US5495959A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making substractive rim phase shifting masks
Assignee: Micron Technology Inc
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Filing: 1995-06-13
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Granted: 1996-03-05
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Expires: 2015-06-13
Abstract
Abstract An improved method for fabricating phase shifting masks suitable for semiconductor manufacture is provided. A photolithographic mask blank comprising a transparent substrate having an opaque layer of a standard thickness is provided. Using a photoresist mask, the opaque layer is patterned and etched with openings to form opaque light blockers. The substrate under the openings is then etched to a predetermined depth using the same photoresist mask or the opaque layer as a hard mask. A phase shift material, such as silicon dioxide, is then deposited over the opaque light blockers and into the openings to form rim phase shifters on the sidewalls of the light blockers and light transmission areas in the openings. The depth of the etch into the substrate and the thickness of the opaque layer determines the amount of the phase shift. These parameters are controlled to achieve a phase shift of 180° or odd multiple thereof.
Inventors
- 👤 J. Brett Rolfson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:56
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/29
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
175 words
A method for forming a rim phase shifting mask for semiconductor manufacture comprising: forming an opaque layer having a thickness of "t" on a transparent substrate; forming a mask on the opaque layer; etching openings through the opaque layer to the substrate using the mask to form a pattern of opaque light blockers having sidewalls; etching the substrate aligned with the openings to a depth of "d"; removing the mask; and forming phase shifters on the sidewalls of the opaque light blockers and light transmission openings in the openings by conformally depositing a transparent phase shift layer over the opaque light blockers and the sidewalls and over the etched substrate into the openings to a thickness of "P"; said phase shift layer not being etched and remaining in said light transmission openings, such that said rim phase shifters have a width of "P" and a thickness of "t"+"d"+"P" with "t" and "d" selected for establishing a phase shift for light passing through a rim phase shifter relative to light passing through a light transmission opening.
Claim 2
Independent Claim
175 words
A method for forming a rim phase shifting mask for semiconductor manufacture comprising: forming an opaque layer having a thickness of "t" on a transparent substrate; forming a mask on the opaque layer; etching openings through the opaque layer to the substrate using the mask to form a pattern of opaque light blockers having sidewalls; etching the substrate aligned with the openings to a depth of "d"; removing the mask; and forming phase shifters on the sidewalls of the opaque light blockers and light transmission openings in the openings by conformally depositing a transparent phase shift layer over the opaque light blockers and the sidewalls and over the etched substrate into the openings to a thickness of "P"; said phase shift layer not being etched and remaining in said light transmission openings, such that said rim phase shifters have a width of "P" and a thickness of "t"+"d"+"P" with "t" and "d" selected for establishing a phase shift for light passing through a rim phase shifter relative to light passing through a light transmission opening.
Claim 3
Dependent Claim
32 words
The method as recited in claim 1 and wherein the mask is removed prior to etching the substrate and the opaque layer is used as a hard mask for etching the substrate.
Claim 4
Dependent Claim
43 words
The method as recited in claim 1 and wherein the thickness "t" of the opaque layer and depth "d" of the etched substrate are selected to form rim phase shifters adapted to provide a phase shift of approximately 180° times an odd integer.
Claim 5
Dependent Claim
20 words
The method as recited in claim 1 and wherein the substrate and opaque layer are formed as a mask blank.
Claim 6
Dependent Claim
27 words
The method as recited in claim 1 and wherein the phase shift material is selected from the group of materials consisting of silicon dioxide and silicon nitride.
Claim 7
Dependent Claim
28 words
The method as recited in claim 1 and wherein the opaque material is selected from the group of materials consisting of chromium, aluminum, tungsten, gold, and iron oxide.
Claim 8
Independent Claim
186 words
A method for forming a rim phase shifting mask for semiconductor manufacture comprising: forming an opaque layer having a thickness of "t" on a transparent substrate; depositing and patterning a layer of photoresist on the opaque layer and etching openings through the opaque layer to the substrate to form a pattern of opaque light blockers having sidewalls; removing the photoresist; etching the substrate aligned with the openings to a depth of "d"; forming phase shifters on the sidewalls of the opaque light blockers and light transmission openings in the openings by conformally depositing a transparent phase shift material over the opaque layer and openings to a thickness of "P"; said phase shift material not being etched and remaining in said light transmission openings and on the sidewalls to a thickness of "P"; and selecting "t" and "d" to form the rim phase shifters so that light passing through the rim phase shifters travels a distance through the phase shift material of "t"+"d"+"P" and is phase shifted relative to light passing through the light transmission openings which travels a distance through the phase shift material of "P".
