US4933304A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for reducing the surface reflectance of a metal layer during semiconductor processing
Assignee: STMicroelectronics lnc USA
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Filing: 1988-11-03
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Granted: 1990-06-12
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Expires: 2008-11-03
Abstract
Abstract The method for producing the surface reflectance of the metal layer during semiconductor processing includes the step of roughening the surface of a metal layer prior to forming the photoresist thereon. The roughened surface reduces reflections that can cause metal notching effects. The step of roughening the surface includes depositing a layer (34) of aluminum which is substantially thinner than the thickness of the primary metal layer by a sputtering process.
Inventors
- 👤 Fusen Chen
- 👤 Yih-Shung Lin
- 👤 Fu-Tai Liou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:27
CPC Classifications
H; H10; H10P; H10P76/00; H10P76/20; H10P76/204; H10P76/2041; H10P76/2043; H10P95/00; Y; Y10; Y10S; Y10S148/00; Y10S148/138; Y10S148/158; Y10S438/00; Y10S438/942; Y10S438/948; Y10S438/952
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
86 words
A method for forming a metal line on a semiconductor structure, comprising: depositing a layer of metal over the semiconductor structure having a predetermined reflectance; sputtering on a thin layer of the same metal over the surface of the metal layer to a predetermined thickness; forming a layer of photoresist on the surface of the metal layer; patterning and developing the photoresist layer; and etching the metal layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor structure.
Claim 2
Independent Claim
86 words
A method for forming a metal line on a semiconductor structure, comprising: depositing a layer of metal over the semiconductor structure having a predetermined reflectance; sputtering on a thin layer of the same metal over the surface of the metal layer to a predetermined thickness; forming a layer of photoresist on the surface of the metal layer; patterning and developing the photoresist layer; and etching the metal layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor structure.
Claim 3
Independent Claim
131 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize, wherein a layer of aluminum oxide is formed on the surface thereof after stabilization; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 4
Independent Claim
131 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize, wherein a layer of aluminum oxide is formed on the surface thereof after stabilization; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 5
Independent Claim
128 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; back sputtering the primary layer of aluminum to remove native oxide; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; pattering and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 6
Independent Claim
128 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; back sputtering the primary layer of aluminum to remove native oxide; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; pattering and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 7
Independent Claim
109 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer to a thickness of less than 100Å; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 8
Independent Claim
109 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer to a thickness of less than 100Å; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 9
Independent Claim
146 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; subjecting the primary layer of aluminum to a rapid thermal anneal process at a predetermined temperature and for a predetermined time to increase the roughness on the surface thereof; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 10
Independent Claim
146 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; subjecting the primary layer of aluminum to a rapid thermal anneal process at a predetermined temperature and for a predetermined time to increase the roughness on the surface thereof; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 11
Independent Claim
141 words
A method for forming a metal line on a semiconductor structure, comprising: forming a layer of barrier metal on the semiconductor structure to a thickness that increases the roughness on the barrier metal layer; sputtering a primary layer of aluminum over the barrier metal layer to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 12
Independent Claim
141 words
A method for forming a metal line on a semiconductor structure, comprising: forming a layer of barrier metal on the semiconductor structure to a thickness that increases the roughness on the barrier metal layer; sputtering a primary layer of aluminum over the barrier metal layer to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer to a predetermined thickness such that the overall reflectance is reduced below the predetermined reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer in accordance with the patterned photoresist layer to form a pattern on the surface of the semiconductor substrate.
Claim 13
Dependent Claim
18 words
The method of claim 6 wherein the barrier metal is titanium and the thickness is greater than 1800Å.
Claim 14
Independent Claim
99 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer with the secondary layer providing a substantial decrease in reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer to form the metal line.
Claim 15
Independent Claim
99 words
A method for forming a metal line on a semiconductor structure, comprising: sputtering a primary layer of aluminum over the substrate to a predetermined thickness, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a secondary layer of aluminum over the surface of the primary layer with the secondary layer providing a substantial decrease in reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer to form the metal line.
Claim 16
Independent Claim
163 words
A method for forming a metal line on a semiconductor structure, comprising; forming a barrier metal layer of titanium on the surface of the semiconductor structure; the barrier metal layer having a thickness that exceeds a predetermined thickness such that when the barrier metal layer of titanium exceeds the predetermined thickness, the roughness of the surface thereof is increased; sputtering a primary layer of aluminum over the titanium layer to a predetermined thickness, the roughness of the titanium layer being translated to the surface of the primary aluminum layer, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a thin layer of aluminum over the surface of the primary layer with the secondary layer providing a substantial decrease in reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer to form the metal line.
Claim 17
Independent Claim
163 words
A method for forming a metal line on a semiconductor structure, comprising; forming a barrier metal layer of titanium on the surface of the semiconductor structure; the barrier metal layer having a thickness that exceeds a predetermined thickness such that when the barrier metal layer of titanium exceeds the predetermined thickness, the roughness of the surface thereof is increased; sputtering a primary layer of aluminum over the titanium layer to a predetermined thickness, the roughness of the titanium layer being translated to the surface of the primary aluminum layer, the primary layer having a predetermined reflectance; allowing the primary layer of aluminum to stabilize; sputtering on a thin layer of aluminum over the surface of the primary layer with the secondary layer providing a substantial decrease in reflectance; forming a layer of photoresist on the surface of the secondary aluminum layer; patterning and developing the photoresist layer; and etching the combined primary aluminum layer and secondary aluminum layer to form the metal line.
Claim 18
Dependent Claim
19 words
The method of claim 9 wherein the thickness of the barrier metal layer of titanium is greater than 1800Å.
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) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |