Patent US6482555B2 successfully refreshed from Google Patents.
US6482555B2
Expired / Lapsed
US
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Method of patterning sub-0.25λ line features with high transmission, “attenuated” phase shift masks
Assignee: ASML Netherlands BV
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Filing: 2001-10-15
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Granted: 2002-11-19
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Expires: 2021-10-15
Abstract
Abstract A method for making a mask for optically transferring a lithographic pattern corresponding to an integrated circuit from the mask onto a semiconductor substrate by use of an optical exposure tool. The method includes the steps of de-composing the existing mask patterns into arrays of “imaging elements.” The imaging elements are π-phase shifted and are separated by non-phase shifting and sub-resolution elements referred to as anti-scattering bars (ASBs). In essence, the ASBs are utilized to de-compose the larger-than-minimum-width mask features to form “halftone-like” imaging patterns. The placement of the ASBs and the width thereof are such that none of the π-phase shifting elements are individually resolvable, but together they form patterns substantially similar to the intended mask features.
Inventors
- 👤 J. Fung Chen
- 👤 Roger Caldwell
- 👤 Tom Laidig
- 👤 Kurt E. Wampler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:24
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/20; G03F7/2051; G03F7/2059; G03F7/2063; G03F1/00; G03F1/26; G03F1/32; G03F1/30; G03F1/34; G03F1/36; G03F7/70; G03F7/70058; G03F7/70125; G03F7/70216; G03F7/70283
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
133 words
A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate a mask for use in a lithography process, said generation of said mask comprising the steps of: creating said mask having a lithographic pattern corresponding to an integrated circuit, said mask having a plurality of features to be printed; and de-composing at least one of said plurality of features having a width exceeding a predetermined value into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, wherein the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable.
Claim 2
Dependent Claim
133 words
A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate a mask for use in a lithography process, said generation of said mask comprising the steps of: creating said mask having a lithographic pattern corresponding to an integrated circuit, said mask having a plurality of features to be printed; and de-composing at least one of said plurality of features having a width exceeding a predetermined value into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, wherein the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable.
Claim 3
Dependent Claim
25 words
The computer program product of claim 1 , wherein the space between each of said plurality of π-phase shifting elements comprises a non-phase shifting material.
Claim 4
Dependent Claim
54 words
The computer program product of claim 1 , wherein each of said plurality of π-phase shifting elements has a width between 0.20*(λ/NAo) and 0.35*(λ/NAo), where λ equals the wavelength of the light source emitted by an optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 5
Dependent Claim
52 words
The computer program product of claim 1 , wherein each of said non-phase shifting elements has a width not greater than 0.35*(λ/NAo), where λ equals the wavelength of the light source emitted by an optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 6
Dependent Claim
44 words
The computer program product of claim 1 , wherein said predetermined value is 1.22(λ/NAo), where λ equals the wavelength of the light source emitted by an optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 7
Dependent Claim
36 words
The computer program product of claim 3 , wherein each of said plurality of π-phase shifting elements are equally spaced from one another, and each of said plurality of π-phase shifting elements have the same width.
Claim 8
Dependent Claim
73 words
The computer program product of claim 6 , wherein said distance between each of said plurality of π-phase shifting elements and the width of each of said plurality of π-phase shifting elements define a halftone period, said halftone period being less than 0.61*(λ/NAo), where λ equals the wavelength of the light source emitted by an optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 9
Dependent Claim
17 words
The computer program product of claim 1 , wherein each of said non-phase shifting elements is transparent.
Claim 10
Dependent Claim
46 words
The computer program product of claim 1 , wherein the generation of said mask further comprises placing scattering bars adjacent to any isolated π-phase shifting elements, each of said scattering bars having a width sufficiently narrow such that none of the individual scattering bars are resolvable.
Claim 11
Dependent Claim
25 words
The computer program product of claim 1 , wherein said π-phase shifting elements are characterized by a percentage of transmission ranging from 6% to 100%.
Claim 12
Independent Claim
118 words
A method for optically transferring a lithographic pattern corresponding to an integrated circuit from mask onto a semiconductor substrate by use of an optical exposure tool, said method comprising the step of: creating said mask having said lithographic pattern corresponding to said integrated circuit, said mask having at least one feature to be printed, said feature having a defined width; de-composing said feature into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable, and illuminating said mask utilizing off-axis illumination.
Claim 13
Independent Claim
118 words
A method for optically transferring a lithographic pattern corresponding to an integrated circuit from mask onto a semiconductor substrate by use of an optical exposure tool, said method comprising the step of: creating said mask having said lithographic pattern corresponding to said integrated circuit, said mask having at least one feature to be printed, said feature having a defined width; de-composing said feature into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable, and illuminating said mask utilizing off-axis illumination.
Claim 14
Dependent Claim
23 words
The method of claim 11 , wherein said π-phase shifting elements are characterized by a percentage of transmission ranging from 6% to 100%.
Claim 15
Dependent Claim
35 words
The method of claim 11 , wherein said de-composing of said feature into a plurality of said π-phase shifting elements assists in the minimization of optical proximity effects associated with the printing of said feature.
Claim 16
Dependent Claim
35 words
The method of claim 13 , further comprising the step of adjusting the distance between said π-phase shifting elements so as to compensate for said optical proximity effects associated with the printing of said feature.
Claim 17
Dependent Claim
65 words
The method of claim 11 , wherein each of said plurality of π-phase shifting elements has a width between 0.20*(λ/NAo) and 0.35*(λ/NAo), and each of said non-phase shifting elements has a width not greater than 0.35*(λ/NAo), where λ equals the wavelength of the light source emitted by said optical exposure tool, and NAo equals the numerical aperture of an objective lens of said exposure tool.
Claim 18
Dependent Claim
34 words
The method of claim 12 , wherein each of said plurality of π-phase shifting elements are equally spaced from one another, and each of said plurality of π-phase shifting elements have the same width.
Claim 19
Dependent Claim
71 words
The method of claim 13 , wherein said distance between each of said plurality of π-phase shifting elements and the width of each of said plurality of π-phase shifting elements define a halftone period, said halftone period being less than 0.61*(λ/NAo), where λ equals the wavelength of the light source emitted by an optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 20
Dependent Claim
15 words
The method of claim 11 , wherein each of said non-phase shifting elements is transparent.
Claim 21
Dependent Claim
44 words
The method of claim 11 , wherein the creating of said mask further comprises placing scattering bars adjacent to any isolated π-phase shifting elements, each of said scattering bars having a width sufficiently narrows such that one of the individual scattering bars are resolvable.
Claim 22
Independent Claim
135 words
A method for optically transferring a lithographic pattern corresponding to an integrated circuit from a mask onto a substrate by use of an optical exposure tool, said method comprising the step of: creating said mask having said lithographic pattern corresponding to said integrated circuit, said mask having at least one feature to be printed, said feature having a defined width; de-composing said feature into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable, and adjusting the distance between said π-phase shifting elements so as to compensate for optical proximity effects associated with the printing of said feature.
Claim 23
Independent Claim
135 words
A method for optically transferring a lithographic pattern corresponding to an integrated circuit from a mask onto a substrate by use of an optical exposure tool, said method comprising the step of: creating said mask having said lithographic pattern corresponding to said integrated circuit, said mask having at least one feature to be printed, said feature having a defined width; de-composing said feature into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable, and adjusting the distance between said π-phase shifting elements so as to compensate for optical proximity effects associated with the printing of said feature.
Claim 24
Dependent Claim
27 words
The method of claim 20 , further comprising the step of illuminating said mask utilizing off-axis illumination so as to transfer said lithographic pattern onto said substrate.
Claim 25
Dependent Claim
23 words
The method of claim 20 , wherein said π-phase shifting elements are characterized by a percentage of transmission ranging from 6% to 100%.
Claim 26
Dependent Claim
66 words
The method of claim 20 , wherein each of said plurality of π-phase shifting elements has a width between 0.20*(λ/NAo), and 0.35*(λ/NAo), and each of said non-phase shifting elements has a width not greater than 0.35*(λ/NAo), where λ equals the wavelength of the light source emitted by said optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 27
Dependent Claim
44 words
The method of claim 20 , wherein the generation of said mask further comprises placing scattering bars adjacent to any isolated π-phase shifting elements, each of said scattering bars having a width sufficiently narrow such that none of the individual scattering bars are resolvable.
Claim 28
Dependent Claim
148 words
A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate a mask for use in a lithography process, said generation of said mask comprising the steps of: creating said mask having a lithographic pattern corresponding to an integrated circuit, said mask having at least one feature to be printed, said feature having a defined width; de-composing said feature into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable, and adjusting the distance between said π-phase shifting elements so as to compensate for optical proximity effects associated with the printing of said feature.
Claim 29
Dependent Claim
148 words
A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate a mask for use in a lithography process, said generation of said mask comprising the steps of: creating said mask having a lithographic pattern corresponding to an integrated circuit, said mask having at least one feature to be printed, said feature having a defined width; de-composing said feature into a plurality of π-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by a non-phase shifting element, the distance between each of said plurality of π-phase shifting elements is such that none of the individual π-phase shifting elements are resolvable, and adjusting the distance between said π-phase shifting elements so as to compensate for optical proximity effects associated with the printing of said feature.
Claim 30
Dependent Claim
25 words
The computer program product of claim 25 , wherein said π-phase shifting elements are characterized by a percentage of transmission ranging from 6% to 100%.
Claim 31
Dependent Claim
68 words
The computer program product of claim 25 , wherein each of said plurality of π-phase shifting elements has a width between 0.20*(λ/NAo) and 0.35*(λ/NAo), and each of said non-phase shifting elements has a width not greater than 0.35*(λ/NAo), where λ equals the wavelength of the light source emitted by an optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 32
Dependent Claim
46 words
The computer program product of claim 25 , wherein the generation of said mask further comprises placing scattering bars adjacent to any isolated π-phase shifting elements, each of said scattering bars having a width sufficiently narrow such that none of the individual scattering bars are resolvable.
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