JPH03108735A - Method and apparatus for comparison inspection - Google Patents

Abstract

PURPOSE:To inspect even a minute foreign matter or a minute pattern defect without the effect of an arrangement error between chips with a picture element being enlarged by shifting either of the image of the chip or a detecting element by the quantity of the arrangement error which is obtained by detecting the reference mark of each chip, and detecting the image. CONSTITUTION:Many chips 20 having same shape are formed on one substrate 1. The images of two chips 20 are detected and compared. Thus a foreign matter or a pattern defect is inspected. In this comparison inspecting method, a reference mark 22 of each chip 20 is detected in either before the start of the inspection or during the inspection, and the arrangement error of each chip 20 is obtained. Then, either of the image of the chip 20 or a detecting element 5 is shifted by the quantity of said arrangement error when the foreign matter or the pattern defect is inspected, and said image is detected. Thereafter, the difference between the images of two chips is obtained. When the signal of disagreement is detected, it is judged that the foreign matter or the pattern defect is present. For example, a detected-image shifting means 19 is provided between an objective lens 4 and the detecting element 5 on the substrate 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a comparative inspection method and apparatus, particularly for inspecting foreign objects and pattern defects in a large number of chips of the same shape formed on a wafer, which is a substrate. The present invention relates to a comparative inspection method and apparatus suitable for carrying out.

[Prior Art] As a conventional technology of this type, there is a technology described in Japanese Patent Application Laid-Open No. 59-6536. In this conventional technology, in order to detect foreign objects and pattern defects on the wafer, light is shined onto the wafer from an oblique direction or from above, and scattered light generated from the foreign objects and pattern defects is detected. Therefore, the same location in two chips on a wafer is detected, the two are compared, and a mismatched portion is determined to be a foreign object or a pattern defect.

However, since the chips on the wafer are exposed one by one using a reduction projection exposure apparatus, there is a misalignment between the chips (see FIG. 11). If the detection element is used to scan the chip in this state, different positions on the chip will be detected and the same image will not be obtained.

Therefore, in the conventional technique described in Japanese Patent Application Laid-Open No. 61-151410, the positional deviation between chips is left as is,
The method used is to reduce the pixel size of the detection element, digitize the image, store it in memory, and gradually shift the signal within the memory element so that the two coincide. However, this method requires the pixel size to be extremely small, so
The inspection time was long, which was a big problem in practice.

Therefore, in order to shorten the detection time by increasing the pixel size and comparatively inspect the pixels, the conventional technique described in Japanese Patent Application Laid-open No. 1-59469 smoothes the image and reduces the influence of positional deviation between chips. method is adopted.

[Problems to be Solved by the Invention] In the above-described conventional technology, if the pixels are made small, it takes too much time during inspection, and if the pixels are made large, the inspection is directly affected by alignment errors between chips, and large foreign particles of 1 to 3 μm or more are detected. There was a problem that only large pattern defects could be detected.

The first object of the present invention is to provide a comparative inspection method capable of inspecting minute foreign matter or minute pattern defects of about 0.3 to 0.5 μm without being affected by alignment errors between chips while keeping pixels large. Our goal is to provide the following.

A second object of the present invention is to provide a comparative inspection method that can continuously and efficiently inspect a large number of chips even if there is a positional shift between the chips.

Furthermore, a third object of the present invention is to provide a comparative inspection method that is capable of inspecting even more minute foreign objects or minute pattern defects.

A fourth object of the present invention is to provide a comparison inspection device that can accurately implement the method described above.

[Means for Solving the Problem] The first objective is to detect the reference mark of each chip either before the start of the test or during the test to determine the alignment error of each chip and to detect foreign objects or pattern defects. During inspection, either the image of the chip or the detection element is shifted by the amount of the alignment error and the image is detected, and then the difference between the image signals of the two chips is determined. This is achieved by determining that there is a pattern defect.

The second purpose is to illuminate the reference mark in the chip using a strobe while the chip is being scanned, and to instantly detect the detected image with a storage type image sensor or with a TV equipped with a shutter. This is achieved by instantaneously detecting the reference mark using a camera, and then reading out the image signal from the image sensor to determine the position of the reference mark.

Furthermore, the third object is achieved by vertically epi-illuminating the substrate and detecting specularly reflected light with the detection element when inspecting foreign matter or pattern defects using the detection element.

The fourth object is achieved by providing a detection image shifting means for shifting the image of the chip between the objective lens and the detection element on the substrate.

Furthermore, the fourth object can also be achieved by providing the detection element itself with a driving means for shifting the detection element in the direction of displacement of the image of the chip, instead of the detection image shifting means.

[Operations] In the comparative inspection method of the present invention, the alignment error of each chip is determined by detecting the reference mark of each chip either before the start of the test or during the test.

Next, when inspecting foreign matter or pattern defects, the image is detected while either the chip image or the detection element is shifted by the amount of the alignment error. Next, the difference between the image signals of the two chips is determined, and when a mismatch signal is output, it is determined that there is a foreign object or a pattern defect.

This makes it possible to inspect even small foreign objects or small pattern defects of about 0.3 to 0.5 μm without being affected by alignment errors between chips while keeping the pixels large.

In addition, in the comparative inspection method of the present invention, during the scanning of the chip, the reference mark in the chip is illuminated using a strobe, and the detected image is instantaneously detected with a storage type image sensor, or a TV with a shutter is used. Instant detection using a camera.

After that, the image signal is read out from the image sensor and the position of the reference mark is determined. Thereby, even if there is a positional shift between chips, a large number of chips can be continuously and efficiently inspected.

Further, in the comparative inspection method of the present invention, when inspecting foreign matter or pattern defects using the detection element, vertical epi-illumination is applied onto the substrate, and specularly reflected light is detected by the detection element. As a result, it is possible to inspect even more minute foreign objects or minute pattern defects.

Further, in the comparative inspection apparatus of the present invention, a detected image shifting means for shifting the image of the chip is provided between the objective lens on the substrate and the detecting element. Thereby, the method of the present invention can be carried out accurately.

8- And, in the comparative inspection apparatus of the present invention, the detection element itself is provided with a driving means for shifting the detection element in the direction of displacement of the image of the chip. Therefore, even with this device,
The method of the present invention can be carried out accurately.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an apparatus for carrying out the comparative inspection method of the present invention.

The comparative inspection apparatus shown in FIG.
, X and Y direction drive motors 42 and 43 that drive this in the X and Y directions, X and Y direction position detectors 17 and 18, and semiconductor lasers 3a and 3b that illuminate the wafer 1 on the wafer stage 16. , 3c, 3d, the objective lens 4 of the wafer 1 placed on the wafer stage 16, the dichroic mirror 14 and spatial filter 6 arranged on the optical path of this, the detection element 5, and the lower part of the detection element 5. A parallel flat plate 19 for image shifting, which is an image shifting means, half mirrors 12 and 13, a strobe 11, a TV camera 15 which is an image sensor, an inspection circuit connected to the detection element 15, and a chip reference. A detection microscope 30 for detecting the coordinates of marks, a mercury lamp 203, and a microcomputer that exchanges information with and controls each part (FIG. 3).

(see reference numeral 36 in FIG. 5).

A wafer 1, which is a substrate, is mounted on the wafer stage 16. Further, the wafer stage 16 is operated to move in the X and Y directions by x and y direction drive motors 42 and 43.

The x and Y direction position detectors 17 and 18 are operated by a microcomputer 36.
In response to the command, the moving position of the wafer stage 16 in the X and Y directions is detected, and the detected values are input to the microcomputer 36.

The semiconductor lasers 3a to 3d are arranged so as to illuminate the detection area 8 of the chip of the wafer 1 obliquely from above.

The objective lens 4 is configured to focus scattered light from foreign objects and pattern defects on the chip onto the detection element 5.

The dichroic mirror 14 includes semiconductor lasers 38 to
It transmits 3D light and reflects light from the strobe 11 and xenon lamp.

The spatial filter 6 is a partial light shielding plate, and is designed to expose foreign matter and pattern defects on the chip.

To entry 1 above, the robot 11 and the TV camera 15 are the microcomputer 3.
The strobe 11 emits light in response to the command from the chip 2.
0 reference mark 22 is illuminated, and while this reference mark 22 is being illuminated, the TV camera 15 is used to illuminate the reference mark 22.
is imaged, the image is input to the microcomputer 36, and the image is input to the microcomputer 36.
6, the coordinates of the reference mark 22 of each chip 20 are determined.

The test circuit includes a delay memory 201 and a binarization circuit 20.
2, the difference between the currently detected image signal 9b and the previous delayed signal 7b output from the delay memory 201 is determined, and the difference signal is binarized by a binarization circuit 202 and output. It is supposed to be done.

The mercury lamp 203 is configured to vertically illuminate the detection area 8 of the chip in place of the oblique illumination by the semiconductor lasers 3a to 3d.

FIG. 2 is a perspective view of the detection element.

The detection element 5 shown in FIG.

Second. Third. 4th. ... pixel 91.92.93.9
4. A one-dimensional linear image sensor with an array of ... is used. In this detection element 5, the first. 2nd゜3rd. 4th. ... pixels 91.92.93.94.・・・
・It is designed to convert the brightness at the position into an electrical signal and output it.

FIG. 3 is a diagram showing the structure of the parallel plate for image shifting, and FIG. 4 is an explanatory diagram of the same operation.

The parallel plate 19 for image shifting, which is a detection image shifting means, has a parallel plate glass 19 between the detection element 5 and the objective lens 4.
'. One end of the parallel plate glass 19' is elastically supported by a leaf spring 60, and the other end is supported by a piezo element 61. When a voltage is applied to the piezo element 61 to cause it to expand or contract, the parallel glass plate 19' is tilted, the optical path is shifted, and the real image 62 is shifted to either the left or the right.

Figure 5 shows one of the shifting means for image position deviation. 12- FIG. 7 is a perspective view showing another embodiment.

In this embodiment, a piezo element 63 serving as a driving means is attached to the detection element 5 itself. As a result, when a voltage is applied to the piezo element 63 to cause it to expand or contract, the direct detection element 5 is shifted in the direction of the positional shift of the chip image.

FIG. 6 is a perspective view showing a reference mark coordinate detection device.

The coordinate detection device shown in FIG. 6 includes a detection microscope 30, the X and Y direction position detectors, an output counter 32 provided at 7.18, a keyboard 34, and a display 35. It is configured. And detection microscope 3
0, the coordinates of the chip 20 are detected by the x and y direction position detectors 17 and 18, read by the output counter 32, input to the microcomputer 36 by the keyboard 34, and stored in the microcomputer 36. with 20 chips
Calculate the length of. The display 35 displays the overall shape of the wafer 1 and the shape 2 position of each chip 20,
Erase the unnecessary parts and transfer these 9 positions to the microcomputer 3.
6. In addition, in a similar manner, the distance between the reference marks 22 in each chip 20 is measured and inputted to the microcomputer 36, and the microcomputer 36
The position of the reference mark 22 is detected.

FIG. 7 is a system diagram of a control system of a foreign matter and pattern defect detection device on a patterned wafer, FIG. 8 is an explanatory diagram of reference marks on a chip of the wafer, and FIG. 9(a).

(b) + (c) and (d) are explanatory diagrams of the method for detecting the reference mark coordinates, Fig. 10 (a) and (b) are explanatory diagrams of the method for detailed inspection of the reference mark coordinates, and Fig. 11 is an illustration of the method for finely inspecting the reference mark coordinates. FIG. 3 is an explanatory diagram of positional deviation and detected position shift.

According to these figures, the operation of the comparison inspection device of the embodiment and an example of the comparison inspection method of the present invention will be explained.

