JP2000357719A - Method and device for inspecting substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To analyze the original state by imaging a defect on a substrate surface at a magnitude for discrimination, recording the picture corresponding to the position coordinate of an imaged point, and then image-processing for the position coordinate of the defect, so that the original condition of the current defect position is confirmed based on it. SOLUTION: An inspection device 100 comprises a position control means 4 for placing a semiconductor substrate 2, position storing means 6, camera 7, image processing means 9, comparison means 13 between an image data 10 and a reference data 12, coordinate calculating means 16, and defect coordinate recording means 18, etc. Further, a picture recording means 130 which records a picture signal 8 of the camera 7 by relating to a position coordinate data 15 for an X-Y table 3 at imaging, and a regenerating means 140 which regenerates/displays the picture on a monitor 21, are provided. A signal switching means 120 selectively connects the picture signal which represents a defect position coordinate outputted by a picturizing means 19 in dots, the picture signal 8 outputted from the camera 7, and the picture signal from a regenerating means 140 to the monitor 21 for re-observing the appearance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor substrate,
In particular, the present invention relates to a method of external appearance inspection and defect analysis such as adhesion of foreign matter, scratches and misalignment, and an inspection apparatus used therefor.

[0002]

2. Description of the Related Art Semiconductor substrates are processed through a number of manufacturing steps. Since a fine pattern deformed on the surface in the middle of the process makes the element including the defect defective, it is necessary to find such a defect and take measures to reduce the occurrence thereafter. Therefore, an inspection device that automatically finds such defects is used. FIG. 2 is a block diagram conceptually showing this. The conventional inspection apparatus 1 includes an XY table 3 on which a semiconductor substrate 2 is placed and moved in XY.
The XY table 3 is also movable in the rotation (θ) direction so that the direction of the semiconductor substrate 2 placed thereon can be adjusted to the X axis and the Y axis. An XY table position control means 4 for moving the XY table 3 while controlling it with high accuracy is provided. The XY table position control means 4 uses the current X
-Outputs the position information 5 of the Y table. Then, the table position storage means 6 stores the current XY as a digital value.
The position coordinates of the table are stored.

On the other hand, above the XY table 3, a camera 7 for enlarging and photographing a narrow portion of the surface of the semiconductor substrate 2 is arranged. The video signal 8 outputted therefrom is subjected to a binarization process or the like by the image processing means 9 to obtain image data 10 which can be easily compared.

[0004] Reference data recording means 11 is provided,
The image data when there is no defect is the reference data 12.
Is recorded as

The image data 10 and the reference data 12
Are compared by the comparing means 13, and a portion having a difference between the two is recognized as a defect. Then, the position coordinate data 14 of the defect in the image is output. Then, the position coordinate data 14 in the image of the defect and the position coordinate data 15 of the current XY table stored in the table position storage means 6 are stored.
The coordinate value of the defect on the semiconductor substrate 2 is calculated by the coordinate calculation means 1.
The defect coordinate recording means 18 records the position coordinate data 17 of this defect for each defect.

[0006] Then, the image forming means 19 converts the data into a video signal as a plot image and converts the data into a signal switching means 20.
The position of the defect is displayed as a point on the monitor 21 through the monitor.

[0007] The video signal 8 from the camera 7 is provided to a monitor 21 via a signal switching means 20 so that the surface of the semiconductor substrate 2 can be observed on the monitor 21.

A control means for controlling these means and input means such as a keyboard and a mouse attached thereto are provided, but are not shown.

A description will be given of a defect inspection method using the conventional inspection apparatus configured as described above. (1) First, the semiconductor substrate 2 to be inspected is placed on the XY table 3 and the pattern arrangement direction is adjusted to the moving direction (X axis, Y axis) of the XY table. Then, with the specific position (for example, a specific pattern around the center) of the semiconductor substrate 2 aligned with the specific position (for example, the intersection of the cross line of the camera 7), the coordinate origin of the XY table is obtained. (2) Then, the feed pitch of the XY table is set. The feed pitch is determined based on a balance between the pattern pitch (chip size) of the semiconductor substrate and the field of view of the camera 7. In other words, the same pattern is observed periodically to such an extent that the fields of view slightly overlap (there is no place where observation is impossible). For example, a feed pitch is set to be an integer fraction of the pattern pitch. (3) Next, the reference data recording means 11 stores the reference data 12
Write. When one chip pattern is divided into a plurality of observation fields and observed, it must be recorded for each observation. Various methods have been proposed. For example, a method may be used in which the captured image is confirmed on the monitor 21 without any defect by a person, and the data of the screen is recorded. As an automatic method, a method of sequentially comparing image data at a plurality of locations at the same pattern position and recording the image data as a correct pattern if there is no difference, or comparing the image data at the same pattern position at a plurality of locations with each other Since the method of selecting the pattern that seems to be the most correct has been announced, such a way is fine. (4) After the preparation as described above, the XY table 3 is moved (by feeding at a set pitch) to place the end of the semiconductor substrate 2 in the field of view of the camera 7 set to a predetermined magnification and start. Are sequentially photographed and subjected to image processing and compared with the reference data 12. If a defect is found, the position coordinate data 17 is recorded in the defect coordinate recording means 18, and this is shown on the monitor 21. The situation will be described in more detail with reference to FIG. 3 showing a screen of the monitor 21. The outline 30 of the semiconductor substrate is displayed. However, this is not obtained by observing the outer periphery of the true semiconductor substrate 2 but is an outer shape obtained by calculating the diameter of the semiconductor substrate and the position coordinates of a specific pattern. Observation is performed while moving at a predetermined pitch in the X direction from the visual field 31 at the start position indicated by the broken line, and the found defect is displayed at points 32a, 32b, and 32c indicating the position of the defect. Then, when reaching the end of the semiconductor substrate, the line is changed in the Y direction and moved in the −X direction. And at the current observation position, the field of view 33
Is displayed, and if there is a defect, a point 32d indicating the position is also displayed. Then, when the inspection over the entire surface of the semiconductor substrate 2 is completed, points 32a and 32 indicating the positions of the defects are provided.
b ... are all displayed. (5) When analyzing the content of the defect, if automatic observation is designated, the XY table 3 moves so that points 32a, 32b,... Indicating the defect position are sequentially positioned at the center of the field of view of the camera 7. At the same time, the signal switching means 20 supplies the video signal 8 to the monitor 21 so that a person can observe and analyze the defect. In this case, observation with changing the magnification of the camera 7 is also free. When the observation of one point is completed, the semiconductor substrate 2 moves to the next defective point by a simple command such as pressing a return key of a keyboard. In the case where one semiconductor substrate 2 has a large number of defects, it is not necessary to observe all the points, so that the observation may be performed by sampling. In this case, if the position coordinates of the defect are indicated by dots on the screen, for example, if the position is designated by a mouse pointer, the semiconductor substrate moves to a position where the point is photographed.

As described above, a person observes a defective portion on a monitor screen, analyzes the content, estimates the cause, and contributes to the subsequent measures.

Then, the position coordinate data 1 of those defects
Since 7 is recorded in the defect coordinate recording means 18, if the semiconductor substrate remains, the appearance of the defective portion can be observed again.

[0012]

However, although the inspection apparatus described above records the position coordinates of a defect, it does not record an image or an image obtained by processing the image. I can't see how it was before. For example, when two inspections are performed as in a first inspection step in which a similar inspection is performed in a relatively earlier step and a second inspection step in which a similar inspection is performed at a relatively later step, the first inspection step is conspicuous. When a large number of defects are detected in the second inspection step and the defects are not detected in the second inspection step, as a result of the external observation of the defect location on the monitor screen in the second inspection step, those defects are found in the first inspection step. If it can be concluded that the error occurred in a step between the step and the second inspection step, the result can be fed back to the step and used for a countermeasure. However, it is difficult to know in which process it occurred. For example, there was a small thing that could not be detected as a defect, such as a nucleus or an origin, which did not exist at all in the first inspection step, and that grew in subsequent steps. Often, you want to check. However, the semiconductor substrate observed in the first inspection step has already been worked on up to the second inspection step, so there is no same semiconductor substrate. And
There is no record of the video. Further, since the appearance of a non-defective part is not normally observed, it is not stored in the human memory.

In view of the above, the present invention provides an inspection apparatus having a function of recording a defect position coordinate in a conventional inspection apparatus having a function of recording an image so as to correspond to the position coordinate data. The present invention provides an inspection method for checking a previous state and analyzing a defect as necessary, even if construction is performed and the original state is not maintained.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a semiconductor substrate manufactured through a plurality of manufacturing steps. Photographing the surface of the semiconductor substrate at an identifiable magnification, recording an image in correspondence with the position coordinates of the photographing location, and performing the above-described second manufacturing process after the first manufacturing process. Photographing the surface of the semiconductor substrate on which the image of the surface was recorded in the first manufacturing process, obtaining the position coordinates of the defect by performing image processing, and recording the position coordinate data thereof; Selecting and reproducing the video recording containing the position based on the position and confirming the position of the current defect on the monitor in the first manufacturing process. It provides a test method of a semiconductor substrate to be. According to this inspection method, even if the cause of a defect or the like detected in the inspection in the second manufacturing process is difficult to understand only by observing the external appearance at that time, the image of the previous process is observed while leaving it. In some cases, it is easy to analyze.

In order to perform such an inspection, the present invention provides an XY system in which a semiconductor substrate is placed and moved to XY.
A table and an XY table.
A camera for photographing the surface of the semiconductor substrate mounted on the table, and reference data recording means for recording image data corresponding to a pattern having no defect as reference data,
Comparing the image data obtained by performing image processing on the video signal output from the camera and the reference data, recognizing a portion having a difference between the two as a defect, and calculating position coordinate data of the defect in the image, The operation of calculating the coordinate value of the defect on the semiconductor substrate with the position coordinate data of the XY table and recording the defect coordinate data in the defect coordinate recording means is performed by sending the XY table at a predetermined feed pitch. Repeat
By specifying the coordinate data value of the defect, XY
In an inspection apparatus configured to move a table to position the position within a field of view of the camera and to display an image on the monitor, an image signal output from the camera is converted into an XY image at the time of shooting. Provided is an inspection apparatus characterized by including video recording means for recording in association with position coordinates of a table and reproduction means for reproducing and displaying the video on a monitor. According to this inspection apparatus, not only the position coordinates of the defect but also the image are recorded, so that the processing of the semiconductor substrate proceeds, and the appearance can be observed without maintaining the original state.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of an inspection apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram conceptually showing this. The same parts as those of the conventional inspection apparatus shown in FIG. The inspection apparatus 100 includes an XY table 3 on which the semiconductor substrate 2 is placed and which moves in the XY direction, an XY table position control means 4 which controls the XY table 3 with high precision, and A table position storage means 6 for storing the position coordinates of the Y table as digital values, a camera 7 for photographing the surface of the semiconductor substrate 2, an image processing means 9 for processing a video signal 8 outputted therefrom, an image in the case where there is no defect Reference data recording means 1 in which data is recorded as reference data 12
1. Comparison means 13 for comparing the image data 10 output from the image processing means 9 with the reference data 12, coordinate calculation means 16 for calculating the position coordinate value of a defect, and recording the position coordinate data 17 of this defect for each defect Defect coordinate recording means 18,
The imaging means 19 for converting the data into a video signal as a plot image, the monitor 21 and the like may be the same as those of the conventional apparatus shown in FIG.

As a feature of this apparatus, the position coordinate data 1 of the XY table 3 when the image signal 8 of the camera 7 is photographed is taken.
5 and a reproducing means 140 for reproducing and displaying the video on the monitor 21.
These video recording means 130 and reproduction means 140 may be, for example, a video tape recorder. Preferably, random access like a hard disk is more convenient.

The signal switching means 120 in the apparatus includes a video signal indicating the position coordinates of the defect output by the imaging means 19 as a point and a video signal 8 output from the camera 7.
And a video signal from the reproducing means 140 is selectively connected to the monitor 21.

A control means for controlling these means and input means such as a keyboard and a mouse are provided, but are not shown.

A description will be given of a defect inspection method using the inspection apparatus 100 of the present invention configured as described above. A plurality of appearance defects (for example, two times in a first inspection step which is a relatively earlier step and a second inspection step which is a relatively later step) in a manufacturing process of a semiconductor substrate manufactured through a plurality of manufacturing steps. (1) First, the semiconductor substrate 2 to be inspected is placed on the XY table 3 and the pattern arrangement direction is changed to the moving direction of the XY table (X-axis). , Y axis). Then, the coordinate origin of the XY table is determined in a state where a specific position (for example, a specific pattern around the center) of the semiconductor substrate is aligned with a specific position (for example, an intersection of a cross line of the camera 7). (2) Then, the feed pitch of the XY table is set. The feed pitch is determined based on a balance between the pattern pitch (chip size) of the semiconductor substrate and the field of view of the camera 7. In other words, the same pattern is observed periodically to such an extent that the fields of view slightly overlap (there is no place where observation is impossible). For example, a feed pitch is set to be an integer fraction of the pattern pitch. (3) Next, the reference data recording means 11 stores the reference data 12
Write. When one chip pattern is divided into a plurality of observation fields and observed, it must be recorded for each observation. The method is the same as that of the above-described conventional apparatus. (5) After the preparation as described above, the XY table 3 is moved (by feeding at the set pitch) to place the end of the semiconductor substrate 2 in the field of view of the camera 7 set to a predetermined magnification and start. Are sequentially photographed and subjected to image processing and compared with the reference data 12. If a defect is found, the position coordinate data 17 is recorded in the defect coordinate recording means 18, and this is shown on the monitor 21. The situation is the same as in the case of the conventional device described above. At the same time, the video recording means 130 records each shooting screen. (6) When analyzing the content of the defect, if the automatic observation is designated, the point indicating the defect position (32 in FIG. 3)
a, 32b...) are sequentially moved to the center of the field of view of the camera 7, and the signal switching means 120 provides the video signal 8 to the monitor 21 so that a person can observe and analyze the defect. . In this case, observation with changing the magnification of the camera 7 is also free. When the observation of one point is completed, the semiconductor substrate moves to the next defective point by a simple command such as pressing a return key of a keyboard. If there is a large number of defects on one semiconductor substrate, it is not necessary for a person to observe all the points, so it is sufficient to observe them in a sampling manner. In this case, the position coordinates of the defects are represented by dots. For example, if the user designates a point on a screen with a mouse pointer, the semiconductor substrate moves to a position where the point is photographed. (7) As described above, a person observes a defective portion on a monitor screen, analyzes the inside, estimates a cause, and uses the result for subsequent measures. (8) Then, the processing for the semiconductor substrate 2 proceeds,
In the second inspection process, the steps (1) to (5) are performed in the same manner. Then, the same defect analysis as in the step (6) is performed. As a result, if the cause of the defect is understood, it is used for a countermeasure. If it is not possible to make a clear analysis and want to check what the appearance was at the time of the first inspection step, the position coordinates of the defect to be checked out of the video recordings recorded in the first inspection step Is reproduced on the call monitor 21 and checked. Therefore, it was possible to confirm whether the defects found in the second inspection process were completely absent in the first inspection process, or that there were small origins that could not be detected as defects, and that they grew in subsequent processes. Therefore, it is useful for estimating the cause process.

[0021]

According to the inspection apparatus of the present invention, each image screen shot by the camera can be recorded irrespective of the presence or absence of a defect, and the position coordinate data of the defect is also recorded. Even if the semiconductor substrate has not progressed through the process and has not retained its shape, the external appearance can be observed again. According to the inspection method of the present invention using the inspection apparatus when performing the appearance inspection a plurality of times, the position of the defect is set to the position of the previous defect in order to analyze the cause of the defect found in the subsequent inspection process. At the time of the inspection process, it is possible to confirm what the condition is, and analysis becomes easy.

[Brief description of the drawings]

FIG. 1 is a block diagram conceptually showing an example of an inspection apparatus according to the present invention.

FIG. 2 is a block diagram conceptually showing a conventional inspection apparatus.

FIG. 3 is a monitor screen during inspection.

[Explanation of symbols]

 Reference Signs List 2 semiconductor substrate 3 XY table 7 camera 8 video signal from camera 9 image processing means 11 reference data recording means 10 image data 12 reference data 13 comparing means 14 position coordinate data of defect in image 15 XY table Position coordinate data 16 Coordinate calculating means 17 Coordinate data of defect on semiconductor substrate 18 Defect coordinate recording means 21 Monitor 100 Inspection device 120 Signal switching means 130 Video recording means 140 Reproduction means

Claims (2)

[Claims] In a desired first manufacturing process in a manufacturing process of a semiconductor substrate manufactured through a plurality of manufacturing processes, a surface of the semiconductor substrate is photographed at a magnification at which a defect generated in the semiconductor substrate can be identified. Recording an image in correspondence with the position coordinates of: a semiconductor substrate on which an image of the surface has been recorded in the first manufacturing step in a desired second manufacturing step which is a post-step of the first manufacturing step; Photographing the surface, performing image processing to determine the position coordinates of the defect and recording the position coordinate data, and selecting and reproducing the video recording including the position based on the position coordinate data of the defect. Checking the position of the current defect on the monitor in the first manufacturing process. 2. An X-moving device, wherein a semiconductor substrate is placed and moved in XY.
A Y-table, a camera arranged above the XY-table, for photographing the surface of the semiconductor substrate placed on the XY-table, and image data corresponding to a pattern without defects are recorded as reference data. A reference data recording unit, comparing image data obtained by performing image processing on a video signal output from the camera with the reference data, recognizing a portion having a difference between the two as a defect, and detecting a defect in the image. The operation of calculating the position coordinate data, calculating the coordinate values of the defect on the semiconductor substrate with the position coordinate data of the XY table, and recording the coordinate data of the defect in the defect coordinate recording means is performed by the XY method. By sending the table at a predetermined feed pitch and repeating, and specifying the coordinate data value of the defect, XY
In an inspection apparatus configured to move a table to position the position within a field of view of the camera and to display an image there on a monitor, a video signal output from the camera is converted into an X-
An inspection apparatus comprising: video recording means for recording in association with position coordinates of a Y table; and reproducing means for reproducing and displaying the video on a monitor.