US4369099A
Expired / Lapsed
US
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Photoelectrochemical etching of semiconductors
Assignee: AT&T Inc
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Filing: 1981-01-08
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Granted: 1983-01-18
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Expires: 2001-01-08
Abstract
Abstract A process is described for etching p-type semiconductors using a photoelectrochemical etching process. This etching process is highly advantageous because the etching site is highly defined by the incident light and the etching rate can be controlled in a number of ways including light intensity and electrode potential.
Inventors
- 👤 Paul A. Kohl
- 👤 Frederick W. Ostermayer, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 04:38
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/617; C; C25; C25F; C25F3/00; C25F3/02; C25F3/12; C25F3/14; H10P50/20; H10P52/00; H10P95/00; H10P95/70; Y; Y10; Y10S; Y10S204/00; Y10S204/09
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
161 words
A process for fabricating devices comprising at least one compound semiconductor material selected from the group consisting of III-V and II-VI compound semiconductor material with a given band gap in which the compound semiconductor material is photoelectrochemically etched by a procedure comprising the step of passing electrical energy through a semiconductor electrode comprising compound semiconductor material, electrochemical solution and counter electrode characterized in that; (a) the compound semiconductor material is p-type (b) the electrical energy is applied to the semiconductor electrode in the form of pulses comprising reducing pulses and oxidizing pulses, in which said reducing pulses have a semiconductor electrode potential such as to reduce the semiconductor material and said oxidizing pulses have a semiconductor electrode potential such as to oxidize the semiconductor material; (c) the electrochemical solution removes the reduction and oxidation products of the photoelectrochemical etching reaction; and (d) the semiconductor material is irradiated by radiation with photon energy greater than the band gap of the semiconductor material.
Claim 2
Dependent Claim
161 words
A process for fabricating devices comprising at least one compound semiconductor material selected from the group consisting of III-V and II-VI compound semiconductor material with a given band gap in which the compound semiconductor material is photoelectrochemically etched by a procedure comprising the step of passing electrical energy through a semiconductor electrode comprising compound semiconductor material, electrochemical solution and counter electrode characterized in that; (a) the compound semiconductor material is p-type (b) the electrical energy is applied to the semiconductor electrode in the form of pulses comprising reducing pulses and oxidizing pulses, in which said reducing pulses have a semiconductor electrode potential such as to reduce the semiconductor material and said oxidizing pulses have a semiconductor electrode potential such as to oxidize the semiconductor material; (c) the electrochemical solution removes the reduction and oxidation products of the photoelectrochemical etching reaction; and (d) the semiconductor material is irradiated by radiation with photon energy greater than the band gap of the semiconductor material.
Claim 3
Dependent Claim
26 words
The process of claim 1 in which a nonmetallic element is reduced by the reducing pulses and a metallic element is oxidized by the oxidizing pulse.
Claim 4
Dependent Claim
33 words
The process of claim 1 in which the p-type semiconductor material is made by doping and the doping level is in the range from 10 15 to 10 19 atoms per cubic centimeter.
Claim 5
Dependent Claim
21 words
The process of claim 3 in which the dopant is selected from the group consisting of zinc, cadmium, silicon and germanium.
Claim 6
Dependent Claim
15 words
The process of claim 1 in which the electrochemical solution comprises a strong aqueous acid.
Claim 7
Dependent Claim
32 words
The process of claim 5 in which the strong acid is selected from the group consisting of sulfuric acid, phosphoric acid, perchloric acid, nitric acid, hydrochloric acid, sulfamic acid and sulfurous acid.
Claim 8
Dependent Claim
23 words
The process of claim 6 in which the strong acid has a concentration in terms of hydrogen ions between 0.01 and 6.0 Molar.
Claim 9
Dependent Claim
17 words
The process of claim 7 in which the electrochemical solution further comprises at least one bridging ligand.
Claim 10
Dependent Claim
30 words
The process of claim 8 in which the bridging ligand comprises at least one ion selected from the group consisting of thiocyanate ion, iodide ion, oxalate ion and cyanide ion.