In a comparative inspection for foreign matter or pattern defects on the chips 20 of the wafer 1, the wafer 1 to be inspected is first mounted on the wafer stage 6.

Then, as shown in FIG.
is obliquely irradiated by semiconductor lasers 3a, ab, 3c, and 3d, and the scattered light of the foreign object or pattern is focused by the objective lens 4 and detected by the detection element 5. At this time, a spatial filter 6 is provided at the Fourier transform surface of the objective lens 4 in order to remove the pattern image as much as possible and make the image of foreign matter or pattern defects visible. However, this alone cannot completely remove the pattern components, so the electrical signal of the image of the detection area of the previous chip 7a is memorized and the difference between it and the image of the currently detected chip 9a is calculated. When a differential signal is generated, this is determined to be a foreign object or a pattern defect.

The test circuit includes a delay memory 201 and a binarization circuit 20.
2, the difference between the image signal 9b of the currently detected chip 9a and the delayed signal 7b of the previous chip 7a output from the delay memory 201 after a certain time delay is calculated, and the difference signal is calculated. is binarized by the binarization circuit 202, and when a signal "1" is output, it is determined that there is a foreign object or a pattern defect.

Next, reference marks for determining chip alignment errors will be explained.

In semiconductor chips, circuit patterns are formed on a silicon wafer by exposing it to light many times. At this time, it is necessary to accurately align and expose the circuit pattern to be exposed this time on the previously exposed circuit pattern. This includes the 8th
As shown in the figure, a reference mark 22 is attached to a portion of the chip 20.
The current reference mark 22 is accurately positioned over the reference mark 22 printed on the wafer 1 in the previous exposure, and the circuit pattern 21 is exposed together with the reference mark 22. Therefore, this reference mark 22 is formed in every chip 20, and the position of the chip 20 can be determined by determining the position of this reference mark 22.

In this embodiment of the present invention, the position of the reference mark 22 is first detected at high speed to obtain its coordinates, and then these coordinate values are used to inspect foreign objects or pattern defects by comparing chips. be.

To do this, first find the rough position of the reference mark.

To obtain the rough position of the reference mark, the reference mark coordinate detection device shown in FIG. 6 is used, and the coordinates detection device shown in FIG.
), (c) and (d).

That is, the wafer 1 is set on the wafer stage 16, the lower left end 31 of the chip 20 in FIG. . Coordinates at this time (xl.

yt) to the X direction position detector 17. X direction position detector 18
is read by the output counter 32 of. Next, the upper right end 33 of the chip 20 is positioned in the same manner to obtain the coordinates (X,).

yt). This gives the coordinates of point 31 (xl.

yx), chip length Δx (=Xt-x□), Δy (=
'/a Vl) is understood.

Next, input X□, y□, ΔX, Δy, and the diameter d of the wafer from the keyboard 34, and the ninth
Output the shape shown in Figure (b), delete unnecessary parts, and see Figure 9 (
Output the shape of c). Next, the distance nx, fly of the reference mark 22 within the chip 20 shown in FIG. 9(d) is determined by the method described above using the detection microscope 30 shown in FIG.

Using the above-mentioned Xxr'/□rΔX, Δy+QX+Qy and the information shown in FIG.
yct) (1=1 r 2t "').

Next, the precise position coordinates of the reference mark are determined.

In order to obtain the precise position coordinates of the reference mark 22, the control system including the microcomputer 36 is operated as shown in FIG. 7, and the procedure is performed as shown in FIGS. 10(a) and 10(b).

That is, the rough position coordinates (xo() of all reference marks 22).

yct) 41 to the microcomputer 36. In FIG. 1, the Y-direction drive motor 43 is moved until the output of the X-direction position detector 18 becomes yS□ in FIG. 10(a), and then stopped.

In this state, the wafer stage 16 is moved by the X direction drive motor 42.
Move it in the X direction and stop it at the right end. Next, the Y-direction drive motor 43 is moved until the output of the X-direction position detector 18 reaches ySt, and then stopped. In this state, the wafer stage 16 is moved in the -X direction by the X-direction drive motor 42 and stopped at the left end. The movement during this time is shown in FIG. 10(a).

The wafer stage 16 moves in the ±X direction at a speed of 150 wn/s.

Since the wafer stage 16 passes over the reference mark 22 while moving in the X direction, the X direction position output 4 is shown in FIG.
5 is input into the microcomputer 36, and this is X e t +XC
3+ xc4. . . , etc., a signal is sent to the strobe light emitting circuit 46 to cause the strobe 11 to emit light.

As a result, the reference mark 22 is detected by the TV camera 15, and the coordinate value of the reference mark 22 captured by the TV camera 15 (
ζ1. Find η,). For the specific method of obtaining
The conventional technique described in Japanese Patent No. 2284 is used.

The coordinate values of the reference mark 22 taken by the TV camera 15 are shown on the TV monitor 37 in FIG. 10(b).

The flashing time of the strobe 11 is 0.2 μsec, and the wafer 1 moves by 0.03 μm during this time, which causes a detection error, but this is a big problem in order to obtain the target accuracy of ±0.05 μm. It won't be. Reference mark 22
is detected on the TV monitor 37 in FIG. 10(b),
If there were no alignment error, the reference mark 22 would be at the center of the TV monitor 37, but in reality, there is an alignment error, so the reference mark 22 would be located at the center of the TV monitor 37.
1. It is detected with a shift of η.

Therefore, the precise position coordinates of the reference mark 22 are (Xo).

+ζi+'jar+η,).

Next, a method of driving the wafer stage when detecting foreign matter or pattern defects will be described.

When detecting foreign matter or pattern defects, the wafer stage 16 shown in FIG. 1 is driven at a constant speed in the The wafer stage 16 is moved in the Y direction by a distance of the width W, and the wafer stage 16 is driven again in the X direction at a constant speed. In the meantime, as shown in FIG. 1, foreign matter or pattern defects are detected from the difference in signals between the currently detected chip 9a and the previously detected chip 7a. Therefore, as shown in FIG. 11, when the array intervals of the chips 20 are irregular, the detection position also needs to be shifted by the positional deviation of the chips 20.

In FIG. 11, the coordinates of the reference mark are point 50 (x3□).

ysx) + point 51 (XS21 ysJ r point 52 (
Xs3+ysa). The wafer stage moves in the X direction, scans between points 53 and 54, and then scans between points 55 and 54.
Point 56 must be scanned and then points 57-58 must be scanned.

To do this, move the image at point 54 from point 54 to point 55 at a distance of 3'.
S.

It is necessary to shift by ys□. Further, at point 56, it is necessary to shift from point 56 to point 57 by a distance of 3'S3Ysa. This shifting method will be explained next.

In the image shifting parallel plate 19 of the detected image shifting means shown in FIGS. 1, 3, and 4, when a voltage is applied to the piezo element 61 and the piezo element 61 is expanded, the parallel plate glass 19' shifts to the fourth position.
As shown in the figure, when the real image 62 is tilted upward to the right and shifted to the left, and when the piezo element 61 is conversely reduced, the parallel plate glass 19' is tilted downward to the right and the real image 62 is shifted to the right.

In addition, in the embodiment shown in FIG. 5 of the means for shifting the detection element 1 to the positional deviation image, a piezo element 63 is used as a drive means for the detection element 5, and a voltage is applied to this piezo element 63, When 63 is expanded or contracted, the detection element 5 itself shifts 1~, and it acts in the same way as when the image is shifted.

As a control method, as shown in FIG. 7, a Y-direction shift amount signal 70 is sent to a piezo element drive circuit 71 to drive the piezo element 61 or 63.

As the detection element 5, as shown in FIG. 2, a linear image sensor is used. Therefore, the detection element 5
detects an image, the detection signal 90 is transmitted from pixel 91→92→
The brightness at each position is converted into an electrical signal and output in the order of 93→94. In the comparison test in FIG. 11, the 91st pixel at point 55 must be compared with the detection signal of the 91st pixel at point 53. Therefore, the position of the wafer stage 16 (X in FIG.
When the output of the direction position detector 17 becomes XS, -a, the scanning of the detection element 5 is reset to start from the 91st pixel. That is, when the X-direction scanning start signal 73 shown in FIG. 7 is issued, the reset signal generating circuit resets the scanning of the detection element 5 and starts from the 91st pixel.

Even when the wafer stage 16 is reciprocated at high speed through the above operations, the delayed signal 7b in FIG. 1 and the currently detected image signal 9b become image signals at the same location on the adjacent chips 7a and 9a. Therefore, if there is no foreign object or pattern defect, the difference signal will be zero. By detecting this differential signal, minute foreign matter or pattern defects can be detected.

Although the case where the positional deviation of all chips on a wafer is detected has been described above, in reality, the correction may be made for each exposure unit of the exposure apparatus when forming chips. For example, when the exposure area in FIG. 1 is 20 x 20 mm,

The positions of the reference marks may be found at intervals of 20II in both the Y direction. Thereby, the time for detecting the position of the reference mark can be shortened.

Next, FIG. 12 is an explanatory diagram showing another embodiment of the comparative inspection method of the present invention.

In this embodiment, all chips 20 of wafer 1 are
Instead of finding the position of the reference mark 22 of A-+B
Find the position of the reference mark 22 at the time of C-+D-+ while shifting the image position in the
Scan E-+F-+G-+H→■, then find the position of the next reference mark 22 when scanning I-)J.

It is also possible to continue the following scans. Thereby, the overall inspection time can be shortened.

The above example describes the case of oblique illumination using a semiconductor laser, but in other embodiments, a xenon lamp, mercury lamp, halogen lamp, or tungsten lamp is used as the illumination light source, and dark field illumination is performed uniformly from the surroundings. Foreign matter or pattern defects may also be detected.

Furthermore, instead of oblique illumination or dark field illumination, the wafer 1 may be vertically epi-illuminated using the mercury lamp 203 in FIG. 1, and the specularly reflected light may be detected by the detection element 5. For lighting,
In addition to the mercury lamp 203, there are halogen lamps, xenon lamps, and tungsten lamps.

A laser or the like may also be used.

[Effect of the invention] The arrangement error of chips on an LSI wafer is usually ±0.3 to
0.4 μm existed, making it difficult to compare and inspect the two chips. According to the comparative inspection method of the present invention, the alignment error of each chip is determined by detecting the reference mark of each chip either before the start of inspection or during the inspection, and when inspecting foreign matter or pattern defects, the alignment error is calculated. After detecting the image while shifting either the chip image or the detection element, the difference between the image signals of the two chips is determined, and when a mismatch signal is output, it is determined that there is a defective object or pattern defect. Since the chip arrangement error can be measured with an accuracy of ±0.1 μm, comparative inspection can be performed with this accuracy. Therefore,
This method has the effect of being able to detect minute foreign particles or minute pattern defects of about 0.3 to 0.4 μm, which have been difficult to do in the past.

According to the comparative inspection method of the present invention, during the scanning of the chip, the reference mark in the chip is illuminated using a strobe, and the detected image is instantaneously detected with a storage type image sensor, or - Instant detection using an attached TV camera, and then reading out the image signal from the image sensor to determine the position of the reference mark, so even if there is a misalignment between chips, a large number of chips can be continuously detected. This has the effect of allowing efficient inspection.

Furthermore, according to the comparative inspection method of the present invention, when inspecting foreign matter or pattern defects using the detection element, the substrate is vertically epi-illuminated and the specularly reflected light is detected by the detection element. Alternatively, it is effective in inspecting minute pattern defects.

In this way, by the comparative testing method of the present invention, 0.3 to 0.5μ
m foreign objects or pattern defects can be detected.
This will greatly contribute to the development of next generation 0.3μm LSI (applied to 64M DRAM, etc.) and the improvement of yield during mass production.

Further, according to the comparative inspection device of the present invention, since the detection image shifting means for shifting the image of the chip is provided between the objective lens on the substrate and the detection element, the above-mentioned method can be carried out accurately. be.

According to the comparative inspection device of the present invention, in place of the detected image shifting means, the detecting element itself is provided with a driving means for shifting the detecting element in the direction of displacement of the image of the chip. This has the advantage that the method described above can be carried out accurately.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of an apparatus for implementing the comparative inspection method of the present invention, Fig. 2 is a perspective view of a detection element, Fig. 3 is a front view of a parallel plate for image shifting, and Fig. 4 is the same. FIG. 5 is a perspective view showing another embodiment of the image shifting means;
FIG. 6 is a perspective view showing a reference mark coordinate detection device;
The figure is a system diagram of the control system of the device for detecting foreign matter and pattern defects on patterned wafers, Figure 8 is an explanatory diagram of reference marks on wafer chips, Figures 9 (a), (b), (c),
(d) is an explanatory diagram of the method for detecting the reference mark coordinates, FIGS. 10 (a) and (b) are explanatory diagrams of the method for detailed inspection of the reference mark coordinates, and FIG. 11 is an explanation of the positional deviation of the chip and the shift of the detection position. 12 are explanatory diagrams showing other embodiments of the comparative inspection method of the present invention. 1... Wafer, 3a-3d... Semiconductor laser, 4.
... Objective lens, 5... Detection element, 7a... Previous chip, 8... Detection area on the chip, 9a... Chip currently being detected, 11... Strobe, 14・・・
・Dichroic mirror, 15...TV camera, 16
...Wafer stage, 17°18...X and Y direction position detector, 19...Parallel plate for image shift, 201...
- Delay memory, 202...Binarization circuit, 7b...Delayed signal, 9b...Currently detected image signal, 203...
・Mercury lamp for vertical epi-illumination, 20...chip, 22・
...Reference mark, 30...Reference mark detection microscope,
36 microcomputer, 37- 'I' V monitor, 'J s2
Y S1+ yS3'/Sa... Chip position shift, 61... Parallel plate piezo element for image shift, 6
3... Piezo element for driving the detection element.

Claims (1)

[Claims] 1. Forming a large number of chips of the same shape on one substrate,
In a comparative inspection method that detects foreign objects or pattern defects by detecting and comparing the images of the two chips, the reference mark of each chip is detected either before the start of the test or during the test. After determining the alignment error and detecting the image while shifting either the chip image or the detection element by the amount of the alignment error when inspecting foreign objects or pattern defects, determining the difference between the image signals of the two chips, A comparative inspection method characterized in that when a mismatch signal is output, it is determined that there is a foreign object or a pattern defect. 2. During the scanning of the chip, the reference mark in the chip is
2. The comparative inspection method according to claim 1, characterized in that a strobe is used for illumination, a detected image is instantaneously detected by a storage type image sensor, and then an image signal is read from the image sensor to determine the position of the reference mark. . 3. While scanning the chip, instantly detect the reference mark inside the chip using a TV camera with a shutter, and then
2. The comparative detection method according to claim 1, wherein the position of the reference mark is determined by reading out an image signal from a V-camera. 4. The comparative inspection method according to claim 1, wherein when inspecting foreign matter or pattern defects using the detection element, the substrate is vertically epi-illuminated and specularly reflected light is detected by the detection element. 5. Forming many chips of the same shape on one substrate,
In a comparative inspection device that detects and compares images of the two chips to detect foreign matter or pattern defects, a detection image shifting means shifts the image of the chip between the objective lens and the detection element on the substrate. A comparative inspection device characterized by being provided with. 6. The comparative inspection apparatus according to claim 4, characterized in that, in place of the detected image shifting means, the detecting element itself is provided with a driving means for shifting the detecting element in the direction of displacement of the image of the chip.