US3929589A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective area oxidation of III-V compound semiconductors
Assignee: AT&T Inc
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Filing: 1974-02-08
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Granted: 1975-12-30
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Expires: 1994-02-08
Abstract
Abstract A method for selectively oxidizing the surface of a III-V compound semiconductor wafer. A photoresist mask is first formed on the surface of the semiconductor leaving exposed the areas to be oxidized. The semiconductor is then made the anode in an electrolytic cell wherein the electrolyte comprises water and a source of ions for adjusting the pH or providing conductivity to the solution. In a preferred embodiment, the wafer is a gallium containing compound semiconductor and in particular GaAs, and the electrolyte is water and an ammonium acid phosphate. The oxide is grown electrolytically only into the exposed areas of the wafer, and the photoresist may then be stripped off leaving the desired oxide pattern.
Inventors
- 👤 Felix Ermanis
- 👤 Bertram Schwartz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:25
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6312; C; C25; C25D; C25D11/00; C25D11/02; C25D11/32; C25D5/00; C25D5/02; H10D; H10D99/00; H10P14/6324; H10P50/00; H10P50/60; H10P50/61; H10P50/617; H10P95/00
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
120 words
A METHOD FOR FORMING AN OXIDE ON SELECTED PORTIONS OF THE SURFACE OF A GALLIUM CONTAINING COMPOUND SEMICONDUCTOR COMPRISING THE STEPS OF: FORMING A MASK OF A PHOTORESIST MATERIAL OVER THE SURFACE OF SAID SEMICONDUCTOR SO AS TO LEAVE EXPOSED SELCTED PORTIONS OF THE SURFACE TO BE OXIDIZED; MAKO ING THE SEMICONDUCTOR THE ANODE IN AN ELECTROLYTIC CELL WHEREIN THE ELECTROLYTE COMPRISES H2O AND A MATERIAL OF THE COMPOSITION (NH4)3-X HX PO4 WHERE X=0 - 2, AND PASSING A CURRENT THROUGH SAID CELL SO AS TO GROW OXIDE INTO THE EXPOSED POSITIONS OF THE SEMICONDUCTOR SURFACE; AND REMOVING THE PHOTORESIST MASK FROM THE SURFACE OF THE SEMICONDUCTOR SO AS TO LEAVE THE OXIDE ON THE SELECTED PORTIONS OF THE SURFACE.
Claim 2
Independent Claim
120 words
A METHOD FOR FORMING AN OXIDE ON SELECTED PORTIONS OF THE SURFACE OF A GALLIUM CONTAINING COMPOUND SEMICONDUCTOR COMPRISING THE STEPS OF: FORMING A MASK OF A PHOTORESIST MATERIAL OVER THE SURFACE OF SAID SEMICONDUCTOR SO AS TO LEAVE EXPOSED SELCTED PORTIONS OF THE SURFACE TO BE OXIDIZED; MAKO ING THE SEMICONDUCTOR THE ANODE IN AN ELECTROLYTIC CELL WHEREIN THE ELECTROLYTE COMPRISES H2O AND A MATERIAL OF THE COMPOSITION (NH4)3-X HX PO4 WHERE X=0 - 2, AND PASSING A CURRENT THROUGH SAID CELL SO AS TO GROW OXIDE INTO THE EXPOSED POSITIONS OF THE SEMICONDUCTOR SURFACE; AND REMOVING THE PHOTORESIST MASK FROM THE SURFACE OF THE SEMICONDUCTOR SO AS TO LEAVE THE OXIDE ON THE SELECTED PORTIONS OF THE SURFACE.
Claim 3
Dependent Claim
23 words
The method according to claim 1 wherein the semiconductor is selected from the group consisting of GaP, GaAs, AlGaAs, AlGaP, InGaP, and InGaAs.
Claim 4
Dependent Claim
19 words
The method according to claim 1 wherein the pH of the electrolyte is within the range 5 - 9.
Claim 5
Dependent Claim
34 words
The metHod according to claim 1 wherein areas of conductive material are included on the surface of said semiconductor and said photoresist mask is formed over said surface including said areas of conductive material.
Claim 6
Dependent Claim
15 words
The method according to claim 1 wherein a constant potential is applied to said cell.
Claim 7
Dependent Claim
15 words
The method according to claim 1 wherein a constant current is applied to said cell.
Claim 8
Dependent Claim
15 words
The method according to claim 1 wherein the applied potential is a pulsed d.c. potential.
Claim 9
Dependent Claim
20 words
The method according to claim 1 wherein the temperature of the electrolyte is at the boiling point of said solution.
Claim 10
Dependent Claim
19 words
The method according to claim 1 wherein the applied potential lies within the range of 5 - 175 volts.
Claim 11
Dependent Claim
18 words
The method according to claim 1 wherein the breakdown voltage of the photoresist is at least 104 volts/cm.
Claim 12
Independent Claim
119 words
A method for forming an oxide on selected portions of the surface of a GaAs semiconductor comprising the steps of: forming a mask of a photoresist material over the surface of said semiconductor so as to leave exposed selected portions of the surface to be oxidized; making the semiconductor the anode in an electrolytic cell wherein the electrolyte comprises H2O and a material of the composition (NH4)3-x Hx PO4 where x 0 - 2, and passing a current through said cell so as to grow an oxide into the exposed portions of the semiconductor surface; and removing the photoresist mask from the surface of the semiconductor so as to leave the oxide on the selected portions of the surface.
Claim 13
Independent Claim
119 words
A method for forming an oxide on selected portions of the surface of a GaAs semiconductor comprising the steps of: forming a mask of a photoresist material over the surface of said semiconductor so as to leave exposed selected portions of the surface to be oxidized; making the semiconductor the anode in an electrolytic cell wherein the electrolyte comprises H2O and a material of the composition (NH4)3-x Hx PO4 where x 0 - 2, and passing a current through said cell so as to grow an oxide into the exposed portions of the semiconductor surface; and removing the photoresist mask from the surface of the semiconductor so as to leave the oxide on the selected portions of the surface.
Claim 14
Dependent Claim
19 words
The method according to claim 11 wherein the pH of the electrolyte is within the range 5 - 9.
Claim 15
Dependent Claim
34 words
The method according to claim 11 wherein areas of conductive material are included on the surface of said semiconductor and said photoresist mask is formed over said surface including said areas of conductive material.
Claim 16
Dependent Claim
15 words
The method according to claim 11 wherein a constant potential is applied to said cell.
Claim 17
Dependent Claim
15 words
The method according to claim 11 wherein a constant current is applied to said cell.
Claim 18
Dependent Claim
15 words
The method according to claim 11 wherein the applied potential is a pulsed d.c. potential.
Claim 19
Dependent Claim
20 words
The method according to claim 11 wherein the temperature of the electrolyte is at the boiling point of said solution.
Claim 20
Dependent Claim
19 words
The method according to claim 11 wherein the applied potential lies within the range of 5 - 175 volts.
Claim 21
Dependent Claim
18 words
The method according to claim 11 wherein the breakdown voltage of the photoresist is at least 104 volts/cm.
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) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |