US4517226A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metallization process of a wafer back
Assignee: STMicroelectronics SRL
•
Filing: 1983-06-10
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Granted: 1985-05-14
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Expires: 2003-06-10
Abstract
Abstract On the back of a wafer there are deposited firstly a gold layer and then an aluminium layer (eventually including a small silicon percent). It is finally carried out a thermic treatment at low temperature, which causes the aluminium migration towards the wafer through the gold layer.
Inventors
- 👤 Livio Baldi
- 👤 Aldo Maggis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:48
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/001; H; H10; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10P; H10P95/00; H10P95/50; B23K2035/008
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
56 words
Metallization process of a silicon wafer back, comprising, in succession, the deposition of a first gold layer, the deposition of a second layer of aluminum and the thermic treatment by annealing to temperature lower than the eutectic gold-silicon temperature of the wafer with superimposed layers whereby the aluminum migrates through the gold layer toward the wafer.
Claim 2
Dependent Claim
56 words
Metallization process of a silicon wafer back, comprising, in succession, the deposition of a first gold layer, the deposition of a second layer of aluminum and the thermic treatment by annealing to temperature lower than the eutectic gold-silicon temperature of the wafer with superimposed layers whereby the aluminum migrates through the gold layer toward the wafer.
Claim 3
Dependent Claim
14 words
Process according to claim 1, characterized in that said aluminium layer containes silicon traces.
Claim 4
Dependent Claim
23 words
Process according to claim 1, characterized in that said thermic treatment is effected at a temperature lower than that of the gold-silicon eutectic.
Claim 5
Dependent Claim
20 words
Process according to claim 3, characterized in that said thermic treatment is effected at a temperature of about 320° C.
Claim 6
Dependent Claim
23 words
Process according to claim 1, characterized in that the thickness of said aluminium and gold layers is in a ratio variable about 1:6.
Claim 7
Dependent Claim
22 words
Process according to claim 1, characterized in that the quantity of aluminium is not greater than 50% of the quantity of gold.
References Cited (Backward Citations)
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Cited
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Cited
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Cited
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Cited
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Cited
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Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-05-13 | 1988-11-12 | 1989-05-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-13 | 1992-11-12 | 1993-05-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-13 | 1996-11-12 | 1997-05-14 | $7700.00 | Window Closed / Lapsed |