US5759724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making multi-phase, phase shifting masks
Assignee: Micron Technology Inc
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Filing: 1997-03-31
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Granted: 1998-06-02
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Expires: 2017-03-31
Abstract
Abstract A method for making a phase shifting mask includes forming an opaque layer on a transparent substrate, and then etching phase shifters and phase transition areas in the substrate using a staged etch process. During the staged etch process, resist masks can be used to etch exposed areas of the substrate to selected intermediate depths to form the phase transition areas, and then to a final depth to form phase shifters. Following each etch stage, a corresponding etch mask can be desensitized rather than being stripped, to provide a multi-layered structure for protecting the opaque layer and substrate during subsequent etch steps. Preferably, the desensitized etch masks can be cleaned during the staged etch process to remove particulates using a non aggressive cleaning agent, such as DI water, and then stripped at the same time at the end of the process. In an alternate embodiment, the phase shifters rather than being etched into the substrate, can be formed in a deposited layer, such as a layer of spin-on-glass.
Inventors
- 👤 J. Brett Rolson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:45
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/28
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
86 words
A method for making a phase shifting mask comprising: providing a transparent substrate with an opaque layer; forming a primary mask pattern on the opaque layer; and forming phase shifters for the primary mask pattern by forming a first resist mask on the substrate, etching the substrate to a first depth using the first resist mask, desensitizing the first resist mask, forming a second resist mask on the desensitized first resist mask, and then etching the substrate to a second depth using the second resist mask.
Claim 2
Independent Claim
86 words
A method for making a phase shifting mask comprising: providing a transparent substrate with an opaque layer; forming a primary mask pattern on the opaque layer; and forming phase shifters for the primary mask pattern by forming a first resist mask on the substrate, etching the substrate to a first depth using the first resist mask, desensitizing the first resist mask, forming a second resist mask on the desensitized first resist mask, and then etching the substrate to a second depth using the second resist mask.
Claim 3
Dependent Claim
24 words
The method as claimed in claim 1 further comprising cleaning the substrate and desensitized first resist mask prior to forming the second resist mask.
Claim 4
Dependent Claim
22 words
The method as claimed in claim 1 further comprising following etching to the second depth, stripping the first and second resist masks.
Claim 5
Dependent Claim
39 words
The method as claimed in claim 1 further comprising desensitizing the second resist mask, forming a third resist mask on the desensitized second resist mask and then etching the substrate to a third depth using the third resist mask.
Claim 6
Dependent Claim
33 words
The method as claimed in claim 4 wherein the third depth is selected to provide a 180° phase shift and the first and second depths are selected to provide 60° phase shift increments.
Claim 7
Independent Claim
70 words
A method for making a phase shifting mask comprising: providing a mask blank comprising a transparent substrate and an opaque layer; patterning the opaque layer to form a primary mask pattern; forming phase shifters and phase transition areas for the mask pattern by etching the substrate in at least two stages using successively deposited and desensitized resist masks; and following etching of the substrate, stripping all of the resist masks.
Claim 8
Independent Claim
70 words
A method for making a phase shifting mask comprising: providing a mask blank comprising a transparent substrate and an opaque layer; patterning the opaque layer to form a primary mask pattern; forming phase shifters and phase transition areas for the mask pattern by etching the substrate in at least two stages using successively deposited and desensitized resist masks; and following etching of the substrate, stripping all of the resist masks.
Claim 9
Dependent Claim
19 words
The method as claimed in claim 6 further comprising cleaning the desensitized resist masks prior to each etching stage.
Claim 10
Dependent Claim
29 words
The method as claimed in claim 6 wherein the desensitized resist masks are desensitized using a method selected from the group consisting of UV flooding, heating, and dry etching.
Claim 11
Dependent Claim
25 words
The method as claimed in claim 6 and wherein the second resist mask covers a larger area of the substrate than the first resist mask.
