US4894351A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making a silicon IC with planar double layer metal conductors system
Assignee: Allegro Microsystems LLC
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Filing: 1988-02-16
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Granted: 1990-01-16
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Expires: 2008-02-16
Abstract
Abstract A process for providing in an integrated circuit on which there are to be formed at least two levels of metal conductors, includes depositing a first blanket layer of silicon dioxide over the first metal film conductors, spinning on a silicon glass precursor compound carried by an organic vehicle and heat curing to produce a silica coat, covering this sheet by spinning on a layer of photoresist resin and subsequently etching back this stack of insulating layers to leave a thinned but contiguous first silicon dioxide layer, to leave only thick plug portions of the underlying silica coat in deepest recess regions of the underlying silicon dioxide layer and to leave none of the photoresist layer. This presents a particularly smooth surface over which the second pattern of metal conductors may be formed with good step coverage in the metal cross-over regions and, in initially smooth regions at which vias are to be formed, leaves essentially no trace of the sacrificial photoresist resin nor of the partially sacrificial silica coat.
Inventors
- 👤 Michael W. Batty
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:46
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/071; H10W20/092
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
194 words
A method for making a silicon integrated circuit with a double metal film system of conductors comprising: (a) forming over a side of a silicon substrate a first metal film having one and another portion separated by a gap; (b) depositing a first blanket silicon dioxide layer over said substrate side and said first metal film so that the surface of said first layer has a depression at said gap; (c) depositing a silica coat directly over said blanket silicon dioxide layer to be thicker at said gap than over said first metal film portions; (d) spinning on a layer of an organic resin over said silica coat and curing said resin; (e) using an etching process for removing at about the same rate said resin, said silica and said silicon dioxide, etching until said resin coating is entirely removed and until at areas over which said resin layer had been thinnest prior to said etching, said silica coat is removed and the exposed regions of said first blanket silicon dioxide layer are thinned; (f) depositing a second silicon dioxide layer, and (g) forming over said second silicon dioxide layer a second metal film.
Claim 2
Independent Claim
194 words
A method for making a silicon integrated circuit with a double metal film system of conductors comprising: (a) forming over a side of a silicon substrate a first metal film having one and another portion separated by a gap; (b) depositing a first blanket silicon dioxide layer over said substrate side and said first metal film so that the surface of said first layer has a depression at said gap; (c) depositing a silica coat directly over said blanket silicon dioxide layer to be thicker at said gap than over said first metal film portions; (d) spinning on a layer of an organic resin over said silica coat and curing said resin; (e) using an etching process for removing at about the same rate said resin, said silica and said silicon dioxide, etching until said resin coating is entirely removed and until at areas over which said resin layer had been thinnest prior to said etching, said silica coat is removed and the exposed regions of said first blanket silicon dioxide layer are thinned; (f) depositing a second silicon dioxide layer, and (g) forming over said second silicon dioxide layer a second metal film.
Claim 3
Dependent Claim
54 words
The method of claim 1 wherein said depositing a silica coat is comprised of spinning on a liquid coat of siloxane polymer in an organic vehicle and heating to a temperature of from 250° C. to 450° C. to drive off said vehicle and to at least partially transform said liquid coat to silica.
Claim 4
Dependent Claim
44 words
The method of claim 1 wherein said etching is continued and stopped only after said silica coat is entirely removed in all areas extending more than 10 microns in all directions wherein said outer surface of said first silicon dioxide layer is essentially planar.
Claim 5
Dependent Claim
61 words
The method of claim 3 additionally comprising forming a via hole through said second silicon dioxide layer and through said first silicon dioxide layer at one of said areas over which said resin layer had been thinnest prior to forming said second metal film, said forming said second metal film including filling said via hole with metal contacting said silicon substrate.
Claim 6
Dependent Claim
13 words
The method of claim 1 wherein said organic resin is a novalac resin.
Claim 7
Dependent Claim
12 words
The method of claim 1 wherein said organic resin is a photoresist.
Claim 8
Dependent Claim
12 words
The method of claim 1 wherein said organic resin is a polyimide.
Claim 9
Dependent Claim
16 words
The method of claim 1 wherein said first metal film is aluminum or an aluminum alloy.
Claim 10
Dependent Claim
21 words
The method of claim 1 wherein said first silicon dioxide layer is accomplished by a plasma enhanced chemical vapor deposition process.
Claim 11
Dependent Claim
30 words
The method of claim 1 wherein said forming said second metal film is accomplished by sputtering while heating said substrate to a temperature of from 300° C. to 450° C.
Claim 12
Dependent Claim
34 words
The method of claim 1 wherein prior to said etching the average thickness of said silica coat is less than 3000 Å and the thickness of said photoresist layer is greater than 3000 Å.
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) | 1993-01-15 | 1993-07-17 | 1994-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-15 | 1997-07-17 | 1998-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-15 | 2001-07-17 | 2002-01-16 | $7700.00 | Window Closed / Lapsed |