EP0401795A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Phase-shifting photomask for negative resist and process for forming isolated, negative resist pattern using the phaseshifting photomask
Assignee: Oki Electric Industry Co Ltd
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Filing: 1990-06-06
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Granted: —
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Expires: 2010-06-06
Abstract
Abstract A photomask for a negative resist used for forming a resist image in the form of an isolated pattern. The photomask (40; 60; 70; 80; 90; 100; 120; 140) comprises a substrate (42; 82; 92; 102; 122; 142) transparent to an exposure light and a mask pattern (44; 62; 84 and 86; 94 and 96; 110; 132; 154) on the substrate. The mask pattern is formed of a phase-shifting layer (44; 62) alone or of a phase-shifting layer(s) (86; 96; 116; 130; 150) and a light-screening layer(s) (84; 94; 112; 124; 152). The phase-shifting layer is capable of shifting the phase of the light transmitted therethrough relatively to the phase of the light transmitted through the area of the photomask other than the area of the phase-shifting layer. A phase-shifting layer may be provided in such a way to substantially surround a light-screening layer having a width permitting of no resolution by itself. A phase-shifting layer may be provided in such a way to fill up an auxiliary aperture (114; 128; 148) provided in a light-screening layer. The portion of the phase-shifting layer filled in the aperture having a width permitting of no resolution by itself. With the use of the photomask, such a fine space or hole resist pattern as to exceed the resolution limit can be formed with excellent resolution and focus margin. A process for forming an isolated resist pattern using the photomask is also disclosed.
Inventors
- 👤 Hideyuki Jinbo
- 👤 Yoshio Yamashita
- 👤 Yoichi Tomo
- 👤 Yoshiyuki Kawazu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 02:01
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/29; G03F1/30
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
112 words
A photomask (40; 60; 70) adapted to be used in a projection aligner to project the mask pattern thereof in the form of an isolated pattern on the surface of a wafer having a negative resist film formed thereon, comprising: a substrate (42) transparent to an exposure light, and a mask pattern (44; 62; 64) provided on said substrate; wherein said mask pattern is formed of a phase-shifting layer (44; 62; 64) capable of transmitting said exposure light therethrough and shifting the phase of said exposure light transmitted therethrough relatively to the phase of said exposure light transmitted through the area of the photomask other than the area of said phase-shifting layer.
Claim 2
Dependent Claim
112 words
A photomask (40; 60; 70) adapted to be used in a projection aligner to project the mask pattern thereof in the form of an isolated pattern on the surface of a wafer having a negative resist film formed thereon, comprising: a substrate (42) transparent to an exposure light, and a mask pattern (44; 62; 64) provided on said substrate; wherein said mask pattern is formed of a phase-shifting layer (44; 62; 64) capable of transmitting said exposure light therethrough and shifting the phase of said exposure light transmitted therethrough relatively to the phase of said exposure light transmitted through the area of the photomask other than the area of said phase-shifting layer.
Claim 3
Dependent Claim
62 words
A photomask (40; 60) as claimed in claim 1, wherein said mask pattern (44; 62) formed of said phase-shifting layer (44; 62) is in a striped form to thereby enable the mask pattern to be projected as said isolated pattern on the surface of said wafer to form a space pattern in the form of said isolated pattern in said negative resist.
Claim 4
Dependent Claim
62 words
A photomask (40; 70) as claimed in claim 1, wherein said mask pattern (44; 64) formed of said phase-shifting layer (44; 64) is in a quadrate form to thereby enable said mask pattern to be projected as the isolated pattern on the surface of said wafer to form a hole pattern in the form of said isolated pattern in the negative resist.
Claim 5
Dependent Claim
61 words
A photomask as claimed in claim 1, wherein the width W of said mask pattern formed of said phase-shifting layer is such as to be expressed by the following equation: W = P λ NA wherein 0 < P ≦ 0.6, λ stands for the wavelength of said exposure light, and NA stands for the numerical aperture of the projection aligner.
