JPH11102060A - Mask for exposing fine pattern and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposing mask correcting the fine deviation of a pattern by proximity effect occurring when super-high resolution technique is used. SOLUTION: As to this exposing mask constituted of a phase shift film having an asymmetric hole pattern which has a second hole pattern 61 in the vicinity of a first hole pattern 6, and which does not have another hole pattern in the point-symmetric position of the pattern 61 with respect to the pattern 6 and a transparent base plate; the correction amount of the positions of the patterns 6 and 61 is calculated in accordance with pitch between the patterns 6 and 61, and the positions of the patterns 6 and 61 are corrected so as to avoid that the fine deviation of the pattern caused by the light proximity effect made stronger by the phase shift film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a fine pattern exposure mask having an adjacent pattern and a method for manufacturing the same.

[0002]

2. Description of the Related Art With regard to miniaturization of integrated circuits, in the field of photolithography, resolution has been improved by shortening the exposure wavelength. However, 256 Mbit DRA
In order to cope with miniaturization of M and 1 gigabit DRAMs and further integrated circuits, an exposure technique called a super-resolution technique such as a phase shift method or an annular illumination method is being introduced.

For the hole pattern exposure, a phase shift method using a halftone phase shift mask is very effective. When the hole pattern has periodicity (such as a memory device), the annular illumination method is also effective. A method of exposing a hole pattern using a halftone phase shift mask has been proposed in Japanese Patent Application Laid-Open No. 4-136854.

Hereinafter, an exposure technique using a conventional halftone phase shift mask will be described with reference to FIGS. FIG. 5 is a plan view of the halftone phase shift mask. Reference numeral 9 in FIG. 6 is an optical image on the wafer transferred by the mask. Opening 6 and Opening 6
1 and the halftone phase shift film 2 have a phase difference of 180 °,
The transmittance is about 2% to 20%. These openings 6, 61
The light that has passed through and the light that has passed through the phase shift film 2 and whose phase has been inverted by 180 ° overlap with each other, and an optical image 9 with good contrast as shown in FIG. 6 (XX ′ cross-sectional view) can be obtained. As a result, the resist pattern obtained from the optical image 9 can have a high resolution and a wide depth of focus.

Reference numeral 7 denotes a transparent substrate which is a glass substrate on which the phase shift film 2 is formed, and reference numeral 8 denotes an optical image obtained from one opening of the halftone phase shift mask. Next, an exposure technique using a conventional annular illumination method will be described with reference to FIGS.

FIG. 8 is a sectional view showing the principle of exposure by the annular illumination method. The exposure light 13 obliquely incident from the annular illumination causes diffraction at the light shielding film 5. Of these, -1 order and 0
Second-order or zero-order and first-order diffracted lights (15, 14) pass through a projection lens 17 and are projected onto a wafer. On this wafer, an optical image 12 is given by two-beam interference. The optical image 12 caused by the two-beam interference has a better contrast than the optical image given by the three-beam interference by the ordinary illumination system. The resist pattern obtained from the optical image 12 has a high resolution and a wide focus. Can have depth.

In the drawings, reference numerals 6 'and 61' denote openings, and 11 denotes an optical image obtained from one opening.
The halftone phase shift mask 2 shown in FIGS. 5 and 6 is more susceptible to an adjacent pattern than a normal exposure method. Here, when the hole pattern is asymmetrically close, the optical image of the hole pattern is also asymmetric, and as a result, as shown in FIG.
0 has a problem that the eyes are misaligned from a desired position.

Also, when the annular illumination shown in FIG. 8 is used, it is more susceptible to the influence of an adjacent pattern than the ordinary exposure method. Here, when the second opening 61 is provided near the opening 6 and a hole pattern having no hole pattern at the point symmetric position of the second opening 61 asymmetrically approaches the opening 6, The optical image of the pattern is also asymmetric,
As a result, as shown in FIG.
Has a problem that the eyes are misaligned from a desired position.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to remedy the above-mentioned disadvantages of the prior art, especially when asymmetrically arranged hole patterns are exposed using a halftone phase shift mask or annular illumination. It is an object of the present invention to provide a halftone phase shift mask, a ring illumination exposure mask, and a method for manufacturing the same, which are masks for fine pattern exposure that can prevent the misalignment of the optical pattern seen in the above.

[0010]

SUMMARY OF THE INVENTION The present invention basically employs the following technical configuration to achieve the above object. That is, according to a first aspect of the present invention, a second hole pattern is arranged near a first hole pattern, and another hole pattern is located at a point symmetrical position of the second hole pattern with respect to the first hole pattern. The first and second hole patterns adjacent to each other pass through a center point of the first hole pattern and are parallel to at least one side of the first hole pattern. The second hole pattern is arranged in a positional relationship such that the center point of the second hole pattern does not exist on the line. As a second aspect of the present invention, the second hole pattern is located near the first hole pattern. An asymmetric hole pattern having no hole pattern at the point symmetry position of the second hole pattern with respect to the first hole pattern. In an exposure mask comprising a halftone phase shift film having a halftone phase shift film and a transparent substrate, a gap between the first and second hole patterns is prevented so that pattern misalignment does not occur due to an optical proximity effect enhanced by the halftone phase shift film. A fine pattern exposure mask, wherein a correction amount of the position of the first and second hole patterns is obtained according to the pitch of the pattern, and the position of the hole pattern is corrected based on the correction amount. According to a third aspect, in addition to the above-described configuration, the correction amount is obtained as a function of the exposure wavelength, the numerical aperture of the lens, and the pattern pitch of the first and second hole patterns, and is corrected in a direction away from each other. As a fourth mode, if the exposure wavelength λ, the numerical aperture NA of the lens, and the pattern pitch P are set, the correction amount S becomes the correction amount. = {-0.563A · exp (-11.5A + 6.14) +6.19 × 1
0 ⁻³ ｝ × P / 0.4 where A = P · NA / λ.

According to a fifth aspect of the present invention, a second hole pattern is provided near the first hole pattern, and the second hole pattern is located at a point symmetrical position with respect to the first hole pattern with respect to the second hole pattern. Chromium or chromium oxide with an asymmetric hole pattern that does not have a hole pattern, or an exposure mask consisting of a laminated film and a transparent substrate, the pattern misalignment occurs due to the optical proximity effect when using the annular illumination method A correction amount of the position of the hole pattern is obtained in accordance with the pitch of the first and second hole patterns so that the position of the first and second hole patterns is corrected based on the correction amount. This is a fine pattern exposure mask characterized in that:

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The fine exposure mask according to the present invention employs the above-described technical configuration.
Having a second hole pattern near the hole pattern of
A halftone phase shift mask or an exposure mask for an annular illumination method in which a hole pattern is provided asymmetrically with respect to the first hole pattern and has no other hole pattern at a point symmetric position of the second hole pattern. When a pattern is transferred onto a substrate by using, the arrangement of the hole patterns is corrected according to the pitch between adjacent patterns so that the transferred pattern is not misaligned from a desired position due to the proximity effect of exposure light. Thereby, the occurrence of the misalignment can be prevented.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fine exposure mask according to the present invention. FIG. 1 is a plan view of a halftone phase shift mask, FIG. 3 is a graph showing a pattern position correction amount, and FIG. 4 is a graph showing an effect of the present invention. As shown in FIG. A phase shift film 2 having an asymmetric hole pattern having no other hole pattern at a point symmetrical position of the second hole pattern 61 with respect to the first hole pattern 6 with respect to the first hole pattern 6. In the exposure mask made of the transparent substrate 7, the hole patterns 6, 61 are adjusted according to the pitch 4 between the hole patterns 6, 61 so that pattern misalignment does not occur due to the optical proximity effect enhanced by the phase shift film 2. A fine pattern exposure mask, wherein a correction amount at the position of 61 is obtained, and the positions of the hole patterns 6 and 61 are corrected based on the correction amount. It is shown.

That is, the second hole pattern 1 is arranged in the vicinity of the first hole pattern, and there is no other hole pattern at point-symmetric positions of the second hole patterns 11 and 12 with respect to the first hole pattern 1. In the exposure mask including the asymmetric hole pattern, the first and second hole patterns adjacent to each other pass through a center point C ₀ of the first hole pattern and are parallel to at least one side of the first hole pattern 1. A fine pattern exposure mask is shown, wherein the masks are arranged in such a manner that the center points C ₁ and C ₂ of the second hole pattern do not exist on the axes X and Y.

The correction amount is obtained as a function of the exposure wavelength, the numerical aperture of the lens, and the pattern pitch of the hole patterns 6 and 61, and is corrected in a direction away from each other.
Assuming that the exposure wavelength is λ, the numerical aperture of the lens is NA, and the pattern pitch is P, the correction amount S is: correction amount S = ｛− 0.563A · exp (−11.5A + 6.14) + 6.19 × 10 ⁻³ ｝ × P / 0.4 (1) Here, it is characterized in that A = P · NA / λ.

Referring to the present invention in more detail, FIG.
5 is an example of the exposure mask of the present invention in a halftone phase shift. Reference numerals 1 and 11 denote mask openings (mask patterns) of the present invention, 2 denotes a halftone phase shift film, and 6 and 61 denote mask openings of conventional hole patterns, that is, hole openings in design. As shown in FIG. 1, in the present invention, the positions of the openings 6 and 61 of the mask are corrected in consideration of the proximity effect.

As a result, the pattern pitch 4 between the mask pattern 6 and the mask pattern 61 is corrected in a direction away from each other like the mask patterns 1 and 11, and the pattern pitch 4 between the mask pattern 6 and the mask pattern 62 is similarly changed. Corrections are made in directions away from each other as in the mask patterns 1 and 12, respectively. FIG. 3 shows the normalized spatial frequency (exposure wavelength λ,
5 is a graph showing a relationship between a numerical aperture NA of a lens and a function of a pattern pitch P) and a correction amount S for opening a pattern at a designed position. In the graph, "plus" in the correction amount indicates correction in a direction in which the patterns approach each other, and "minus" indicates correction in a direction in which the patterns move away from each other. Open circles indicate the relationship between the spatial frequency A and the correction amount S in the phase shift film 2.

The solid line a in the graph is based on the equation (1), and the relationship between the spatial frequency A and the correction amount S is expressed by the equation (1).
Approximately matches. FIG. 4 is a comparison of the amount of misalignment before and after the correction performed using the correction equation (1). White circles indicate the amount of eye misalignment before correction by the phase shift method, and white squares indicate the amount of eye misalignment after correction. By performing the correction according to the present invention, the amount of misregistration can be significantly improved. For example, when the pitch P of the contact hole pattern is 0.4 μm, the exposure wavelength λ is 0.248 μm, and the numerical aperture NA is 0.55, the amount of misalignment is corrected from 0.027 μm to −0.004 μm.
Could be suppressed.

FIG. 2 shows another embodiment of the present invention.
Is an example of the exposure mask of the present invention in annular illumination. Also,
FIG. 3 is a graph showing the amount of pattern position correction, and FIG. 4 is a graph showing the effect of the present invention. In the exposure mask composed of chromium or chromium oxide having an asymmetric hole pattern or its laminated film 5 and the transparent substrate 7, A correction amount of the positions of the hole patterns 6 and 61 is obtained according to the pitch 4 of the hole patterns 6 and 61 so that the pattern misalignment does not occur due to the optical proximity effect when the band illumination method is used, A fine pattern exposure mask is shown in which the positions of the hole patterns 6 and 61 are corrected based on the correction amount.

The correction amount is obtained as a function of the exposure wavelength, the numerical aperture of the lens, and the pattern pitch of the hole patterns 6 and 61, and is corrected in a direction away from each other. The exposure wavelength λ, the numerical aperture NA of the lens, the pattern pitch Assuming that P is the correction amount S, the correction amount S = ｛− 0.629 A · exp (−14.0 A + 6.37) −4.73 × 10 ⁻³ ｝ × P / 0.4 (2) where A = P · NA / Λ.

Next, this embodiment will be described.
1 'and 11' are mask openings (mask patterns) of the present invention, and 6 'and 61' are mask openings of conventional hole patterns, that is, hole pattern openings in design. As shown in FIG. 2, in the present invention, the positions of the openings 6 'and 61' of the light shielding film 5 are corrected in consideration of the proximity effect in the same manner as in FIG.

FIG. 3 shows the normalized spatial frequency (a function of the exposure wavelength λ, the numerical aperture NA of the lens, and the pattern pitch P) in the hole arrangement of FIG. 2 and the correction for opening the pattern at the designed position. 6 is a graph of a relationship with an amount S. In the graph, "plus" in the correction amount indicates correction in a direction in which the patterns approach each other, and "minus" indicates correction in a direction in which the patterns move away from each other. The black circles indicate the relationship between the spatial frequency A and the correction amount S in the phase shift mask.

The solid line b in the graph is based on the equation (2), and the relationship between the spatial frequency and the correction amount substantially matches the equation (2). FIG. 4 is a comparison of the amount of misalignment before and after correction performed using the above-described correction formula. The black circles indicate the amount of eye misalignment before correction by the annular illumination method, and the black squares indicate the amount of eye misalignment after correction. By performing the correction according to the present invention, the amount of misregistration can be significantly improved. For example, a contact hole pattern pitch P = 0.4 μm, an exposure wavelength λ = 0.248 μm,
When the numerical aperture was NA = 0.55, the amount of misregistration could be suppressed from 0.008 μm to −0.0003 μm by performing the correction.

[0024]

According to the present invention, it is possible to suppress the misregistration of the resist pattern due to the optical proximity effect generated by the phase shift method and the annular illumination method. As a result, the yield of the memory device can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a halftone phase shift mask of the present invention.

FIG. 2 is a plan view of an exposure mask for annular illumination according to the present invention.

FIG. 3 is a graph showing a pattern position correction amount according to the present invention.

FIG. 4 is a graph showing a comparison of the amount of misregistration between the prior art and the present invention.

FIG. 5 is a plan view of a halftone phase shift mask for explaining a conventional technique.

FIG. 6 is a diagram showing a cross-sectional view and an optical image of a halftone phase shift mask for explaining a conventional technique.

FIG. 7 is a plan view of a wafer on which a hole pattern is formed for explaining the problem of FIG. 6;

FIG. 8 is a cross-sectional view of a ring illumination method for explaining a conventional technique.

9 is a plan view of a wafer exposed by the annular illumination method for explaining the problem of FIG. 8;

[Explanation of symbols]

1, 1 'Mask opening of hole pattern of the present invention 2 Halftone phase shift film 4 Pattern pitch (P) 5 Light shielding film 6, 6' Mask opening of conventional hole pattern 7 Transparent substrate 8 Halftone phase shift mask 1 Optical image obtained from one aperture 9 Optical image obtained by halftone phase shift mask 10, 10 'resist pattern (opening) 11 Optical image obtained from one aperture of normal mask using annular illumination method 12 Optical image obtained by the annular illumination method 13 Incident light by the annular illumination method 14 First-order diffracted light by the annular illumination method 15 0-order diffracted light by the annular illumination method 16-1st-order diffracted light by the annular illumination method 17 Projection lens

Claims (13)

