JPH0750036B2 - Surface inspection device and surface inspection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface inspection apparatus and an inspection method for detecting foreign matter on the surface of an inspection object such as a semiconductor wafer.

[Prior Art] As a surface inspection device for inspecting a surface of a semiconductor wafer or the like, a light beam is applied to the surface of an object to be inspected, and foreign matter is detected based on a photoelectric conversion signal of the reflected light to detect the foreign matter. There is one that stores the detected position information of the observation field of view.

Further, as in Japanese Patent Laid-Open No. 61-79112, in order to detect a chip having a defect, first, a foreign substance is roughly inspected macroscopically, its position is stored, and then the position is microscopically measured. There is a method in which a chip with a foreign substance is inspected and a match with a reference pattern is detected corresponding to the chip to determine whether or not the chip is defective.

The former surface inspection apparatus is generally capable of displaying a monitor of the surface of the inspection object within the observation field of view and taking a photograph of the surface of the inspection object, in addition to such a foreign matter detection function. This is to specify the content of the foreign matter.

The latter surface inspection apparatus is an inspection for eliminating defective products, and improves the product yield by improving the inspection accuracy.

[Problems to be Solved] In manufacturing a semiconductor integrated circuit, not only is it possible to grasp the presence or absence of foreign matter on the surface of a semiconductor wafer and the number of foreign matter at various stages, but also the foreign matter detected at a certain stage may be detected in a cleaning process. It is also necessary to investigate whether it has been removed or whether it has developed into a defect in the subsequent process.

However, the conventional surface inspection apparatus cannot directly and efficiently compare the change and influence of the previously detected foreign matter. Therefore, conventionally, it has been necessary to take a very inefficient method of taking a photograph of the wafer surface at various stages and comparing the photographs at each stage to evaluate the influence of foreign matters and the cleaning process. I didn't get it.

[Object of the Invention] Therefore, the object of the present invention is configured so that it is possible to directly and easily examine the presence or absence of foreign matter or the like on the surface of the object to be inspected previously detected, and the influence thereof. It is an object of the present invention to provide a surface inspection apparatus and an inspection method therefor which solve the conventional problems.

[Means for Solving the Problems] A surface inspection apparatus according to the present invention made to achieve the above object observes a surface of an object to be inspected, detects foreign matters on the surface, and includes an observation field of view. A surface inspection apparatus for imaging a portion of a surface of an inspection object and displaying the captured image on a display, which has a first mode and a second mode, and an observation field of view in which foreign matter or the like is detected for an inspection object in the first mode. The position information and the captured image at that time are stored in the storage means, and the observation field of view is positioned based on the position information stored in the storage means in the second mode with respect to the inspected object that has been subjected to a certain process. The captured image at that time is displayed on the display, and the captured image corresponding to the position of the observation field of view stored in the storage means is displayed on the display or another display. It is intended to.

In the inspection method of the present invention, the first mode and the second mode are changed to a first step of storing in the storage means, and a second step after a certain process is performed, This is a method of displaying the inspection object on the display.

[Operation] With such a configuration, for example, in manufacturing a semiconductor integrated circuit, it is possible to directly and efficiently check the change and influence of foreign matter on a semiconductor wafer as follows.

First, a semiconductor wafer at a certain stage is set in the surface inspection apparatus of the present invention, and the apparatus is operated at the first time corresponding to the first mode or the first step to detect foreign matters or the like on the semiconductor wafer. . The semiconductor wafer at the subsequent stage is set in the same apparatus, and the same apparatus is operated at the second mode or the second time point corresponding to the second step. that way,
The observation field of view is positioned at the position where the foreign matter was detected before, and the current state of the semiconductor wafer surface in the observation field of view is displayed on the display, and at the same time, the state before the semiconductor wafer surface corresponding to the observation field of view is displayed. Since the displayed images are compared with each other, it is possible to directly and easily grasp how the previously detected foreign matter has changed or affected by the comparison by comparing both displayed images.

