JPH0460547A - Method for forming pattern for mask - Google Patents

Abstract

PURPOSE:To transfer all of plural patterns with high dimensional accuracy by eliminating an effect caused by coma aberration by forming a dummy pattern on both ends of the plural patterns. CONSTITUTION:The direction and the size of the optical system of an exposure device that the coma aberration is generated is measured in respective areas in a field and the direction of the composite vector thereof is defined as the average in-plane direction of the optical system that the coma aberration is generated. In the case that plural line patterns l1 - l5 are formed in directions B - B' within 45 deg. with respect to the average in-plane direction A - A' of the optical system of the exposure device that the coma aberration is generated, the dummy patterns ls and le are formed at both ends of the plural line patterns l1 - l5. Thus, the dimensional accuracy of all patterns which are transferred is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Summary) A mask brim pattern forming method, particularly a mask pattern forming method that improves the dimensional accuracy of a pattern transferred to a resist film, is based on a plurality of patterns formed on a mask. The purpose of the present invention is to provide a mask pattern forming method that allows all patterns to be transferred to be formed with high dimensional accuracy. When forming a plurality of patterns in which a plurality of patterns are arranged in a row within 45 degrees with respect to the in-plane direction, a dummy pattern is placed on the side of the pattern in the outermost row of the plurality of patterns. The system is configured to provide the following.

[Industrial application field]

The present invention relates to a method for forming a pattern on a mask, and more particularly, to a method for forming a pattern on a mask that improves the dimensional accuracy of a pattern transferred to a resist film.

[Conventional technology]

As semiconductor devices become more highly integrated, there is a strong desire for smaller design rules. To this end, we have developed a method to improve resolution using a high-resolution resist process such as the three-layer resist method, and a phase shift mask in which an auxiliary pattern that inverts the phase of the exposure light is formed around the main pattern. A method has been proposed to improve resolution by utilizing the interference effect of exposure light transmitted through an auxiliary pattern.

These methods are aimed at improving the resolution of individual patterns formed on the mask,
To date, no technical idea has been disclosed that attempts to improve the transfer dimensional accuracy of individual patterns belonging to a pattern group by applying some means to a pattern group consisting of a plurality of patterns6. The present invention is based on the latter technical idea.

[Invention tries to solve! I! For example, using a stepper with a numerical aperture of 0.45,
When exposing a high-resolution resist film by irradiating a line (wavelength: 365 nm), if the pattern formed on the mask is a 1:1 line-space pattern as shown in FIG. 4(a), the exposure and The shape of the developed and transferred resist pattern is as shown in FIG. The line patterns 11 and 1 are formed to have dimensions different from the designed dimensions. To give a specific example, the design dimensions are 0.65n and 0.6n, respectively.
.

In the case of 0.55n and 0.5n, the line pattern I!
, I and l are shown in Table 1.

The purpose of the present invention is to eliminate this drawback, and is to transfer a pattern group consisting of a plurality of patterns formed on a mask, so that all the transferred patterns are formed with high dimensional accuracy. An object of the present invention is to provide a method for forming a mask pattern.

[Means to solve the problem]

The above object can be achieved by any of the following means.

The first method is to form a plurality of patterns in which a plurality of patterns are arranged in a row within 45 degrees with respect to the average in-plane direction in which coma aberration peculiar to the optical system occurs. This is a mask pattern forming method in which a dummy pattern is provided on the side of a pattern in the outermost row of a plurality of patterns. When forming a plurality of patterns in which patterns are arranged in a plurality of rows in a direction of 45 degrees, the side of the pattern in the outermost row of the plurality of patterns is perpendicular to the direction of the plurality of pattern rows. This is a mask pattern forming method in which a dummy pattern is provided on the side of a pattern in the outermost row of a plurality of patterns formed in rows in the direction of the mask.

[Effect]

Measuring the direction and magnitude of comatic aberration in the optical system of the exposure device in each region within the field (i!i angle),
The direction of their combined vector is defined as the average in-plane direction in which coma aberration of the optical system occurs.

When a resist film is exposed and developed using a mask in which multiple patterns are formed in the average in-plane direction where coma aberration of the optical system of the exposure device occurs, out of the multiple transferred resist patterns, the It was confirmed that the pattern dimensions deviated from the predetermined dimensions. The amount of misalignment was not large enough to be a problem before high-resolution technologies such as improved resist processes and the use of phase shift masks were applied, but now that resolution has improved and patterns have become finer. It has become too large to be ignored.

The inventor of the present application has proposed that when forming a plurality of patterns in a direction within 45 degrees with respect to the average in-plane direction where coma aberration occurs in an optical system, dummy patterns are formed at both ends of the plurality of patterns. In addition, when forming a plurality of patterns in a direction of exactly 45 degrees, by forming dummy patterns at both ends of the plurality of patterns and at both ends of the plurality of patterns formed in a direction perpendicular to the direction, It has been found that the dimensional accuracy of all patterns to be transferred can be improved.

This effect is taught by aberration theory, but
Since this requires extremely difficult mathematical expression, we omit it. However, it has been experimentally confirmed that this effect is achieved.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A mask pattern forming method according to an embodiment of the present invention will be described below with reference to the drawings.

Refer to FIG. 1 A plurality of (five in the figure) line patterns It+,
A case will be described in which a mask is manufactured by forming 1*..., l.

A plurality of line patterns 7 in the direction B-B' within 45 degrees with respect to the average in-plane direction A-A' in which coma aberration of the optical system of the exposure device occurs! , ,2. ...-! , if you want to form multiple line patterns! ! ,1,! !・
Dummy patterns ls and ! are placed on both ends of . , form. It was confirmed that when the line pattern size is 0.5n or more, all line patterns (5 lines in the figure) transferred to the resist film using this mask are formed according to the designed dimensions. .

Refer to FIG. 2 For the meandering line pattern l formed in the peripheral circuit when forming the memory cell, a dummy pattern 1. is placed at the position shown in FIG. and 1. By providing this, a pattern with high dimensional accuracy can be transferred.

Refer to Figure 3. Hole-like or island-like pattern when forming memory cells! , the dummy pattern 11 and ! are placed at position 1 as shown in FIG. , it is possible to transfer a pattern with high dimensional accuracy.

In addition, when forming multiple patterns in a direction exactly 45 degrees with respect to the average in-plane direction where coma aberration occurs in the optical system, both ends of the multiple patterns and the direction perpendicular to the formation direction of the multiple patterns It is effective to form dummy patterns at both ends of each of the plurality of patterns formed in the direction.

By forming the pattern, the effects of comatic aberration were eliminated, and all of the multiple patterns were transferred with high dimensional accuracy. As a result, in combination with the use of high-resolution resist processes, phase shift masks, etc., it has become possible to provide advanced fine pattern formation technology.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a method for forming a mask pattern according to an embodiment of the present invention. FIGS. 2 and 3 are diagrams showing examples of arrangement of dummy patterns. FIG. 4 is a diagram showing the shape of a line pattern transferred using a mask according to the prior art. C Effects of the Invention] As explained above, in the mask pattern forming method according to the present invention, a plurality of patterns are arranged in a direction within 45 degrees with respect to the average in-plane direction in which coma aberration of the optical system occurs. When forming a mask, dummy butter is placed on both ends of the plurality of patterns.Transparent substrate.1. ...Dummy pattern, ~l, ...Line pattern, ...Meandering line pattern, ...Island-remaining pattern.

Claims (1)

[Scope of Claims] [1] Forming a plurality of patterns in which a plurality of patterns are arranged in a row in a direction within 45 degrees with respect to an average in-plane direction in which coma aberration peculiar to an optical system occurs. A method for forming a pattern on a mask, characterized in that a dummy pattern is provided on the side of a pattern in the outermost row of the plurality of patterns. [2] When forming a plurality of patterns in which a plurality of patterns are arranged in a row at an angle of 45 degrees to the average in-plane direction where coma aberration peculiar to an optical system occurs, A dummy pattern is provided on the side of the pattern in the outermost row and on the side of the pattern in the outermost row of a plurality of patterns whose rows are formed in a direction perpendicular to the row direction of the plurality of patterns. Characteristic mask pattern formation method.