JP2006275921A - Pattern evaluation method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately and speedily evaluate pattern shapes by a simple constitution. <P>SOLUTION: The contour of a pattern P2 to be evaluated is detected. The contour of a reference pattern RP2 to be a criterion of evaluation of the pattern P2, an reference pattern to which an allowed value L is previously given, is detected. An allowable range AS2 of the pattern P2 is created on the basis of both the contour of a reference pattern RP2 and the allowable value L. Then by determining the relative locational relation between the detected contour of the pattern P2 and the allowable range AS2, the inclusion relation between the contour of the pattern P2 and the allowable range is determined. On the basis of determination results, the quality of the pattern P2 is determined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pattern evaluation method and a program.

  A method of evaluating the shape of a pattern to be evaluated using a difference from the reference pattern as an index is widely used in various industrial fields. For example, in the field of semiconductor device pattern evaluation, an SEM image obtained by an SEM (Scanning Electron Microscope) apparatus is acquired as an evaluation image of a created pattern, while a reference pattern serving as a reference for shape evaluation is created in advance from design data. A method for determining the quality of the processed shape of the device pattern using these SEM images and reference patterns has been proposed. An example of these methods will be described as conventional technology.

  First, a pattern outline of an SEM image that is an inspection image is detected. Further, when a CAD figure is given as a design pattern in a binary file such as GDSII, pattern contour data is acquired from the data. Next, the positions of both patterns are detected by image matching. Specifically, the degree of difference or similarity is obtained while changing the relative positions of both patterns, and the position where the value representing the degree is maximized or minimized is detected. In general, parameters such as cross-correlation and normalized correlation obtained by normalizing image brightness are used as the degree of difference. By the above matching process, the SEM image outline and the CAD figure are superimposed.

  Next, one or several ROIs are set in the superimposed pattern, and the dimension between the contours of both patterns in the ROI is measured. The pass / fail of the inspection pattern is determined by comparing one or several dimension values obtained in this way with a separately defined standard.

However, in the above-described prior art, since the pattern shape is evaluated with several dimension values, a large number of ROIs must be set in order to evaluate a complicated pattern, and the large number of dimension data obtained in this way. There is also a problem that a great deal of calculation work is required to analyze. Furthermore, even if such a great deal of effort is required, for example, when the pattern shape is more complicated than the general rounding of the pattern corner, sufficient performance can be demonstrated for the pattern analysis. There wasn't.
JP2004-185019 JP2003-188074 JP2002-328015 JP2002-31525 JP2001-338304 JP2000-293690 JP 10-222672 A Japanese Patent Laid-Open No. 6119452 JP-A-6-96214 JP 6-44362 A JP 5-324836

  An object of the present invention is to provide a pattern evaluation method that enables highly accurate and quick evaluation with a simple configuration, and a program that causes a computer to execute the evaluation method.

  The present invention aims to solve the above problems by the following means.

That is, according to the present invention,
A procedure for detecting an outline of an evaluation target pattern to be evaluated;
A procedure for detecting a contour of a reference pattern, which is a reference pattern that serves as an evaluation reference for the pattern to be evaluated, and in which a parameter representing the tolerance of the pattern to be evaluated is given in advance.
Generating an allowable range of the pattern to be evaluated based on the parameters of the reference pattern and contour data;
A procedure for determining an inclusion relationship between the contour of the pattern to be evaluated and the allowable range by obtaining a relative positional relationship between the contour of the pattern to be evaluated and the allowable range;
A procedure for determining pass / fail of the evaluated pattern based on the obtained determination result;
A pattern evaluation method is provided.

Moreover, according to the present invention,
A procedure for detecting an outline of an evaluation target pattern to be evaluated;
A procedure for detecting a contour of a reference pattern, which is a reference pattern that serves as an evaluation reference for the pattern to be evaluated, and in which a parameter representing the tolerance of the pattern to be evaluated is given in advance.
A procedure for aligning the pattern to be evaluated and the reference pattern;
Generating an allowable range of the pattern to be evaluated based on the parameters of the reference pattern and contour data;
A procedure for determining an inclusion relationship between the contour and the allowable range by superimposing the contour of the pattern to be evaluated and the allowable range based on the alignment result;
A procedure for determining pass / fail of the evaluated pattern based on the obtained determination result;
A pattern evaluation method is provided.

Moreover, according to the present invention,
A program for causing a computer to execute the pattern evaluation method described above is provided.

  According to the present invention, a pattern can be quickly evaluated with high accuracy and a simple configuration.

  Embodiments of the present invention will be described with reference to the drawings. In the following, a description will be given by taking a shape inspection of a fine pattern formed in a semiconductor device manufacturing process such as a photolithography process or an etching process. However, it should be noted that the present invention is not limited to a fine pattern of a semiconductor device, but can be applied to general shape inspection of patterns used in products in various other industrial fields.

(1) First Embodiment A first embodiment of the present invention will be described with reference to FIGS. A feature of the present embodiment is that a reference pattern as a pattern for giving an evaluation reference for an evaluation pattern and a parameter called an allowable value are prepared in advance, and the allowable range of the evaluation pattern (“allowance range of evaluation pattern shape”) is used. And the quality of the evaluated pattern is determined based on the inclusion relationship between the obtained allowable range and the evaluated pattern.

  FIG. 1 is a diagram showing a partial contour of a pattern P2, which is an example of a pattern to be evaluated. FIG. 2 is a diagram showing a partial contour of a reference pattern RP2 of the pattern P2 shown in FIG. In the present embodiment, the reference pattern RP2 is a design pattern based on the design data of the pattern to be evaluated P2. The reference pattern is not limited to the design pattern as long as it gives an evaluation reference for the pattern to be evaluated, and any pattern may be used. For example, simulation result data may be used.

  In the present embodiment, the distance L from the contour of the reference pattern RP2 is set as an allowable value as a parameter. Therefore, the allowable range of the evaluation pattern P2 is generated as a set of all points separated from the contour of the reference pattern RP2 shown in FIG. In addition to the method of specifying these point sets as allowable ranges, distance conversion processing is performed on the pattern RP2 shown in FIG. 2, and contour lines of the distance L are obtained on the inside and outside of the pattern RP2 from the result, Any method such as a method of defining the sandwiched area as an allowable range may be used. The point to be noted in the present embodiment is that the allowable range of the evaluation pattern P2 is defined by the distance L from the contour of the reference pattern RP2, and this distance L is used as an allowable value in the evaluation of the pattern P2. It is a value given in advance. That is, the distance L is a value determined according to the pattern to be evaluated as a shape determination specification. An example of the allowable range generated in this way is shown in FIG. Since the tolerance value is the distance L in common between the inside and outside of the pattern, the tolerance range AS2 shown in FIG. 3 is generated so as to form a band having a width of 2L. The tolerance value does not need to be common between the inside and outside of the pattern. For example, as shown in the tolerance range AS4 shown in FIG. 4, the tolerance value has a tolerance value of 2L inside the pattern and a tolerance value of L outside the pattern. Different tolerance values can be set on the inner side and the outer side of the pattern so as to be generated as a band-like region having a width of 3 L as a whole. Further, different allowable values can be set for each component of the pattern according to the required specification of the pattern, not limited to the inside and outside of the pattern.

  Next, the quality of the pattern to be evaluated is determined by checking whether or not the outline of the evaluation pattern is included in the allowable range of the pattern to be evaluated generated by the above-described method, for example. More specifically, for example, the relative position of the contour of the pattern to be evaluated P2 is scanned with respect to the allowable range AS2, and the relative position for the entire contour of the pattern to be evaluated P2 to be within the allowable range AS2 is calculated. . As shown in FIG. 5, when the pattern to be evaluated P2 is within the allowable range AS2 at a certain relative position, the pattern to be evaluated P2 is accepted and determined as a non-defective product. On the other hand, as shown in FIG. 6, when this relative position is not obtained, the pattern P2 to be evaluated is rejected and determined to be defective.

(2) Second Embodiment A second embodiment of the present invention will be described with reference to FIGS. The feature of this embodiment is that an allowable range is generated by convolving a unit pattern defined in advance with the outline of a reference pattern.

  FIG. 7 shows an example of the unit pattern. The unit pattern UP2 shown in the figure is a square whose side is a. As for the unit pattern UP2, in addition to the length a of one side, the coordinates of a point P that is an arbitrary point inside the square and intersects the outline of the reference pattern are also given. The value of the length a and the coordinates of the point P The position is an allowable value. Next, as shown in FIG. 8, the unit pattern UP2 is matched with the reference pattern RP2 at the point P so that the point P overlaps the outline of the reference pattern RP2, and then the point P follows the outline of the reference pattern RP2. The unit pattern UP2 is moved along the contour of the reference pattern RP2. By recording the trajectory drawn by the contour of the unit pattern UP2 at this time, as shown in FIG. 9, an allowable range AS6 including a band-shaped region having a width a is generated. The allowable range AS6 shown in FIG. 9 has an angular corner portion, and is clearly different from the allowable range AS2 in FIG. 3 in this respect.

  After that, the quality of the pattern to be evaluated can be determined by the method described in the first embodiment with respect to the allowable range AS6 thus generated.

  In the above description, a square pattern is exemplified as the unit pattern. However, the shape is not limited to a square, and a circle, an ellipse, etc. can be used in addition to a rectangle. FIG. 10 shows an example of a rectangular unit pattern, and FIG. 11 shows an allowable range generated using the unit pattern UP4 of FIG. If a circular or elliptical unit pattern is employed, an allowable range having a rounded corner can be generated, as in the allowable range AS2 of FIG.

(3) Third Embodiment In the above-described embodiment, the relative position between the allowable range generated from the reference pattern and the evaluated pattern is scanned without previously aligning the evaluated pattern and the reference pattern. By doing so, the inclusive relation between the two in all positional relations was verified. In contrast to this, the feature of the present embodiment is that alignment is performed in advance between the pattern to be evaluated and the reference pattern prior to generation of the allowable range. As a result, it is possible to determine the quality of the pattern to be evaluated only by examining only the inclusion relationship at the position where the alignment has been performed in advance. In this case, for example, design data of an evaluation pattern can be used as the reference pattern.

