JPH05346405A - How to inspect pattern shape - Google Patents

Abstract

PURPOSE:To provide a method for inspecting pattern profile of a matter produced based on an original pattern in which a product can be tested with practically sufficient accuracy without taking account of real accuracy. CONSTITUTION:In a method for inspecting pattern profile of a matter 11 produced based on an original pattern by comparing a bit map 12 obtained through pattern recognition of the matter 11 with a bit map 22 obtained through the recognition of the original pattern 21, discontinuous point of bit is detected in the vicinity of not-matched point on the bit maps when they do not match with each other. Bit map only at a detected point is then deleted from both bit maps and then the bit maps 14, 15 are compared 15 with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a pattern shape of an object manufactured based on an original figure pattern.

When inspecting the shape of an object obtained by processing based on an original figure pattern, such as a reticle used in the manufacture of semiconductors, when a bit map is used for comparison, the shape of an acute-angled portion is particularly unclear. It was easily clarified, there was no problem in actual use, and when the shape of the acute-angled portion was unclear, it was sometimes determined to be defective. It has been required to develop a method for inspecting a pattern shape easily and accurately even for an object having an acute-angled portion.

[0003]

2. Description of the Related Art As semiconductor integrated circuits have become larger and more highly integrated, masks, reticles, etc. used in manufacturing have become finer and finer and more precise. The pattern of the reticle is processed and manufactured based on a pattern created by the designer performing a process such as utilizing a CAD system. Then, the state of observing the surface graphic pattern of the obtained product and the original graphic pattern (design data) are compared and collated to determine whether the product is good or bad.

Naturally, there is a demand for reliable manufacture and inspection of products in a short time. Therefore, it is known to use a bitmap as a means for comparing and collating patterns. That is, the product is observed with a CCD or the like to obtain a map in which the presence or absence of an object on the surface corresponds to "1" or "0".
For the original figure pattern, a map is obtained by mechanically dividing the figure and creating a correspondence table of "1" and "0". If a logical operation is performed for each of the maps on a bit-by-bit basis, the states of both maps can be compared and collated by the number of mismatches.

[0005]

Regarding the original figure pattern, when a figure having a corner with an acute angle is designed, a product having such a shape cannot be manufactured as a product, so-called a corner. It has a dull shape. When the corner is less blunt, it does not cause any particular problem when using the actual product. However, in the case of comparison and matching by the bit map method as described above, it is always judged that the shape is different if the “subdivided bits” are used. Therefore, it is extremely accurate if it depends only on mechanical judgment, but even if it is a practical product, if it is measured for a long time, it may be judged as defective as a result.

An object of the present invention is to improve the above-mentioned drawbacks and provide a pattern shape inspection method for inspecting a product with an accuracy of a practically sufficient degree without causing a problem in true accuracy. Especially.

[0007]

FIG. 1 is a diagram showing the principle configuration of the present invention. In FIG. 1, 11 is an object manufactured based on an original figure pattern, 21 is an original figure pattern, 12 is a bitmap for the former 11, 22 is a bitmap for the latter 21, 13 is means for comparison / determination, 14,
Reference numeral 24 indicates each bitmap in which the non-matching bits are deleted, and 15 indicates the second comparing means.

Object 11 manufactured based on the original figure pattern
In the method of inspecting the pattern shape of the object 11 manufactured based on the graphic pattern by comparing the bitmap 12 obtained by recognizing the pattern with the bitmap 22 obtained by recognizing the original graphic pattern 21, Has the following configuration. That is, the two bitmaps 12 and 22 obtained by the pattern recognition are compared to determine a match / mismatch, and when they do not match, a discontinuous portion in a bit near the coordinates of the mismatch point on the bitmap is detected, and then Only the bit at the detected location is deleted from both bitmaps, and the processed bitmaps 14 and 24 are compared with each other.

[0009]

The comparing means 13 compares the bitmap 12 created for the object 11 shown in FIG. 1 with the bitmap 22 obtained by recognizing the original figure pattern 21 for the object 11. If they match, it means that the inspection of the object 11 is passed, and the process proceeds to the next step. If they do not match, the continuity / discontinuity of the bits near the coordinates of the disagreement point is judged. Then, a process of finding a discontinuous portion of "0" and "1" bits and deleting "1" at the boundary from both bitmaps 12 and 22 is performed. The resulting bit maps 14 and 24 are compared by the second comparison means 15. If they match, it can be determined that the previous mismatch was a pseudo defect.

[0010]

FIG. 2 is a block diagram showing steps up to the initial comparison of bitmaps as an embodiment of the present invention. In FIG. 2, 31 is a reticle shown as an example of an object manufactured based on an original figure pattern, 32 is a light source, 33 is an image detector, and 34 is an A / D converter. The image of the reticle 31 is stored in the bitmap 12 via the A / D converter 34. Reference numeral 35 is a database storing inspection data as an example of an original figure pattern, and 36 is a table for defining an image range of the reticle 31. The data of the database 35 is partially stored in the bitmap 22 via the data extracting means 36. Reference numeral 37 denotes an image overlay determination unit, which overlays the bitmaps 12 and 22 to determine whether they match.
Judge discrepancies.

FIGS. 3 and 4 are views for explaining the processing after checking the bit map coincidence by the processing shown in FIG. 2 as an embodiment of the present invention. 3A shows an original figure pattern, and FIG. 3B shows its bit map. FIG. 4 shows data on a product manufactured based on the figure of FIG. 3, FIG. 4A shows a product pattern, and FIG. 4B shows its bit map. Further, FIGS. 3C and 4C show the calculated values of each bit in the X and Y directions, and FIGS. 3D and 4D show a bit map in which a portion recognized as a vertex is deleted.

In the original figure pattern shown in FIG. 3A, for example, in the design drawing of the original figure, 1 indicates the whole range for obtaining the bitmap, 2 is the figure pattern of the original figure, 3 is a margin portion, 2P and 2Q are the original figures. The acute-angled apex part in 2 is shown. FIG. 1B is a bit map obtained for the pattern of FIG. 1A, in which a portion where a figure exists is represented by a bit “1” and a portion where the figure does not exist is represented by a bit “0”. Initially, the bitmap shown in FIG. 3B and the bitmap shown in FIG. It can be detected that the bits at the point indicated by 2P in FIG. 3 are “mismatch”. If a mismatch is detected, processing is performed for each bitmap. The process detects the discontinuity for each bit near the coordinates of the mismatch point on the bitmap,
It is to delete it.

Therefore, the following processing is performed. That is, FIG. 3C
Performs the operation in the direction indicated by the thick arrow in the bitmap of FIG. 3B, and sets "1" in the direction in which there is even one bit "1".
Shows a bit string obtained by rearranging the direction with no one as “0”. 3D, the position of the first "1" at which the change from the bit "1" to the bit "0" occurs in the bit string in FIG. 3C is detected as a "vertex", and the bit "1" at that position is deleted. It is shown that. In other words, converting "1" at each vertex into "0". Therefore, the remaining bitmap has a shape in which the vertices of the original figure pattern are omitted.

In FIG. 4, the bitmap is obtained in the same manner as in FIG.
It shows what can be obtained by dropping the vertices. Therefore, comparing FIG. 3 and FIG. 4, even if there is a blunt in the vicinity 2Q of the product in FIG. 4A, it is the same in each drawing D in which the bitmap is calculated. At this time, the shape shown in FIG. 4A does not result in a defective product.

FIG. 5 shows an operation flowchart for performing each processing operation of FIGS. 3 and 4 as an embodiment of the present invention. In FIG. 5, reference numeral 30 is a database of original figure patterns, and 40 is a product pattern. 41 and 42 indicate that the product pattern is processed. Three
Bit maps are expanded at 1 and 43, respectively.
Then, at 32 and 44, the respective arithmetic processings in the X and Y directions are performed on the bitmap, and at 33 and 45, the vertex detection of each pattern is performed. One or more of the bits determined to be vertices at 34 and 46 are deleted. And 5
At 0, the remaining bits are compared and collated.

FIG. 6 shows that the bit indicating a flaw found in the bitmap of the object to be inspected is not found in the bitmap of the original figure, so that the former is a flaw and is a defect.

[0017]

As described above, according to the present invention, the bitmaps are initially inspected, and the detailed check is performed only when there is a mismatch. For this reason, unnecessary inspection is not performed, and for a bitmap that causes a mismatch, a sharpness of the shape is deleted such that the acute angle portion on the pattern is deleted at the position determined as the "vertex", and the processing is performed. The subsequent bitmaps are compared and collated. Therefore, if the bits for “eliminating the acute angle part” of the bitmap are predetermined so that a practically usable pattern can be obtained, there are defects that cannot be practically used and practically usable. It is possible to easily distinguish the dullness of the pattern. Therefore, according to the present invention, the efficiency of the inspection process can be improved.
The time can be shortened, and it is particularly effective when processing a fine object such as a semiconductor manufacturing technology.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention. .

FIG. 2 is a block diagram for explaining an embodiment of the present invention.

FIG. 3 is a diagram illustrating an original figure pattern and its processing.

FIG. 4 is a diagram illustrating a product pattern and its processing.

5 is an operation flowchart for performing each processing operation of FIGS. 3 and 4. FIG.

FIG. 6 is a diagram showing a state where there is a “scratch” as an example of the present invention.

[Explanation of symbols]

11 Object 12 Bitmap 21 Original Figure Pattern 22 Bitmap 13 Comparison / Determination Means 14 Processed Bitmap 24 Processed Bitmap 15 Second Comparison Means

Claims (1)

[Claims] 1. An object manufactured based on an original figure pattern (1
Bitmap (12) obtained by pattern recognition for 1),
In the method of inspecting the pattern shape of the object manufactured based on the graphic pattern by comparing (13) with the bitmap (22) obtained by recognizing the original graphic pattern (21), both the patterns obtained by the pattern recognition are obtained. The bit maps (12) and (22) are compared to determine a match / mismatch (13) .If they do not match, a discontinuous point in the bit near the coordinates of the mismatch point on the bitmap is detected, and the next detected point is detected. Only the bits are deleted from both bitmaps, and the processed bitmap (1
4) A method for inspecting a pattern shape, which is characterized by comparing (24).