US5240796A
Expired / Lapsed
US
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Method of fabricating a chromeless phase shift reticle
Assignee: Micron Technology Inc
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Filing: 1991-07-09
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Granted: 1993-08-31
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Expires: 2011-07-09
Abstract
Abstract A method of fabricating a chromeless phase shift reticle. The method includes the steps of: depositing a layer of material on a transparent substrate to a thickness of "t"; patterning and anisotropically etching the material to form a pattern of openings to the substrate; depositing a phase shifter material over the layer of material and into the openings; polishing by chemical mechanical planarization (CMP) the phase shifter material; and selectively wet etching the initially deposited layer of material. This process forms a chromeless phase shift reticle having a pattern of phase shifters of a thickness of "t" with a pattern of light transmissive areas on the substrate therebetween. The thickness "t" and a phase shifter material index of refraction may be selected to achieve a 180° phase shift between light transmitted through a phase shifter relative to light transmitted through a light transmissive area on the substrate.
Inventors
- 👤 Ruojia Lee
- 👤 J. Brett Rolfson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:13
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/26; G03F1/34
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
118 words
A method of fabricating a chromeless phase shift reticle comprising: forming a layer of material on a transparent substrate to a predetermined thickness; patterning the layer of material to form a pattern of openings to the substrate; depositing a phase shifter material over the layer of material and into the openings; polishing and planarizing the phase shifter material to a thickness of "t" to provide a substantially optically flawless surface for producing a phase shift of light during photopatterning; and removing the patterned layer of material from the substrate to form a pattern of phase shifter having a thickness of "t" on the substrate with a pattern of light transmissive areas on the substrates between the phase shifters.
Claim 2
Independent Claim
118 words
A method of fabricating a chromeless phase shift reticle comprising: forming a layer of material on a transparent substrate to a predetermined thickness; patterning the layer of material to form a pattern of openings to the substrate; depositing a phase shifter material over the layer of material and into the openings; polishing and planarizing the phase shifter material to a thickness of "t" to provide a substantially optically flawless surface for producing a phase shift of light during photopatterning; and removing the patterned layer of material from the substrate to form a pattern of phase shifter having a thickness of "t" on the substrate with a pattern of light transmissive areas on the substrates between the phase shifters.
Claim 3
Dependent Claim
58 words
The method as recited in claim 1 and wherein: the thickness "t" of the layer of material and an index of refraction determined by the phase shifter material are selected to produce phase shifters which produce a phase shift of light passed through the phase shifters relative to light passed through a light transmissive area of approximately 180°.
Claim 4
Dependent Claim
18 words
The method as recited in claim 2 and wherein: the layer of material is an electrically conductive material.
Claim 5
Dependent Claim
31 words
The method as recited in claim 3 and wherein: the electrically conductive material is written and anisotropically dry etched to form the openings by a photolithographic process including an anisotropic etch.
Claim 6
Dependent Claim
22 words
The method as recited in claim 4 and wherein: the electrically conductive material is removed from the substrate by a selective etch.
Claim 7
Dependent Claim
29 words
The method as recited in claim 5 and wherein: the substrate is formed of Quartz and is polished on both sides prior to fabrication of the phase shifting reticle.
Claim 8
Dependent Claim
19 words
The method as recited in claim 6 and wherein: the phase shifter material is silicon dioxide (SiO 2 ).
Claim 9
Dependent Claim
15 words
The method as recited in claim 7 and wherein: the electrically conductive material is Aluminum.
Claim 10
Dependent Claim
15 words
The method as recited in claim 7 and wherein: the electrically conductive material is Chrome.
Claim 11
Dependent Claim
23 words
The method as recited in claim 7 and wherein: the phase shifter material is conformally deposited with a blanket chemical vapor deposition (CVD).
Claim 12
Dependent Claim
20 words
The method as recited in claim 7 and wherein: the phase shifter material is polished by chemical mechanical planarization (CMP).
Claim 13
Independent Claim
183 words
A method of fabricating a chromeless phase shift reticle for use in semiconductor photolithography comprising: depositing an electrically conductive layer of material on a transparent substrate to a thickness of "t"; patterning and anisotropically etching the electrically conductive layer to form a pattern of openings to the substrate using a photolithography/dry etching process with the openings having generally vertical sidewalls; conformally depositing a phase shifter material over the electrically conductive layer and into the openings; chemically mechanically planarizing (CMP) the phase shifter material to polish and planarize the phase shifter material to an endpoint of the electrically conductive layer to provide a substantially optionally flawless surface for producing a phase shift of light during photopatterning; selectively etching the electrically conductive layer to remove the electrically conductive layer using a selective etch such that phase shifters are formed on the substrate in a pattern with light transmissive openings therebetween with the thickness "t" and index of refraction of the phase shifters selected to provide a 1802 phase shift for light passed through a phase shifter relative to light passed through a light transmissive area.
Claim 14
Independent Claim
183 words
A method of fabricating a chromeless phase shift reticle for use in semiconductor photolithography comprising: depositing an electrically conductive layer of material on a transparent substrate to a thickness of "t"; patterning and anisotropically etching the electrically conductive layer to form a pattern of openings to the substrate using a photolithography/dry etching process with the openings having generally vertical sidewalls; conformally depositing a phase shifter material over the electrically conductive layer and into the openings; chemically mechanically planarizing (CMP) the phase shifter material to polish and planarize the phase shifter material to an endpoint of the electrically conductive layer to provide a substantially optionally flawless surface for producing a phase shift of light during photopatterning; selectively etching the electrically conductive layer to remove the electrically conductive layer using a selective etch such that phase shifters are formed on the substrate in a pattern with light transmissive openings therebetween with the thickness "t" and index of refraction of the phase shifters selected to provide a 1802 phase shift for light passed through a phase shifter relative to light passed through a light transmissive area.
Claim 15
Dependent Claim
30 words
A method of forming a chromeless phase shift reticle as recited in claim 12 and further comprising: polishing the substrate on both sides during initial formation of a substrate blank.
Claim 16
Dependent Claim
31 words
The method of forming a chromeless phase shift reticle as recited in claim 13 and wherein: the substrate is Quartz, and the phase shifter material is silicon dioxide (SiO 2 ).
Claim 17
Dependent Claim
21 words
The method of forming a chromeless phase shift reticle as recited in claim 14 wherein: the electrically conductive material is aluminum.
Claim 18
Dependent Claim
28 words
The method of forming a chromeless phase shift reticle as recited in claim 15 and wherein: selective etching is with a mixture of sulfuric Acid and Hydrogen Peroxide.
Claim 19
Dependent Claim
23 words
The method of forming a chromeless phase shift reticle as recited in claim 15 and wherein: selective etching is with hot Phosphoric Acid.
Claim 20
Dependent Claim
22 words
The method of forming a chromeless phase shift reticle as recited in claim 14 and wherein: the electrically conductive material is Chrome.
Claim 21
Dependent Claim
30 words
The method of forming a chromeless phase shift reticle as recited in claim 18 and wherein: selective etching is with a mixture of an acid, Cerric Ammonium Nitrate, and water.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-30 | 1997-03-01 | 1997-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-30 | 2001-03-01 | 2001-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-30 | 2005-03-01 | 2005-08-31 | $7700.00 | Window Closed / Lapsed |