JPH04361548A - Method and device for defect detection - Google Patents

Abstract

PURPOSE:To detect a defect easily so as to prevent the occurrence of pseudo defects by a method wherein a comparing design pattern used for an automatic inspection in an automatic alignment process is selected and collated with an inspection pattern by comparison. CONSTITUTION:The X, Y dimensions of a mark are obtained from alignment data. Furthermore, the type of a mask 13 to be inspected on an XYtheta staage 14 is determined through a mask name recognition section 22 basing on the X, Y dimensional of the mark. A design pattern data group are converted into checking data by a reference data forming section 26 to obtain a reference data group. A design pattern corresponding to the type of the recognized mask 13 is fetched from the reference data group and compared with the pattern by a comparison circuit 25. By this setup, a design pattern correspondent to a specimen such as a mask to be checked can be automatically selected.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a defect inspection technique for determining the presence or absence of a defect by comparing a pattern formed on a photomask or the like with a designed pattern. The present invention relates to a defect inspection method and inspection device that recognize types.

0002

2. Description of the Related Art Conventionally, in order to inspect a pattern formed on a photomask or the like, a light beam is scanned over the mask and reflected light or transmitted light from the mask is detected to obtain pattern data to be inspected. The presence or absence of a defect has been determined by comparing and collating this inspected pattern data with the design pattern data.

Here, there are many types of mask patterns, and a design pattern corresponding to the pattern to be inspected must be selected in advance. This selection is made by the operator selecting a design pattern corresponding to the mask to be inspected from among the files.

However, this type of method has the following problems. That is, it is necessary to select a comparative design pattern corresponding to the mask to be inspected from the mask file, load the mask to be inspected into the device, and input the number, name, etc. on the data file of the corresponding design pattern. It takes time for the operator. Furthermore, if the operator incorrectly inputs the correspondence between the design pattern and the mask to be inspected, false defects will occur frequently, making it impossible to carry out actual inspection.

[0005] Furthermore, when carrying out continuous inspection of 10 sheets or the like, if the operator makes an operational error and sets the masks to be inspected one by one out of alignment with the input design data, all 10 sheets inspected continuously will be Pseudo defects occur frequently, resulting in a large loss of time.

[0006]

As described above, in conventional pattern defect inspection, it is necessary for the operator to select a comparative design pattern corresponding to the mask to be inspected.
This has led to complicated operations and the occurrence of false defects.

The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to automatically select a design pattern corresponding to a sample to be inspected, such as a mask to be inspected, and to enable easy operation. An object of the present invention is to provide a defect inspection method and an inspection apparatus that can facilitate the process and prevent the occurrence of pseudo defects.

[0008]

[Means for Solving the Problems] The gist of the present invention is that once a sample such as a mask to be inspected is set, a comparison design pattern is automatically created in the conventional auto-alignment process to be used for inspection. The purpose is to select the test pattern and compare and match it with the design pattern.

That is, the present invention measures the positions of a plurality of alignment marks formed on a sample, recognizes the position of a pattern formed on the sample from the measured position information, and In a defect inspection method that compares the pattern to be inspected and the design pattern based on information and determines the presence or absence of a defect in the pattern to be inspected, a difference in shape representing the type of pattern in some or all of the plurality of alignment marks is used. is set up, and during defect inspection, the shape of each alignment mark is measured to recognize the pattern type, a design pattern corresponding to the recognized pattern type is selected, and the selected design pattern and the inspected pattern are It is characterized by comparing patterns.

The present invention also provides a defect inspection apparatus for carrying out the above method, which includes a means for measuring the positions and shapes of a plurality of alignment marks formed on a sample, and a means for measuring the positions and shapes of a plurality of alignment marks formed on a sample, and a means for measuring the positions and shapes of a plurality of alignment marks formed on a sample, and a means for measuring the positions and shapes of a plurality of alignment marks formed on a sample. means for selecting a design pattern corresponding to the pattern; means for detecting a pattern to be inspected by scanning a light beam over a pattern on a sample based on the measured mark position; The present invention is characterized by comprising a means for determining the presence or absence of a defect by comparing the design pattern with the design pattern obtained. Further, as desirable embodiments of the present invention, the following (1) to
(3) can be mentioned. (1) The size of the mark in the X and Y directions is used as the shape representing the pattern type expressed by the alignment mark. (2) The information expressed by the alignment mark is the pattern type and mask file information of the inspection data of the mask to be inspected. (3) The information expressed by the alignment mark is the pattern type and inspection level information of the mask to be inspected.

[0011]

[Operation] In addition to confirming the center position of the alignment mark in the conventional auto-alignment process, the dimensions of the alignment mark (X and Y direction dimensions) are recognized, and for example, the center position of the alignment mark dimension can be changed. The size can be changed on the order of several micrometers without any problem. Further, although the alignment mark is generally square, it can be made into a rectangle in each of the X and Y directions to provide a necessary number of types.

[0012]Although the number of alignment marks is four to recognize the pattern position and correct the expansion/contraction, the number can be increased as necessary, and the number of design data to be used can be determined according to the X and Y dimensions. Information such as name or information on inspection level (size of defect to be detected) is displayed.

[0013] From the information expressed by the dimensions of the alignment mark obtained during alignment, the name, inspection level, etc. indicating the design data of the mask to be inspected is recognized, and the design data and the automatically selected design data are recognized. Perform defect inspection while comparing.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a mask defect inspection apparatus according to an embodiment of the present invention. 11-16 in the figure
1 is an optical system for obtaining an inspection pattern, 11 is an illumination lamp, 12 is an illumination lens, 13 is a mask to be inspected, 14 is a sample stage, 15 is an objective lens, and 16 is an imaging device such as a CCD.

In the figure, 20 to 26 are circuit systems for determining the presence or absence of defects, 20 is a CPU that performs various controls, 21 is an XY dimension recognition unit that recognizes the dimensions of the mark in the X and Y directions from alignment information, 22 is a mask name recognition unit that recognizes the type of mask from the dimensions of the mark in the X and Y directions; 23 is a mark position recognition unit that recognizes the position of the mark from alignment information; and 24 is a mask that recognizes the position of the mask from the mark position. A position recognition section 25 is a pattern comparison section that compares the pattern to be inspected and a design pattern, and 26 is a reference data creation section for creating and storing a plurality of types of design pattern data.

FIG. 2 shows a schematic configuration of the mask 13 to be inspected. Alignment marks 1 to 4 are arranged at k pitches at the four corners of a square mask 13 with a length of L mm. In the center of the mask 13, an inspection pattern 5 is arranged.

The four alignment marks 1 to 4 have the same center coordinates, and their X and Y dimensions vary on the order of several μm, as shown in the alignment mark shape examples shown in FIGS. 3(a) to 3(d). It has become.

Here, each alignment mark 1 to 4 is
Both of them show 2 digits of information for the "mask name" in each of the X and Y dimensions, and 8 with 4 alignment marks.
It is designed to display digits of information.

Furthermore, the center coordinates of alignment marks 1 to 4 are the same when all inspection masks have the same size, and when performing alignment, it is only necessary to know the size as information about the mask to be inspected. After the alignment is completed, the "mask name" is recognized from the X and Y dimension measurement results of the mark, the design data is read out and inspected, and the inspection is performed by comparing the data with the imaged data recognized by the inspection device. Next, a pattern defect inspection method using the above device will be explained.

The light from the illumination lamp 11 is focused by the illumination lens 12 and irradiated onto the mask 13 to be inspected.
4 in one direction. Then, the transmitted light of the mask 13 is imaged on the image sensor 16 via the objective lens 15. Here, alignment information can be obtained by irradiating light onto the mark, and pattern information can be obtained by irradiating light onto the pattern.

First, light is irradiated onto the mark to obtain alignment information, and from this alignment information, the X and Y dimensions of the mark are determined by the XY dimension recognition section 21. Furthermore, from the X and Y dimensions of the mark, the mask name recognition unit 22
The type of mask 13 to be inspected on the Yθ stage 14 is identified.

[0023] Further, the reference data creation section 26 converts the design pattern data group inputted from the MT or the like into data used for inspection to obtain a reference data group. and,
The inspected mask 13 recognized above from the reference data group
The design pattern corresponding to the type is called and supplied to the pattern comparison section 25.

On the other hand, information on the pattern to be inspected is obtained from the output of the image sensor 16 by irradiating light onto the pattern,
The comparison circuit unit 25 compares this pattern to be inspected with the called design pattern. Then, the portions that do not match are determined to be defects. Here, before obtaining the pattern information, the mark position is recognized in advance from the alignment information by the mark position recognition unit 23, and then the mark position is recognized by the mask position recognition unit 24.
The mask position is recognized by Then, based on this position, the pattern to be inspected and the design pattern are compared.

As described above, in this embodiment, the type of mask to be inspected can be recognized from the X and Y dimensions of alignment marks 1 to 4, and a design pattern corresponding to the recognized mask can be selected. . Therefore, the operator can omit the operation of selecting a design pattern,
Moreover, inconveniences such as selecting an incorrect design pattern can be prevented. Therefore, it is possible to save labor in defect inspection, and furthermore, it is possible to perform efficient defect inspection by eliminating the occurrence of false defects due to operator error.

It should be noted that the present invention is not limited to the above-mentioned embodiments. The pattern information expressed by the alignment mark is not limited to the size of the X and Y dimensions, but can utilize differences in mark shape. Moreover, what is expressed by the mark shape is not limited to the mask name, but may also express the inspection level of the mask to be inspected, or even both the mask name and the inspection level. Further, in the embodiment, defect inspection of a pattern formed on a mask has been described, but the present invention can be applied to defect inspection of a pattern formed not only on a mask but also on a wafer or other sample. In addition, various modifications can be made without departing from the gist of the present invention.

[0027]

Effects of the Invention As detailed above, according to the present invention, once a sample such as a mask to be inspected is set, the auto-alignment process that has been carried out in the past will automatically set the sample for comparison to be used for inspection. It is possible to select a design pattern and compare and match the inspection pattern and the design pattern. Therefore, it is possible to realize a defect inspection method and inspection apparatus that can automatically select a design pattern corresponding to a sample to be inspected, such as a mask to be inspected, and that can facilitate operation and prevent the occurrence of false defects. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a pattern defect inspection apparatus according to an embodiment of the present invention;

FIG. 2 is a plan view showing the mark and pattern arrangement on the mask used in the example;

FIG. 3 is a schematic diagram showing an example of alignment marks on a mask.

[Explanation of symbols]

1 to 4...Alignment mark, 5...pattern, 11...Illumination lamp, 12...Illumination lens, 13...mask, 14...sample stage, 15...Objective lens, 16...Image sensor, 20...CPU, 21...XY dimension recognition section, 22...Mask name recognition unit, 23... Mark position recognition unit, 24...Mask position recognition unit, 25...Pattern comparison section, 26...Reference data creation section.

Claims (2)

[Claims] Claim 1: Measuring the positions of a plurality of alignment marks formed on a sample, recognizing the position of a pattern formed on the sample from the measured position information, and using the recognized position information as a reference. In a defect inspection method in which a pattern to be inspected and a design pattern are compared to determine the presence or absence of a defect in the pattern to be inspected, some or all of the plurality of alignment marks are provided with a difference in shape representing the type of pattern. Then, during defect inspection, the shape of each alignment mark is measured to recognize the pattern type, a design pattern corresponding to the recognized pattern type is selected, and the selected design pattern and the pattern to be inspected are A defect inspection method characterized by comparing. 2. Means for measuring the position and shape of a plurality of alignment marks formed on a sample; means for selecting a design pattern corresponding to a pattern to be inspected from the measured mark shape; means for detecting a pattern to be inspected by scanning a light beam over a pattern on a sample based on the position of the mark; and comparing the detected pattern to be inspected and the selected design pattern to determine the presence or absence of a defect. 1. A defect inspection device comprising: means for determining.