JPH03215861A - Formation of pattern - Google Patents

Abstract

PURPOSE:To improve the electric characteristic and the yield of a device by comparing a transfer pattern to be masked with the shape of a pattern formed on a mask and correcting the pattern of the mask whose fidelity is deteriorated. CONSTITUTION:The line patterns 12a - 12e are obtained when the line patterns 11a - 11e are transferred on a wafer being a side to be transferred by an exposure device and the patterns 12a - 12e are compared with the patterns 11a - 11e. By the aberration of the lens of the exposure device, the shape of the pattern 12a on the left side among the patterns 12a - 12e is smaller than the pattern 11a and the shape of the pattern 12e on the right side is larger than the pattern 11e. However, when the deformed quantity thereof is over a prescribed allowable quantity, the shapes of the patterns 11a and 11e are corrected and formed so that the pattern 11a becomes large by as much as the deterioration of the fidelity {a broken line (c)} and the pattern 11e becomes small by as much as the deterioration of the fidelity {a broken line (d)}. Then, the patterns 11a - 11e are transferred on the wafer by the exposure device.

Description

[Detailed Description of the Invention] [Summary] Regarding a pattern forming method, it is possible to transfer a pattern group formed on a transfer side to a transfer target side without degrading fidelity, and improve the electrical characteristics and The purpose of the present invention is to provide a method for forming a pattern that can improve the yield, and the method includes forming a pattern on the mask in advance, and transferring the pattern to the masked object using an exposure device. After that, the shape of the transferred pattern of the mask and the pattern formed on the mask are compared,
Regarding a transferred pattern whose shape fidelity has deteriorated by more than a predetermined tolerance than the shape of the pattern formed on the mask, the mask pattern is configured to be corrected based on the fidelity deterioration. .

[Industrial application field]

The present invention relates to a pattern forming method, and more particularly to a pattern forming method that can faithfully transfer a group of patterns formed on a mask onto a transfer target side without being affected by the characteristics of an exposure device.

BACKGROUND ART In recent years, as semiconductor devices have become more highly integrated, there has been a demand for finer design rules, and techniques such as increasing the resolution of resist processes and phase shifting have been proposed.

However, due to characteristics such as aberration of the lens of the exposure device, it is possible to transfer the pattern formed on the transfer side of the mask or the like to the wafer on the transferred side without deteriorating the fidelity, that is, without causing any change in the pattern shape. cannot be transferred to the top.

Therefore, it is required to transfer a pattern formed on a mask onto a wafer with pattern fidelity (dimensional characteristics) commensurate with high resolution.

[Conventional technology]

Hereinafter, the conventional technology will be specifically explained based on the drawings.

FIG. 6 is a diagram showing a conventional pattern forming method, and shows a pattern formed on a mask on the transfer side.

In the conventional mask pattern forming method, as shown in Fig. 6(a), a pattern is formed on the mask from square openings 1 and chromium 2 (light-shielding film), and a predetermined resolution is set. The pattern is transferred to a resist on a wafer (not shown) using an exposure device. Therefore, a pattern corresponding to the shape of the opening is formed on the wafer.

However, in reality, due to the aberration of the lens of the exposure device, the aperture 1 did not form a rectangular shape, and the peripheral edge was not transferred, resulting in a distorted shape. For this reason, Fig. 6(b) to (
As shown in FIG. 6(d), auxiliary patterns 3a to 5a are provided in advance on the peripheral edges of the openings 3 to 5 of the mask, so that the shape of the openings to be transferred onto the wafer is the same as that of the opening 1 shown in FIG. 6(a). It was corrected so that it had a corresponding rectangular shape. In this pattern forming method, auxiliary patterns 3a to 5a are provided in the openings 3 to 5 in order to correct the shape of the pattern to match the shape of the pattern previously transferred onto the wafer, that is, to improve resolution. Moreover, it is a micro pattern forming method that improves the resolution of a single point pattern.

On the other hand, as shown in FIG.
In the case of a transfer side mask (see FIG. 5(a)) on which a so-called line-and-space pattern is formed, in which pattern group 6 consisting of patterns a to 7d is formed, the pattern is transferred to the wafer by an exposure device. When transferred onto the wafer, the left line pattern 8a of the line patterns 8a to 8e transferred onto the wafer is smaller than the line pattern 6a, as shown in FIG. 5(b), due to the aberration of the lens of the exposure device. Furthermore, the line pattern 8e on the right side has become larger than the line pattern 6e. That is, the line patterns 6a to 6a formed on the transfer mask in advance
After transferring 6e onto the wafer, line patterns 6a to 6e are transferred onto the wafer.
6e with the line patterns 8a to 8e, the shapes of the line patterns 8a and 8e on both sides are smaller than the desired line pattern shape (indicated by broken lines a and b) by a predetermined tolerance (
Shape fidelity (dimensional characteristics) exceeding (e.g. 0.2 μm)
has deteriorated.

[Problem to be solved by the invention]

In the conventional mask in which a plurality of pattern groups 6 are formed on a mask as described above, there is no pattern forming method that corresponds to the pattern correction shown in FIG. 6 described above.

Therefore, when forming a pattern group composed of a plurality of patterns on the transfer side, the present invention is to transfer the pattern group formed on the transfer side to the transferred side without degrading the fidelity (dimensional characteristics). It is an object of the present invention to provide a method of forming a pattern that can improve the electrical characteristics and yield of dehyss.

[Means to solve the problem]

In order to achieve the above object, the pattern forming method according to the present invention is a method of forming a pattern on a mask, in which a pattern is formed on the mask in advance, the pattern is transferred to the masked object by an exposure device, and then the pattern is transferred to the mask. Compare the shape of the transferred pattern on the mask with the shape of the pattern formed on the mask, and determine which of the transferred patterns the shape fidelity has deteriorated by more than a predetermined tolerance than the shape of the pattern formed on the mask. Regarding this, the mask pattern is corrected based on the fidelity degradation.

[Effect]

FIG. 4 is a diagram explaining the principle of the present invention.

FIG. 4(a) shows a pattern formed on the mask that is the transfer side, and lla~11.8 shows a line pattern formed on the mask that is the transfer side, and the patterns lla~l
ie forms a pattern group 11.

FIG. 4(b) shows line patterns 12a to 12e when line patterns lla to lie are transferred onto a wafer, which is the transfer target side, by an exposure device, and the pattern 12a
Comparing the line patterns lla to lla to 12e, the patterns 12a to 11e are
12e, the shape of the left line pattern 12a is the rice pattern I. 1a, and the shape of the right line pattern 1.28 is larger than the line pattern l1e, and this amount of deformation is within a predetermined tolerance (for example,
If the fidelity (dimensional characteristics) deteriorates by more than 0.2 μm, the line pattern is
The shapes of a and lie are corrected, and the line pattern 11.8 is enlarged by the amount of fidelity degradation as shown in Figure 4 (a).
In addition, the line pattern lle is formed to be smaller by the amount of fidelity degradation (indicated by a broken line d). And line pattern 11. A to 11e are transferred onto a wafer by an exposure device. For this reason, Figure 4 (C
), line patterns 133 to 13e of desired dimensions (approximately the same shape as line patterns lla and 11e) are transferred onto the wafer.

Therefore, the buckoon group 11 formed on the mask is transferred onto the wafer without degrading the fidelity (dimensional characteristics). As a result, a pattern group forming technique suitable for future high-resolution processes can be obtained, and the electrical characteristics and yield of the dehyss can be improved.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a diagram showing a first embodiment of the pattern forming method according to the present invention, FIG. 1(a) is a diagram showing the line pattern, and FIG. It is a diagram transferred onto a wafer as a side. Note that this embodiment applies the present invention to a line and space pattern.

First, the configuration will be explained. In FIG. 1(a), 21a
21e are line patterns formed on the mask which is the transferred side, 22a to 22d are space patterns provided between the line patterns 21a to 21e, and these line patterns 21a
~21e and 22a~22d constitute the pattern group 23, and the line pattern 2
1a to 21e and space patterns 22a to 22d are configured to have the same shape. Then, this pattern group 23 was transferred onto a wafer based on the following exposure conditions (resolution).

Design values of line width pattern size of line patterns 21a to 21d: 0.65 μm, 0.6 μm, 0.55
4 types: μm, 0.5 μm, exposure wavelength of exposure device: i-line 365 r+n+, numerical aperture of projection lens of exposure device:
0.45 resist di-novolac type resin (TSMR365 IR manufactured by Tokyo Ohka Kogyo Co., Ltd.).

As a result, line patterns 24a to 24e as transfer patterns as shown in FIG. 1(b) were transferred onto the wafer. And the central line patterns 24b to 24d
While the design value dimensions were obtained up to 0.5 μm,
The line pattern 24a and the line pattern 24e had deterioration in fidelity (dimensional characteristics) as shown in the table below depending on the pattern size of the line width. Note that fidelity deterioration here refers to the pattern 21a formed on the mask in advance.
0 After being transferred onto the wafer by an optical device, the shapes of the patterns 24a to 24e transferred onto the wafer are within a predetermined tolerance range (for example,
0.12 μm), and the desired transfer shape cannot be obtained.

(Unit: μm) As is clear from this table, pattern size dependence tends to be sufficiently correctable by linear approximation. Then, the line pattern 22 a , 0.6 at the design value of 0.6.
Line pattern 22 at 55 μm and 0.5 μm
a and 22e, the deterioration in fidelity with respect to the desired design value of line patterns 21a and 21e exceeds the allowable 11 range (0.12 μm), so the corresponding deterioration in fidelity is corrected to line patterns 21a and 21e. do. When this pattern group is exposed using a newly formed mask (not shown), the pattern transferred onto the wafer can have desired dimensional characteristics (design values).

In this way, in this embodiment, when forming a pattern group composed of a plurality of line patterns on a mask, the pattern group formed on the mask is transferred onto a wafer without degrading the fidelity (dimensional characteristics). I can do it. Therefore, the electrical characteristics and yield of the dehyss can be improved.

FIG. 2 is a diagram showing a second embodiment of the pattern forming method according to the present invention, and this embodiment shows a memory pattern shape in a processing step for determining transistor characteristics of an SRAM. FIG. 2(a) shows line patterns 312 to 31d with a line width of 0.5 μm, which are part of a pattern group (not shown) formed on a mask, and FIG. 2(b) shows line patterns 31a to 31d by exposure. 12 ? transferred onto the wafer by the device? In-patterns 32a to 32d are shown. Note that in this example, those in which the fidelity is significantly degraded due to lens aberration are extracted and shown. Even in this embodiment, the line pattern 3 is based on the exposure conditions shown in the first embodiment.
As a result of correction of 12 to 31d, the design value is 0.5 μm
However, the fidelity was corrected to line patterns 318 to 31'd and a line pattern was formed. As a result of exposure, the deterioration in fidelity was 0.
We were able to achieve a value of 0.01 μm or less, which can be ignored in terms of the electrical characteristics of the device.

FIG. 3 shows a line pattern of a third embodiment of the pattern forming method according to the present invention. In FIG. 3, 4 is a pattern group consisting of line patterns 6, . ing. In this embodiment, the line widths of the line patterns l2 to An-1 in the pattern group 41 transferred onto the wafer are 13, which is a value that does not pose a problem with the design value, so l7!7
By correcting the design value by the amount of deterioration in fidelity, the same effect as in the first embodiment can be obtained.

〔Effect of the invention〕

According to the present invention, the pattern group formed on the transfer side can be transferred to the transfer target side without degrading the fidelity, so that the electrical characteristics and yield of the device can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating a first embodiment of a pattern forming method according to the present invention, FIG. 2 is a diagram explaining a second embodiment of a pattern forming method according to the present invention, and FIG. 3 is a diagram illustrating a second embodiment of a pattern forming method according to the present invention. 4 is a diagram explaining the basic principle of the present invention, and FIG. 5 is a diagram illustrating a pattern formed on the transfer side and a pattern formed on the transfer target 14 side. FIG. 6 is a diagram showing a conventional pattern forming method. 212-21e... Line pattern (pattern), 22a-22d... Pace pattern (pattern), 24a-24e... Line pattern (
transfer pattern). 15 Hole hem Figure age Putter 2 of the third embodiment Figure 3 JP-A-3-215861 (7) 1 (a) Figure 5 (j)) Figure 6 showing the conventional pattern forming method

Claims (1)

[Claims] A method of forming a pattern on a mask, wherein a pattern is formed on the mask in advance, the pattern is transferred to a masked object by an exposure device, and then the shape of the transferred pattern of the masked object and the shape of the pattern formed on the mask are respectively Compare,
Regarding the transfer pattern whose shape fidelity has deteriorated by more than a predetermined tolerance than the shape of the pattern formed on the mask, the mask pattern is corrected based on the fidelity deterioration. A method for forming a pattern characterized by: