US6312854B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of patterning sub-0.25 lambda line features with high transmission, “attenuated” phase shift masks
Assignee: ASML Netherlands BV
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Filing: 1999-03-16
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Granted: 2001-11-06
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Expires: 2019-03-16
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 pi-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 pi-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
2026-11-08 18:03
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: 36
Claim 1
Independent Claim
123 words
A method for making a mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said method comprising the steps of: creating said mask having said lithographic pattern corresponding to said integrated circuit, said mask having a plurality of features to be printed; and de-composing each 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
Independent Claim
123 words
A method for making a mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said method comprising the steps of: creating said mask having said lithographic pattern corresponding to said integrated circuit, said mask having a plurality of features to be printed; and de-composing each 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
29 words
The method of claim 1 , wherein each of said plurality of features having a width less than said predetermined value is implemented with a single π-phase shifting element.
Claim 4
Dependent Claim
23 words
The method of claim 1 , wherein the space between each of said plurality of π-phase shifting elements comprises a non-phase shifting material.
Claim 5
Dependent Claim
52 words
The method 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 said optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 6
Dependent Claim
20 words
The method of claim 4 , wherein each of said non-phase shifting elements has a width not greater than 0.35*(λ/NAo).
Claim 7
Dependent Claim
12 words
The method of claim 1 , wherein said predetermined value is 1.22(λ/NAo).
Claim 8
Dependent Claim
34 words
The method of claim 4 , 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 9
Dependent Claim
41 words
The method of claim 7 , 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).
Claim 10
Dependent Claim
13 words
The method of claim 1 , wherein said non-phase shifting element is transparent.
Claim 11
Dependent Claim
38 words
The method of claim 1 , further comprising 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 12
Independent Claim
134 words
A method for making a mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said method comprising the steps 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; and 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, each of said π-phase shifting elements having a width greater than the width of said feature, 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 13
Independent Claim
134 words
A method for making a mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said method comprising the steps 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; and 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, each of said π-phase shifting elements having a width greater than the width of said feature, 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 14
Dependent Claim
37 words
The method of claim 11 , wherein each of said plurality of π-phase shifting elements has a width w1, and a separation w2, said plurality of π-phase shifting elements defining a critical halftone period which equals w1+w2.
Claim 15
Dependent Claim
34 words
The method of claim 12 , wherein said mask is utilized in a photolithography process comprising an exposure source having an associated wavelength λ and an objective lens having an associated numerical aperture NAo.
Claim 16
Dependent Claim
24 words
The method of claim 13 , wherein said critical halftone period of said non-resolvable π-phase shifting elements is less than 0.61 multiplied by (λ/NAo).
Claim 17
Dependent Claim
37 words
The method of claim 11 , further comprising placing scattering bars adjacent 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 18
Dependent Claim
52 words
The method of claim 15 , wherein the distance from a scattering bar to an isolated π-phase shifting element equals K s (λ/NAo), λ equaling the wavelength of the exposure source, NAo equaling the numerical aperture of the objective lens of the exposure source, and K s ranging from 0.55 to 0.70.
Claim 19
Dependent Claim
46 words
The method of claim 15 , wherein the width of each scattering bar equals K w (λ/NAo), λ equaling the wavelength of the exposure source, NAo equaling the numerical aperture of the objective lens of the exposure source, and K w ranging from 0.20 to 0.25.
Claim 20
Dependent Claim
107 words
A photolithography mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said mask comprising: a plurality of features corresponding to elements of said integrated circuit to be printed; each of said plurality of features having a width exceeding a predetermined value comprising 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 21
Dependent Claim
107 words
A photolithography mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said mask comprising: a plurality of features corresponding to elements of said integrated circuit to be printed; each of said plurality of features having a width exceeding a predetermined value comprising 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 22
Dependent Claim
53 words
The photolithography mask of claim 18 , 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 said optical exposure tool, and NAo equals the numerical aperture of an objective lens of said optical exposure tool.
Claim 23
Dependent Claim
19 words
The photolithography mask of claim 19 , wherein said non-phase shifting element has a width not greater than 0.35*(λ/NAo).
Claim 24
Dependent Claim
13 words
The photolithography mask of claim 19 , wherein said predetermined value is 1.22(λ/NAo).
Claim 25
Dependent Claim
39 words
The photolithography mask of claim 19 , wherein each of said plurality of π-phase shifting elements are equally spaced from one another by a predetermined distance, and each of said plurality of π-phase shifting elements have the same width.
Claim 26
Dependent Claim
48 words
The photolithography mask of claim 22 , 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 define a halftone period of said plurality of π-phase shifting elements, said halftone period being less than 0.61*(λ/NAo).
Claim 27
Dependent Claim
14 words
The photolithography mask of claim 18 , wherein said non-phase shifting element is transparent.
Claim 28
Dependent Claim
38 words
The photolithography mask of claim 18 , further comprising placing scattering bars adjacent 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 29
Dependent Claim
124 words
A photolithography mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said mask comprising: a plurality of π-phase shifting elements corresponding to a feature to be printed, said feature to be printed having a defined width, and a plurality of non-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by one of said non-phase shifting elements, wherein each of said π-phase shifting elements has a width greater than the width of said feature to be printed, and 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 30
Dependent Claim
124 words
A photolithography mask for optically transferring a lithographic pattern corresponding to an integrated circuit from said mask onto a semiconductor substrate by use of an optical exposure tool, said mask comprising: a plurality of π-phase shifting elements corresponding to a feature to be printed, said feature to be printed having a defined width, and a plurality of non-phase shifting elements, each of said plurality of π-phase shifting elements being separated from one another by one of said non-phase shifting elements, wherein each of said π-phase shifting elements has a width greater than the width of said feature to be printed, and 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 31
Dependent Claim
38 words
Thle photolithography mask of claim 26 , wherein each of said plurality of π-phase shifting elements has a width w1, and a separation w2, said plurality of π-phase shifting elements defining a critical halftone period which equals w1+w2.
Claim 32
Dependent Claim
35 words
The photolithography mask of claim 27 , wherein said mask is utilized in a photolithography process comprising an exposure source having an associated wavelength λ and an objective lens having an associated numerical aperture NAo.
Claim 33
Dependent Claim
25 words
The photolithography mask of claim 28 , wherein said critical halftone period of said non-resolvable π-phase shifting elements is less than 0.61 multiplied by (λ/NAo).
Claim 34
Dependent Claim
37 words
The photolithography mask of claim 26 , further comprising scattering bars adjacent 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 35
Dependent Claim
53 words
The photolithography mask of claim 30 , wherein the distance from a scattering bar to an isolated π-phase shifting element equals K s (λ/NAo), λ equaling the wavelength of the exposure source, NAo equaling the numerical aperture of the objective lens of the exposure source, and K s ranging from 0.55 to 0.70.
Claim 36
Dependent Claim
47 words
The photolithography mask of claim 30 , wherein the width of each scattering bar equals K w (λ/NAo), λ equaling the wavelength of the exposure source, NAo equaling the numerical aperture of the objective lens of the exposure source, and K w ranging from 0.20 to 0.25.
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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) | 2004-11-05 | 2005-05-07 | 2005-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-11-05 | 2009-05-07 | 2009-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-11-05 | 2013-05-07 | 2013-11-06 | $7700.00 | Window Closed / Lapsed |