US4957873A
Expired / Lapsed
US
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Process for forming isolation trenches in silicon semiconductor bodies
Assignee: STMicroelectronics NV
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Filing: 1989-09-21
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Granted: 1990-09-18
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Expires: 2009-09-21
Abstract
Abstract Isolation trenches are formed in a semiconductor, e.g. silicon, substrate by selectively doping the substrate and preferentially oxidizing the doped material. Typically the dopant is arsenic or phosphorus and preferably the substrate is doped to a level of at least 5×10 19 cm -3 .
Inventors
- 👤 Sureshchandra M. Ojha
- 👤 Paul J. Rosser
- 👤 Philip B. Moynagh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:33
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6308; H10P14/6309; H10P14/6322; H10P14/65; H10P14/6502; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/0125; H10W10/10; H10W10/13; Y; Y10; Y10S; Y10S438/00; Y10S438/966
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
164 words
A method of fabricating an oxide-filled isolation trench in a major surface of a silicon semiconductor substrate, the trench having a width of about 1 micron and having a depth exceeding its width, the method consisting of the steps of applying a mask to said surface, said mask having an opening defining the position and width of the trench, implanting phosphorus or arsenic dopant ions into the substrate via said opening to a concentration of at least 5×10 20 cm -3 and to a depth of about 8 microns, removing the mask, and subjecting the dopant substrate to an oxygen atmosphere at a temperature of 850° to 950° C. at a pressure of 10 to 20 atmospheres so as to convert preferentially the doped silicon to silicon oxide to depth of about 6 microns and a width of about 1 micron thereby forming the isolation trench, said preferential conversion of doped silicon to silicon oxide being confined substantially to a linear growth of oxide.
Claim 2
Independent Claim
164 words
A method of fabricating an oxide-filled isolation trench in a major surface of a silicon semiconductor substrate, the trench having a width of about 1 micron and having a depth exceeding its width, the method consisting of the steps of applying a mask to said surface, said mask having an opening defining the position and width of the trench, implanting phosphorus or arsenic dopant ions into the substrate via said opening to a concentration of at least 5×10 20 cm -3 and to a depth of about 8 microns, removing the mask, and subjecting the dopant substrate to an oxygen atmosphere at a temperature of 850° to 950° C. at a pressure of 10 to 20 atmospheres so as to convert preferentially the doped silicon to silicon oxide to depth of about 6 microns and a width of about 1 micron thereby forming the isolation trench, said preferential conversion of doped silicon to silicon oxide being confined substantially to a linear growth of oxide.
Claim 3
Dependent Claim
21 words
A method as claimed in claim 1, wherein said dopant ions are implanted at an energy of 50 to 150 KeV.
References Cited (Backward Citations)
JPS5383465A
Cited
JPS58170030A
Cited
JPS594137A
Cited
JPS59100552A
Cited
JPS6097637A
Cited
US4717687A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |