JP2001034743A - Method and device for comparison and checking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect minute foreign matters of a size of about 0.2 to 0.5 μm or a minute pattern defect without being affected by the array error between chips while pixels are kept large. SOLUTION: This device defects the position of a reference mark formed in accordance with each of at least two chips among a large number of chips formed on a substrate (wafer) 1 and then calculates the array errors of the chips. When a difference image is obtained by comparing the detection image of one chip with the detection image of the other chip while a detection element 5 detects the image of the one chip and a memory 201 delays and stores the image, respectively, the image of the other chip is detected by the element 5 in a state in which, e.g. a parallel plate 19 corrects the array error.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a comparative inspection method and apparatus, and more particularly to a method and apparatus for inspecting a plurality of chips of the same shape on a wafer as a substrate for the presence of foreign matter and pattern defects. And a comparative inspection method.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 59-65 discloses this kind of prior art.
There is a technique described in Japanese Patent Publication No. 36. In this conventional technique, in order to detect the presence or absence of a foreign substance or a pattern defect on a wafer, light is applied obliquely or from above to the wafer to detect scattered light generated from the foreign substance or the pattern defect. Since scattered light is generated, the same location in two chips on the wafer is detected, the two are compared, and the mismatched portion is determined as a foreign substance or a pattern defect.

However, since chips on a wafer are exposed one by one by a reduction projection exposure apparatus, each chip has a misalignment (see FIG. 11). When scanning on the chip using the detection element in this state, different positions on the chip are detected, and the same image cannot be obtained.

Therefore, in the prior art described in Japanese Patent Application Laid-Open No. 61-151410, the position shift between chips is kept as it is, the pixel size of the detection element is reduced, the image is digitized and stored in memory. A method is employed in which the signals are shifted little by little in the element so that the two coincide. However, in this method, since the pixel size needs to be extremely small, the inspection time becomes long, which has been a serious problem in practical use.

In order to reduce the detection time by increasing the pixel size and to compare and inspect the pixels, see Japanese Patent Laid-Open No. 1-59469.
In the prior art described in Japanese Patent Application Laid-Open No. H10-209, a method is adopted in which an image is smoothed to reduce the influence of positional displacement between chips.

[0006]

In the above-mentioned prior art, when the size of the pixel is small, the inspection time is too long.
There is a problem that only large foreign matters or large pattern defects of m or more can be detected.

It is an object of the present invention to provide an image processing apparatus in which the size of a pixel is kept large and is not affected by an alignment error between chips.
An object of the present invention is to provide a comparative inspection method and an apparatus thereof capable of inspecting even about m foreign matter or minute pattern defect.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to inspect a plurality of chips of the same shape formed on a substrate to detect foreign substances on the substrate or pattern defects in the chips. At least two of the chips
Detecting a position of a reference mark formed corresponding to each of the chips to determine an alignment error of the at least two chips; detecting and storing an image of one of the chips formed in a large number; Comparing the stored image of one chip with an image obtained by detecting another chip of the plurality of formed chips in a state where the obtained arrangement error is corrected, and storing the stored one chip A difference between the image of the other chip and the image of the detected other chip, a foreign matter on the substrate, based on the difference of the obtained image, or a comparative inspection method of detecting the pattern defect, wherein the reference mark of the reference mark Detecting a position to obtain an alignment error of the at least two chips is performed by detecting a position of the reference mark formed on a predetermined chip among the plurality of formed chips, and Other images obtained by detecting the chip of a number formed chips for one chip of images the memory, the sequence error obtained is achieved by being a corrected image.

