JP3857483B2 - Exposure method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exposure method for exposing a semiconductor circuit pattern using a charged particle beam.
[0002]
[Prior art]
As semiconductor devices are highly integrated, miniaturization of circuit patterns is accelerating. An exposure apparatus using an electron beam has been developed for a long time as a semiconductor manufacturing apparatus for realizing this miniaturization. However, it has been pointed out that the electron beam exposure apparatus takes much longer exposure time than other exposure means.
[0003]
In recent years, attempts have been made to solve such a problem by a block exposure method using a character aperture in which characteristic repeated portions of a semiconductor circuit pattern are formed in advance.
[0004]
According to this block exposure method, the exposure time is considerably shortened as compared with the conventional method. However, when a character aperture capable of dealing with any semiconductor circuit pattern is prepared, there is a problem that the number of character apertures becomes enormous.
[0005]
[Problems to be solved by the invention]
As described above, there is a problem that the number of character apertures becomes enormous when an attempt is made to prepare character apertures that can handle all semiconductor circuit patterns using the block exposure method.
[0006]
An object of the present invention is to provide an exposure method that can reduce the number of character apertures.
[0007]
[Means for Solving the Problems]
[Constitution]
The present invention is configured as follows to achieve the above object.
[0008]
(1) The present invention (Claim 1) is an exposure method in which a characteristic repeating portion of a semiconductor circuit pattern is exposed by a charged particle beam using a character aperture , and an arbitrary region is selected from the semiconductor circuit pattern. Extract and divide it into multiple meshes, and divide the pattern data in the code book in which the pattern included in the character aperture is pre-coded into multiple meshes that are the same as the mesh and compare the corresponding areas of the meshes Thus, exposure is performed with a charged particle beam using a character aperture of a pattern encoded in pattern data included in the code book that is most similar to the arbitrary region .
[0009]
[Action]
The present invention has the following operations and effects by the above configuration.
[0010]
According to the present invention, an image pattern recognition system does not prepare all character apertures that can correspond to a semiconductor circuit pattern, but uses a semiconductor circuit pattern in which characteristic repeated portions of an actual semiconductor circuit pattern are pre-coded as a code book. By using and selecting the most similar ones, it is possible to cope with as few character apertures as possible.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
FIG. 1 is a flowchart for explaining an exposure method according to an embodiment of the present invention.
[0013]
First, an arbitrary area 12 is extracted from the LSI pattern (semiconductor circuit pattern) data 11 (FIG. 2A) (step S1). Next, the extracted region is divided into a plurality of meshes 13 (FIG. 2B) (step S2).
[0014]
Next, the pattern data in the code book 21 as shown in FIG. 3 created so that it can be selected by (x, y) coordinates as a library is divided into the same mesh (step S3). At this time, the size of the character aperture data area of the code book 21 may not be the same as the size of the extracted LSI pattern area.
[0015]
Next, each mesh of the LSI pattern after the division is white (0) or black (1) is compared with each area of the mesh in the code book (step S4), and the white (0) portion or black (1) Those whose total area is greater than or equal to a preset numerical value are selected (step S5). At this time, for example, 90% or more of the same one may be selected, and if more than half of the mesh area having the LSI pattern is black, all may be handled as black.
[0016]
Next, the character aperture in the code book most similar to the LSI pattern of the extracted area is selected from the character aperture data in the selected code book under the pre-set preconditions, and the It is represented by the coordinates of the code book (step S6).
[0017]
Further, if the image pattern recognition result does not match 100%, the character aperture in the code book may be selected as long as it does not affect the semiconductor circuit characteristics (for example, 90% or more). This not only reduces the number of character apertures that need to be prepared, but also enables data like vector quantization without the need for complex calculations by using a semiconductor circuit pattern in the codebook for the image pattern recognition system. Data compression that takes a block of a certain size from a two-dimensional array of character apertures in a compression algorithm, etc., compares this with a codebook of the same size, finds the most similar pattern among them, and assigns the pattern number Can be decoded in a short time with very simple hardware.
[0018]
Finally, all the LSI patterns are divided into figures, and electron beam exposure is performed using the selected character apertures (step S7).
[0019]
For example, as shown in FIG. 4 (a), when the mesh is rough, if the black portion is more than half, the figure is as shown in FIG. 4 (b), and characterization is easy. As a result, the number of characters is greatly reduced.
[0020]
Further, as shown in FIG. 5, for example, when the black portion occupies a large area, if there are m or more continuous blacks, n is assumed to be black, and no matching calculation is performed. Perform collation calculation again. If n + 1 is white, check n. By repeating this calculation, the calculation time can be greatly shortened.
[0021]
Or, since the outline information of the figure is important, the calculation time can be further reduced if only the area where the outline exists is collated.
[0022]
According to this embodiment, instead of preparing all the character apertures that can correspond to a semiconductor circuit pattern, image pattern recognition is performed from a semiconductor circuit pattern in which characteristic repeated portions of an actual semiconductor circuit pattern are pre-coded into a codebook. By using the system and selecting the most similar one, it is possible to cope with as few character apertures as possible.
[0023]
In addition, this invention is not limited to the said embodiment. For example, it can be used not only for electron beam exposure but also for exposure using a charged particle beam such as an ion beam. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.
[0024]
【The invention's effect】
As described above, according to the present invention, not all the character apertures that can correspond to the semiconductor circuit pattern are prepared, but the characteristic repeating portion of the actual semiconductor circuit pattern is extracted from the semiconductor circuit pattern pre-coded into the codebook. By using the image pattern recognition system and selecting the most similar one, it is possible to cope with as few character apertures as possible.
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining an exposure method according to an embodiment of the present invention.
FIG. 2 is a diagram showing LSI pattern (semiconductor circuit pattern) data.
FIG. 3 is a diagram showing a data array in a code book.
FIG. 4 is a diagram showing an example of characterization.
FIG. 5 is a diagram showing an example of characterization.
[Explanation of symbols]
11 ... LSI pattern data 12 ... extracted area 13 ... mesh 21 ... code book

Claims (1)

An exposure method for exposing a characteristic repeating portion of a semiconductor circuit pattern with a charged particle beam using a character aperture,
Extract an arbitrary area from the semiconductor circuit pattern and divide it into multiple meshes, and divide the pattern data in the codebook in which the pattern included in the character aperture is precoded into the same multiple meshes as the mesh By comparing each corresponding area of the mesh, exposure is performed with a charged particle beam using a character aperture of the pattern encoded in the pattern data included in the code book that is most similar to the arbitrary area An exposure method characterized by the above.

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