[Claims] 1. An asymmetric hole pattern in which a second hole pattern is arranged near a first hole pattern, and there is no other hole pattern at a point symmetrical position of the second hole pattern with respect to the first hole pattern. In the exposure mask, the first and second hole patterns adjacent to each other pass through a center point of the first hole pattern, and a second hole pattern on an axis parallel to at least one side of the first hole pattern. Characterized in that the masks are arranged in a positional relationship such that the center point does not exist. 2. An asymmetric hole having a second hole pattern in the vicinity of a first hole pattern and having no other hole pattern at a point symmetric position of the second hole pattern with respect to the first hole pattern. In an exposure mask comprising a halftone phase shift film having a pattern and a transparent substrate, the first and second hole patterns are formed so that pattern misalignment does not occur due to an optical proximity effect enhanced by the halftone phase shift film. A fine pattern exposure mask, wherein an amount of correction of the positions of the first and second hole patterns is determined according to a pitch between the holes, and the position of the hole pattern is corrected based on the amount of correction. 3. The method according to claim 2, wherein the correction amount is obtained as a function of an exposure wavelength, a numerical aperture of a lens, and a pattern pitch of the first and second hole patterns, and is corrected in a direction away from each other. For fine pattern exposure. 4. Assuming an exposure wavelength λ, a numerical aperture NA of a lens, and a pattern pitch P, the correction amount S is: correction amount S = 補正 −0.563A · exp (−11.5A + 6.14) + 6.19 × 1
0 ^-3} × P / 0.4, where claims 2 or 3 fine pattern exposure mask wherein a is A = P · NA / λ. 5. An asymmetric hole having a second hole pattern in the vicinity of the first hole pattern and having no other hole pattern at a point symmetric position of the second hole pattern with respect to the first hole pattern. In an exposure mask comprising a chromium having a pattern, chromium oxide or a laminated film thereof and a transparent substrate, the first and second exposure masks are formed so that pattern misalignment does not occur due to an optical proximity effect when an annular illumination method is used. A correction amount of the position of the first and second hole patterns is obtained according to a pitch of the second hole pattern, and the position of the hole pattern is corrected based on the correction amount. mask. 6. The apparatus according to claim 5, wherein the correction amount is obtained as a function of an exposure wavelength, a numerical aperture of a lens, and a pattern pitch of the first and second hole patterns, and is corrected in a direction away from each other. For fine pattern exposure. 7. Assuming an exposure wavelength λ, a numerical aperture NA of a lens, and a pattern pitch P, the correction amount S is: correction amount S = ｛− 0.629 A · exp (−14.0 A + 6.37) −4.73 × 1
0 ^-3} × P / 0.4 where, A = P · NA / claim 5 or 6 fine pattern exposure mask wherein a is lambda. 8. When an exposure mask is manufactured using a halftone phase shift film, a correction amount for correcting a pattern misalignment due to an optical proximity effect with respect to a preset mask pattern position is obtained. A method for manufacturing a fine pattern exposure mask, comprising disposing a mask pattern by displacing the mask pattern from a preset position of the mask pattern by the correction amount. 9. The method for manufacturing a fine pattern exposure mask according to claim 8, wherein the correction amount is obtained as a function of an exposure wavelength, a numerical aperture of a lens, and a pattern pitch, and is corrected in a direction away from each other. . 10. Assuming an exposure wavelength λ, a numerical aperture NA of a lens, and a pattern pitch P, the correction amount S is: correction amount S = ｛− 0.563A · exp (−11.5A + 6.14) + 6.19 × 1
0 ⁻³ ｝ × P / 0.4 Here, A = P · NA / λ. The method of manufacturing a mask for exposing fine patterns according to claim 8 or 9, wherein A = P · NA / λ. 11. A correction amount for correcting a pattern misalignment due to an optical proximity effect with respect to a preset mask pattern position when manufacturing an exposure mask using chromium, chromium oxide, or a laminated film of these. Wherein the mask pattern is arranged by displacing the mask pattern from the preset mask pattern position by the correction amount. 12. The method according to claim 11, wherein the correction amount is obtained as a function of an exposure wavelength, a numerical aperture of a lens, and a pattern pitch, and is corrected in a direction away from each other. . 13. Given an exposure wavelength λ, a numerical aperture NA of a lens, and a pattern pitch P, the correction amount S is as follows: correction amount S = ｛− 0.629 A · exp (−14.0 A + 6.37) −4.73 × 1
0 ^-3} × P / 0.4 where claim 11 or 12 method for producing a fine pattern exposure mask wherein a is A = P · NA / λ.