JPS60126830A - Scanning method for defect inspecting device of pattern - Google Patents

Abstract

PURPOSE:To prevent the deviation in the line direction to an image and to perform a higher- precision defect inspection on a pattern by a method wherein the scanning is performed in a condition that a one-dimentioal line sensor, which is used for scanning, has been inclined at a constant angle to the scanning region in a body to be inspected. CONSTITUTION:An image sensor 23 consisting of a bit array of one line component is supported by a supporting stand 50 and the sensor 23 is provided in such a rotatable state as indicated by right and left arrows with the axis 51 thereof as a center. One ed of the supporting stand 50 is energized to the downward direction by a spring 52 and one end of a rotating shaft 53 is sbutted in close contact to the lower edge of the suporting stand 50 between the axis 51 and the spring 52. The other end of the rotating shaft 53 is energized to the downward direction by a spring 54, and at the same time, is abutted on an eccentric cam 55. The eccentric cam 55 is rotated by a motor 56 under the control of the control unit and holds the image sensor 23 in a condition that the sensor 23 has been inclined at a constant angle to the scanning region in a body to be inspected. The image sensor 23 is inclined clockwise by a constant angle, which is decided by the scanning rate in the Y direction, and when an ordinary scanning is performed, scanning data, in which a deviation to the scanning region has been prevented, are obtaind. Moreover, as an image enlarged to 25 times has been projected on the image senosr 23, a higher-precision defect inspection on the pattern becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pattern defect inspection apparatus, and more particularly to a scanning method used in a reticle pattern defect inspection apparatus used in the manufacture of semiconductor integrated circuits.

In order to inspect defects in a reticle pattern conventionally created by placing a mask in close contact with a silicon wafer and photoetching it, the applicant filed a patent application filed in Japanese Patent Application No. 56-1.
No. 44740, PG (Pattern Generation) used when creating a mask master
) We are developing a device that can perform highly reliable defect inspection by comparing the information stored on the tape with the actual pattern produced based on this tape.

However, in this device, the one-dimensional line sensor used for scanning is placed parallel to the X direction of the scanning area in the subject, and scanning is performed while the subject is continuously moved in the Y direction. Therefore, as shown in Figure 1,
There was a problem that the beginning and end of one line of scanning data were shifted with respect to the scanning area. This deviation is 1μm for the width 11000I1 in the X direction, assuming that the size of the unit pixel is 1μm.
This is not a problem for conventional patterns that do not require a high pattern density, but for recent ICs.

When detecting defects in high-density patterns such as LSIs, it has become a problem of manpower.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a scanning method for use in a pattern defect inspection apparatus that can prevent deviation of scan data from a scan area and perform highly accurate defect inspection.

The scanning method of the present invention detects defects in a pattern of an object to be inspected, particularly defects in a pattern of a mask used for manufacturing semiconductor integrated circuits, using reference information read from a recording medium that stores reference information corresponding to the pattern of the object to be inspected. In the defect inspection method that automatically detects defects by comparing the pattern with the scanning information obtained by actually scanning the pattern of the object, the one-dimensional hollow sensor valley used for scanning, and the scanning area in the object. This is characterized in that scanning is performed with the camera tilted at a constant angle to prevent deviations in the line direction from the image.

The present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram showing the overall configuration of a pattern defect inspection apparatus that implements the scanning method of the present invention. The overall configuration can be broadly classified into stage units 10. Video signal conversion unit 30. It consists of three units, control units 1 to 40. The operation of each part will be briefly explained below in the order described above.

First, in the stage unit 10, a pattern (for example, a reticle pattern, etc.) of the object 18 is irradiated with light from a light source 11, and the transmitted light is incident on an image sensor 23 consisting of a bit array to obtain one line of scanning data. After obtaining the scan data, the scan data is output to the control section 40. The image sensor 23 is kept tilted at a constant angle with respect to the scanning area in the subject by the sensor rotation unit 24. This tilt angle is controlled by the control unit 40 in accordance with the moving speed of the table, etc. The objective lens 17 equipped with an automatic focusing mechanism 14 magnifies the transmitted light by, for example, 25 times, and rotates in the opposite direction to the X direction depending on the direction of scanning. The autofocus IN structure used in this example is based on Japanese Patent Publication No. 54-3134 by the applicant.
This mechanism is the same as that proposed in Publication No. 8. Selection and scanning of the scanning area are performed using the X table 15. This is carried out by driving the Y table 16 by a drive mechanism 13.12. The X and Y tables 15 and 16 are controlled by detecting their movements with linear encoders 19 and 20 and supplying them to the C stage position collector 21. Here, a deviation in the X and Y directions is detected, and a correction signal obtained from the deviation is supplied to each drive mechanism 13.12.

