JP3017839B2 - Defect inspection method and inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection technique for judging the presence or absence of a defect by comparing a pattern formed on a photomask or the like with a design pattern, and more particularly to a pattern of a pattern to be inspected based on an alignment mark. The present invention relates to a defect inspection method and an inspection apparatus that recognize a type.

[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 on the mask, and reflected light or transmitted light from the mask is detected to obtain pattern data to be inspected. The presence / absence of a defect is determined by comparing the pattern data to be inspected with the design pattern data.

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

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 inspection target mask into the apparatus, and input the number, name, etc. in the data file of the corresponding design pattern, It takes operator time and effort. Further, if the operator inputs the correspondence between the design pattern and the mask to be inspected by mistake, pseudo defects occur frequently, and a substantial inspection cannot be performed.

When a continuous inspection of ten or the like is performed, if the mask to be inspected is shifted one by one with respect to the input design data due to an operation error of the operator, all of the ten consecutively inspected inspections are performed. Pseudo defects occur frequently, resulting in a large loss of time.

[0006]

As described above, in the conventional pattern defect inspection, it is necessary for an operator to select a comparison design pattern corresponding to a mask to be inspected.
As a result, the operation becomes complicated and pseudo defects are generated.

The present invention has been made in consideration of the above circumstances, and has as its object to automatically select a design pattern corresponding to a sample to be inspected, such as a mask to be inspected, and to operate it. It is an object of the present invention to provide a defect inspection method and an inspection device capable of facilitating the inspection and preventing occurrence of a pseudo defect.

[0008]

The gist of the present invention is to provide a comparative design pattern which is automatically used for inspection in a conventional auto alignment process by setting a sample such as a mask to be inspected. And comparing and comparing the inspection pattern with the design pattern.

That is, according to the present invention, the positions of a plurality of alignment marks formed on a sample are measured, the position of a pattern formed on the sample is recognized from the measured position information, and the recognized position is determined. In a defect inspection method for comparing a pattern to be inspected with a design pattern based on information to determine whether or not there is a defect in the pattern to be inspected, a difference in shape representing a pattern type is partially or entirely included in a plurality of alignment marks. Is provided, the shape of each alignment mark is measured at the time of defect inspection, the pattern type is recognized, a design pattern corresponding to the recognized pattern type is selected, and the selected design pattern and the inspection target are inspected. It is characterized by comparing with a pattern.

According to another aspect of the present invention, there is provided a defect inspection apparatus for performing the above method, wherein a means for measuring positions and shapes of a plurality of alignment marks formed on a sample and an inspection are to be performed based on the measured mark shapes. Means for selecting a design pattern corresponding to the pattern, means for scanning the pattern on the sample with a light beam on the basis of the measured mark position to detect the pattern to be inspected, and selecting the detected pattern to be inspected. Means for comparing the design pattern with the determined design pattern to determine the presence or absence of a defect. Further, as the preferred embodiment of the present invention, the following (1) ~
(3) (1) The size of the mark in the X and Y directions is used as the shape representing the pattern type represented by the alignment mark. (2) The information expressed by the alignment mark is the mask file information of the inspection data of the inspection target mask together with the pattern type. (3) The information expressed by the alignment mark is the inspection level information of the inspection target mask together with the pattern type.

[0011]

In addition to confirming the center position of the alignment mark in the conventional automatic alignment process, the size of the alignment mark (dimensions in the X and Y directions) is recognized, and for example, the center position of the alignment mark size is changed. Without changing the size on the order of several μm. Although the alignment mark is generally a square, a required number of types are provided by making the alignment mark a rectangle in each of the X and Y directions.

Although the number of alignment marks is four and pattern position recognition and expansion / contraction correction are performed, the number is increased as necessary, and the number of design data to be used according to the X and Y dimensions is increased. Information such as a name or information of an inspection level (defect size to be detected) is displayed.

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

[0014]

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

FIG. 1 is a schematic configuration diagram showing a mask defect inspection apparatus according to one embodiment of the present invention. In the figure, 11 to 16
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 image sensor such as a CCD.

In the figure, reference numerals 20 to 26 denote circuit systems for determining the presence / absence of a defect, 20 denotes a CPU for performing various controls, 21 denotes an XY dimension recognition unit for recognizing the X and Y dimensions of the mark from alignment information. Reference numeral 22 denotes a mask name recognizing unit for recognizing the type of the mask from the X and Y dimensions of the mark, 23 a mark position recognizing unit for recognizing the position of the mark from the alignment information, and 24 a mask for recognizing the position of the mask from the mark position. A position recognition unit, 25 is a pattern comparison unit that compares the pattern to be inspected with the design pattern, and 26 is a reference data creation unit 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 four pitches at four corners on a mask 13 having a length of L mm square. The inspection pattern 5 is arranged at the center of the mask 13.