Claim 6
Dependent Claim
71 words
A photomask as claimed in claim 1, wherein the thickness d of said mask pattern formed of said phase-shifting layer is such as to be expressed by the following equation: d = (ℓ+ k)λ/(n - 1) wherein 1/4 ≦ k ≦ 3/4, λ stands for the wavelength of said exposure light, n stands for the refractive index at λ of said phase-shifting layer, and ℓ is 0 or a positive integer.
Claim 7
Dependent Claim
178 words
A photomask (80; 90) adapted to be used in a projection aligner to project the mask pattern thereof in the form of an isolated pattern on the surface of a wafer having a negative resist film formed thereon, comprising: a substrate (82; 92) transparent to an exposure light, and a mask pattern (84 and 86; 94 and 96) provided on said substrate; wherein said mask pattern is constituted of a light-screening layer (84; 94) and a phase-shifting layer (86; 96), said light-screening layer being incapable of transmitting said exposure light therethrough and having a width permitting of no resolution by itself, and said phase-shifting layer being capable of transmitting the exposure light therethrough and shifting the phase of the exposure light transmitted therethrough relatively to the phase of the exposure light transmitted through the area of the photomask other than the area of said phase-shifting layer; and wherein said phase-shifting layer with one and the same width is provided in contact with said light-screening layer in such a way as to at least substantially surround said light-screening layer.
Claim 8
Dependent Claim
178 words
A photomask (80; 90) adapted to be used in a projection aligner to project the mask pattern thereof in the form of an isolated pattern on the surface of a wafer having a negative resist film formed thereon, comprising: a substrate (82; 92) transparent to an exposure light, and a mask pattern (84 and 86; 94 and 96) provided on said substrate; wherein said mask pattern is constituted of a light-screening layer (84; 94) and a phase-shifting layer (86; 96), said light-screening layer being incapable of transmitting said exposure light therethrough and having a width permitting of no resolution by itself, and said phase-shifting layer being capable of transmitting the exposure light therethrough and shifting the phase of the exposure light transmitted therethrough relatively to the phase of the exposure light transmitted through the area of the photomask other than the area of said phase-shifting layer; and wherein said phase-shifting layer with one and the same width is provided in contact with said light-screening layer in such a way as to at least substantially surround said light-screening layer.
Claim 9
Dependent Claim
83 words
A photomask (80) as claimed in claim 6, wherein said light-screening layer (84) is in a striped form and said phase-shifting layer (86) is constituted of first and second striped phase-shifting layer areas (86, 86) separately disposed on the respective sides of said light-screening layer (84), whereby said mask pattern (84 and 86) can be projected as said isolated pattern on the surface of said wafer to form a space pattern in the form of said isolated pattern in the negative resist film.
Claim 10
Dependent Claim
67 words
A photomask (90) as claimed in claim 6, wherein said light-screening layer (94) is in a quadrate form and said phase-shifting layer (96) is disposed all around said light-screening layer, whereby the mask pattern (94 and 96) can be projected as said isolated pattern on the surface of said wafer to form a hole pattern in the form of said isolated pattern in said negative resist film.
Claim 11
Dependent Claim
66 words
A photomask as claimed in claim 6, wherein the thickness d of said phase-shifting layer is such as to be expressed by the following equation: d = (ℓ+ k)λ/(n - 1) wherein 1/4 ≦ k ≦ 3/4, λ stands for the wavelength of said exposure light, n stands for the refractive index at λ of said phase-shifting layer, and ℓ is 0 or a positive integer.
Claim 12
Dependent Claim
218 words
A photomask (100; 120; 140) adapted to be used in a projection aligner to project the mask pattern thereof in the form of an isolated pattern on the surface of a wafer having a negative resist film formed thereon, comprising: a substrate (102; 122; 142) transparent to an exposure light, and a mask pattern (110; 132; 154) provided on said substrate; wherein said mask pattern is formed of a light-screening layer (112; 124; 152) and a phase-shifting layer (116; 130; 150), said light-screening layer being incapable of transmitting said exposure light therethrough, and said phase-shifting layer being capable of transmitting said exposure light therethrough and shifting the phase of said exposure light transmitted therethrough relatively to the phase of said exposure light transmitted through the area of the photomask other than the area of said phase-shifting layer; wherein said phase-shifting layer is provided in such a way as to fill up therewith an auxiliary aperture (114; 128; 148) provided in said light-screening layer; wherein the portion of said phase-shifting layer with which said auxiliary aperture is filled up has a width permitting of no resolution by itself; and wherein the areas of said light-screening layer respectively existing around sides of said phase-shifting layer and in the width-wise direction of said phase-shifting layer have one and the same width.
Claim 13
Dependent Claim
218 words
A photomask (100; 120; 140) adapted to be used in a projection aligner to project the mask pattern thereof in the form of an isolated pattern on the surface of a wafer having a negative resist film formed thereon, comprising: a substrate (102; 122; 142) transparent to an exposure light, and a mask pattern (110; 132; 154) provided on said substrate; wherein said mask pattern is formed of a light-screening layer (112; 124; 152) and a phase-shifting layer (116; 130; 150), said light-screening layer being incapable of transmitting said exposure light therethrough, and said phase-shifting layer being capable of transmitting said exposure light therethrough and shifting the phase of said exposure light transmitted therethrough relatively to the phase of said exposure light transmitted through the area of the photomask other than the area of said phase-shifting layer; wherein said phase-shifting layer is provided in such a way as to fill up therewith an auxiliary aperture (114; 128; 148) provided in said light-screening layer; wherein the portion of said phase-shifting layer with which said auxiliary aperture is filled up has a width permitting of no resolution by itself; and wherein the areas of said light-screening layer respectively existing around sides of said phase-shifting layer and in the width-wise direction of said phase-shifting layer have one and the same width.
Claim 14
Dependent Claim
66 words
A photomask (120) as claimed in claim 10, wherein said areas of said light-screening layer (112; 124) and said phase-shifting layer (116; 130) are in a striped form to thereby enable said mask pattern (110; 132) to be projected as said isolated pattern on the surface of said wafer to form a space pattern in the form of said isolated pattern in said negative resist film.
Claim 15
Dependent Claim
64 words
A photomask (110; 154) as claimed in claim 10, wherein said light-screening layer (112; 152) and said phase-shifting layer (116; 150) are in a quadrate form to thereby enable said mask pattern (110; 154) to be projected as said isolated pattern on the surface of said wafer to form a hole pattern in the form of said isolated pattern in said negative resist film.
Claim 16
Dependent Claim
67 words
A photomask as claimed in claim 10, wherein the thickness d of the phase-shifting layer is such as to be expressed by the following equation: d = (ℓ+ k) λ/(n - 1) wherein 1/4 ≦ k ≦ 3/4, λ stands for the wavelength of said exposure light, n stands for the refractive index at λ of the phase-shifting layer, and ℓ is 0 or a positive integer.
Claim 17
Dependent Claim
20 words
A photomask as claimed in claim 1, wherein the amount of phase shift by said phase-shifting layer is preferably 180°.
Claim 18
Dependent Claim
20 words
A photomask as claimed in claim 6, wherein the amount of phase shift by said phase-shifting layer is preferably 180°.
Claim 19
Dependent Claim
20 words
A photomask as claimed in claim 10, wherein the amount of phase shift by said phase-shifting layer is preferably 180°.
Claim 20
Dependent Claim
68 words
A process for forming resist image in the form of an isolated pattern using the photomask (40; 60; 70) of claim 1, comprising the step of applying a negative resist (210) on an underlying layer (200), the step of exposing the resulting negative resist film through said photomask for use in isolated pattern projection to a light, and the step of developing the light-exposed negative resist film (210).
Claim 21
Dependent Claim
67 words
A process for forming resist image in the form of an isolated pattern using the photomask (80; 90) of claim 6, comprising the step of applying a negative resist (210) on an underlying layer (200), the step of exposing the resulting negative resist film through said photomask for use in isolated pattern projection to a light, and the step of developing the light-exposed negative resist film (210).
Claim 22
Dependent Claim
68 words
A process for forming resist image in the form of an isolated pattern using the photomask (100; 120; 140) of claim 10, comprising the step of applying a negative resist (210) on an underlying layer (200), the step of exposing the resulting negative resist film through said photomask for use in isolated pattern projection to a light, and the step of developing the light-exposed negative resist film (210).
References Cited (Backward Citations)
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