US3898141A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrolytic oxidation and etching of III-V compound semiconductors
Assignee: AT&T Inc
•
Filing: 1974-02-08
•
Granted: 1975-08-05
•
Expires: 1994-02-08
Abstract
Abstract A method for oxidation and etching of a III-V compound semiconductor in a single solution. The semiconductor is made the anode in an electrolytic cell wherein the electrolyte is water raised to a pH of 8 or above by a source of hydroxyl ions such as NH4OH. When an appropriate electric field is established in the cell, an oxide is grown into the surface of the semiconductor. Then the field is lowered or turned off and the oxide dissolves faster than it is grown resulting in an etching of the semiconductor material previously consumed in forming the oxide. The method permits electrochemical thinning of a semiconductor layer for such uses as FETS and IMPATTS and further allows formation of passivating layers on etched surfaces in situ.
Inventors
- 👤 Felix Ermanis
- 👤 Bertram Schwartz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:55
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6312; H10P14/6324; H10P50/00; H10P50/60; H10P50/61; H10P50/617
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
44 words
The method according to claim 1 wherein the first and third magnitude of electric field are established by applying a first constant potential to said cell and the second magnitude of electric field is established by applying a second constant potential to said cell.
Claim 2
Dependent Claim
44 words
The method according to claim 1 wherein the first and third magnitude of electric field are established by applying a first constant current to said cell and the second magnitude of electric field is established by applying a second constant current to said cell.
Claim 3
Dependent Claim
22 words
The method according to claim 2 wherein the difference between the first potential and the second potential is at least 10 volts.
Claim 4
Dependent Claim
22 words
The method according to claim 2 wherein the difference between the first potential and the second potential is at least 100 volts.
Claim 5
Dependent Claim
22 words
The method according to claim 3 wherein the difference between the first current and the second current is at least 5 milliamps/cm2.
Claim 6
Dependent Claim
15 words
The method according to claim 1 wherein the electrolyte is held at the boiling point.
Claim 7
Independent Claim
174 words
A method for thinning a compound semiconductor comprising a material selected from the group consisting of GaAs, GaP, AlGaAs, AlGaP, InGaP, InGaAs and GaAsP comprising the steps of: making the semiconductor the anode in an electrolytic cell wherein the electrolyte comprises water and an amount of NH4OH sufficient to set the pH of the electrolyte to within the range 8-12; applying a first potential to said cell of sufficient magnitude so as to grow an oxide into the surface of the semiconductor; applying a second potential to said cell which is lower than said first potential and which is initially insufficient to grow any further oxide into said surface so as to dissolve a portion of the oxide grown into said surface; applying a third potential to said cell sufficient to grow further oxide into said surface when the rate of dissolution of the oxide is approximately equal to the rate of formation of oxide into said surface at said second potential; and repeating said oxidation and dissolution until a desired thickness is achieved.
Claim 8
Dependent Claim
40 words
The method according to claim 8 further comprising the step of re-applying a magnitude of potential sufficient to grow further oxide into said surface subsequent to reaching the desired thickness so as to grow a passivating oxide into said surface.
Claim 9
Independent Claim
159 words
A method for thinning of a semiconductor materiaL comprising GaAs comprising the steps of: making the semiconductor the anode in an electrolytic cell wherein the electrolyte comprises water and an amount of NH4OH sufficient to set the pH of the electrolyte to within the range 8-12; applying a first potential to said cell of sufficient magnitude so as to grow an oxide into the surface of the semiconductor; applying second potential to said cell which is lower than said first potential and which is initially insufficient to grow any further oxide into said surface so as to dissolve a portion of the oxide grown into said surface; applying a third potential to said cell sufficient to grow further oxide into said surface when the rate of dissolution of the oxide is approximately equal to the rate of formation of oxide into said surface at said second potential; and repeating said oxidation and dissolution until a desired thickness is reached.
Claim 10
Dependent Claim
17 words
The method according to claim 10 wherein the third potential is approximately equal to the first potential.
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) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |