US5376235A
Expired / Lapsed
US
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Method to eliminate corrosion in conductive elements
Assignee: Micron Technology Inc
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Filing: 1993-07-15
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Granted: 1994-12-27
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Expires: 2013-07-15
Abstract
Abstract A semiconductor wafer is washed in a dilute phosphoric acid solution after the metal features have been patterned and etched, thereby removing substantially all of the residual oxide, chlorine, and/or fluorine contamination which remains on the features. This will substantially eliminate corrosion of the features. The phosphoric acid wash also substantially prevents voids from forming during a subsequent alloy step. The features can include bond pads, vias, contacts, interconnects, etc.
Inventors
- 👤 Rodney C. Langley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:22
CPC Classifications
H; H10; H10P; H10P70/00; H10P70/20; H10P70/27; H10P70/273
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
61 words
A method for eliminating corrosion on metal features, said method comprising the following steps of: etching a metal feature with a phosphoric acid solution, said metal feature being disposed on a semiconductor substrate, wherein said phosphoric acid solution does not contain chromic acid, said phosphoric acid solution comprises deionized water and phosphoric acid in the range a ratio of approximately 20:1.
Claim 2
Independent Claim
61 words
A method for eliminating corrosion on metal features, said method comprising the following steps of: etching a metal feature with a phosphoric acid solution, said metal feature being disposed on a semiconductor substrate, wherein said phosphoric acid solution does not contain chromic acid, said phosphoric acid solution comprises deionized water and phosphoric acid in the range a ratio of approximately 20:1.
Claim 3
Dependent Claim
34 words
The method according to claim 1, further comprising the following steps of: patterning a conductive layer disposed on said semiconductor substrate; and selectively removing portions of said conductive layer, thereby defining said metal feature.
Claim 4
Dependent Claim
34 words
The method according to claim 2, wherein said metal feature comprises at least one of the features selected from the group comprising a contact, an interconnect, a bus, a via, and a bond pad.
Claim 5
Dependent Claim
20 words
The method according to claim 2, further comprising the following step of: exposing said semiconductor substrate to a heat treatment.
Claim 6
Dependent Claim
21 words
The method according to claim 4, wherein said heat treatment is accomplished at a temperature in the range of 350°-450° C.
Claim 7
Dependent Claim
39 words
A process for passivating conductive features, said process comprising the following steps of: fabricating said conductive features comprising at least one metallic layer; and dipping said conductive features in an aqueous phosphoric solution which does not contain chromic acid.
Claim 8
Dependent Claim
39 words
A process for passivating conductive features, said process comprising the following steps of: fabricating said conductive features comprising at least one metallic layer; and dipping said conductive features in an aqueous phosphoric solution which does not contain chromic acid.
Claim 9
Dependent Claim
21 words
The process according to claim 6, wherein said conductive features comprise a metal stack, said metal stack comprising a reflective film.
Claim 10
Independent Claim
57 words
A method for creating metal features, said method comprising the following step of: disposing a conductive layer superjacent a semiconductor substrate; patterning a mask layer superjacent said conductive layer; etching said conductive layer, thereby defining said metal features; removing said mask layer; and washing said substrate in a cleansing solution, wherein said cleansing solution comprises phosphoric acid.
Claim 11
Independent Claim
57 words
A method for creating metal features, said method comprising the following step of: disposing a conductive layer superjacent a semiconductor substrate; patterning a mask layer superjacent said conductive layer; etching said conductive layer, thereby defining said metal features; removing said mask layer; and washing said substrate in a cleansing solution, wherein said cleansing solution comprises phosphoric acid.
Claim 12
Dependent Claim
21 words
The method according to claim 8, wherein said cleansing solution further comprises at least one of deionized water and potassium nitrate.
Claim 13
Dependent Claim
39 words
The method according to claim 9, wherein said cleansing solution comprises said deionized water and said phosphoric acid in an approximate ratio of 10:1 to 50:1, at a temperature in the approximate range of 40° C. to 60° C.
Claim 14
Dependent Claim
33 words
The method according to claim 10, wherein said metal feature comprises at least one of the features of the group comprising a bond pad, an interconnect, a via, a contact, and a bus.
Claim 15
Dependent Claim
21 words
The method according to claim 11, further comprising the step of: passivating said metal feature prior to removing said mask layer.
Claim 16
Dependent Claim
19 words
The method according to claim 11, further comprising the step of: heating the substrate, thereby alloying said metallic feature.
Claim 17
Dependent Claim
18 words
The method according to claim 13, wherein said substrate is heated to a temperature less than 500° C.
Claim 18
Dependent Claim
32 words
The process according to claim 6, wherein said conductive features comprise at least one of the materials selected from the group consisting of Al, Ti, Cu, TiN, Si, Mo, Cr, and Pd.
Claim 19
Dependent Claim
24 words
The process according to claim 15, wherein said solution comprises water and phosphoric acid in a ratio in the range of 10:1 to 50:1.
Claim 20
Dependent Claim
22 words
The process according to claim 16, wherein said solution is at a temperature in the range of 40° C. to 60° C.
Claim 21
Dependent Claim
20 words
The process according to claim 17, wherein said phosphoric acid removes fluorine, chlorine, and oxide residues from said conductive features.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-12-26 | 1998-06-27 | 1998-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-26 | 2002-06-27 | 2002-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-26 | 2006-06-27 | 2006-12-27 | $7700.00 | Window Closed / Lapsed |