US4574466A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High quality gate oxides for VLSI devices
Assignee: GTE Communication Systems Corp
•
Filing: 1984-12-10
•
Granted: 1986-03-11
•
Expires: 2004-12-10
Abstract
Abstract In a 1.2 micron CMOS process, the gate oxide is formed by growing a 1000 Angstrom thickness of sacrificial oxide, immediately performing an oxide strip and then effecting a thin gate oxidation. The gate oxidation step is characterized by a temperature ramp from 700 to 950 degrees Centigrade in a flow of 9 liters per minute nitrogen and 0.36 liters per minute oxygen. At the 950 degrees Centigrade point, the nitrogen flow ceases and the oxygen flow increases to 9 liters per minute. The temperature is then downwardly ramped to 900 degrees Centigrade.
Inventors
- 👤 George F. Hagner
- 👤 Kothandaraman Ravindhran
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:46
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01332; H10D64/01336; H10D64/01346; H10D64/01352; H10P; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6308; H10P14/6309; H10P14/65; H10P14/6502; H10P14/6322; Y; Y10; Y10S; Y10S148/00; Y10S148/081; Y10S148/118
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
107 words
A method of forming a gate oxide layer for a CMOS device, the method comprising the steps of: (a) growing a predetermined thickness of sacrificial oxide on a semiconductor surface, (b) performing an immediate wet chemical oxide strip of predetermined portions of the sacrificial layer, (c) establishing a flow consisting essentially of approximately 9 liters per minute nitrogen and 0.36 liters per minute oxygen during a temperature ramp from 700 to 950 degrees Centigrade, (d) at 950 degrees Centigrade, causing the nitrogen flow to cease and the oxygen flow to increase to 9 liters per minute, and (e) downwardly ramping temperature from 950 to 900 degrees Centigrade.
Claim 2
Independent Claim
107 words
A method of forming a gate oxide layer for a CMOS device, the method comprising the steps of: (a) growing a predetermined thickness of sacrificial oxide on a semiconductor surface, (b) performing an immediate wet chemical oxide strip of predetermined portions of the sacrificial layer, (c) establishing a flow consisting essentially of approximately 9 liters per minute nitrogen and 0.36 liters per minute oxygen during a temperature ramp from 700 to 950 degrees Centigrade, (d) at 950 degrees Centigrade, causing the nitrogen flow to cease and the oxygen flow to increase to 9 liters per minute, and (e) downwardly ramping temperature from 950 to 900 degrees Centigrade.
Claim 3
Dependent Claim
20 words
A method according to claim 1 wherein the sacrificial oxide layer is grown to a thickness of approximately 1000 Angstroms.
References Cited (Backward Citations)
US4214919A
Cited
US4518630A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-03-10 | 1989-09-09 | 1990-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-10 | 1993-09-09 | 1994-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-10 | 1997-09-09 | 1998-03-11 | $7700.00 | Window Closed / Lapsed |