The apparatus may be configured such that a stage is mounted on the substrate and is movable in the X and Y directions within a plane, and a plurality of chips are formed on the substrate mounted on the stage. Detecting means for detecting the pattern of the pattern and outputting an image of the pattern as an image signal, storage means for delay-storing the image of the pattern detected by the detecting means, and the chip formed by the plurality of chips detected by the detecting means An array error calculating means for calculating an array error between the at least two chips from an image of a reference mark formed corresponding to each of at least two chips, and an array error calculated by the array error calculating means. Image shift means for correcting by shifting an optical image of the pattern of the chip relative to a photoelectric conversion unit in the detection means; and The image of the pattern of one of the multiple chips formed in the plurality of chips stored in the storage unit in a state where the column error is corrected, and the image of the other chip among the multiple formed chips detected by the detection unit. A difference image detecting means for obtaining a difference from a pattern image, and a defect detecting means for detecting a foreign substance on the substrate or a pattern defect in the chip based on the difference between the images obtained by the difference image detecting means. It is achieved by providing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 12. Prior to that, the outline of the present invention will be described. Is calculated. Next, at the time of inspection for a foreign substance or a pattern defect, the image is detected while shifting either the image of the chip or the detection element by the amount of the alignment error. Then, the difference between the image signals of the two chips is obtained, and when a mismatch signal is output, it is determined that there is a foreign substance or a pattern defect. As a result, it is possible to inspect a small foreign matter or a small pattern defect of about 0.3 to 0.5 μm without being affected by an alignment error between chips while keeping the pixel large. In addition, during scanning of the chip, the reference mark in the chip is illuminated using a strobe, and the detected image is instantly detected by a storage type image sensor, or instantly detected by a TV camera with a shutter. I do. Thereafter, the image signal is read from the image sensor, and the position of the reference mark is obtained. Thus, even if there is a displacement between chips, a large number of chips can be continuously and efficiently inspected.

Further, when inspecting a foreign substance or a pattern defect by the detection element, the substrate is vertically illuminated by epi-illumination, and regular reflection light is detected by the detection element. As a result, it is possible to inspect fine foreign matter or fine pattern defects even more. Furthermore, an image shift means for shifting the image of the chip is provided between the objective lens and the detection element on the substrate. As a result, the present invention can be appropriately implemented. Apart from this, the same effect can be obtained even if 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.

Now, the present invention will be described in detail. 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. 1 includes a wafer stage 16, X and Y direction motors 42 and 43 for driving the wafer stage 16 in X and Y directions, an X and Y direction position detector 17,
18, a semiconductor laser 3a, 3b, 3c, 3d for illuminating the wafer 1 on the wafer stage 16, and an objective lens 4 for the wafer 1 mounted on the wafer stage 16.
And a dichroic mirror 1 arranged on the optical path of the
4, a spatial filter 6, a detecting element 5, an image-shifting parallel plate 19 as image shifting means disposed below the detecting element 5, half mirrors 12, 13 and a strobe 11, and a TV camera 15 as an image pickup element.
An inspection circuit connected to the detection element 5, a detection microscope 30 for detecting coordinates of a reference mark of the chip, and a mercury lamp 2
And a microcomputer (see reference numeral 36 in FIGS. 3 and 5) for exchanging information with each unit and controlling each unit.

On the wafer stage 16, the wafer 1, which is a substrate, is mounted. Also, the wafer stage 1
Reference numeral 6 denotes an X, Y direction drive motor 42, 43, which is operated to move in the X, Y directions.

The X and Y direction position detectors 17 and 18 are:
In response to a command from the microcomputer 36, the movement position of the wafer stage 16 in the X and Y directions is detected, and the detected value is input to the microcomputer 36.

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

The objective lens 4 focuses scattered light of foreign matter on a chip or a pattern defect on a detection element 5.

The dichroic mirror 14 transmits light from the semiconductor lasers 3a to 3d and reflects light from the strobe 11 and the xenon lamp.

The spatial filter 6 is a partial light-shielding plate, which makes foreign matters and pattern defects of a chip obvious.

The strobe 11 and the TV camera 15 are
The strobe 11 emits light in response to a command from the microcomputer 36, illuminates the reference mark 22 of the chip 20, and while the reference mark 22 is illuminated, the TV camera 15 captures an image of the reference mark 22, Is input to the microcomputer 36, and the microcomputer 36 calculates the coordinates of the reference mark 22 of each chip 20.

The test circuit comprises a delay memory 201, 2
The image signal 9 currently being detected.
b and the immediately preceding delay signal 7b output from the delay memory 201, and the difference signal is converted to a binarization circuit 202.
And binarized and output.

The mercury lamp 203 includes semiconductor lasers 3a to 3a.
Instead of the oblique illumination by 3d, the detection area 8 of the chip is vertically illuminated.

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

The detecting element 5 shown in FIG. 2 includes first, second, third, fourth,... Pixels 91, 92, 93, 9
A one-dimensional linear image sensor in which 4,... Are arranged is used. The detection element 5 converts the brightness at the positions of the first, second, third, fourth,... Pixels 91, 92, 93, 94,. .

FIG. 3 is a view showing the structure of the parallel plate for image shift, and FIG. 4 is an explanatory view of the operation.

The image shift parallel flat plate 19 serving as an image shift means is provided as 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 expand and contract, the parallel plate glass 19 'is inclined, and the optical path shifts,
The real image 62 is shifted left or right.

FIG. 5 shows the detection element 5 for the image displacement.
FIG. 10 is a perspective view showing another embodiment of the image shift method of FIG.

In this embodiment, a piezo element 63 as a driving means is attached to the detecting element 5 itself. As a result, when a voltage is applied to the piezo element 63 to expand and contract,
The direct detection element 5 shifts in the direction of displacement of the image of the chip.

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

The coordinate detecting device shown in FIG. 6 includes a detecting microscope 30, output counters 32 provided in the X and Y direction position detectors 17 and 18, a keyboard 34, and a display 35. Have been. Then, the chip 20 is put in the visual field of the detection microscope 30, and this chip 2
0 coordinates are detected by the X and Y direction position detectors 17 and 18,
The data is read by the output counter 32, input to the microcomputer 36 by the keyboard 34, stored in the microcomputer 36, and the length of the chip 20 is calculated. The display 35 displays the entire shape of the wafer 1 and the shape and position of each chip 20, deletes unnecessary portions, and inputs these shapes and positions to the microcomputer 36. In a similar manner, the distance between the reference marks 22 in each chip 20 is measured and input to the microcomputer 36, and the microcomputer 36 detects the position of the reference mark 22 on each chip 20.

FIG. 7 is a system diagram of a control system of a device for detecting foreign matter and a pattern defect on a patterned wafer, FIG. 8 is an explanatory diagram of a reference cook on a chip of the wafer, and FIGS. 9 (a), 9 (b) and 9 (b).
(C) and (d) are explanatory diagrams of a method of detecting reference mark coordinates, FIGS. 10 (a) and (b) are explanatory diagrams of a fine inspection method of reference mark coordinates, and FIG. FIG.

The operation of the comparative inspection apparatus of the above embodiment and an example of the comparative inspection method of the present invention will be described with reference to these figures.

In the comparative inspection of foreign matter or pattern defects on the chip 20 of the wafer 1, first, the wafer 1 to be inspected is mounted on the wafer stage 16.

Then, as shown in FIG. 1, the detection area 2 on the wafer 1 is irradiated obliquely by the semiconductor lasers 3a, 3b, 3c and 3d, and the scattered light of the foreign matter or the pattern is condensed by the objective lens 4. , Detected by the detecting element 5. At this time, a spatial filter 6 is provided at the position of the Fourier transform surface of the objective lens 4 in order to remove the image of the pattern as much as possible and to make the image of the foreign matter or the pattern defect visible. However, this alone cannot completely remove the components of the pattern,
The electric signal of the image of the detection area of the immediately preceding chip 7a is stored, and the difference from the image of the currently detected chip 9a is calculated.
When a difference signal is generated, this is determined as a foreign substance or a pattern defect.

The test circuit comprises a delay memory 201, 2
A delay circuit 201, which is provided with a value conversion circuit 202, and an image signal 9b of the currently detected chip 9a and a delay signal 7b of the immediately preceding chip 7a output from the delay memory 201 with a certain delay.
Is obtained, the difference signal is binarized by a binarization circuit 202, and when a signal "1" is output, it is determined that there is a foreign substance or a pattern defect.

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

In the case of a semiconductor chip, a circuit pattern is formed on a silicon wafer by exposing it many times. At this time, it is necessary to accurately align the circuit pattern to be exposed this time on the circuit pattern that has been exposed immediately before and then perform the exposure. For this purpose, as shown in FIG. 8, a reference mark 22 is provided on a part of the chip 20 and the current reference mark 22 is placed on the reference mark 22 printed on the wafer 1 in the previous exposure.
Are accurately aligned, and the circuit pattern 21 and the reference mark 22 are exposed. Therefore, this reference mark 2
2 is formed in all the chips 20, and the position of the chip 20 can be known by determining its position.

In this embodiment of the present invention, first, the position of the reference mark 22 is detected at a high speed to obtain the coordinates, and then, using this coordinate value, an inspection for a foreign substance or a pattern defect by chip comparison is realized. Is what you do.

First, the coarse position of the reference mark is obtained. In order to obtain the coarse position of the reference mark, a coordinate detection device for the reference mark shown in FIG.
This is performed in the manner shown in (b), (c) and (d).

That is, the wafer 1 is placed on the wafer stage 16
It is set on the upper side, and the lower left end 31 of the chip 20 in FIG. 9A is visually determined by the detection microscope 30 and positioned at the center of the visual field of the detection microscope 30. The coordinates (x ₁ , y
₁ ) is read by the output counter 32 of the X-direction position detector 17 and the Y-direction position detector 18. Next, the upper right end 33 of the chip 20 is positioned in the same manner, and the coordinates (x ₂ , y ₂ )
Read. Thus, the coordinates (x ₁ , y ₁ ) of the point 31
And the chip length Δx (= x ₂ −x ₁ ), Δy (= y ₂ −y
₁ ) I understand.

Next, x ₁ , y ₁ ,
.DELTA.x, .DELTA.y and the diameter d of the wafer are input, the shape shown in FIG. 9B is output to the display 35, and unnecessary portions are deleted to output the shape shown in FIG. 9C. Next, the distances lx, l of the reference mark 22 in the chip 20 shown in FIG.
y is determined by the aforementioned method using the detection microscope 30 in FIG.
Input from the keyboard 34.

The above described x ₁ , y ₁ , Δx, Δy, l
Using the x and ly and the information shown in FIG.
Automatically calculates the coarse position coordinates (x _ci , y _ci ) (i = 1, 2,...) Of all the reference marks 22 on the wafer 1.

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

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

That is, the coarse position coordinates (x _ci , y _ci ) 41 of all the reference marks 22 are input to the microcomputer 36. In FIG. 1, the Y-direction drive motor 43 is moved and stopped until the output of the Y-direction position detector 18 reaches y _s1 in FIG.
In this state, the wafer stage 16 is
To move in the X direction and stop at the right end. Next, the Y-direction drive motor 43 is moved and stopped until the output of the Y-direction position detector 18 becomes _ys2 . In this state, the wafer stage 1
6 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. The wafer stage 16 moves in the ± X direction at a speed of 150 mm / s.

[0046] Since passes over the reference mark 22 while the wafer stage 16 is moving in the X direction, enter the X-direction position output 45 to the microcomputer 36 in FIG. 7, this is x _c2, x
_When it matches with _c3 , _xc4 ,...
And the strobe 11 emits light.

As a result, the reference mark 22 is detected by the TV camera 15 and passes through the binarization circuit 47 and the position recognition circuit 48 shown in FIG.
Of the coordinates (ζ _i , η _i ) are obtained. The specific method is based on the prior art described in Japanese Patent Publication No. 56-2284. Reference mark 22 taken by the TV camera 15
Are shown on the TV monitor 37 in FIG.

The light emission time of the strobe 11 is 0.2 μsec.
During this time, the wafer 1 moves by 0.03 μm, and this corresponds to a detection error.
It is not a big problem to get μm accuracy. The reference mark 22 is detected by the TV monitor 37 in FIG. 10B, and if there is no alignment error, the reference mark 22 comes to the center of the TV monitor 37. However, since there is actually an alignment error, ζ _i , η _i from the center It is detected only by shifting. Therefore, the precise position coordinates of the reference mark 22 are (x _ci + ζ _i , y c _i
+ Η _i ).

Next, a method of driving the wafer stage upon detection of a foreign substance or a pattern defect will be described.

When detecting a foreign substance or a pattern defect, the wafer stage 16 shown in FIG. 1 is driven at a constant speed in the X direction, and the inside of the width w is detected by the detection microscope 30. 16 is width w in the Y direction
And the wafer stage 16 is driven again at a constant speed in the −X direction. In the meantime, the currently detected chip 9a and the immediately preceding chip 7a as shown in FIG.
Foreign matter or pattern defect is detected from the difference between the signals. Therefore, as shown in FIG. 11, when the arrangement intervals of the chips 20 are irregular, the detection position also needs to be shifted by the position shift of the chip 20.

In FIG. 11, the coordinates of the reference mark
0 ( _xs1 , _ys1 ), point 51 ( _xs2 , _ys2 ), point 52 (x
_s3 , _ys3 ). The wafer stage moves in the X direction,
After scanning between points 53 and 54, points 55 to 56 must be scanned, and thereafter points 57 to 58 must be scanned. For this purpose, it is necessary to shift the image at point 54 to point 54 → point 55 by a distance y _s2 -y _s1. Also, point 56
In has to be shifted to a point 56 → point 57 by a distance y _s3 -y _s2. This shift method will be described below.

In the image shifting means of the image shifting parallel flat plate 19 shown in FIGS. 1, 3 and 4, when a voltage is applied to the piezo element 61 and the piezo element 61 is extended, as shown in FIG. When the real image 62 shifts to the left and the piezo element 61 is contracted, the parallel plate glass 19 'tilts to the right and the real image 62 shifts to the right.

In the embodiment shown in FIG. 5 of the method of shifting the detecting element with respect to the displacement image, a piezo element 63 is used as a driving means of the detecting element 5, and a voltage is applied to the piezo element 63 to When 63 is expanded and contracted,
The detection element 5 itself shifts and operates 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 driving circuit 71,
The piezo element 61 or 63 is driven.

As shown in FIG. 2, the detecting element 5
A linear image sensor is used. Therefore,
When the detection element 5 detects an image, the detection signal 90 becomes the pixel 9
The brightness at each position is converted into an electric signal in the order of 1 → 92 → 93 → 94 and output. In the comparison test shown in FIG. 11, the 91st pixel at the point 55 must be compared with the detection signal of the 91st pixel at the point 53. Therefore, when the position of the wafer stage 16 (the output of the X-direction position detector 17 in FIG. 1) becomes x _s2 −a, the scanning of the detecting element 5 is reset so that the scanning is started from the 91st pixel. That is, when the X-direction scanning start signal 73 shown in FIG. 7 is output, the scanning of the detecting element 5 is reset by the reset signal generation circuit, and the ninth scanning is started.
Start from one pixel.

Even when the wafer stage 16 is reciprocated at a high speed by the above operation, the delay signal 7b shown in FIG.
Since there is an image signal at the same location on a, the difference signal becomes zero if there is no foreign matter or pattern defect. By detecting the difference signal, a minute foreign matter or a pattern defect can be detected.

The above description has been made of the case where the displacement of all the chips on the wafer is detected. However, in practice, the correction may be made for each exposure unit of the exposure apparatus when the chips are formed. For example, FIG.
Is 20 × 20 mm, the X and Y directions are 2
The positions of the reference marks may be obtained at 0 mm intervals. Thereby, the time for detecting the position of the reference mark can be reduced.

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

In this embodiment, the positions of the reference marks 22 of all the chips 20 of the wafer 1 are not determined first, but the positions of the reference marks 22 are determined when A → B, and the image position is determined using the coordinate values. While shifting in the X and Y directions
It is also possible to scan in the order of → D → E → F → G → H → I, then obtain the position of the next reference mark 22 at the time of scanning I → J, and continue the following scanning. Thereby, the inspection time as a whole can be shortened.