Correction in the Y direction is performed. In addition, since this correction has a problem in terms of accuracy, especially in the X direction, a correction signal for the deviation in the X direction from the stage position collector 21 is supplied to the image sensor driver 22 to image the Of the light incident on the P1 array in the sensor 23, the remaining 12 bits at the left end and right end are used to obtain scanning data at 1,000 points by shifting them to account for the error.

Next, the video conversion unit 30 in FIG. 2 will be explained. PG tape created by CAD system etc.
It is converted into an inspection reticle tape 31 having the format of this system and supplied to a video conversion unit. After this reticle tape 31 is attached to the tape unit 32, the file at the location corresponding to the reticle mask 18 being inspected on the stage section 1o is transferred via the magnetic tape control section 36 under the control of the CPU in the control unit 40. It is read from the reticle chip 731 and stored in one of two magnetic tape memories. Based on the coordinate group of points on the reticle tape 31 stored in this magnetic tape memory, the video signal converter 35 converts the coordinates into an image under the control of the synchronization signal from the magnetic tape controller 36, and then creates two images. It is stored in one of the video memories provided. The data stored in the video memory as an image is read out by the video signal output control section 39 in accordance with the portion scanned by the image sensor 23 of the stage section 1o under the control of the magnetic tape control section 36, and is read out by the video signal output control section 39 under the control of the magnetic tape control section 36 is output to the comparator 45.

Stage unit 10 created as described above. The power from both video conversion units 1 to 30 is supplied to a control unit 40. In the control unit 40, a comparator 45 compares the output signals in order to detect a defective part.

A signal after the comparison operation has been completed via the comparator 45 is supplied to a data processing section 47, where various processing is performed. The data processing unit 47 includes various I10 interfaces, R'AM,
It is composed of a ROM, a CPU, and a display section, and processed data is output from a printer 48. Further, each image is displayed on the monitors 41 to 44, and the processing thereof can be checked.

FIG. 3 is a perspective view showing the configuration of a sensor rotating section that implements the scanning method of the present invention. An image sensor 23 consisting of a bit array for one line is supported by a support base 50 and is rotatable about a pivot shaft 51 as shown by left and right arrows. One end of the support base 50 is biased downward by a spring 52, and one end of a rotating shaft 53 is in contact with the lower edge between the pivot shaft 51 and the spring 52. The other end of the rotating shaft 53 is biased downward by a spring 54 and is in contact with an eccentric cam 55. The eccentric cam 55 is the control unit 1
The image sensor 23 is rotated by a motor 56 under the control of 40 to keep the image sensor 23 tilted at a constant angle with respect to the scanning area. For example, when scanning is performed by moving the image sensor 23 downward, that is, by moving the subject stage upward, if normal scanning is performed by tilting the image sensor 23 clockwise by a certain angle determined by the scanning speed in the Y direction in FIG. Scan data can be obtained that prevents misalignment with respect to the region. At this time, it is difficult to tilt the image sensor at an angle that is deviated by 1 μm from 1000 μm with the sensor rotating part described above, but in this application, the image is magnified 25 times and projected onto the image sensor. In practice, the above-mentioned angle can be achieved by moving the end of the image sensor by 25 μm, and the sensor rotation unit of the present invention can be used. Furthermore, according to the scanning method of the present invention,
Since the sensor rotating section 24 has the above-described configuration, even if the scanning speed changes, the tilt angle can be easily changed in response to the change.

As is clear from the detailed explanation above, according to the scanning method used in the pattern defect inspection apparatus of the present invention,
Since the image sensor is scanned while being tilted at a certain angle with respect to the scanning area in the object, it is possible to prevent the scanning data from shifting with respect to the scanning area, thereby enabling highly accurate defect inspection.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the deviation of scan data with respect to the scan area, FIG. 2 is a block diagram showing the overall configuration of a pattern defect inspection apparatus that implements the scanning method of the present invention, and FIG. 3 is a diagram showing the scanning method of the present invention. FIG. 3 is a perspective view showing the configuration of a sensor rotation unit that implements the method. 10... Stage unit 30... Video signal conversion unit 40... Control units 1 to 5o... Support stand 51...
・Pivot 52.54...Spring 53...Rotation axis 55
...Eccentric cam 56...Motor.

Claims (1)

[Scope of Claims] 1. Defects in the pattern of the object to be inspected, particularly defects in the pattern of a mask used in the manufacture of semiconductor integrated circuits, are detected by reference information read from a recording medium storing reference information corresponding to the pattern of the object to be inspected. In a defect inspection method that automatically detects defects by comparing the pattern of the object and the scanning information obtained by actually scanning the pattern of the object, the one-dimensional line sensor used for scanning is A scanning method used in a pattern defect inspection apparatus, characterized in that scanning is performed at a fixed angle tilt to prevent deviation in the line direction with respect to the image. 2. A scanning method used in a pattern defect inspection apparatus, characterized in that the tilt angle can be freely selected. A scanning method used in a pattern defect inspection apparatus according to claim 1.