The center coordinates of the four alignment marks 1 to 4 are the same, and the X and Y dimensions change on the order of several μm, respectively, as in the alignment mark shapes shown in FIGS. 3 (a) to 3 (d). It has become.

Here, each of the alignment marks 1 to 4 is
In both cases, the information of two digits of “mask name” is shown in each of the X and Y dimensions.
Digit information can be shown.

The center coordinates of the alignment marks 1 to 4 are the same when the size is the same for all the inspection masks, and when alignment is performed, only the size needs to be known as the information of the inspection target mask. After the alignment is completed, the "mask name" is recognized from the measurement result of the X and Y dimensions of the mark, the design data is read and inspected, and the inspection is performed by comparing the data with the image data recognized by the inspection apparatus.
Next, a pattern defect inspection method using the above apparatus will be described.

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

First, the mark is irradiated with light to obtain alignment information, and the X and Y dimensions of the mark are determined by the XY dimension recognition unit 21 from the alignment information. Further, the mask name recognizing unit 22 calculates X
The type of the inspection target mask 13 on the Yθ stage 14 is identified.

The reference data creation unit 26 converts the design pattern data group input from the MT or the like into data used for inspection to obtain a reference data group. And
Inspection mask 13 recognized from the reference data group
Are called and supplied to the pattern comparing unit 25.

On the other hand, by irradiating the pattern with light, pattern information to be inspected is obtained from the output of the image pickup device 16,
The test pattern and the called design pattern are compared by the comparison circuit unit 25. Then, a part that does not match is determined as a defect. Here, before obtaining the pattern information, the mark position is recognized in advance by the mark position recognition unit 23 from the alignment information.
Is used to recognize the mask position. Then, based on this position, the pattern to be inspected is compared with the design pattern.

As described above, in this embodiment, the type of the mask to be inspected can be recognized from the X and Y dimensions of the alignment marks 1 to 4, and the design pattern corresponding to the recognized mask can be selected. . Therefore, the operation of selecting the design pattern by the operator can be omitted,
In addition, inconveniences such as selecting an incorrect design pattern can be prevented. For this reason, it is possible to save labor in the defect inspection, and it is possible to perform the defect inspection efficiently without generating a pseudo defect due to an operator error.

The present invention is not limited to the embodiment described above. The pattern information expressed by the alignment mark is not limited to the size of the X and Y dimensions, but may use the difference in the mark shape. In addition, the expression using the mark shape is not limited to the mask name, but may be an expression indicating the inspection level of the inspection target mask, or both the mask name and the inspection level. In the embodiment, the defect inspection of the pattern formed on the mask has been described. However, the present invention is not limited to the mask and can be applied to the defect inspection of the pattern formed on a wafer or other samples. In addition, various modifications can be made without departing from the scope of the present invention.

[0027]

As described above in detail, according to the present invention, when a sample such as a mask to be inspected is set, a comparative sample which is automatically used for inspection in an auto alignment process which has been conventionally performed. It is possible to select a design pattern and compare and check the inspection pattern with the design pattern. Therefore, it is possible to automatically select a design pattern corresponding to a sample to be inspected such as a mask to be inspected, and to realize a defect inspection method and an inspection apparatus capable of facilitating operation and preventing occurrence of a pseudo defect. It becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing marks and pattern arrangement on a mask used in the embodiment.

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

[Explanation of symbols]

 1-4 alignment mark, 5 pattern, 11 illumination lamp, 12 illumination lens, 13 mask, 14 sample stage, 15 objective lens, 16 imaging element, 20 CPU, 21 XY dimension recognition unit Reference numeral 22: mask name recognition unit 23: mark position recognition unit 24: mask position recognition unit 25: pattern comparison unit 26: reference data creation unit

Claims (3)

(57) [Claims] 1. A method for measuring positions of a plurality of alignment marks formed on a sample, recognizing a 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 for comparing a pattern to be inspected with a design pattern to determine whether or not there is a defect in the pattern to be inspected, a difference in shape representing a pattern type is provided in a part or all of the plurality of alignment marks. In the meantime, at the time of defect inspection, the shape of each alignment mark is measured to recognize the type of the pattern, a design pattern corresponding to the recognized pattern type is selected, and the selected design pattern and the pattern to be inspected are compared with each other. A defect inspection method characterized by comparing A means for measuring positions and shapes of a plurality of alignment marks formed on the sample; a means for selecting a design pattern corresponding to a pattern to be inspected from the measured mark shapes; Means for scanning the pattern on the sample with a light beam on the basis of the detected mark position to detect the pattern to be inspected, and comparing the detected pattern to be inspected with the selected design pattern to determine whether there is a defect. A defect inspection apparatus comprising: a determination unit. 3. A pattern represented by the alignment mark.
The difference between the shapes of the marks in the X and Y directions
2. The method according to claim 1, wherein the size is used.
Defect inspection method.