Claim 12
Independent Claim
116 words
A method for making a phase shifting mask comprising: providing a transparent substrate; forming a first resist mask on the substrate configured to expose selected areas of the substrate; etching the selected areas to a first depth using the first resist mask to form phase transition areas; desensitizing the first resist mask; forming a second resist mask on the desensitized first resist mask, said second resist mask covering additional portions of the substrate than the first resist mask and configured to partially expose the selected areas of the substrate; etching the partially exposed selected areas to a second depth using the second resist mask to form phase shifters; and stripping the first and second resist masks.
Claim 13
Independent Claim
116 words
A method for making a phase shifting mask comprising: providing a transparent substrate; forming a first resist mask on the substrate configured to expose selected areas of the substrate; etching the selected areas to a first depth using the first resist mask to form phase transition areas; desensitizing the first resist mask; forming a second resist mask on the desensitized first resist mask, said second resist mask covering additional portions of the substrate than the first resist mask and configured to partially expose the selected areas of the substrate; etching the partially exposed selected areas to a second depth using the second resist mask to form phase shifters; and stripping the first and second resist masks.
Claim 14
Dependent Claim
20 words
The method as claimed in claim 10 wherein stripping the first and second resist masks is at a same time.
Claim 15
Dependent Claim
23 words
The method as claimed in claim 10 further comprising cleaning the desensitized first resist mask prior to etching the partially exposed selected areas.
Claim 16
Dependent Claim
30 words
The method as claimed in claim 10 wherein the desensitized first resist mask is desensitized using a method selected from the group consisting of UV flooding, heating, and dry etching.
Claim 17
Dependent Claim
28 words
The method as claimed in claim 10 further comprising desensitizing the second resist mask forming a third resist mask thereon and etching the substrate to a third depth.
Claim 18
Independent Claim
125 words
A method for making a phase shifting mask comprising: providing a transparent substrate with an opaque layer; etching the opaque layer with openings to form a primary mask pattern; forming phase shifters and phase transition areas on the substrate using a staged etch process comprising: forming a first resist mask on the opaque layer and substrate, etching the substrate to a first depth using the first resist mask, desensitizing the first resist mask, cleaning the desensitized first resist mask, forming a second resist mask on the desensitized first resist mask and on portions of the etched substrate, etching exposed portions of the substrate to a second depth using the second resist mask, and then stripping the first and second resist masks at a same time.
Claim 19
Independent Claim
125 words
A method for making a phase shifting mask comprising: providing a transparent substrate with an opaque layer; etching the opaque layer with openings to form a primary mask pattern; forming phase shifters and phase transition areas on the substrate using a staged etch process comprising: forming a first resist mask on the opaque layer and substrate, etching the substrate to a first depth using the first resist mask, desensitizing the first resist mask, cleaning the desensitized first resist mask, forming a second resist mask on the desensitized first resist mask and on portions of the etched substrate, etching exposed portions of the substrate to a second depth using the second resist mask, and then stripping the first and second resist masks at a same time.
Claim 20
Dependent Claim
38 words
The method as claimed in claim 15 further comprising desensitizing the second resist mask, forming a third resist mask on the desensitized second resist mask and etching the substrate to a third depth using the third resist mask.
Claim 21
Dependent Claim
39 words
The method as claimed in claim 16 wherein the second resist mask covers additional portions of the substrate than the first resist mask and the third resist mask covers additional portions of the substrate than the second resist mask.
Claim 22
Dependent Claim
38 words
The method as claimed in claim 17 further comprising desensitizing the third resist mask, forming a fourth resist mask on the desensitized third resist mask and etching the substrate to a fourth depth using the fourth resist mask.
Claim 23
Dependent Claim
30 words
The method as claimed in claim 18 wherein the cleaning step comprises spraying or dipping in a cleaning agent selected from the group consisting of DI water and N-butyl acetate.
Claim 24
Independent Claim
107 words
A method for making a phase shifting mask comprising: providing a transparent substrate with an opaque layer thereon; forming a mask pattern by etching the opaque layer; forming phase transition areas for the mask pattern by forming a first resist mask on the substrate, etching the substrate to a first depth, desensitizing the first resist mask, forming a second resist mask on the desensitized first resist mask, etching the substrate to a second depth; desensitizing the second resist mask; and forming phase shifters for the mask pattern by forming a third resist mask on the desensitized second resist mask and etching the substrate to a third depth.
Claim 25
Independent Claim
107 words
A method for making a phase shifting mask comprising: providing a transparent substrate with an opaque layer thereon; forming a mask pattern by etching the opaque layer; forming phase transition areas for the mask pattern by forming a first resist mask on the substrate, etching the substrate to a first depth, desensitizing the first resist mask, forming a second resist mask on the desensitized first resist mask, etching the substrate to a second depth; desensitizing the second resist mask; and forming phase shifters for the mask pattern by forming a third resist mask on the desensitized second resist mask and etching the substrate to a third depth.
Claim 26
Dependent Claim
22 words
The method as claimed in claim 20 further comprising cleaning the desensitized first resist mask prior to forming the second resist mask.
Claim 27
Dependent Claim
22 words
The method as claimed in claim 20 further comprising cleaning the desensitized second resist mask prior to forming the third resist mask.
Claim 28
Dependent Claim
21 words
The method as claimed in claim 20 further comprising stripping the first, second and third resist masks at a same time.
Claim 29
Dependent Claim
30 words
The method as claimed in claim 20 wherein desensitizing the first and second resist masks comprises a process selected from the group consisting of UV flooding, heating and dry etching.
Claim 30
Dependent Claim
41 words
The method as claimed in claim 20 wherein the second resist mask covers a larger area of the substrate than the first resist mask and the third resist mask covers a larger area of the substrate than the second resist mask.
Claim 31
Dependent Claim
37 words
The method as claimed in claim 20 wherein the third depth is selected to achieve a phase shift of 180° and the first and second depths are selected to achieve phase shifts of 60° and 120° respectively.
Claim 32
Independent Claim
162 words
A method for forming a phase shifting mask comprising: providing a mask blank comprising a transparent substrate and an opaque layer; etching the opaque layer to form a primary mask pattern; forming a first resist mask on the substrate; etching the substrate to a first depth using the first resist mask to form a phase transition area; desensitizing the first resist mask; forming a second resist mask on the desensitized resist mask, said second resist mask covering a larger area of the substrate than the first resist mask; etching the substrate to a second depth using the second resist mask; desensitizing the second resist mask; forming a third resist mask on the desensitized second resist mask, said third resist mask covering a larger area of the substrate than the second resist mask; etching the substrate to a third depth using the third resist mask; and stripping the first and second desensitized resist masks and the third resist mask at a same time.
Claim 33
Independent Claim
162 words
A method for forming a phase shifting mask comprising: providing a mask blank comprising a transparent substrate and an opaque layer; etching the opaque layer to form a primary mask pattern; forming a first resist mask on the substrate; etching the substrate to a first depth using the first resist mask to form a phase transition area; desensitizing the first resist mask; forming a second resist mask on the desensitized resist mask, said second resist mask covering a larger area of the substrate than the first resist mask; etching the substrate to a second depth using the second resist mask; desensitizing the second resist mask; forming a third resist mask on the desensitized second resist mask, said third resist mask covering a larger area of the substrate than the second resist mask; etching the substrate to a third depth using the third resist mask; and stripping the first and second desensitized resist masks and the third resist mask at a same time.
Claim 34
Dependent Claim
37 words
The method as claimed in claim 27 wherein the third depth is selected to achieve a phase shift of 180° and the first and second depths are selected to achieve phase shifts of 60° and 120° respectively.
Claim 35
Dependent Claim
33 words
The method as claimed in claim 27 further comprising desensitizing the third resist mask, forming a fourth resist mask on the desensitized third resist mask and etching the substrate to a fourth depth.
Claim 36
Dependent Claim
18 words
The method as claimed in claim 27 further comprising processing a semiconductor wafer using the phase shifting mask.
Claim 37
Independent Claim
101 words
A method for making a phase shifting mask comprising: providing a transparent substrate; forming an opaque layer on the phase layer and patterning the opaque layer to form a primary mask pattern; forming a phase layer on the substrate; forming phase shifters for the primary mask pattern by forming a first resist mask on the phase layer, etching the phase layer to a first depth using the first resist mask, desensitizing the first resist mask, forming a second resist mask on the desensitized first resist mask, and then etching the phase layer to a second depth using the second resist mask.
Claim 38
Independent Claim
101 words
A method for making a phase shifting mask comprising: providing a transparent substrate; forming an opaque layer on the phase layer and patterning the opaque layer to form a primary mask pattern; forming a phase layer on the substrate; forming phase shifters for the primary mask pattern by forming a first resist mask on the phase layer, etching the phase layer to a first depth using the first resist mask, desensitizing the first resist mask, forming a second resist mask on the desensitized first resist mask, and then etching the phase layer to a second depth using the second resist mask.
Claim 39
Dependent Claim
40 words
The method as claimed in claim 31 further comprising desensitizing the second resist mask, forming a third resist mask on the desensitized second resist mask, and then etching the phase layer to a third depth using the third resist mask.
Claim 40
Dependent Claim
16 words
The method as claimed in claim 31 wherein the phase layer comprises a spin on glass.
Claim 41
Dependent Claim
17 words
The method as claimed in claim 31 wherein etching the phase layer comprises a dry etch process.
Claim 42
Dependent Claim
26 words
The method as claimed in claim 31 wherein desensitizing the resist comprises a method selected from the group consisting of UV flooding, heating, and dry etching.
Claim 43
Dependent Claim
22 words
The method as claimed in claim 31 further comprising cleaning the desensitized first resist mask prior to forming the second resist mask.
Claim 44
Independent Claim
138 words
A method for making a phase shifting mask comprising: providing a transparent substrate; forming an opaque layer on the phase layer and patterning the opaque layer to form a primary mask pattern; forming a transparent phase layer on the opaque layer and substrate, said phase layer selected to provide a phase shift of 180°; forming a first resist mask on the phase layer and etching the phase layer adjacent to an edge of the opaque layer to a first depth; desensitizing the first resist mask; forming a second resist mask on the desensitized first resist mask and etching the phase layer adjacent to the edge to a second depth; desensitizing the second resist mask; and forming a third resist mask on the desensitized second resist mask and etching the phase layer adjacent to the edge to the substrate.
Claim 45
Independent Claim
138 words
A method for making a phase shifting mask comprising: providing a transparent substrate; forming an opaque layer on the phase layer and patterning the opaque layer to form a primary mask pattern; forming a transparent phase layer on the opaque layer and substrate, said phase layer selected to provide a phase shift of 180°; forming a first resist mask on the phase layer and etching the phase layer adjacent to an edge of the opaque layer to a first depth; desensitizing the first resist mask; forming a second resist mask on the desensitized first resist mask and etching the phase layer adjacent to the edge to a second depth; desensitizing the second resist mask; and forming a third resist mask on the desensitized second resist mask and etching the phase layer adjacent to the edge to the substrate.
Claim 46
Dependent Claim
15 words
The method as claimed in claim 37 wherein the phase layer comprises spin on glass.
Claim 47
Dependent Claim
22 words
The method as claimed in claim 38 further comprising cleaning the desensitized first resist mask prior to forming the second resist mask.
Claim 48
Dependent Claim
22 words
The method as claimed in claim 39 further comprising cleaning the desensitized second resist mask prior to forming the third resist mask.
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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) | 2001-06-01 | 2001-12-01 | 2002-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-06-01 | 2005-12-01 | 2006-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-06-01 | 2009-12-01 | 2010-06-02 | $7700.00 | Window Closed / Lapsed |