US4389291A
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Photoelectrochemical processing of InP-type devices
Assignee: AT&T Inc
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Filing: 1981-06-19
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Granted: 1983-06-21
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Expires: 2001-06-19
Abstract
Abstract A process is described for photoelectrochemically etching n-type indium phosphide and closely related compound semiconductors such as indium gallium arsenide and indium gallium arsenide phosphide. Such a process is advantageous because the etching is confined to where light is incident to the surface of the semiconductor. In addition, the shape of the configuration etched out of the semiconductor can be controlled by the light incident on the surface of the semiconductor. For example, undercutting can be minimized by use of parallel rays incident on the surface of the semiconductor to be etched.
Inventors
- 👤 Paul A. Kohl
- 👤 Frederick W. Ostermayer, Jr.
- 👤 Catherine Wolowodiuk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 04:28
CPC Classifications
C; C25; C25F; C25F3/00; C25F3/02; C25F3/12; C25F3/14; H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/617; Y; Y10; Y10T; Y10T428/00; Y10T428/22; Y10T428/31504
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
173 words
A process for fabricating devices comprising at least one n-type III-V compound semiconductor in which the Group III part of the compound semiconductor comprises at least 50 weight percent indium and the process comprises at least one step in which the n-type semiconductor compound is photoelectrochemically etched by an oxidation-reduction reaction in an electrolytic solution characterized in that a. the oxidation is carried out by irradiating the n-type 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 potential of the conduction band minimum and the potential of the valence band maximum so that the elements in the n-type III-V compound semiconductor are all oxidized to form oxidation products that are soluble in the electrolytic solution, 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
173 words
A process for fabricating devices comprising at least one n-type III-V compound semiconductor in which the Group III part of the compound semiconductor comprises at least 50 weight percent indium and the process comprises at least one step in which the n-type semiconductor compound is photoelectrochemically etched by an oxidation-reduction reaction in an electrolytic solution characterized in that a. the oxidation is carried out by irradiating the n-type 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 potential of the conduction band minimum and the potential of the valence band maximum so that the elements in the n-type III-V compound semiconductor are all oxidized to form oxidation products that are soluble in the electrolytic solution, 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
28 words
The process of claim 1 in which the III-V compound semiconductor is selected from the group consisting of indium phosphide, indium gallium arsenide and indium gallium arsenide phosphide.
Claim 4
Dependent Claim
37 words
The process of claim 2 in which the III-V compound semiconductor has the formula Ga x In 1-x As y P 1-y in which x ranges from 0.27 to 0.31 and y ranges from 0.58 to 0.74.
Claim 5
Dependent Claim
12 words
The process of claim 1 in which the electrolytic solution is acidic.
Claim 6
Dependent Claim
19 words
The process of claim 4 in which the electrolytic solution is made acid by the addition of hydrochloric acid.
Claim 7
Dependent Claim
24 words
The process of claim 5 in which the reduction potential of the oxidizing agent on the hydrogen scale ranges from -0.1 to +0.8 volts.
Claim 8
Dependent Claim
27 words
The process of claim 6 in which the oxidizing agent is selected from the group consisting of pentavalent vanadium, hexavalent chromium, bromine in water and tetravalent iridium.
Claim 9
Dependent Claim
17 words
The process of claim 7 in which the electrolytic solution contains aqueous hydrochloric acid and chromium trioxide.
Claim 10
Dependent Claim
18 words
The process of claim 1 in which the oxidizing agent has a concentration between 0.1 Molar and saturation.
Claim 11
Dependent Claim
19 words
The process of claim 9 in which the concentration of the oxidizing agent ranges from 0.5 to 1.5 Molar.
Claim 12
Dependent Claim
12 words
The process of claim 1 in which the electrolytic solution is basic.
Claim 13
Dependent Claim
26 words
The process of claim 11 in which the oxidizing agent is selected from the group consisting of divalent sulfur ion, trivalent cobalt ion and iodate ion.
Claim 14
Dependent Claim
15 words
The process of claim 1 in which the radiation is produced by a laser source.
Claim 15
Dependent Claim
40 words
The process of claim 1 in which the III-V compound semiconductor is doped with an element selected from the group consisting of tin sulfur and tellurium in the concentration range from 10 15 to 10 19 atoms per cubic centimeter.
Claim 16
Dependent Claim
21 words
The process of claim 14 in which the concentration range is from 10 17 to 10 18 atoms per cubic centimeter.
Claim 17
Dependent Claim
9 words
A device made by the process of claim 1.
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) | 1986-06-20 | 1986-12-20 | 1987-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-20 | 1990-12-20 | 1991-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-20 | 1994-12-20 | 1995-06-21 | $7700.00 | Window Closed / Lapsed |