US4869999A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming pattern and projection aligner for carrying out the same
Assignee: Hitachi Ltd
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Filing: 1987-08-10
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Granted: 1989-09-26
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Expires: 2007-08-10
Abstract
Abstract An area on a photoresist film which is formed on a substrate surface having a topography, is exposed a plurality of times in such a manner that the image plane of a mask pattern is formed at a plurality of positions which are spaced apart from a reference plane in the substrate in the direction of an optical axis, and then the photoresist film is developed to form a resist pattern. According to the above method, the effective focal depth of the projection aligner used is enhanced, and moreover the reduction of the image contrast at the photoresist film is very small by the plural exposure operations. Accordingly, a fine pattern can be formed accurately on the substrate surface having the topography.
Inventors
- 👤 Hiroshi Fukuda
- 👤 Norio Hasegawa
- 👤 Toshihiko Tanaka
- 👤 Toshiei Kurosaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:49
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/7055; G03F7/70575; G03F7/20; G03F7/2022; G03F7/70216; G03F7/70241; G03F7/70325; G03F7/70333; G03F7/708; G03F7/70858
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
124 words
A method of forming a pattern, comprising the steps of: exposing a desired portion of a photoresist film in accordance with a mask pattern by a reduction projection aligner to change the solubility of the exposed portion, the photoresist film being formed on a surface of a semiconductor substrate, the surface of the substrate having a topography, an exposure operation for exposing the desired portion of the photoresist film being performed in such a manner that a plurality of reduced images of the same mask pattern are formed at a plurality of different positions spaced apart from each other in the direction of the optical axis of the reduction projection aligner; and developing the photoresist film to form a pattern of the photoresist film.
Claim 2
Independent Claim
124 words
A method of forming a pattern, comprising the steps of: exposing a desired portion of a photoresist film in accordance with a mask pattern by a reduction projection aligner to change the solubility of the exposed portion, the photoresist film being formed on a surface of a semiconductor substrate, the surface of the substrate having a topography, an exposure operation for exposing the desired portion of the photoresist film being performed in such a manner that a plurality of reduced images of the same mask pattern are formed at a plurality of different positions spaced apart from each other in the direction of the optical axis of the reduction projection aligner; and developing the photoresist film to form a pattern of the photoresist film.
Claim 3
Dependent Claim
52 words
A method of forming a pattern, as claimed in claim 1, wherein the exposure operation is performed a plurality of times in such a manner that the substrate is disposed at a plurality of positions spaced apart from each other in the direction of the optical axis of the reduction projection aligner.
Claim 4
Dependent Claim
18 words
A method of forming a pattern, as claimed in claim 1, wherein the exposure operation is performed twice.
Claim 5
Dependent Claim
20 words
A method of forming a pattern as claimed in claim 1, wherein the exposure operation is performed is three times.
Claim 6
Dependent Claim
30 words
A method of forming a pattern, as claimed in claim 1, wherein the distance between adjacent ones of the plural positions lies in a range from 1 to 3.5 μm.
Claim 7
Dependent Claim
72 words
A method of forming a pattern, as claimed in claim 1, wherein the surface of the substrate having a topography is an uneven surface, and the exposure operation is performed in such a manner that the image of the mask pattern is formed at a plurality of different spaced apart positions from each other and from a reference plane in the substrate along the same optical axis of the reduction projection aligner.
Claim 8
Dependent Claim
49 words
A method of forming a pattern, as claimed in claim 1, wherein the image of a mask pattern is formed at a plurality of different positions spaced apart from each other and from a reference plane in the substrate along the same optical axis of the reduction projection aligner.
Claim 9
Dependent Claim
72 words
A method of forming a pattern as claimed in claim 1, wherein the exposure operation for exposing the desired portion of the photoresist film including a region between a top and a bottom of the topography is performed so that the reduced images formed at a plurality of different positions spaced apart from each other are formed on the photoresist film continuously from the top of the topography to the bottom thereof.
Claim 10
Dependent Claim
53 words
A method of forming a pattern as claimed in claim 1, wherein the exposure operation is performed a plurality of times in such a manner that the substrate is disposed at a plurality of stationary positions spaced apart from each other in the direction of the optical axis of the reduction projection aligner.
References Cited (Backward Citations)
US3798036A
Cited
US4239790A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-25 | 1993-03-27 | 1993-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-25 | 1997-03-27 | 1997-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-25 | 2001-03-27 | 2001-09-26 | $7700.00 | Window Closed / Lapsed |