US6338922B1
Expired / Lapsed
US
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Optimized alternating phase shifted mask design
Assignee: International Business Machines Corp
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Filing: 2000-05-08
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Granted: 2002-01-15
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Expires: 2020-05-08
Abstract
Abstract A method for reducing lens aberrations sensitivity and proximity effects of alternating phase shifted masks is described. The critical features of a chip design layout are first identified. Multiple, narrow phase regions and auxiliary phase transitions, which provide additional opaque features, are then formed alongside the critical features such that a grating pattern of substantially uniform pitch is printed. Together with a complementary trim mask, the circuit pattern so delineated has reduced sensitivity to lens aberrations and proximity effects.
Inventors
- 👤 Lars W. Liebmann
- 👤 Alfred K. Wong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:37
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70425; G03F1/00; G03F1/26; G03F1/30
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
94 words
A method of improving across field line width variation in alternating phase shifted mask lithography comprising the steps of: providing a chip layout having a plurality of features; determining which of the plurality of features are critical features; forming a plurality of phase regions on either side of the critical features such that a grating pattern of substantially uniform pitch is formed on a mask layout; providing a complementary mask pattern to selectively erase undesired printed images of the grating pattern; and reconstructing features of the chip layout to form a desired mask layout.
Claim 2
Independent Claim
94 words
A method of improving across field line width variation in alternating phase shifted mask lithography comprising the steps of: providing a chip layout having a plurality of features; determining which of the plurality of features are critical features; forming a plurality of phase regions on either side of the critical features such that a grating pattern of substantially uniform pitch is formed on a mask layout; providing a complementary mask pattern to selectively erase undesired printed images of the grating pattern; and reconstructing features of the chip layout to form a desired mask layout.
Claim 3
Dependent Claim
49 words
The method of claim 1 further including the step of: forming auxiliary phase transitions as determined by available space between the plurality of phase regions such that grating pattern of substantially uniform pitch is formed on a mask layout comprising the plurality of features and the auxiliary phase transitions.
Claim 4
Dependent Claim
36 words
The method of claim 2 wherein during the step of forming auxiliary phase transitions, a width of the auxiliary phase transition is substantially equal to a width of a most narrow one of the critical features.
Claim 5
Dependent Claim
38 words
The method of claim 2 wherein during the step of forming auxiliary phase transitions, a minimum spacing required to form the auxiliary phase transition is substantially equal to two phase regions widths plus one auxiliary phase transition width.
Claim 6
Dependent Claim
37 words
The method of claim 1 further including the steps of: forming auxiliary phase transitions determined by available space surrounding the critical features; and forming additional phase regions on either side of the auxiliary phase transitions as needed.
Claim 7
Dependent Claim
33 words
The method of claim 1 wherein in the step of forming a plurality of phase regions, a width of each phase region is substantially equal to a minimum spacing between the critical shapes.
Claim 8
Dependent Claim
33 words
The method of claim 1 wherein the step of providing a complementary mask pattern comprises providing a bright field block mask when the mask layout comprises a dark field alternating phase shifted mask.
Claim 9
Dependent Claim
33 words
The method of claim 1 wherein the step of providing a complementary mask pattern comprises providing a dark field trim mask when the mask layout comprises a bright field alternating phase shifted mask.
Claim 10
Dependent Claim
30 words
The method of claim 1 wherein in the step of forming alternating phase regions, the phase regions formed on either side of the critical features are substantially different by 180°.
Claim 11
Dependent Claim
31 words
The method of claim 1 wherein in the step of forming alternating phase regions, the phase regions formed on either side of the critical features are about 0° and about 180°.
Claim 12
Dependent Claim
34 words
The method of claim 1 wherein the step of forming phase regions of uniform width enhances across field line width variation by reducing sensitivity of the mask layout to lens aberrations and proximity effects.
Claim 13
Dependent Claim
35 words
The method of claim 1 wherein the step of forming phase regions of uniform width enhances across field line width variation by reducing sensitivity of the mask layout to phase width dependent line width bias.
Claim 14
Independent Claim
123 words
A method of reducing the effects of lens aberrations in alternating phase shifted mask lithography comprising the steps of: providing a chip layout having a plurality of features; determining which of the plurality of features are critical features; forming auxiliary phase transitions as determined by available space surrounding the critical features; forming phase regions of uniform width on either side of the critical features and the auxiliary phase transitions such that a grating pattern of substantially uniform pitch is formed on a mask layout; providing a complementary mask pattern to selectively delete any undesired printed images of the grating pattern; and reconstructing the features of the chip layout by deleting any undesired printed images of the grating pattern with the complementary mask pattern.
Claim 15
Independent Claim
123 words
A method of reducing the effects of lens aberrations in alternating phase shifted mask lithography comprising the steps of: providing a chip layout having a plurality of features; determining which of the plurality of features are critical features; forming auxiliary phase transitions as determined by available space surrounding the critical features; forming phase regions of uniform width on either side of the critical features and the auxiliary phase transitions such that a grating pattern of substantially uniform pitch is formed on a mask layout; providing a complementary mask pattern to selectively delete any undesired printed images of the grating pattern; and reconstructing the features of the chip layout by deleting any undesired printed images of the grating pattern with the complementary mask pattern.
Claim 16
Dependent Claim
25 words
The method of claim 13 wherein the step of forming phase regions is determined by available spacing between the critical features of the mask layout.
Claim 17
Dependent Claim
28 words
The method of claim 13 wherein during the step of forming phase regions, each phase region is substantially equal in width to a minimum spacing between critical features.
Claim 18
Dependent Claim
36 words
The method of claim 13 wherein during the step of forming auxiliary phase transitions, a width of the auxiliary phase transition is substantially equal to a width of a most narrow one of the critical features.
Claim 19
Dependent Claim
33 words
The method of claim 13 wherein the step of providing a complementary mask pattern comprises providing a bright field block mask when the mask layout comprises a dark field alternating phase shifted mask.
Claim 20
Dependent Claim
33 words
The method of claim 13 wherein the step of providing a complementary mask pattern comprises providing a dark field trim mask when the mask layout is a bright field alternating phase shifted mask.
Claim 21
Dependent Claim
29 words
The method of claim 13 wherein in the step of forming phase regions, the phase regions formed on either side of the critical features are substantially different by 180°.
Claim 22
Dependent Claim
30 words
The method of claim 13 wherein in the step of forming phase regions, the phase regions formed on either side of the critical features are about 0° and about 180°.
Claim 23
Dependent Claim
31 words
The method of claim 13 wherein the step of forming phase regions enhances across field line width variation by reducing sensitivity of the mask layout to lens aberrations and proximity effects.
Claim 24
Dependent Claim
32 words
The method of claim 13 wherein the step of forming phase regions enhances across field line width variation by reducing sensitivity of the mask layout to phase width dependent line width bias.
Claim 25
Dependent Claim
35 words
The method of claim 13 wherein in the step of forming phase regions of uniform width, the phase regions on either side of the critical features are of an arbitrary phase differing by about 180°.
Claim 26
Independent Claim
152 words
A method of generating a mask layout comprising the steps of: providing a chip layout having a plurality of features; determining which of the plurality of features are critical features; forming phase regions of uniform width on either side of the critical features, the width of the phase regions substantially equal to a minimum spacing between the critical features, the phase regions alternating by about 180°; forming auxiliary phase transitions as determined by available space between the phase regions such that a grating pattern of substantially uniform pitch is formed on a mask layout comprising the critical features and the auxiliary phase transitions; forming additional phase regions alongside the auxiliary phase transitions; providing a complementary mask pattern to selectively delete any undesired printed images of the grating pattern; and reconstructing the critical features of the mask layout by deleting any undesired printed images of the grating pattern with the complementary mask pattern.
Claim 27
Independent Claim
152 words
A method of generating a mask layout comprising the steps of: providing a chip layout having a plurality of features; determining which of the plurality of features are critical features; forming phase regions of uniform width on either side of the critical features, the width of the phase regions substantially equal to a minimum spacing between the critical features, the phase regions alternating by about 180°; forming auxiliary phase transitions as determined by available space between the phase regions such that a grating pattern of substantially uniform pitch is formed on a mask layout comprising the critical features and the auxiliary phase transitions; forming additional phase regions alongside the auxiliary phase transitions; providing a complementary mask pattern to selectively delete any undesired printed images of the grating pattern; and reconstructing the critical features of the mask layout by deleting any undesired printed images of the grating pattern with the complementary mask pattern.
Claim 28
Dependent Claim
34 words
The method of claim 24 further including the step of printing the mask layout using a first exposure such that a grating pattern is formed in an exposed photoresist layer of a target substrate.
Claim 29
Dependent Claim
34 words
The method of claim 24 further including the step of printing the complementary mask pattern using a second exposure to delete any undesired printed images of the grating pattern formed in a first exposure.
Claim 30
Dependent Claim
29 words
The method of claim 24 wherein the step of forming phase regions provides multiple, narrow phase regions alongside the critical features reducing sensitivity to lens aberrations and proximity effects.
Claim 31
Dependent Claim
30 words
The method of claim 24 wherein the step of forming phase regions provides multiple, narrow phase regions alongside the critical features reducing sensitivity to phase width dependent line width bias.
Claim 32
Dependent Claim
30 words
The method of claim 24 wherein in the step of forming phase regions, a width of each phase region is substantially equal to a minimum spacing between the critical shapes.
Claim 33
Dependent Claim
33 words
The method of claim 24 wherein the step of providing a complementary mask pattern comprises providing a bright field block mask when the mask layout comprises a dark field alternating phase shifted mask.
Claim 34
Dependent Claim
33 words
The method of claim 24 wherein the step of providing a complementary mask pattern comprises providing a dark field trim mask when the mask layout comprises a bright field alternating phase shifted mask.
Claim 35
Dependent Claim
30 words
The method of claim 24 wherein in the step of forming alternating phase regions, the phase regions formed on either side of the critical features are substantially different by 180°.
Claim 36
Dependent Claim
31 words
The method of claim 24 wherein in the step of forming alternating phase regions, the phase regions formed on either side of the critical features are about 0° and about 180°.
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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) | 2005-01-14 | 2005-07-16 | 2006-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-01-14 | 2009-07-16 | 2010-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-01-14 | 2013-07-16 | 2014-01-15 | $7700.00 | Window Closed / Lapsed |