In the above case, the inspection device does not have to be the same device.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of a surface inspection apparatus according to the present invention. In this figure, 10 is a semiconductor wafer 12 (inspection object)
Is a table for holding. This table 10 is XY
Left and right (X) direction, front and back (Y) by Z stage mechanism 14
And a vertical (Z) direction, and is rotated by a motor (not shown). Reference numeral 16 denotes a moving motor (not shown) of the XYZ stage mechanism 14 and a drive circuit for the rotation driving motor. The means for detecting the horizontal position and the rotational angle position of the table 10 are also provided in the XYZ stage mechanism 14, but they are not shown.

In this surface inspection apparatus, foreign matter is detected while moving the observation field of view on the surface of the semiconductor wafer 12 in a spiral shape. Such movement of the observation field of view is performed by rotating the table 12 and moving in the X direction.

20 is an S for generating an S-polarized laser beam for foreign matter inspection
It is a polarized laser light source. The S-polarized laser beam is applied obliquely to the surface of the semiconductor wafer 12 in the observation field of view at an angle of, for example, 2 degrees. The reflected laser light of the S-polarized laser beam in the vertical direction is guided to the S-polarized light cut filter 24 via the optical system 22, where only the P-polarized light component is extracted and enters the photomultiplier 26.

Here, when the semiconductor wafer 12 is a wafer with a plank film without a pattern (or a mirror-finished wafer), the S-polarized laser light is specularly reflected and is not reflected in the Z direction unless foreign matter is present in the irradiation spot. However, if there is a foreign substance, it is diffusely reflected by the foreign substance and also reflected in the Z direction. Since the surface of a foreign substance generally has minute irregularities, the reflected laser light contains a considerable amount of P-polarized component.

On the other hand, in the case of a patterned wafer, if a pattern exists in the irradiation spot of S-polarized laser light, it is also reflected in the Z direction, but the surface of the pattern is microscopically smooth, so the reflected laser light is Almost only S-polarized component, P
The polarization component is extremely small.

In this way, when there is a foreign substance in the observation field of view, the incident light amount (P-polarized component) of the photomultiplier 26 increases, and therefore the output signal voltage of the photomultiplier 26 increases. Therefore, by comparing the output signal voltage with a specific threshold value, it is possible to determine the presence or absence of foreign matter in the observation field of view. This determination is performed by the determination circuit 28, and the determination output signal is "1" when there is a foreign matter and "0" when there is no foreign matter.

Reference numeral 30 denotes a television camera, which picks up an image of a portion of the semiconductor wafer surface including the observation field of view through the optical system 22 and outputs information of the picked-up image as an NTSC signal. This NTSC signal is input to the television receiver 32 as a display for displaying a captured image. Reference numeral 34 is a lamp as a light source for imaging by the television camera 30, and irradiates a portion including an observation visual field on the surface of the semiconductor wafer through the optical system 22.

Reference numeral 40 is an image storage device such as a video tape recorder for storing the image picked up by the television camera 30, and 42 is a control circuit for controlling the recording and reproduction thereof. The NTSC signal output from the television camera 30 is input to the image storage device 40 via the control circuit 42. Reference numeral 44 denotes a television receiver as a display for reproducing and displaying the image stored in the image storage device 40, to which the NTSC signal output from the image storage device 40 is input.

In this surface inspection device, control of each part thereof, storage of data of detected foreign matters, and the like are performed by program control. Elements for that purpose are a microprocessor 50 and a memory 52. The drive circuit 16, the control circuit 42, the keyboard 56, and the floppy disk device 58 are connected to the microprocessor 50 via the interface circuit 54. The program is designed to be loaded from the floppy disk device 58 into the memory 52. The foreign substance data can be saved in the floppy disk device 58 or loaded in the memory 52.

Next, the overall operation of the surface inspection device will be described. This surface inspection device has two operation modes, and either operation mode can be designated by the keyboard 56.

First, the operation when the first mode is designated will be described. FIG. 2 is a schematic flowchart of the operation.

This mode is specified by keyboard 56
When the start key is pressed, the microprocessor 50 starts executing the program 52A in the first mode. First, the drive motor of the XYZ stage 14 is controlled through the drive circuit 16 so that the X and Y direction positions of the observation field are aligned with the inspection start position (step 100). When the positioning is completed, the drive circuit 16 drives the table 10 drive motor and the X-direction drive motor of the XYZ stage mechanism.
The table 10 is rotated at a constant speed and moved in the X direction at a constant speed (step 105). from here,
The actual inspection begins. TV camera 30 at each time
The image of the surface of the semiconductor wafer captured by is displayed on the television receiver 32.