(4) Program Each series of procedures of the pattern evaluation method described in the first to third embodiments may be incorporated into a program and read by a computer for execution. Thereby, each series of procedures in the pattern evaluation method according to the present invention can be realized using a general-purpose computer. The series of steps of the pattern evaluation method described above may be stored in a recording medium such as a flexible disk or a CD-ROM as a program for causing a computer to execute the program, and read and executed by a computer. The recording medium is not limited to a portable medium such as a magnetic disk or an optical disk, but may be a fixed recording medium such as a hard disk device or a memory. Further, a program incorporating a series of procedures of the pattern evaluation method described above may be distributed via a communication line (including wireless communication) such as the Internet. Furthermore, a program incorporating the series of steps of the pattern evaluation method described above is stored in a recording medium via a wired line or a wireless line such as the Internet in an encrypted, modulated or compressed state. May be distributed.

(5) Manufacturing Method of Semiconductor Device By incorporating the pattern evaluation method described in the first to third embodiments into an inspection process in manufacturing a semiconductor device, a semiconductor device can be manufactured with high throughput and yield. It becomes possible.

  Although some of the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can of course be applied in various modifications within the technical scope thereof.

It is a figure which shows the partial outline of an example of the to-be-evaluated pattern which is evaluation object. It is a figure which shows the partial outline of the reference | standard pattern of the pattern shown in FIG. It is a figure which shows an example of the tolerance | permissible_range prescribed | regulated by the distance from the outline of a reference pattern, and a reference pattern. It is a figure which shows another example of the tolerance | permissible_range prescribed | regulated by the distance from the outline of a reference | standard pattern, and a reference | standard pattern. It is a figure which shows an example when it determines with it being bad because the outline of an evaluation pattern is not included with respect to the tolerance | permissible_range of the produced | generated evaluation pattern. It is a figure which shows an example when it determines with a non-defective product since the outline of an evaluation pattern is included with respect to the tolerance | permissible_range of the produced | generated evaluation pattern. It is a figure which shows an example of a unit pattern. It is explanatory drawing which shows the method of producing | generating a tolerance | permissible_range using a unit pattern by the 2nd Embodiment of this invention. It is a figure which shows an example of the tolerance | permissible_range produced | generated using the unit pattern shown in FIG. It is a figure which shows another example of a unit pattern. It is a figure which shows an example of the tolerance | permissible_range produced | generated using the unit pattern shown in FIG.

Explanation of symbols

AS2, AS4, AS6 Allowable range L, 2L, a, b Parameter indicating tolerance (allowable value)
P2 Pattern to be evaluated RP2 Reference pattern UP2, UP4 Unit pattern

Claims (5)

A procedure for detecting an outline of an evaluation target pattern to be evaluated;
A procedure for detecting a contour of a reference pattern, which is a reference pattern that serves as an evaluation reference for the pattern to be evaluated, and in which a parameter representing the tolerance of the pattern to be evaluated is given in advance.
Generating an allowable range of the pattern to be evaluated based on the parameters of the reference pattern and contour data;
A procedure for determining an inclusion relationship between the contour of the pattern to be evaluated and the allowable range by obtaining a relative positional relationship between the contour of the pattern to be evaluated and the allowable range;
A procedure for determining pass / fail of the evaluated pattern based on the obtained determination result;
A pattern evaluation method comprising: A procedure for detecting an outline of an evaluation target pattern to be evaluated;
A procedure for detecting a contour of a reference pattern, which is a reference pattern that serves as an evaluation reference for the pattern to be evaluated, and in which a parameter representing the tolerance of the pattern to be evaluated is given in advance.
A procedure for aligning the pattern to be evaluated and the reference pattern;
Generating an allowable range of the pattern to be evaluated based on the parameters of the reference pattern and contour data;
A procedure for determining an inclusion relationship between the contour and the allowable range by superimposing the contour of the pattern to be evaluated and the allowable range based on the alignment result;
A procedure for determining pass / fail of the evaluated pattern based on the obtained determination result;
A pattern evaluation method comprising: The parameter is a distance of an arbitrary value that is common to at least one of the inner side and the outer side from the contour point of the reference pattern for at least one of the components of the reference pattern
3. The pattern according to claim 1, wherein the allowable range is generated by setting a range that is separated from the contour point of the reference pattern by the arbitrary distance to the inside and the outside of the reference pattern. 4. Evaluation methods. The parameter is a value that specifies the shape of a unit pattern of an arbitrary shape, as well as the position coordinates of an arbitrary point in the shape,
The said tolerance | permissible_range is produced | generated by convolving the said unit pattern with the outline of the said reference pattern so that the said arbitrary points of the said unit pattern may follow the outline of the said reference pattern. The pattern evaluation method as described.   The program which makes a computer perform the pattern evaluation method in any one of Claims 1 thru | or 4.

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