US4482443A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photoelectrochemical etching of n-type silicon
Assignee: Nokia Bell Labs
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Filing: 1983-12-30
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Granted: 1984-11-13
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Expires: 2003-12-30
Abstract
Abstract Photoelectrochemical processing of semiconductors is highly desirable because of its versatility and simplicity. The invention is a photoelectrochemical etching procedure for n-type silicon in which an alcohol based solution of hydrofluoric acid is used as the electrolyte. This procedure is useful for the fabrication of a variety of silicon devices.
Inventors
- 👤 Duane E. Bacon
- 👤 Jeffrey R. Bessette
- 👤 Paul A. Kohl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:23
CPC Classifications
C; C25; C25F; C25F3/00; C25F3/02; C25F3/14; C25F3/12; H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/613
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
151 words
A process for fabricating a device comprising n-type silicon semiconductor comprising the step of etching at least part of the semiconductor characterized in that the etching procedure is an electrochemical photoetching procedure in which electric current is passed through the semiconductor, electrolytic solution with conductivity greater than 0.00001 mhos/cm and anode in which the electrochemical photoetching procedure further comprises: a. applying a potential to the semiconductor which is between the maximum potential of the valence band of the semiconductor in the electrolytic solution and the minimum potential of the conduction band of the semiconductor in the electrolytic solution; b. illuminating the part of the surface of the semiconductor to be etched with radiation of sufficient energy to produce holes in the valence band; c. the electrolytic solution comprises solvents and fluoride ions, said solvents comprising alcohol with up to 10 carbon atoms, said solvent having less than 5 weight percent water.
Claim 2
Dependent Claim
151 words
A process for fabricating a device comprising n-type silicon semiconductor comprising the step of etching at least part of the semiconductor characterized in that the etching procedure is an electrochemical photoetching procedure in which electric current is passed through the semiconductor, electrolytic solution with conductivity greater than 0.00001 mhos/cm and anode in which the electrochemical photoetching procedure further comprises: a. applying a potential to the semiconductor which is between the maximum potential of the valence band of the semiconductor in the electrolytic solution and the minimum potential of the conduction band of the semiconductor in the electrolytic solution; b. illuminating the part of the surface of the semiconductor to be etched with radiation of sufficient energy to produce holes in the valence band; c. the electrolytic solution comprises solvents and fluoride ions, said solvents comprising alcohol with up to 10 carbon atoms, said solvent having less than 5 weight percent water.
Claim 3
Dependent Claim
17 words
The process of claim 1 in which the solvent consists of less than 1 weight percent water.
Claim 4
Dependent Claim
19 words
The process of claim 2 in which the solvent consists essentially of alcohol with up to 10 carbon atoms.
Claim 5
Dependent Claim
13 words
The process of claim 3 in which the solvent consists essentially of methanol.
Claim 6
Dependent Claim
12 words
The process of claim 1 in which the electrolytic solution comprises HF.
Claim 7
Dependent Claim
24 words
The process of claim 5 in which the electrolytic solution comprises HF and HCl both in the concentration range from 0.1 to 5 molar.
Claim 8
Dependent Claim
16 words
The process of claim 1 in which the electrolytic solution comprises NH 4 F 2 H.
Claim 9
Dependent Claim
30 words
The process of claim 7 in which the NH 4 F 2 H forms a saturated solution and KF is present in a concentration range between 0.1 and 5 molar.
Claim 10
Dependent Claim
29 words
The process of claim 1 in which the silicon is doped with phosphorus or arsenic in the concentration range from 10 15 to 10 19 atoms per cubic centimeter.
Claim 11
Dependent Claim
19 words
The process of claim 1 in which the photon energy of the radiation is greater than 1.12 electron volts.
Claim 12
Dependent Claim
25 words
The process of claim 1 in which the applied potential at the semiconductor surface is between -0.2 volts and +1.0 volts on the SCE scale.
Claim 13
Dependent Claim
21 words
The process of claim 1 in which the applied potential on the SCE scale is between 1 volt and 5 volts.
References Cited (Backward Citations)
US2861931A
Cited
US3079536A
Cited
US3041258A
Cited
US3527682A
Cited
US4399004A
Cited
US4389291A
Cited
US4404072A
Cited
US4415414A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-11-13 | 1988-05-14 | 1988-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-13 | 1992-05-14 | 1992-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-13 | 1996-05-14 | 1996-11-13 | $7700.00 | Window Closed / Lapsed |