The output signal (determination result information) of the determination circuit 28 and the position information from the XYZ stage mechanism 14 are sampled at fixed time intervals and temporarily stored in an internal register of the microprocessor 50 (step 110). The position of the observation field of view indicated by the position information is compared with a predetermined X-direction end position to determine the end of the inspection (step 11).
Five).

If not, it is determined whether the determination result information is "1" (step 120). If it is "1", it means that the foreign matter is detected in the current observation field of view, so the position information at that time is written in the foreign matter table 52B (step 125). Position information of the detected foreign matter is written in the foreign matter table 52B in the order of detection. Then, by the control circuit 42, the captured image at that time is one frame worth of image storage device
It is stored in 40 (step 130). The frame number information corresponding to the registration order of the position information of the foreign substance table 52B is also recorded together with the information of the captured image.

Then, the process returns to step 110. If the determination result information is “0” in the determination in step 120, steps 125 and 130 are skipped.

If it is determined in step 115 that the detection has ended, the foreign matter table 5
The contents of 2B are added to the identification information of the semiconductor wafer 12 and transferred to the floppy disk device 58 (step 135), and the process is ended.

Next, the operation of the second motor will be described. FIG. 3 is a schematic flowchart of the operation.

This mode is specified by keyboard 56
When the start key is pressed, the microprocessor 50 starts executing the program 52C in the second mode.

First, the content of the foreign matter table (positional information of the observation field of view in which the foreign matter is detected) corresponding to the semiconductor wafer identification information designated by the keyboard 56 is loaded from the floppy disk device 58 to the foreign matter table 52B (step 200).

Next, the position information stored in the foreign matter table 52B is read one by one from the beginning (step 205), and the XYZ stage mechanism 14 and the XYZ stage mechanism 14 are arranged so that the observation field of view moves to the position indicated by the position information. The drive motor of the table 10 is driven by the drive circuit 16 (step 215).

When this positioning is completed, the information of the captured image of the frame number corresponding to the storage order of the position information at that time is output from the image storage device 40 and displayed on the television receiver 44 (step 220). The image captured by the television camera 30 at this point is also displayed on the other television receiver 32. Of course, the image read out from the image storage device 40 in this case is that of the wafer corresponding to the identification information. Otherwise, the corresponding stored image will be selected.

In this way, for the same semiconductor wafer 12, the picked-up image of the portion including the observation field of view in which the foreign matter was detected last time and the picked-up image of the current same portion are simultaneously displayed. Therefore,
By comparing both images, whether the previously detected foreign matter remains this time, whether the foreign matter has developed into a defect,
It is possible to directly understand such things.

In this state, the pressing of the shift key of the keyboard 56 is monitored (step 225).

When the shift key is pressed, the process returns to step 205, the next position information is read out, and the similar observation field of view is positioned and the stored image is displayed.

Step 210 is a step of determining the end. When the processing after step 215 is completed up to the last position information of the foreign matter table, it is determined to be completed in step 210 and the processing is completed.

Since this surface inspection apparatus has the above-described configuration, for example, the semiconductor wafer before the cleaning step is set and operated in the first mode, and the same semiconductor wafer is set after the cleaning step and operated in the second mode. Then, the cleaning process can be easily evaluated by comparing the display screens. Similarly,
It is possible to directly and easily grasp how the foreign matter attached to the semiconductor wafer at a certain stage has an influence thereafter. Therefore, it is possible to easily obtain information necessary for improving the manufacturing process of the semiconductor integrated circuit.

Although one embodiment has been described above, the present invention is not limited to this, and can be appropriately modified and implemented without departing from the scope of the invention.

For example, foreign matter detection and foreign matter position information and a captured image may be recorded even in the second mode.

The present invention can be similarly applied to a surface inspection apparatus that detects foreign matter and the like according to a principle other than the detection principle of the above embodiment.

