JP2000047365A - Manufacture of optical proximity effect correction mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an optical proximity effect mask capable of highly precisely correcting optical proximity effect without lowering the throughput by adding the exposure correction data of at masked electron beam plotting that are decided based on the correction amount of the optical proximity effect in a photolithography process to mask pattern data. SOLUTION: Relation between the correction value of mask dimension and the dimensional error of a resist pattern in the photolithography process is obtained with respect to the designed mask patterns having the various kinds of dimension by the simulation of an optical image or an exposure experiment result. Then, the correction value of the mask dimension required for minimizing the dimensional error is decided. Based on the correction value, the ideal corrected pattern 6 obtained by correcting the dimension of the designed pattern of a mask is formed. Besides, the mask pattern data is constituted of mask shape data and the exposure correction data of a mask electronic beam plotting device decided based on the correction amount of the optical proximity effect. Then, the mask is exposed by changing exposure according to the exposure correction data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method of manufacturing a mask by electron beam (hereinafter, referred to as EB) exposure, and more particularly to a method of manufacturing an optical proximity correction mask capable of correcting an optical proximity effect.

[0002]

2. Description of the Related Art In an optical lithography process in a semiconductor device manufacturing process, a dimensional error between a design pattern 1 and an actual resist pattern 2 caused by an optical proximity effect as shown in FIG. Conventionally, in the optical proximity correction mask used as a countermeasure, a mask dimension correction value that minimizes a pattern dimension error with respect to the design pattern 1 is determined by an optical image simulation or an exposure experiment result. Data obtained by correcting the dimensions of the design pattern 1 is used for mask EB drawing. FIG. 5 (a)
As shown in the figure, this drawing pattern data
Since it is necessary to be on a grid used for drawing (the size is shown in FIG. 5B), the actual corrected pattern 3 is a pattern obtained by rounding the ideal corrected pattern 4 by the grid. ing. Therefore, in the conventional method, the dimension correction amount needs to be an integral multiple of the grid size when drawing the mask EB. Further, conventional drawing pattern data is only pattern shape data written on a grid, and at the time of mask EB drawing, a mask pattern is drawn and exposed with the same exposure amount. This type of technology includes
For example, there is one disclosed in JP-A-6-188179.

[0003]

However, in the above-mentioned prior art, as the dimensions of the design pattern 1 become smaller, finer adjustment of the pattern dimension is also required. Has a problem that the pattern size cannot be corrected by an amount smaller than the grid size because of the limitation of the grid size. For this reason, it was not possible to sufficiently correct the fine dimension pattern, and it was not possible to sufficiently reduce the dimensional error.

On the other hand, it is conceivable to reduce the grid size, but this has a problem that the throughput of mask EB drawing is significantly reduced. Therefore, the present invention provides a method for manufacturing an optical proximity effect correction mask capable of performing optical proximity effect correction with high accuracy without reducing throughput.

[0005]

In order to solve the above-mentioned problems, in the present invention, the exposure amount correction data at the time of mask EB drawing determined by the correction amount of the optical proximity effect generated in an optical lithography process is used as a mask pattern. It is characterized in that the mask is exposed by changing the exposure amount in accordance with the exposure amount correction data when drawing the mask EB in addition to the data. Note that the EB drawing is a plurality of overlapping drawing exposures,
The exposure amount may be changed between each drawing.

The mask pattern data is composed of mask pattern shape data and exposure correction data in a mask EB lithography apparatus determined by the optical proximity effect correction amount, and the mask is formed by changing the exposure amount according to the exposure correction data. By exposing the mask pattern, it is possible to correct a mask dimension smaller than the grid size without reducing the grid size of the mask pattern.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 show a first embodiment of the present invention. In the first embodiment, a mask EB is drawn by using a negative EB resist in a mask EB writing process. Is to create a mask that becomes a dark part.

First, the relationship between the mask dimension correction value and the resist pattern dimension error in the photolithography process is determined for the designed mask patterns of various dimensions by optical image simulation or exposure experiment results. Then, a mask dimension correction value that minimizes the dimension error is determined from the result. Next, an ideal corrected pattern 6 in which the dimensions of the mask design pattern 5 are corrected as shown in FIG. Then, as shown in FIG. 1A, the ideal corrected pattern 6 is rounded to the inside of the pattern by the grid size (shown in FIG. 1B) used in the mask EB drawing apparatus (hereinafter referred to as the inside). A rounded pattern 7 and an outwardly rounded pattern (hereinafter referred to as an outer rounded pattern) 8 are created. The difference pattern of these patterns is divided into each side pattern 9 and each corner pattern 10.

In addition, for each side pattern 9, the fine adjustment amount α, which is the ratio between the grid fineness and the fine adjustment amount α smaller than the grid size, which is the ideal difference between the corrected pattern 6 and the inner rounding pattern 7, is used. Calculate the adjustment rate. Next, the mask EB
Using the negative EB resist used in the drawing, experimentally measuring the relationship between the exposure amount of the side pattern 9 and the EB resist dimensions, the negative EB resist dimensions shown in FIG. In order to adjust to the adjustment rate, the dimension fine adjustment rate, the exposure amount of the inner round pattern 7 and the side pattern 9
A relationship with an exposure amount correction value which is a ratio to the exposure amount is created.

From this relationship, the exposure correction values A and B for each side pattern 9 are obtained. Further, an exposure amount correction value C of each corner pattern is obtained from a value obtained by averaging the exposure amount correction values A and B of the side patterns 9 on both sides of the corner pattern 10. The data composed of the mask pattern shape data and the exposure amount correction data is used as mask EB drawing data. Mask EB
In the drawing, the inner rounding pattern 7 is changed to the exposure amount D, and the exposure amount of each side pattern 9 and the corner pattern 10 is changed to the exposure amount obtained by multiplying the exposure amount D of the inner rounding pattern 7 by the exposure amount correction value K. Expose.

The EB writing may be performed a plurality of times by overlapping exposure, and the exposure amount may be changed between each writing. Therefore, according to this embodiment, it is possible to correct the mask dimension smaller than the grid size without reducing the grid size of the mask pattern data, and to achieve high-precision optical proximity without significantly lowering the mask EB drawing throughput. Effect correction becomes possible.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, a mask is formed by using a positive EB resist in mask drawing, in which a bright portion is outside the design pattern and a dark portion is inside the design pattern. First, the side pattern 9 is formed using a positive EB resist.
Using the results of experimentally measuring the relationship between the exposure amount of the EB resist and the dimensions of the EB resist, the ratio of the fine adjustment ratio shown in FIG. Create a relationship between the exposure correction values.

From the relationship between the fine adjustment rate of the positive EB resist shown in FIG. 4 and the exposure correction value, the exposure correction values A and B for each side pattern 9 and the exposure correction for each corner pattern 10 are obtained. Get the value C. In the mask EB drawing, exposure is performed by changing the exposure amount of each side pattern 9 and the corner pattern 10 to an exposure amount obtained by multiplying the exposure amount D outside the pattern by the exposure amount correction value K with the exposure amount D outside the pattern. .

When it is desired to finely adjust the exposure correction value by using a resist, first, mask data composed of mask pattern shape data and dimension fine adjustment rate data of each side is created. In addition, EB drawing data is created by converting the dimension fine adjustment rate data of each side into an exposure amount correction value. It is to be noted that, as in the above-described embodiment, the EB writing may be performed a plurality of times of overlapping writing exposure, and the exposure amount may be changed between each writing. Therefore, also in this embodiment, it is possible to correct the mask dimension smaller than the grid size without reducing the grid size of the mask pattern data, and to achieve a high-precision optical proximity effect without significantly lowering the mask EB drawing throughput. Correction becomes possible.

[0015]

As described above, according to the present invention, it is possible to correct a mask dimension smaller than the grid size without reducing the grid size of the mask pattern data, thereby significantly increasing the mask EB drawing throughput. There is an effect that highly accurate optical proximity effect correction can be performed without reduction.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is an explanatory diagram showing mask data after proximity effect correction, and FIG. 1B is an explanatory diagram showing a grid size.

FIG. 2 is an explanatory diagram showing an ideal proximity effect correction pattern.

FIG. 3 is a graph showing characteristics of a negative EB resist.

FIG. 4 is a graph showing characteristics of a positive EB resist.

5A and 5B are diagrams illustrating a conventional technique, wherein FIG. 5A is an explanatory diagram illustrating mask data after proximity effect correction, and FIG. 5B is an explanatory diagram illustrating a grid size.

FIG. 6 is an explanatory diagram illustrating a resist pattern using a mask that is not corrected.

[Explanation of symbols]

 5 Design pattern 6 Ideal corrected pattern 7 Pattern rounded inside 8 Pattern rounded outside 9 Side pattern 10 Square pattern

Claims (1)

[Claims] An exposure amount correction data for mask electron beam writing determined by a correction amount of an optical proximity effect generated in an optical lithography process is added to mask pattern data, and an exposure amount correction is performed at the time of mask electron beam writing. A method for manufacturing an optical proximity correction mask, comprising exposing a mask by changing an exposure amount according to data.