a to 30d. On the other hand, if the wavelength bands of the light emitted from each of the light sources 30a to 30d are the same or close to each other, and the light from each of the light sources 30a to 30d cannot be efficiently combined using a dichroic mirror, a half mirror may be used as each of the optical elements 32a to 32d.

In the example shown in FIG. 4, the light from the multiple light sources 30a to 30d is combined one by one, but for example, the light from the multiple light sources 30a to 30d may be combined two by two to generate multiple combined lights, and then the multiple combined lights may be combined. The method of combining can be selected taking into consideration the type and wavelength of the light sources 30a to 30d, and the space. In addition, a light source control unit 28 that controls (drives) each light source is connected to the multiple light sources 30a to 30d. The light source control unit 28 can individually control the output energy of each light source (the intensity of light emitted from the light source) by controlling the drive current and applied voltage of the multiple light sources 30a to 30d. The light source control unit 28 may be configured as a part of the control unit 12 of the imprint apparatus 1. In addition, the light source control unit 28 may be provided individually for each of the multiple light sources 30a to 30d.

The light intensity of the light combined by the optical elements 32a to 32d is adjusted by the adjustment unit 34. The adjustment unit 34 may include, for example, an ND filter. The ND filter is an element that adjusts the intensity of the light passing through it, and the transmittance of the ND filter may be determined, for example, by the type and thickness of the metal film applied to the quartz. The adjustment unit 34 may include multiple ND filters with different transmittances, and adjust the intensity of the light by placing one ND filter selected from them in the light path. In addition, when the adjustment unit 34 includes an ND filter configured to change its transmittance depending on the part through which the light passes, the adjustment unit 34 may adjust the intensity of the light by placing a part of the ND filter corresponding to the desired light intensity in the light path. Here, the adjustment unit 34 may adjust the intensity of the light by controlling the drive current of each of the light source units 30a to 30d without using an ND filter, or may adjust the intensity of the light by combining the ND filter with the control of the drive current of each of the light sources 30a to 30d.

The light that passes through the adjustment unit 34 passes through the diffuser plate 35 and is then guided to the fiber 36. When semiconductor lasers are used as each of the light sources 30a to 30d, the wavelength band of the light emitted from each light source 30a is narrow, at only a few nm, and interference can cause noise (speckle noise) in the observed image. Such speckle noise can be reduced by rotating the diffuser plate 35 to change the waveform state over time. The light emitted from the fiber 36 becomes the light emitted from the light source unit 23.

The ND filters of the adjustment unit 34 may be provided individually for each of the multiple light sources 30a to 30d. In this case, the ND filters may be provided in each optical path before the light emitted from each light source 30a to 30d is combined with other light. As the ND filter, a filter whose transmittance changes depending on the position through which the light passes may be used. In addition, a wavelength selection unit may be provided in which a wavelength filter selected from among multiple wavelength filters that transmit light of different wavelengths with different transmittances is placed in the optical path between the light source unit 23 and the mold 7. In addition, the light combined by the optical elements 32a to 32d may be dispersed by a diffraction grating, and the light amount distribution of the dispersed light may be adjusted by an ND filter or the like whose transmitted light amount changes depending on the location, thereby adjusting the light amount of each wavelength.

5 is a diagram showing the relationship between the light intensity distribution (IL1 to IL4) on the pupil plane of the illumination optical system 22 of the measurement unit 3 and the detection aperture _NA0 on the pupil plane of the detection optical system 21. In the example shown in FIG. 5, the light intensity distribution on the pupil plane of the illumination optical system 22 includes a first pole IL1, a second pole IL2, a third pole IL3, and a fourth pole IL4, which are circular light intensity distributions. Each pole has a peak of light intensity within the pole. With this configuration, the illumination optical system 22 can illuminate the marks 10 and 11 with light that is obliquely incident from a direction perpendicular to the measurement direction (periodic direction) of the diffraction gratings in the marks 10 and 11, and light that is obliquely incident from a direction parallel to the measurement direction.

As shown in FIG. 2, a reflective film 24a that functions as an aperture stop is placed on the pupil plane of the illumination optical system 22, or as shown in FIG. 3, an aperture stop 29b is placed on the pupil plane of the illumination optical system 22, thereby making it possible to form multiple poles (IL1 to IL4) from a single light source unit 23. When forming a pupil intensity distribution having multiple poles (peaks) in this way, multiple light source units are not required, and therefore the detection unit 50 can be simplified or made smaller.

[Interference fringe detection principle]
Next, the principle of generation of interference fringes (moire fringes) formed by the mark 10 (diffraction grating) of the mold 7 and the mark 11 (diffraction grating) of the substrate 8, and a method of measuring the relative position between the mold 7 (mark 10) and the substrate 8 (mark 11) using the interference fringes will be described. FIG. 6( a) shows an example of a diffraction grating 41 in the mark 10 of the mold 7, and FIG. 6( b) shows an example of a diffraction grating 42 in the mark 11 of the substrate 8. The diffraction gratings 41 and 42 have a mutually different period (grating) period (grating pitch) of their periodic patterns (gratings). When the two diffraction gratings 41-42 are brought close to each other and overlapped, the diffracted light from the two diffraction gratings 41-42 interferes with each other, resulting in the appearance of a pattern having a period reflecting the difference in period between the two diffraction gratings 41-42, known as an interference fringe (moiré fringe). The phase of the interference fringe (position of light and dark) changes depending on the relative positions of the two diffraction gratings 41-42, so that the relative positions of the diffraction gratings 41 and 42, i.e., the relative positions of the mold 7 and the substrate 8, can be obtained by detecting the interference fringe.

Specifically, when the diffraction gratings 41 and 42, which have slightly different grating pitches, are superimposed, the diffracted light from these two diffraction gratings 41-42 overlap, generating interference fringes having a period reflecting the difference in period, as shown in FIG. 6(c). As described above, the phase of the interference fringes (position of light and dark) changes depending on the relative positions of the diffraction gratings 41 and 42. For example, when the diffraction gratings 41 and 42 are relatively shifted in the X-axis direction, the interference fringes shown in FIG. 6(c) change to the interference fringes shown in FIG. 6(d). In this way, the phase of the interference fringes changes with a period larger than the amount by which the relative positions of the diffraction gratings 41 and 42 are actually shifted. Therefore, the measurement unit 3 can detect the actual positional shift amount between the diffraction gratings 41 and 42 by magnifying it, and detect the relative positions of the mold 7 and the substrate 8 with high accuracy.

Now consider the case where the two diffraction gratings 41-42 are detected in a bright field to detect the interference fringes (the two diffraction gratings 41-42 are illuminated from the Z-axis direction, and the diffracted light diffracted in the Z-axis direction by the two diffraction gratings 41-42 is detected). In this case, the detection optical system 21 also detects the zeroth order light from each of the diffraction gratings 41-42. Since the zeroth order light reduces the contrast of the interference fringes, it is preferable that the measurement unit 3 has a configuration that does not detect the zeroth order light, that is, a dark field configuration that illuminates the diffraction gratings 41-42 with oblique incidence. In order to detect interference fringes even in a dark field configuration, one of the diffraction gratings 41-42 may be a checkerboard-shaped diffraction grating (first diffraction grating) as shown in FIG. 7(a)(c), and the other may be a diffraction grating (second diffraction grating) as shown in FIG. 7(b)(d). The first diffraction grating shown in FIG. 7(a)(c) is a diffraction grating that has a period in both a direction parallel to the measurement direction (first direction) and a direction perpendicular to the measurement direction (second direction). On the other hand, the second diffraction grating shown in FIG. 7(b)(d) is a diffraction grating that has a period in the X-axis direction of the first diffraction grating shown in FIG. 7(a)(c) only in the direction parallel to the measurement direction (first direction). Note that the first and second directions are not limited to being perpendicular, and measurement is possible as long as they are different from each other.

When the light from the first pole IL1 and the second pole IL2 shown in Fig. 5 is irradiated onto the first diffraction grating and the second diffraction grating shown in Fig. 7(a)-(b), the light is diffracted in the Y-axis direction by the first diffraction grating and also in the X-axis direction. Furthermore, the light diffracted in the X-axis direction by the second diffraction grating, which has a slightly different period, is incident on the detection area (NA ₀ ) on the pupil of the detection optical system 21 as interference fringes having relative position information in the X-axis direction, and is imaged (detected) by the imaging unit 25. This allows the processing unit 26 to determine the relative positions of the two diffraction gratings in the X-axis direction (measurement direction) from the image of the interference fringes obtained by the imaging unit 25.

Similarly, when the light from the third pole IL3 and the fourth pole IL4 shown in Fig. 5 is irradiated onto the first and second diffraction gratings shown in Fig. 7(c)-(d), it is diffracted in the X-axis direction by the first diffraction grating and also in the Y-axis direction. Furthermore, the light diffracted in the Y-axis direction by the second diffraction grating, which has a slightly different period, is incident on the detection area (NA ₀ ) on the pupil of the detection optical system 21 as interference fringes having relative position information in the Y-axis direction, and is imaged (detected) by the imaging unit 25. This allows the processing unit 26 to determine the relative positions of the two diffraction gratings in the Y-axis direction (measurement direction) from the image of the interference fringes obtained by the imaging unit 25.

In this way, in detecting the relative positions of the diffraction gratings shown in Figures 7(a)-(b), the light from the first pole IL1 and the second pole IL2 is used, and the light from the third pole IL3 and the fourth pole IL4 is not used. On the other hand, in detecting the relative positions of the diffraction gratings shown in Figures 7(c)-(d), the light from the third pole IL3 and the fourth pole IL4 is used, and the light from the first pole IL1 and the second pole IL2 is not used. The above-mentioned dark field configuration is particularly useful when the pair of diffraction gratings shown in Figures 7(a)-(b) and the pair of diffraction gratings shown in Figures 7(c)-(d) are placed within the imaging field of the imaging unit 25 to simultaneously (at one time) detect the relative positions in two axial directions.

[Image capture of mark by imaging unit]
Next, a configuration example of the mark 10 on the mold 7 and the mark 11 on the substrate 8 imaged within the imaging field by the imaging unit 25 of the measurement unit 3 will be described. Fig. 8 is a diagram showing the mark 10 on the mold 7 and the mark 11 on the substrate 8 imaged within the imaging field by the imaging unit 25 when the mold 7 and the substrate 8 are brought close to each other (for example, when the mold 7 and the imprint material on the substrate are brought into contact with each other). Fig. 8 shows the imaging field A of the imaging unit 25, and the imaging unit 25 is capable of collectively (at once) imaging each mark within the imaging field A. In the example shown in Fig. 8, the original side mark 51 (first mark), the substrate side mark 52 (second mark), and the interference fringes 53 to 54 are included within the imaging field A of the imaging unit 25.

The original-side mark 51 is a rough measurement mark provided on the mold 7 to roughly measure the relative position between the mold 7 and the substrate 8, and constitutes a part of the mark 10 of the mold 7. On the other hand, the substrate-side mark 52 is a rough measurement mark provided on the substrate 8 to roughly measure the relative position between the mold 7 and the substrate 8, and constitutes a part of the mark 11 of the substrate 8. The processing unit 26 of the measurement unit 3 determines the distance D1 (relative position) between the original-side mark 51 and the substrate-side mark 52 based on the image (image data) obtained by having the imaging unit 25 capture the original-side mark 51 and the substrate-side mark 52. For example, the processing unit 26 can determine the geometric center position of each of the original-side mark 51 and the substrate-side mark 52, and determine the difference between the center position of the original-side mark 51 and the center position of the substrate-side mark 52 as the distance D1. In addition, the original-side mark 51 and the substrate-side mark are designed to be separated from each other in the Y-axis direction by a predetermined reference distance. Therefore, the processing unit 26 can determine the difference between this reference distance and the distance D1 as the deviation in the relative position between the mold 7 and the substrate 8 (i.e., the deviation from the target relative position). In this way, the measurement unit 3 (processing unit 26) can perform a rough measurement (coarse measurement) of the relative position between the mold 7 and the substrate 8 using the original side mark 51 and the substrate side mark 52.

Each of the interference fringes 53-54 is a precision measurement mark for precisely measuring the relative position between the mold 7 and the substrate 8. Each of the interference fringes 53-54 can be formed by overlapping the master-side diffraction grating (third mark) constituting part of the mark 10 of the mold 7 and the substrate-side diffraction grating (fourth mark) constituting part of the mark 11 of the substrate 8. As described above, the master-side diffraction grating and the substrate-side diffraction grating have slightly different periods (grating pitch) in the measurement direction (Y-axis direction), so that when they are overlapped, interference fringes (moiré fringes) are formed in the Y-axis direction. The processing unit 26 of the measurement unit 3 can determine the relative positions of the master-side diffraction grating and the substrate-side diffraction grating, i.e., the relative positions of the mold 7 and the substrate 8, based on the images (image data) obtained by having the imaging unit 25 capture the interference fringes 53-54. In each of the interference fringes 53-54, when the relative position between the mold 7 (master-side diffraction grating) and the substrate 8 (substrate-side diffraction grating) changes, the fringes change by an amount greater than the amount of change. Therefore, the measurement unit 3 (processing unit 26) can measure the relative position between the mold 7 and the substrate 8 more precisely than when the master-side mark 51 and the substrate-side mark 52 are used.

In addition, the interference fringes 53 and 54 have different periods between the diffraction grating on the original side and the diffraction grating on the substrate side, and the phase (position of light and dark) of the interference fringes shifts in different directions when the relative positions of the diffraction gratings change. For example, the period of the diffraction grating on the original side of the interference fringes 53 is slightly larger than the period of the diffraction grating on the substrate side, so when the substrate 8 shifts in the +Y direction relative to the mold 7, the phase (position of light and dark) of the interference fringes 53 shifts in the +Y direction. On the other hand, the period of the diffraction grating on the original side of the interference fringes 54 is slightly smaller than the period of the diffraction grating on the substrate side, so when the substrate 8 shifts in the +Y direction relative to the mold 7, the phase (position of light and dark) of the interference fringes 54 shifts in the -Y direction. By using two types of interference fringes 53 to 54 in this way, the measurement unit 3 (processing unit 26) can measure the relative position between the mold 7 and the substrate 8 more precisely based on the phase difference D2 in the two types of interference fringes 53 to 54.

Here, if the relative positions of the mold 7 (master-side diffraction grating) and the substrate 8 (substrate-side diffraction grating) are shifted by the period of the phase of the interference fringes 53-54, the shift of the period of the phase of the interference fringes at the relative positions cannot be recognized (detected) from the interference fringes 53-54. Therefore, in this embodiment, as shown in FIG. 8, the master-side mark 51 and the substrate-side mark 52 are used as rough measurement marks that can determine the relative positions of the mold 7 and the substrate 8 with lower accuracy than the interference fringes 53-54. By using such rough measurement marks, it is possible to recognize (identify, detect) the shift of the period of the phase of the interference fringes at the relative positions of the mold 7 and the substrate 8. To explain this conceptually, for example, if the relative positions of the mold 7 and the substrate 8 are expressed by a two-digit value, the tens digit value can be obtained using the master-side mark 51 and the substrate-side mark 52, and the ones digit value can be obtained using the interference fringes 53-54.

[Measurement processing by the measurement unit]
Next, the measurement process of the relative position between the mold 7 and the substrate 8 by the measurement unit 3 will be described. As described above, the measurement unit 3 (processing unit 26) causes the image capture unit 25 to capture the master-side mark 51, the substrate-side mark 52, and the interference fringes 53 to 54 included in the imaging field A, and measures the relative position between the mold 7 and the substrate 8 based on the image obtained thereby. However, the master-side mark 51, the substrate-side mark 52, and the interference fringes 53 to 54 may differ from each other in, for example, the material (material quality) constituting the mark, the shape of the mark, the thickness of the mark, and the presence or absence or type of a film deposited on the mark. In this case, the marks 51 to 54 have different reflectances from each other, and a brightness difference occurs between the marks 51 to 54 in the image obtained by the image capture unit 25, so that depending on the magnitude of the brightness difference, it may be difficult to accurately detect the positions of the marks 51 to 54. That is, it may be difficult to accurately measure the relative position between the mold 7 and the substrate 8. This will be described with reference to FIGS. 9 to 10.

9 and 10 are diagrams showing the brightness of each mark 51 to 54 in the image obtained when the master side mark 51, the substrate side mark 52, and the interference fringes 53 to 54 in the imaging field A are imaged under common (same) imaging conditions. FIG. 9 shows ideal characteristics, and FIG. 10 shows actual characteristics. In FIGS. 9 and 10, the vertical axis shows the brightness of each mark 51 to 54 in the image obtained by the imaging unit 25, with the maximum brightness in the image being 100%. The maximum brightness is, for example, the brightness of a pixel with a brightness of 255 (pure white) when the brightness of each pixel in the image is expressed in RGB 256 gradations (0 to 255). Meanwhile, the horizontal axis shows the intensity of the illumination light illuminating each mark 51 to 54 in the imaging field A, with the maximum intensity of the illumination light being 100%. The maximum intensity of the illumination light is, for example, the maximum value of the intensity of the illumination light that can be emitted from the measurement unit 3 (light source unit 23). The intensity of the illumination light can be adjusted, for example, using the adjustment unit 34 (ND filter 34) included in the light source unit 23.

The imaging conditions of the imaging unit 25 include, for example, at least one of the intensity of the illumination light illuminating each of the marks 51 to 54 in the imaging field A, the wavelength of the illumination light illuminating each of the marks 51 to 54, and the charge accumulation time of the imaging unit 25 (image sensor). In this embodiment, an example in which the intensity of the illumination light is used as the imaging condition of the imaging unit 25 will be described. In addition, the allowable range of brightness is a range of brightness that can keep the error in the position of each mark determined (calculated) by the processing unit 26 based on the image obtained by the imaging unit 25 within a target range, and in this embodiment, it is set to a range of 40 to 95%.

In the ideal characteristic shown in FIG. 9, the marks 51 to 54 have approximately the same reflectance, and the brightness difference between the marks 51 to 54 in the image obtained by the imaging unit 25 is relatively small. Therefore, even if common imaging conditions (for example, the intensity of the illumination light is 60%) are used for the marks 51 to 54 in the imaging field A, the brightness of all the marks 51 to 54 in the image can be kept within the allowable range. However, in reality, as shown in FIG. 10, the marks 51 to 54 have different reflectances from each other, so the brightness difference between the marks 51 to 54 in the image obtained by the imaging unit 25 is relatively large. In this case, if common imaging conditions (intensity of the illumination light) are used for the marks 51 to 54 in the imaging field A, marks whose brightness does not fall within the allowable range in the image may be generated. For example, in the example shown in FIG. 10, if the imaging conditions are set so that the brightness of the original side mark 51 in the image falls within the allowable range (for example, if the intensity of the illumination light is set to 20 to 40%), the brightness of the substrate side mark 52 in the image cannot fall within the allowable range. On the other hand, if the imaging conditions are set so that the brightness of the substrate-side mark 52 in the image falls within the allowable range (for example, if the illumination light intensity is set to 80-100%), the brightness of the original-side mark 51 in the image cannot fall within the allowable range.

Therefore, the measurement unit 3 of this embodiment changes the imaging conditions of the imaging unit 25 for two or more marks in the imaging field of view. Specifically, the imaging unit 25 of the measurement unit 3 acquires a first image by imaging the master side mark 51 (first mark) and the board side mark 52 (second mark) that are within the imaging field of view A under a first imaging condition. The imaging unit 25 also acquires a second image by imaging the master side mark 51 and the board side mark 52 that are within the imaging field of view A under a second imaging condition that is different from the first imaging condition. Then, the processing unit 26 of the measurement unit 3 obtains the position of the master side mark 51 in the first image and obtains the position of the board side mark 52 in the second image. This allows the brightness in the images obtained by the imaging unit 25 to be adjusted for each of the master side mark 51 and the board side mark 52, so that the positions of the master side mark 51 and the board side mark 52 can be obtained with high accuracy. That is, the relative positions of the mold 7 (master-side mark 51) and the substrate 8 (substrate-side mark 52) can be determined with high accuracy. Here, the first imaging condition can be set so that the brightness of the master-side mark 51 in the first image obtained by the imaging unit 25 falls within the allowable range. The second imaging condition can be set so that the brightness of the substrate-side mark in the second image obtained by the imaging unit 25 falls within the allowable range. The first imaging condition and the second imaging condition can be set in advance by experiment, simulation, or the like, using a common allowable brightness range.

Figure 11 is a flowchart showing the alignment of the mold 7 and the substrate 8 according to this embodiment. The alignment may include a measurement process of the relative positions of the mold 7 and the substrate 8 by the measurement unit 3. Each step in the flowchart of Figure 11 may be performed by the control unit 12 and/or the processing unit 26 of the measurement unit 3.

Steps S 1 to S 6 are processes for controlling the relative positions of the mold 7 and the substrate 8 based on the results of rough measurement using the master-side marks 51 and the substrate-side marks 52 .
In step S1, the processing unit 26 acquires a first image by having the imaging unit 25 capture images of the marks 51 to 54 in the imaging field of view A under first imaging conditions. Next, in step S2, the processing unit 26 determines (calculates) the position of the original-side mark 51 in the first image acquired in step S1, and stores information on the determined position of the original-side mark 51 in memory.

In step S3, the processing unit 26 acquires a second image by having the imaging unit 25 capture images of each of the marks 51 to 54 in the imaging field of view A under second imaging conditions. The second image is acquired using the same imaging element (the imaging element of the imaging unit 25) as the first image. Furthermore, the imaging by the imaging unit 25 to acquire the second image (i.e., step S3) is performed at a different timing than the imaging by the imaging unit 25 to acquire the first image (i.e., step 1). Next, in step S4, the processing unit 26 determines (calculates) the position of the board-side mark 52 in the second image acquired in step S3, and stores information on the determined position of the board-side mark 52 in memory.

In step S5, the processing unit 26 determines the relative position between the mold 7 and the substrate 8 (shot area) based on the position of the original-side mark 51 determined in step S2 and the position of the substrate-side mark 52 determined in step S4. In step S6, the control unit 12 performs rough alignment between the mold 7 and the substrate 8 based on the relative positions between the mold 7 and the substrate 8 determined in step S5.

Steps S7 to S10 are processes for controlling the relative positions of the mold 7 and the substrate 8 based on the results of precision measurements using the interference fringes 53 to 54.
In step S7, the processing unit 26 acquires a third image by making the imaging unit 25 capture each of the marks 51 to 54 in the imaging field A under a third imaging condition. The third imaging condition is an imaging condition set so that the brightness of the interference fringes 53 to 54 in the third image acquired by the imaging unit 25 falls within an allowable range, and may be different from at least one of the first imaging condition and the second imaging condition. The third imaging condition may be set in advance by experiment, simulation, or the like, using an allowable range of brightness common to the first imaging condition and the second imaging condition. In step S8, the processing unit 26 determines the relative position between the mold 7 and the substrate 8 (shot area) based on the interference fringes 53 to 54 in the third image acquired in step S7. In step S9, the control unit 12 precisely aligns the mold 7 and the substrate 8 based on the relative positions between the mold 7 and the substrate 8 determined in step S8.

Here, a method for determining the position of the mark from the image obtained by the imaging unit 25 in steps S2 and S4 above will be described. Here, an example of determining the position of the mark using a template image will be described. The template image is, for example, a reference image (design image) that defines the dimensions, shape, and position of each mark in the image obtained by the imaging unit 25, and the position of the mark can be determined by comparing the image obtained by the imaging unit 25 with the template image.

In the above step S2, the template image T1 shown in FIG. 12(a) is used. The template image T1 includes a regulation mark M1 that regulates the dimensions, shape and position of the original-side mark 51. The processing unit 26 compares the first image obtained by the imaging unit 25 with the corresponding template image T1, and determines the degree of correlation with the regulation mark M1 for each of the marks 51 to 54 in the first image. The degree of correlation is an index indicating the degree to which the dimensions and shape of the original-side mark 51 included in the first image are similar to the dimensions and shape of the regulation mark M1, and can be calculated using a known image processing technique. As a result, the processing unit 26 can identify, among the marks 51 to 54 in the first image, the marks whose degree of correlation with the regulation mark M1 is equal to or greater than a threshold value (e.g., 80% or greater) and/or whose degree of correlation is the highest, as the original-side mark 51. Then, as shown in FIG. 12(b), the processing unit 26 calculates the positional deviation amount PD1 between the identified original-side mark 51 and the specified mark M1, and can determine the position of the original-side mark 51 based on the position of the specified mark M1 and the positional deviation amount PD1.

Similarly, in the above step S4, the template image T2 shown in FIG. 12(c) is used. The template image T2 includes a regulation mark M2 that regulates the dimensions, shape and position of the board-side mark 52. The processing unit 26 compares the second image obtained by the imaging unit 25 with the corresponding template image T2, and determines the degree of correlation with the regulation mark M2 for each of the marks 51 to 54 in the second image. The degree of correlation is an index indicating the degree to which the dimensions and shape of the board-side mark 52 included in the second image are similar to the dimensions and shape of the regulation mark M2, and can be calculated using a known image processing technique. As a result, the processing unit 26 can identify, among the marks 51 to 54 in the second image, the marks whose degree of correlation with the regulation mark M2 is equal to or greater than a threshold value (e.g., 80% or more) and/or whose degree of correlation is the highest, as the board-side mark 52. Then, as shown in FIG. 12(d), the processing unit 26 calculates the positional deviation PD2 between the identified substrate-side mark 52 and the specified mark M2, and can determine the position of the substrate-side mark 52 based on the position of the specified mark M2 and the positional deviation PD2.

Figure 13 shows images of the original-side mark 51 and the substrate-side mark 52 with respect to the intensity of the illumination light as an imaging condition. Figure 13 (a) shows an image of the original-side mark 51, and Figure 13 (b) shows an image of the substrate-side mark 52. When the brightness of each mark in the image is saturated or weak, each mark image appears larger or smaller relative to the template image. Therefore, it may be difficult to detect the positional deviation amount (PD1, PD2) of the mark without the correlation being equal to or greater than the threshold. That is, in steps S2 and S4, depending on the intensity of the illumination light, it may not be possible to detect (identify) a mark with a correlation degree equal to or greater than the threshold. In this case, it is advisable to calculate the positional deviation amount (PD1, PD2) under conditions where a mark with a correlation degree equal to or greater than the threshold can be identified while changing the intensity of the illumination light, that is, under conditions where the positional deviation amount of the mark can be detected. In other words, images are acquired under multiple conditions with different illumination light intensities, and the condition under which a mark with a correlation degree equal to or greater than a threshold can be identified, i.e., the condition under which the amount of positional deviation of the mark can be detected, can be set as the first or second imaging condition.

For example, as shown in FIG. 10, the imaging unit 25 is caused to acquire images of the original-side mark 51 under imaging conditions in which the illumination light intensity is 5%, 20%, 40%, 60%, 80%, and 100%. In the example of FIG. 10, the brightness of the original-side mark 51 falls within the allowable range in the images acquired under imaging conditions in which the illumination light intensity is 20% and 40%. Therefore, one condition in which the brightness of the original-side mark 51 falls within the allowable range (for example, a condition of 40%) can be set as the first imaging condition. Similarly, the imaging unit 25 is caused to acquire images of the substrate-side mark 52 under imaging conditions in which the illumination light intensity is 5%, 20%, 40%, 60%, 80%, and 100%. In the example of FIG. 10, the brightness of the board-side mark 52 falls within the allowable range in images captured under imaging conditions with illumination light intensities of 80% and 100%. Therefore, one condition under which the brightness of the board-side mark 52 falls within the allowable range (for example, a condition of 100%) can be set as the second imaging condition.

In addition, multiple types of first imaging conditions and multiple types of second imaging conditions may be set. For example, in the example of FIG. 10, the intensity of illumination light (20% and 40%) at which the brightness of the original-side mark 51 in the image falls within an allowable range may be set as multiple types of first conditions. In this case, in step S1, the processing unit 26 acquires multiple first images by having the imaging unit 25 capture each of the marks 51 to 54 in the imaging field A under each of the multiple types of first imaging conditions. Then, in step S2, the position of the original-side mark 51 is determined based on the multiple first images. As an example, the position of the original-side mark 51 may be determined by averaging the positions of the original-side mark 51 calculated from each of the multiple first images, or the position of the original-side mark 51 may be determined from an image (composite image) obtained by combining multiple first images.

Similarly, illumination light intensities (80% and 100%) at which the brightness of the board-side mark 52 in the image falls within an allowable range may be set as multiple types of second conditions. In this case, in step S3, the processing unit 26 acquires multiple second images by having the imaging unit 25 capture images of the marks 51 to 54 in the imaging field A under each of the multiple types of second imaging conditions. Then, in step S4, the position of the board-side mark 52 is determined based on the multiple second images. As an example, the position of the board-side mark 52 may be determined by averaging the positions of the board-side mark 52 calculated from each of the multiple second images, or the position of the board-side mark 52 may be determined from an image (composite image) obtained by combining multiple second images.

The optimal imaging conditions for each mark are determined by the type and combination of marks provided on the mold 7 and substrate 8. Therefore, data on the imaging conditions (intensity of illumination light, wavelength of illumination light, setting of ND filter 34, charge accumulation time of imaging unit 25 (imaging element)) for each type of mold 7 and substrate 8 may be stored in advance in memory as a database. When actually measuring, the imaging conditions can be determined based on the type of mold 7 and substrate 8 and the database. It is also possible to measure the vicinity of the determined imaging conditions and determine the optimal imaging conditions based on the measurement results. In this case, it is preferable to update the database with the determined optimal imaging conditions. By using the database in this way, it is possible to shorten the measurement time for calculating the optimal imaging conditions when measuring the type and combination of marks provided on the same mold 7 and substrate 8.

The imaging in steps S1 and S3 may be performed with the mold holding unit 4 and stage 5 stopped (not driven and controlled). This can reduce measurement errors caused by the vibration of the mold holding unit 4 and stage 5. The imaging conditions may also be increased by changing the illumination light intensity pattern described above. In this case, the averaging effect can further reduce measurement errors caused by the vibration of the mold holding unit 4 and stage 5 during the measurement process.

By performing the above-described process, the relative position between the mold 7 and the substrate 8 can be measured (calculated) with high precision even when the difference in the amount of detected light between the marks in the rough measurement is large. Then, based on the results of this rough measurement, the control unit 12 can precisely control the alignment between the mold 7 and the substrate 8 using the mold holding unit 4 and/or the stage 5 so that the relative positions between the mold 7 and the substrate 8 become the target relative positions.

In addition, the measurement unit 3 switches to precision measurement when the relative position between the mold 7 and the substrate 8 falls within the measurement range of precision measurement (the measurement range of one period of the interference fringes) in the alignment using the rough measurement. The third imaging condition for capturing the interference fringes 53-54 in precision measurement may be set in advance by experiment or simulation, similar to the imaging conditions for rough measurement (first imaging condition, second imaging condition). For example, in the example of FIG. 10, the brightness of the interference fringes 53-54 falls within the allowable range in the images captured under each imaging condition with the illumination light intensity of 40[%] and 60[%]. Therefore, one condition (80[%] or 100[%] condition in FIG. 10 as an example) under which the brightness of the interference fringes 53-54 in the image falls within the allowable range may be set as the third imaging condition. Also, multiple conditions under which the brightness of the interference fringes 53-54 in the image falls within the allowable range may be set as multiple types of third imaging conditions. When transitioning to precision measurement, the measurement unit 3 switches the imaging conditions and performs measurement. Based on the measurement results of this precision measurement, the control unit 12 can precisely control the alignment of the mold 7 and the substrate 8 using the mold holding unit 4 and/or the stage 5 so that the relative positions of the mold 7 and the substrate 8 become the target relative positions.

As described above, the measurement unit 3 of this embodiment causes the imaging unit 25 to acquire a first image using a first imaging condition, and then causes the imaging unit 25 to acquire a second image using a second imaging condition different from the first imaging condition. Then, the relative position between the mold 7 and the substrate 8 is determined based on the position of the original-side mark 51 in the first image and the position of the substrate-side mark 52 in the second image. As a result, even if there is a difference in reflectance between the original-side mark 51 and the substrate-side mark 52, the positions of each of these marks 51-52 can be accurately determined, and the relative position between the mold 7 and the substrate 8 can be measured with high precision.

<Embodiments of a method for manufacturing an article>
The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing an article such as a microdevice such as a semiconductor device or an element having a fine structure. The method for manufacturing an article according to the present embodiment includes a step of forming a pattern on an imprint material supplied (applied) onto a substrate using the above-mentioned imprint apparatus (imprint method), and a step of processing the substrate on which the pattern has been formed in the step. Furthermore, the manufacturing method includes other well-known steps (oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to conventional methods.

The pattern of the cured material formed using the imprinting device is used permanently as at least a part of various articles, or temporarily when manufacturing various articles. The articles include electric circuit elements, optical elements, MEMS, recording elements, sensors, and molds. Examples of electric circuit elements include volatile or non-volatile semiconductor memories such as DRAM, SRAM, flash memory, and MRAM, and semiconductor elements such as LSI, CCD, image sensors, and FPGA. Examples of molds include molds for imprinting.

The pattern of the cured material is used as it is, as at least a part of the component of the article, or is used temporarily as a resist mask. After etching or ion implantation is performed in the substrate processing step, the resist mask is removed.

Next, a specific method for manufacturing the article will be described. As shown in FIG. 14(a), a substrate 1z such as a silicon wafer is prepared on whose surface a workpiece 2z such as an insulator is formed, and then an imprint material 3z is applied to the surface of the workpiece 2z by an inkjet method or the like. Here, the state in which multiple droplets of the imprint material 3z have been applied to the substrate is shown.

As shown in FIG. 14(b), the imprinting mold 4z is placed with the side on which the concave-convex pattern is formed facing the imprinting material 3z on the substrate. As shown in FIG. 14(c), the substrate 1z to which the imprinting material 3z has been applied is brought into contact with the mold 4z, and pressure is applied. The imprinting material 3z fills the gap between the mold 4z and the workpiece 2z. When light is irradiated through the mold 4z in this state as hardening energy, the imprinting material 3z hardens.

As shown in FIG. 14(d), after the imprint material 3z is hardened, the mold 4z and the substrate 1z are separated, and a pattern of the hardened imprint material 3z is formed on the substrate 1z. This hardened pattern has a shape in which the concave portions of the mold correspond to the convex portions of the hardened material, and the convex portions of the mold correspond to the concave portions of the hardened material, i.e., the concave-convex pattern of the mold 4z is transferred to the imprint material 3z.

As shown in FIG. 14(e), when etching is performed using the pattern of the cured material as an etching-resistant mask, the portions of the surface of the workpiece 2z where there is no cured material or where only a thin layer remains are removed, forming grooves 5z. As shown in FIG. 14(f), when the pattern of the cured material is removed, an article is obtained in which grooves 5z are formed on the surface of the workpiece 2z. Here, the pattern of the cured material is removed, but it may also be used as an interlayer insulating film included in a semiconductor element or the like, that is, as a component of an article, without being removed after processing.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to disclose the scope of the invention.

1: Imprint device, 3: Measurement unit (measurement device), 4: Mold holder, 5: Stage, 7: Mold, 8: Substrate, 12: Control unit, 21: Detection optical system, 22: Illumination optical system, 23: Light source, 26: Processing unit, 28: Light source control unit

Claims (13)

A measurement device that measures a relative position between a first member and a second member,
an imaging unit that images the first mark and the second mark in a state in which the first mark provided on the first member and the second mark provided on the second member are within an imaging field of view;
A processing unit that determines a relative position between the first member and the second member;
Equipped with
the imaging unit images the first mark and the second mark using a plurality of types of imaging conditions in which intensities of illumination light illuminating the marks are different from one another, thereby acquiring images under each imaging condition;
The processing unit includes:
when there is a common imaging condition among the plurality of types of imaging conditions under which the brightness of the first mark and the brightness of the second mark in an image are within an allowable range, determining a relative position between the first member and the second member based on a position of the first mark and a position of the second mark in an image obtained under the common imaging condition;
and determining a relative position of the first member and the second member based on a position of the first mark in a first image obtained under a first imaging condition among the plurality of types of imaging conditions under which a brightness of the first mark in an image falls within the tolerance range, and a position of the second mark in a second image obtained under a second imaging condition among the plurality of types of imaging conditions under which a brightness of the second mark in an image falls within the tolerance range. The measurement device according to claim 1, characterized in that, when multiple types of the first imaging conditions are selected from the multiple types of imaging conditions and multiple first images are obtained, the processing unit determines the position of the first mark based on the multiple first images. The measurement device according to claim 2, characterized in that the processing unit determines the position of the first mark by averaging the positions of the first mark in each of the multiple first images. The measurement device according to claim 2, characterized in that the processing unit determines the position of the first mark from a composite image obtained by combining a plurality of the first images. The measurement device according to any one of claims 1 to 4, characterized in that, when multiple types of the second imaging conditions are selected from the multiple types of imaging conditions and multiple second images are obtained, the processing unit determines the position of the second mark based on the multiple second images. The measurement device according to claim 5, characterized in that the processing unit determines the position of the second mark by averaging the positions of the second mark in each of the multiple second images. The measurement device according to claim 5, characterized in that the processing unit determines the position of the second mark from a composite image obtained by combining a plurality of the second images. The measurement device according to any one of claims 1 to 7, characterized in that the first image and the second image are obtained using a common image sensor in the imaging section. The measurement device according to any one of claims 1 to 8, characterized in that the first mark and the second mark are arranged at different positions in the imaging field of view. the imaging unit images an interference pattern generated by overlapping a third mark provided on the first member and a fourth mark provided on the second member; and
the processing unit determines a relative position between the first member and the second member based on the interference fringes in a third image obtained under a third imaging condition among the plurality of types of imaging conditions under which a brightness of the interference fringes in the image falls within the allowable range; and
The third imaging condition is different from at least one of the first imaging condition and the second imaging condition.
10. The measuring device according to claim 1, wherein the measuring device is a measuring device for measuring a temperature of the measuring object. The measurement device according to claim 10, characterized in that the imaging unit images the first mark, the second mark, and the interference fringes while the first mark, the second mark, and the interference fringes are within an imaging field of view. A lithography apparatus for transferring a pattern of a master onto a substrate, comprising:
A measuring device according to any one of claims 1 to 11,
a control unit that controls alignment between the original and the substrate based on a measurement result by the measuring device;
Equipped with
13. A lithography apparatus, comprising: a measuring device that measures a relative position between the original as the first member and the substrate as the second member. forming a pattern on a substrate using the lithographic apparatus according to claim 12;
A processing step of processing the substrate on which the pattern is formed in the forming step,
A method for manufacturing an article, comprising the steps of: manufacturing an article from the substrate processed in the processing step.

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