US5976733A
Expired / Lapsed
US
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Integrated circuit photofabrication masks and methods for making same
Assignee: Toshiba Corp
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Filing: 1998-10-21
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Granted: 1999-11-02
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Expires: 2018-10-21
Abstract
Abstract An attenuated phase shifting mask employs regions of increased light transmissivity adjacent the defined circuit pattern features. Such regions can be provided by partially oxidizing a secondary region of the halftone masking layer. The result is improved image resolution and depth of focus, and a minimization of image shortening effects. In a second primary embodiment, similar improvements, as well as well as sharper corner definition, are obtained by providing on a mask (conventional or phase shifting) a generally rounded, light diffracting topography at edges of the defined circuit pattern features. This can be accomplished, for an elongated hole feature, by depositing a layer of light transmissive material on a conventional mask structure to form a generally convex light transmitting surface overlying an edge of the masking layer. In the case of a line feature, the substrate can be etched to form a recessed region including a generally concave light transmissive surface extending beneath an edge portion of the masking layer.
Inventors
- 👤 Koji Hashimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:57
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/32; G03F1/36; G03F7/00; G03F7/70; G03F7/70216; G03F7/70283
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
68 words
An integrated circuit photofabrication mask comprising: a light transmissive substrate; masking layer forming a circuit pattern on said substrate, for projection onto a light-sensitive material; and a surface topography including a generally rounded light transmissive surface adjacent an edge of a circuit pattern feature, for diffracting exposure light projected therethrough so as to create on said light-sensitive material an apparent mask boundary differing from an actual mask boundary.
Claim 2
Dependent Claim
68 words
An integrated circuit photofabrication mask comprising: a light transmissive substrate; masking layer forming a circuit pattern on said substrate, for projection onto a light-sensitive material; and a surface topography including a generally rounded light transmissive surface adjacent an edge of a circuit pattern feature, for diffracting exposure light projected therethrough so as to create on said light-sensitive material an apparent mask boundary differing from an actual mask boundary.
Claim 3
Dependent Claim
32 words
A mask according to claim 1, wherein said generally rounded surface is a generally convex surface formed by a layer of light transmissive material overlying an edge portion of said masking layer.
Claim 4
Dependent Claim
20 words
A mask according to claim 2, wherein said layer of light transmissive material comprises a layer of SiO 2 .
Claim 5
Dependent Claim
17 words
A mask according to claim 3, wherein said layer of SiO 2 comprises a spin-on-glass (SOG) film.
Claim 6
Dependent Claim
29 words
A mask according to claim 2, wherein the thickness of the layer of light transmissive material does not exceed the thickness of the masking layer by more than 50%.
Claim 7
Dependent Claim
15 words
A mask according to claim 2, wherein said circuit pattern feature comprises an elongated hole.
Claim 8
Dependent Claim
33 words
A mask according to claim 1, wherein said generally rounded surface is a generally concave surface formed by a recessed region of said substrate extending beneath an edge portion of said masking layer.
Claim 9
Dependent Claim
25 words
A mask according to claim 7, wherein the depth of the recessed region does not exceed three times (3×) the thickness of the masking layer.
Claim 10
Dependent Claim
14 words
A mask according to claim 7, wherein said circuit pattern feature comprises a line.
Claim 11
Dependent Claim
17 words
A mask according to claim 7, wherein said recessed region of the substrate is an etched region.
Claim 12
Dependent Claim
23 words
A mask according to claim 1, wherein said mask is an attenuated phase shifting mask and said masking layer comprises a halftone material.
Claim 13
Dependent Claim
21 words
A mask according to claim 11, wherein said halftone material comprises one or more of SiNx, MoSiOxNy, CrOx, C and Cr.
Claim 14
Dependent Claim
14 words
A mask according to claim 1, wherein said masking layer comprises an opaque material.
Claim 15
Independent Claim
81 words
A method of making an integrated circuit photofabrication mask, comprising: arranging a masking layer on a light transmissive substrate in the form of a circuit pattern to be projected onto a light-sensitive material, to form a preliminary mask structure; and forming a generally rounded surface of light transmissive material adjacent an edge of a circuit pattern feature, for diffracting exposure light projected therethrough so as to create on said light-sensitive material an apparent mask boundary differing from an actual mask boundary.
Claim 16
Independent Claim
81 words
A method of making an integrated circuit photofabrication mask, comprising: arranging a masking layer on a light transmissive substrate in the form of a circuit pattern to be projected onto a light-sensitive material, to form a preliminary mask structure; and forming a generally rounded surface of light transmissive material adjacent an edge of a circuit pattern feature, for diffracting exposure light projected therethrough so as to create on said light-sensitive material an apparent mask boundary differing from an actual mask boundary.
Claim 17
Dependent Claim
38 words
A method according to claim 12, wherein said forming comprises depositing a layer of light transmissive material on said preliminary mask structure to form a generally convex light transmitting surface overlying an edge portion of said masking layer.
Claim 18
Dependent Claim
17 words
A method according to claim 15, wherein the layer of light transmissive material comprises SiO 2 .
Claim 19
Dependent Claim
15 words
A method according to claim 16, wherein said SiO 2 is a spin-on-glass (SOG) film.
Claim 20
Dependent Claim
15 words
A method according to claim 15, wherein said circuit pattern feature comprises an elongated hole.
Claim 21
Dependent Claim
29 words
A method according to claim 14, wherein the thickness of the layer of light transmissive material does not exceed the thickness of the masking layer by more than 50%.
Claim 22
Dependent Claim
34 words
A method according to claim 14, wherein said forming comprises etching said substrate to form a recessed region including a generally concave light transmissive surface extending beneath an edge portion of said masking layer.
Claim 23
Dependent Claim
25 words
A method according to claim 20, wherein the depth of the recessed region does not exceed three times (3×) the thickness of the masking layer.
Claim 24
Dependent Claim
23 words
A method according to claim 14, wherein said mask is an attenuated phase shifting mask and said masking layer comprises a halftone material.
Claim 25
Dependent Claim
20 words
A method according to claim 22, wherein said halftone material comprises one or more SiNx, MoSiOxNy, CrOx, C and Cr.
Claim 26
Dependent Claim
14 words
A method according to claim 14, wherein said masking layer comprises an opaque material.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-11-01 | 2003-05-03 | 2003-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-01 | 2007-05-03 | 2007-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-01 | 2011-05-03 | 2011-11-02 | $7700.00 | Window Closed / Lapsed |