US4369090A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for etching sloped vias in polyimide insulators
Assignee: Texas Instruments Inc
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Filing: 1980-11-06
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Granted: 1983-01-18
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Expires: 2000-11-06
Abstract
Abstract A method for the fabrication of a cured polyamic acid film having apertures therein selectively etched to provide sidewalls sloped at a controlled angle. Such films are used in the fabrication of integrated circuits having two or more levels of metallization, to provide electrical insulation between metal levels. The apertures therein are required to have sloped sidewalls in order to enhance the yields of circuits having reliable contact between metal levels.
Inventors
- 👤 Arthur M. Wilson
- 👤 David W. Laks
- 👤 Stephen M. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:28
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/286; H10P50/287; H05; H05K; H05K1/00; H05K1/02; H05K1/03; H05K1/0313; H05K1/032; H05K1/0346; H05K3/00; H05K3/0011; H05K3/0017
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
84 words
A method for the fabrication of a partially cured polyamic acid film having tapered apertures therein, comprising the steps of: (a) forming a polyamic acid iso-indroquinazolinedione resin film on a suitable substrate; (b) curing said film at or near its upper chronostatic temperature of 165° C. (c) selectively masking the resultant cured film with an operational resist, and (d) exposing the masked film to an etchant containing 10-25% by weight tetramethyl ammonium hydroxide whereby tapered apertures are etched in the more completely cured film.
Claim 2
Independent Claim
84 words
A method for the fabrication of a partially cured polyamic acid film having tapered apertures therein, comprising the steps of: (a) forming a polyamic acid iso-indroquinazolinedione resin film on a suitable substrate; (b) curing said film at or near its upper chronostatic temperature of 165° C. (c) selectively masking the resultant cured film with an operational resist, and (d) exposing the masked film to an etchant containing 10-25% by weight tetramethyl ammonium hydroxide whereby tapered apertures are etched in the more completely cured film.
Claim 3
Dependent Claim
17 words
A method as in claim 1 wherein said etchant is an aqueous alcohol solution of tetra-methyammonium hydroxide.
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) | 1986-01-17 | 1986-07-19 | 1987-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-17 | 1990-07-19 | 1991-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-17 | 1994-07-19 | 1995-01-18 | $7700.00 | Window Closed / Lapsed |