In the above description, the case where the semiconductor laser is used to illuminate obliquely has been described. However, as another embodiment, a xenon lamp, a mercury lamp, a halogen lamp, or a tungsten lamp is used as an illumination light source, and the surroundings are uniformly dark. Field illumination may be performed to detect foreign substances or pattern defects.

Also, instead of oblique illumination and dark field illumination,
The wafer 1 may be vertically illuminated by the mercury lamp 203 in FIG. 1 and the specular reflection light may be detected by the detection element 5. As the illumination light, in addition to the mercury lamp 203, a halogen lamp, a xenon lamp, a tungsten lamp, a laser, or the like may be used.

[0062]

The arrangement error of the chips on the LS1 wafer is as follows.
Since there is usually ± 0.3 to 0.4 μm, it was difficult to compare and inspect the two chips. According to the comparative inspection method of the present invention, an alignment error of each chip is obtained by detecting a reference mark of each chip, and when inspecting for a foreign substance or a pattern defect, any of the image of the chip and the detection element is determined by the alignment error. After detecting the image while shifting the image, the difference between the image signals of the two chips is obtained. When a mismatch signal is output, it is determined that there is a foreign substance or a pattern defect. ± 0.1
Since the measurement can be performed with an accuracy of μm, a comparative inspection with this accuracy can be performed. For this reason, 0.3 to 0.4, which was conventionally difficult,
There is an effect that a minute foreign matter or a minute pattern defect of about μm can be detected.

According to the comparative inspection method of the present invention, during scanning of the chip, the reference mark in the chip is illuminated by using a strobe, and the detected image is instantaneously detected by the accumulation type image pickup device. Or a TV camera with a shutter is used for instantaneous detection, and then an image signal is read from the image sensor to determine the position of the reference mark. Thus, there is an effect that the inspection can be performed efficiently.

Further, according to the comparative inspection method of the present invention, when inspecting for foreign matter or pattern defects by the detection element,
Since the substrate is vertically illuminated by epi-illumination and specularly reflected light is detected by the detection element, there is an effect that a fine foreign substance or a fine pattern defect can be further inspected.

As described above, the comparative inspection method of the present invention makes it possible to detect a foreign substance or a pattern defect of 0.3 to 0.5 μm.
(Applied to AM, etc.), and to greatly improve the yield during mass production.

Further, according to the comparative inspection apparatus of the present invention, since the image shift means for shifting the image of the chip is provided between the objective lens and the detection element on the substrate, the above method can be performed accurately. effective.

According to the comparative inspection apparatus of the present invention, instead of the image shifting means, the detecting element itself is provided with a driving means for shifting the detecting element in the direction of the displacement of the image of the chip. This also has the effect that the above method can be performed accurately.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an apparatus for performing a 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 shift;

FIG. 4 is an explanatory view of the operation,

FIG. 5 is a perspective view showing another embodiment of the image shifting method.

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

FIG. 7 is a system diagram of a control system of a device for detecting foreign matter on a patterned wafer and a pattern defect,

FIG. 8 is an explanatory diagram of a fiducial mark on a chip of a wafer;

FIGS. 9A to 9D are explanatory diagrams of a method of detecting reference mark coordinates.

10 (a) and (b) are explanatory diagrams of a fine inspection method of reference mark coordinates,

FIG. 11 is an explanatory diagram of chip displacement and detection position shift;

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer, 3a-3d ... Semiconductor laser, 4 ... Objective lens, 5 ... Detection element, 7a ... Previous chip, 8 ... Detection area on chip, 9a ... Chip currently detected, 11 ...
Strobe, 14 dichroic mirror, 15 TV camera, 16 wafer stage, 17, 18 X, Y direction position detector, 19 parallel plate for image shift, 201 delay memory, 202 binarization circuit, 7b ... Delay signal, 9b
... image signal is detected currently, 203 ... mercury lamp for vertical incident illumination, 20 ... chips, 22 ... reference marks, 30 ... reference mark detection microscope, 36 ... microcomputer, 37 ... TV monitor, y _s2 -y _s1, y _s3 −y _s2 … tip displacement, 6
Reference numeral 1 denotes a parallel plate piezo element for image shift, and 63 denotes a piezo element for driving a detection element.

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[Procedure amendment]

[Submission date] July 11, 2000 (2007.1.
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

The object of the present invention is to inspect a large number of chips of the same shape formed on a substrate, and to detect foreign matter on the substrate or a pattern defect in the chip, thereby continuously connecting the substrate. Detecting a position of a reference mark formed at a predetermined position on the substrate while moving the substrate to determine an arrangement error of the chips; and One of them
Imaging one chip to obtain an image of the one chip and storing the obtained image; and imaging the other chips of the plurality of formed chips while continuously moving the substrate. Obtaining the image of the other chip, and correcting the difference between the stored image of the one chip and the image of the other chip obtained by imaging based on the information on the obtained alignment error, A step of comparing the stored image of one chip and the image of the other chip in which the arrangement error has been corrected to obtain a difference between the two images; and This is achieved by detecting the foreign matter or the pattern defect by the step of detecting the foreign matter or the pattern defect.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009] Further, as an apparatus configuration, a stage means for mounting the substrate thereon and capable of moving in the X and Y directions in a plane, and a method for continuously moving the substrate mounted on the stage means. Detecting means for picking up an image of a pattern of a plurality of chips formed on the substrate and detecting an image of the pattern as an image signal; and one of the chips formed by the plurality of chips detected by the detecting means Storage means for delay-storing the image of the pattern, and a reference mark image formed corresponding to each of the one chip and the other chips among the plurality of chips detected by the detection means. An array error calculating means for obtaining an array error between the chips, and a shift between the image of the one chip and the image of the other chip is compensated based on information of the array error calculated by the array error calculating means. A shift correction unit, and the image of the pattern of the one chip stored in the storage unit and the other chip detected by the detection unit in a state where the alignment error is corrected by the shift correction unit. Difference image detection means for obtaining a difference from the image of the pattern, and defect detection means for detecting a foreign substance on the substrate or a pattern defect in the chip based on the difference between the images obtained by the difference image detection means This is achieved by configuring to have the following.

Claims (2)

[Claims] 1. A method for inspecting a plurality of chips having the same shape formed on a substrate to detect foreign substances on the substrate or pattern defects in the chips, wherein the substrate is continuously moved. Detecting a position of a reference mark formed at a predetermined position on the substrate to determine an arrangement error of the chips; and one of the plurality of chips formed while moving the substrate continuously. Imaging the one chip to obtain an image of the one chip and storing the obtained image; and while continuously moving the substrate, imaging the other chip of the plurality of formed chips and Obtaining an image of the chip, correcting the displacement between the stored image of one chip and the image of the other chip obtained by imaging based on the obtained information of the alignment error, and Note that the error was corrected Comparing the image of one chip and the image of the other chip with each other to determine a difference between the two images; and determining a foreign substance or the pattern defect on the substrate based on information on the determined difference between the two images. And a step of detecting the following. 2. An apparatus for inspecting a large number of chips having the same shape formed on a substrate to detect a foreign substance on the substrate or a pattern defect in the chip. A stage means which can be moved in the X and Y directions, and a detecting means which detects a pattern of chips formed on the substrate mounted on the stage means and outputs an image of the pattern as an image signal. Storage means for delay-storing the image of the pattern detected by the detection means, and a reference mark of the reference mark formed corresponding to at least two of the plurality of chips formed by the detection means. An array error calculating means for calculating an array error between the at least two chips from an image, and an array error calculated by the array error calculating means, Image shifting means for correcting the pattern by optically shifting the optical image of the pattern, and one of the plurality of chips formed in the storage means, wherein the arrangement error is corrected by the image shifting means. Difference image detection means for obtaining a difference between an image of a pattern of one chip and an image of a pattern of another chip among the large number of chips detected by the detection means, and the image obtained by the difference image detection means A defect detecting means for detecting a foreign substance on the substrate or a pattern defect in the chip based on a difference between the two.