Claim 11
Dependent Claim
14 words
The process of claim 1 in which the electrochemical solution comprises weak aqueous acid.
Claim 12
Dependent Claim
40 words
The process of claim 10 in which the weak aqueous acid is selected from the group consisting of adipic acid, benzoic acid, substituted benzoic acid, formic acid, hydrofluoric acid, iodic acid, malonic acid, oxalic acid, phthalic acid and tartaric acid.
Claim 13
Dependent Claim
14 words
The process of claim 1 in which the electrochemical solution comprises strong aqueous base.
Claim 14
Dependent Claim
21 words
The process of claim 12 in which the strong base is selected from the group consisting of NaOH, KOH and LiOH.
Claim 15
Dependent Claim
23 words
The process of claim 13 in which the strong base has a concentration in terms of hydroxyl ion between 0.01 and 1.0 Molar.
Claim 16
Dependent Claim
16 words
The process of claim 14 in which the electrochemical solution comprises in addition a complexing agent.
Claim 17
Dependent Claim
14 words
The process of claim 1 in which the electrochemical solution comprises weak aqueous base.
Claim 18
Dependent Claim
17 words
The process of claim 16 in which the weak aqueous base comprises aqueous ammonia and ammonium ion.
Claim 19
Dependent Claim
19 words
The process of claim 1 in which the semiconductor material comprises aluminum and the electrochemical solution comprises chloride ion.
Claim 20
Dependent Claim
21 words
The process of claim 18 in which the chloride ion is present in the concentration range from 0.001 to 1.0 Molar.
Claim 21
Dependent Claim
49 words
The process of claim 1 in which the semiconductor material is selected from the group consisting of GaAs, GaP, GaSb, InAs, InSb, AlAs, AlP, AlSb, InP, In 1-x Ga x;l As 1-y P y and Ga 1-x Al x As where x and y vary from zero to one.
Claim 22
Dependent Claim
36 words
The process of claim 1 in which the semiconductor material is selected from the group consisting of CdS, CdSe, CdTe, ZuS, ZnSe, ZnTe, ZnO and CdS 1-x Se x where x varies from zero to one.
Claim 23
Dependent Claim
17 words
The process of claim 1 in which the pulses have durations between 10 microseconds and one second.
Claim 24
Dependent Claim
16 words
The process of claim 22 in which the pulse duration varies from one to 100 milliseconds.
Claim 25
Dependent Claim
16 words
The process of claim 23 in which the pulse duration varies from 2 to 30 milliseconds.
Claim 26
Dependent Claim
22 words
The process of claim 1 in which the reduction pulse has electrode potential on the calomel scale between -1.0 and +0.2 volts.
Claim 27
Dependent Claim
16 words
The process of claim 25 in which the electrode potential is between -0.4 and -0.1 volts.
Claim 28
Dependent Claim
23 words
The process of claim 1 in which the oxidation pulse has an electrode potential on the calomel scale between +0.2 and +1.0 volts.
Claim 29
Dependent Claim
16 words
The process of claim 27 in which the electrode potential is between +0.2 and +0.4 volts.
Claim 30
Dependent Claim
15 words
The process of claim 1 in which the radiation on the semiconductor forms a pattern.
Claim 31
Dependent Claim
38 words
The process of claim 1 in which the device comprises two or more compound semiconductor materials with different band gaps and the radiation energy is selected to allow etching of one compound semiconductor and not another compound semiconductor.
Claim 32
Dependent Claim
19 words
The process of claim 1 in which the radiation is incident on the semiconductor only during the reducing pulse.
Claim 33
Dependent Claim
13 words
The process of claim 1 in which the radiation originates from a laser.
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US3265599A
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GB1535061A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-17 | 1986-07-19 | 1987-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-17 | 1990-07-19 | 1991-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-17 | 1994-07-19 | 1995-01-18 | $7700.00 | Window Closed / Lapsed |