The information of the captured image and various kinds of information such as the foreign substance table of the previous embodiment may be stored in the same storage means.

The screen of one display may be divided and the captured image and the stored image may be displayed in a comparable manner.

The present invention can be similarly applied to an apparatus for inspecting the surface of an inspection object other than a semiconductor wafer.

[Effects of the Invention] As described above, according to the present invention, the surface inspection apparatus and the inspection method include the information of the position of the observation field of view in which the foreign matter or the like is detected in the first mode or the first time point and the information at that time. The captured image is stored in the storage means, the observation field of view is positioned based on the position information stored in the storage means in the second mode or the second time point, and the captured image at that time is displayed and stored on the display. Since the picked-up image corresponding to the position of the observation field of view stored in the means is configured to be displayed on this display or another display, for example, in the manufacture of a semiconductor integrated circuit, a change or influence of foreign matter on a semiconductor wafer, etc. It is possible to realize a surface inspection device that enables direct and efficient evaluation of

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of a surface inspection apparatus according to the present invention, FIG. 2 is a schematic flow chart of an operation in a first mode in the same embodiment, and FIG. 3 is an outline of operation in a second mode in the embodiment. It is a flowchart. 10 …… table, 12 …… semiconductor wafer (inspection object), 14
...... XYZ stage mechanism, 20 ... S-polarized laser oscillator, 22
...... Optical system, 24 …… S polarization cut filter, 26 …… Photomultiplier, 30 …… TV camera, 32,44 …… TV receiver (display), 40 …… Image storage device, 50 ・ ・ ・
… Microprocessor, 52… Memory, 52B… Foreign object table.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryoji Nemoto 300 Hisasho, Nakai-cho, Ashigarakami-gun, Kanagawa, Hitachi Electronic Engineering Co., Ltd. Inside the corporation (56) Reference JP 60-15939 (JP, A) JP 56-18708 (JP, A) JP 61-198045 (JP, A) JP 59-10231 (JP, A)

Claims (5)

[Claims] 1. A surface inspection apparatus for observing a surface of an object to be inspected, detecting foreign matters and the like on the surface, imaging a portion of the surface of the object to be inspected including an observation field of view, and displaying a captured image on a display, It has a first mode and a second mode, and in the first mode, information on the position of the observation field of view in which the foreign matter or the like is detected with respect to the object to be inspected and a captured image at that time are stored in the storage means, and a certain process is performed. The observation field of view is positioned with respect to the object to be inspected in the second mode based on the position information stored in the storage unit, and a captured image at that time is displayed on the display and stored in the storage unit. A surface inspection apparatus, which displays a picked-up image corresponding to the position of the observation field of view on the display or another display. 2. The inspected object is a wafer, and the storage means comprises a recording / reproducing device for recording an image in accordance with a television system and a storage device for sequentially storing the position of a foreign substance on the wafer. The device is
The surface inspection apparatus according to claim 1, wherein the captured images are recorded in order of the position of the foreign matter. 3. The storage device has a foreign substance table in which the positions of the foreign substances are sequentially stored in correspondence with the identification information of the wafer, and the picked-up image recorded in the recording / reproducing device is stored in the identification information. It corresponds, It is characterized by the above-mentioned.
The surface inspection device described. 4. A surface inspection method for observing a surface of an object to be inspected, detecting foreign matters and the like on the surface, imaging a portion of the surface of the object to be inspected including an observation field of view, and displaying a captured image on a display, A first step of storing in the storage means information on the position of the detected observation field of view such as a foreign substance of the object to be inspected, and the imaged image at that time, and the object to be inspected after a certain process after the first step The observation field of view is positioned on the object based on the information of the position stored in the storage unit, the captured image at that time is displayed on the display, and the imaging corresponding to the position of the observation field stored in the storage unit is performed. A method for inspecting a surface, comprising displaying an image on the display or another display. 5. The object to be inspected is a wafer, and the storage means comprises a recording / reproducing device for recording an image according to a television system and a storage device for sequentially storing the position of a foreign substance on the wafer. The surface inspection method according to claim 4, wherein the apparatus stores the captured images in the order of the position of the foreign matter.