JP3171149B2 - Fine pattern exposure mask and manufacturing method thereof - Google Patents

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. Immediate Chi, a first aspect of the present invention, the first hole pattern near a second hole pattern, the other to a point symmetric position of the second hole pattern relative to the first hole pattern In an exposure mask consisting of a halftone phase shift film having an asymmetric hole pattern without a hole pattern and a transparent substrate, a pattern misalignment does not occur due to an optical proximity effect enhanced by the halftone phase shift film,
A correction amount of the position of the first and second hole patterns is obtained according to a pitch between the first and second hole patterns, and the position of the hole pattern is corrected based on the correction amount. In a second aspect, in addition to the above configuration, the correction amount is determined by a function of an exposure wavelength, a numerical aperture of a lens, and a pattern pitch of the first and second hole patterns. And are corrected in directions away from each other. As a third mode, the exposure wavelength λ and the numerical aperture of the lens N
A, if the pattern pitch is P, the correction amount S is the correction amount S = ｛− 0.563 A · exp (−11.5 A + 6.14) + 6.19 × 10 ⁻³ ｝ × P / 0.4 where A = P · NA / Λ.

According to a fourth aspect of the present invention, a second hole pattern is provided in the vicinity of the first hole pattern, and a second hole pattern is provided at a point symmetrical position of the second hole pattern with respect to the first 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.

[0014] That is, the second hole pattern 11 is disposed near the first hole pattern 1, there is no other hole patterns with respect to the first hole pattern 1 at a point symmetric position of the second hole pattern 11 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. Second hole pattern on axis X, Y
11 fine pattern exposure mask, wherein the center point C ₁ is arranged in a positional relationship such that it does not exist is shown in.

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 (12)

(57) [Claims] 1. A second hole near a first hole pattern.
A hole pattern, which is located in front of the first hole pattern.
Another hole pattern is located at the point symmetrical position of the second hole pattern.
Half with an asymmetric hole pattern without holes
An exposure mask consisting of a tone phase shift film and a transparent substrate
And the light enhanced by the halftone phase shift film
Avoid pattern misalignment due to proximity effect
Depending on the pitch between the first and second hole patterns
The amount of correction of the positions of the first and second hole patterns is obtained by
The position of the hole pattern based on this correction amount.
For fine pattern exposure, characterized in that
H. 2. The method according to claim 1, wherein the correction amount is an exposure wavelength, a lens aperture.
Number, and the pattern pitch of the first and second hole patterns.
Is calculated by the number and corrected in the direction away from each other.
2. The fine pattern exposure mask according to claim 1, wherein: 3. An exposure wavelength λ, a numerical aperture NA of a lens, a pattern
Given a pitch P, the correction amount S is the correction amount S = ｛− 0.563 A · exp (−11.5 A + 6.14) + 6.19 × 10 ⁻³ ｝ × P / 0.4 where A = P · NA / λ . The fine pattern according to claim 1 or 2, wherein
Exposure mask . 4. A second hole near the first hole pattern.
A hole pattern, which is located in front of the first hole pattern.
Another hole pattern is located at the point symmetrical position of the second hole pattern.
Black with an asymmetric hole pattern without holes
Chromium oxide or its laminated film and a transparent substrate
Optical proximity effect when using annular illumination method in optical mask
To avoid pattern misalignment due to fruits,
According to the pitch of the first and second hole patterns, the
The correction amounts of the positions of the first and second hole patterns are obtained.
The position of the hole pattern is compensated based on this correction amount.
A fine pattern exposure mask characterized by being corrected . 5. The correction amount is an exposure wavelength, an aperture of a lens.
Number, and the pattern pitch of the first and second hole patterns.
Is calculated by the number and corrected in the direction away from each other.
The mask for exposing fine patterns according to claim 4, characterized in that: 6. An exposure wavelength λ, a numerical aperture NA of a lens, a pattern
If Npitchi P the correction amount S here correction amount S = {-0.629A · exp (-14.0A + 6.37) -4.73 × 10 -3} × P / 0.4, is A = P · NA / λ The fine pattern according to claim 4 or 5, wherein
Exposure mask . 7. An exposure apparatus using a halftone phase shift film.
When manufacturing an optical mask, a preset mask pattern
Of the pattern due to the optical proximity effect
The amount of correction for correcting the
The mask pattern is displaced from the turn position by the correction amount.
Characterized by having a mask pattern arranged
A method for manufacturing a mask for pattern exposure . 8. The correction amount is an exposure wavelength, a lens aperture.
It is calculated as a function of number and pattern pitch, and moves away from each other
8. The fine structure according to claim 7, wherein the correction is performed in the direction.
A method for manufacturing a mask for pattern exposure . 9. An exposure wavelength λ, a numerical aperture NA of a lens, a pattern
Given a pitch P, the correction amount S is the correction amount S = ｛− 0.563 A · exp (−11.5 A + 6.14) + 6.19 × 10 ⁻³ ｝ × P / 0.4 where A = P · NA / λ . The fine pattern according to claim 7 or 8, wherein
Manufacturing method of the mask for exposure to light . 10. Chromium, chromium oxide or a product thereof
When manufacturing an exposure mask using a layer film,
The proximity of the mask pattern
A correction amount for correcting the pattern misalignment is determined, and the correction amount is set in advance.
The mask pattern before the specified mask pattern position
The mask pattern is displaced by the correction amount.
A method for producing a fine pattern exposure mask, characterized in that: 11. The correction amount is an exposure wavelength, an aperture of a lens.
It is calculated as a function of number and pattern pitch, and moves away from each other
11. The fine adjustment according to claim 10, wherein the correction is performed in the direction.
A method for manufacturing a fine pattern exposure mask . 12. An exposure wavelength λ, a numerical aperture NA of a lens,
Assuming a turn pitch P, the correction amount S is the correction amount S = ｛− 0.629 A · exp (-14.0 A + 6.37) −4.73 × 10 ⁻³ ｝ × P / 0.4 where A = P · NA / λ . The fine particle according to claim 10 or 11, wherein
A method for manufacturing a mask for pattern exposure .