Claim 9
Independent Claim
186 words
A method for forming a rim phase shifting mask for semiconductor manufacture comprising: forming an opaque layer having a thickness of "t" on a transparent substrate; depositing and patterning a layer of photoresist on the opaque layer and etching openings through the opaque layer to the substrate to form a pattern of opaque light blockers having sidewalls; removing the photoresist; etching the substrate aligned with the openings to a depth of "d"; forming phase shifters on the sidewalls of the opaque light blockers and light transmission openings in the openings by conformally depositing a transparent phase shift material over the opaque layer and openings to a thickness of "P"; said phase shift material not being etched and remaining in said light transmission openings and on the sidewalls to a thickness of "P"; and selecting "t" and "d" to form the rim phase shifters so that light passing through the rim phase shifters travels a distance through the phase shift material of "t"+"d"+"P" and is phase shifted relative to light passing through the light transmission openings which travels a distance through the phase shift material of "P".
Claim 10
Dependent Claim
20 words
The method as recited in claim 7 and wherein the substrate and opaque layer are formed as a mask blank.
Claim 11
Dependent Claim
43 words
The method as recited in claim 8 and wherein t and d are selected using the formula t+d=iλ/2(n-1) where t=thickness of opaque layer d=depth of etch i=an odd integer λ=wavelength of exposure light n=refractive index of phase shift material at the exposure wavelength.
Claim 12
Dependent Claim
20 words
The method as recited in claim 8 and wherein the photoresist is not removed until after the substrate is etched.
Claim 13
Dependent Claim
32 words
The method as recited in claim 8 and wherein the photoresist is removed prior to etching the substrate and the opaque layer is used as a hard mask for etching the substrate.
Claim 14
Dependent Claim
19 words
The method as recited in claim 8 and wherein the substrate is quartz and the opaque layer is chrome.
Claim 15
Independent Claim
190 words
A method for forming a rim phase shifting mask for semiconductor manufacture comprising: providing a mask blank comprising a transparent substrate with an opaque layer having a thickness of "t"; depositing and patterning a layer of photoresist on the opaque layer and etching openings through the opaque layer to the substrate to form a pattern of opaque light blockers having sidewalls; etching the substrate in alignment with the openings to a depth of "d"; removing the photoresist; forming phase shifters on the sidewalls of the opaque light blockers and light transmission openings in the openings by conformally depositing a transparent phase shift layer over the opaque layer and onto the etched substrate to a thickness of "P"; said rim phase shifters self aligned with the sidewalls and having a width of "P" and a thickness measured from a surface of the etched substrate to a surface of the phase shift layer of "t"+"d"+"P"; and said phase shift layer not being etched and remaining in said light transmission openings to achieve a phase shift for light passing through a rim phase shifter relative to light passing through a light transmission opening.
Claim 16
Independent Claim
190 words
A method for forming a rim phase shifting mask for semiconductor manufacture comprising: providing a mask blank comprising a transparent substrate with an opaque layer having a thickness of "t"; depositing and patterning a layer of photoresist on the opaque layer and etching openings through the opaque layer to the substrate to form a pattern of opaque light blockers having sidewalls; etching the substrate in alignment with the openings to a depth of "d"; removing the photoresist; forming phase shifters on the sidewalls of the opaque light blockers and light transmission openings in the openings by conformally depositing a transparent phase shift layer over the opaque layer and onto the etched substrate to a thickness of "P"; said rim phase shifters self aligned with the sidewalls and having a width of "P" and a thickness measured from a surface of the etched substrate to a surface of the phase shift layer of "t"+"d"+"P"; and said phase shift layer not being etched and remaining in said light transmission openings to achieve a phase shift for light passing through a rim phase shifter relative to light passing through a light transmission opening.
Claim 17
Dependent Claim
32 words
The method as recited in claim 13 and wherein the photoresist is removed prior to etching the substrate and the opaque layer is used as a hard mask for etching the substrate.
Claim 18
Dependent Claim
30 words
The method as recited in claim 13 and wherein the opaque layer is a material selected from the group of materials consisting of chromium, aluminum, tungsten, gold, and iron oxide.
Claim 19
Dependent Claim
20 words
The method as recited in claim 13 and wherein the opaque layer has a thickness of between about 800-1200 Å.
Claim 20
Dependent Claim
37 words
The method as recited in claim 13 further comprising directing light through the substrate onto a wafer in a photolithography process to produce light canceling along a rim of a pattern defined by the opaque light blockers.
Claim 21
Dependent Claim
26 words
The method as recited in claim 13 and wherein the substrate is quartz, the opaque layer is chromium and the phase shift material is silicon dioxide.
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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) | 1999-03-05 | 1999-09-04 | 2000-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-05 | 2003-09-04 | 2004-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-05 | 2007-09-04 | 2008-03-05 | $7700.00 | Window Closed / Lapsed |