US4404072A
Expired / Lapsed
US
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Photoelectrochemical processing of III-V semiconductors
Assignee: AT&T Inc
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Filing: 1981-06-22
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Granted: 1983-09-13
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Expires: 2001-06-22
Abstract
Abstract A photoelectrochemical process is described for anisotropic etching of intrinsic III-V compound semiconductors. Such a process is highly advantageous because the etching takes place only where light is incident on the surface of the semiconductor. Thus, various patterns can be etched into the semiconductor surface without the use of a mask, undercutting is minimized where masks are used and the shape of the hole etched out of the surface can be controlled.
Inventors
- 👤 Paul A. Kohl
- 👤 Frederick W. Ostermayer, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:56
CPC Classifications
C; C25; C25F; C25F3/00; C25F3/02; C25F3/14; C25F3/12; H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/617
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
143 words
A process for fabricating a device comprising at least one semi-insulating III-V compound semiconductor, said semi-insulating III-V compound semiconductor having resistivities greater than 10 6 ohm-cm, comprising the step of photoelectrochemically etching the semi-insulating III-V compound semiconductor using an oxidation-reduction reaction in an electrolytic solution characterized in that a. the oxidation reaction is carried out by illuminating the semi-insulating III-V compound semiconductor with radiation comprising photon energy at least as great as the bandgap of the compound semiconductor so as to produce holes that permit oxidation of the compound semiconductor, b. the electrolytic solution comprises oxidizing agent with reduction potential in the electrolytic solution between the flat band potential of the Fermi level and the potential of the maximum of the valence band, and c. the oxidizing agent is reduced on a metallic or p-type surface electrically connected to the III-V compound semiconductor.
Claim 2
Dependent Claim
143 words
A process for fabricating a device comprising at least one semi-insulating III-V compound semiconductor, said semi-insulating III-V compound semiconductor having resistivities greater than 10 6 ohm-cm, comprising the step of photoelectrochemically etching the semi-insulating III-V compound semiconductor using an oxidation-reduction reaction in an electrolytic solution characterized in that a. the oxidation reaction is carried out by illuminating the semi-insulating III-V compound semiconductor with radiation comprising photon energy at least as great as the bandgap of the compound semiconductor so as to produce holes that permit oxidation of the compound semiconductor, b. the electrolytic solution comprises oxidizing agent with reduction potential in the electrolytic solution between the flat band potential of the Fermi level and the potential of the maximum of the valence band, and c. the oxidizing agent is reduced on a metallic or p-type surface electrically connected to the III-V compound semiconductor.
Claim 3
Dependent Claim
33 words
The process of claim 1 in which the intrinsic III-V compound semiconductor is selected from the group consisting of GaP, GaAs, AlAs, AlP, AlSb, InSb, InAs, InP GaInAs, GaInP, GaInAsP, GaAlP and GaAlAs.
Claim 4
Dependent Claim
14 words
The process of claim 2 in which the intrinsic III-V compound semiconductor is GaAs.
Claim 5
Dependent Claim
14 words
The process of claim 3 in which the III-V compound semiconductor is compensated GaAs.
Claim 6
Dependent Claim
30 words
The process of claim 4 in which the GaAs is made semi-insulating by doping with chromium in the concentration range from 10 15 to 10 17 atoms per cubic centimeters.
Claim 7
Dependent Claim
14 words
The process of claim 1 in which the radiation originates from a laser source.
Claim 8
Dependent Claim
13 words
The process of claim 6 in which the oxidizing agent is ferric ions.
Claim 9
Dependent Claim
20 words
The process of claim 7 in which the electrolytic solution comprises 0.5 Molar ferric sulfate and 2.0 Molar sulfuric acid.
Claim 10
Dependent Claim
38 words
The process of claim 1 in which the oxidizing agent is selected from the group consisting of pentavalent vanadium, quadravalent vanadium, I 3 - , PtCl 6 -2 , Fe +3 , IrCl 6 -2 and hexavalent chromium.
Claim 11
Dependent Claim
19 words
The process of claim 9 in which the concentration of the oxidizing agent ranges from 0.1 Molar to saturation.
Claim 12
Dependent Claim
16 words
The process of claim 10 in which the concentration range is from 0.25 to 1.5 Molar.
Claim 13
Dependent Claim
16 words
The process of claim 1 in which the electrolytic solution has a pH less than 4.
Claim 14
Dependent Claim
16 words
The process of claim 1 in which the electrolytic solution has a pH greater than 8.
Claim 15
Dependent Claim
13 words
The process of claim 1 in which the electrolytic solution comprises a buffer.
Claim 16
Dependent Claim
15 words
The process of claim 1 in which the device is a gallium arsenide field-effect transistor.
Claim 17
Dependent Claim
21 words
The process of claim 15 in which the photoelectrochemical etching is used to produce a via hole in semi-insulating gallium arsenide.
References Cited (Backward Citations)
US3890215A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-12 | 1987-03-14 | 1987-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-12 | 1991-03-14 | 1991-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-12 | 1995-03-14 | 1995-09-13 | $7700.00 | Window Closed / Lapsed |