Patent US4648936A successfully refreshed from Google Patents.
US4648936A
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Dopant type and/or concentration selective dry photochemical etching of semiconductor materials
Assignee: United States Department of Energy
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Filing: 1985-10-11
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Granted: 1987-03-10
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Expires: 2005-10-11
Abstract
Abstract A method of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from said first material, said second material substantially not being etched during said method, comprises subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said conditions also being such that the resultant electronic structure of the first semiconductor material under said photon flux is sufficient for the first material to undergo substantial photochemical etching under said conditions and being such that the resultant electronic structure of the second semiconductor material under said photon flux is not sufficient for the second material to undergo substantial photochemical etching under said conditions. In a preferred mode, the materials are subjected to a bias voltage which suppresses etching in n- or p- type material but not in p- or n-type material, respectively; or suppresses etching in the more heavily doped of two n-type or two p-type materials.
Inventors
- 👤 Carol I. H. Ashby
- 👤 James L. Dishman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:12
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/24; H10P50/246
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
152 words
A method of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from said first material, said second material substantially not being etched during said method, comprising subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said conditions also being such that the resultant electronic structure of the first semiconductor material under said photon flux is sufficient for the first material to undergo substantial photochemical etching under said conditions and being such that the resultant electronic structure of the second semiconductor material under said photon flux is not sufficient for the second material to undergo substantial photochemical etching under said conditions.
Claim 2
Independent Claim
152 words
A method of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from said first material, said second material substantially not being etched during said method, comprising subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said conditions also being such that the resultant electronic structure of the first semiconductor material under said photon flux is sufficient for the first material to undergo substantial photochemical etching under said conditions and being such that the resultant electronic structure of the second semiconductor material under said photon flux is not sufficient for the second material to undergo substantial photochemical etching under said conditions.
Claim 3
Dependent Claim
42 words
A method of claim 1 wherein said conditions include a bias voltage applied to each of said materials, the bias voltage being of a polarity and strength whereby said first semiconductor material is etched and said second semiconductor material is not etched.
Claim 4
Dependent Claim
24 words
A method of claim 2 wherein the compositions of the two materials differ primarily by carrier type, one being n-type and the other p-type.
Claim 5
Dependent Claim
35 words
A method of claim 3 wherein said first etched semiconductor material is of p-type, said second non-etched semiconductor material is of n-type and said bias voltage has a negative polarity in said second semiconductor material.
Claim 6
Dependent Claim
12 words
A method of claim 4 wherein each of said materials is GaAs.
Claim 7
Dependent Claim
35 words
A method of claim 3 wherein said first etched semiconductor material is of n-type, said second non-etched semiconductor material is of p-type and said bias voltage has a positive polarity in said second semiconductor material.
Claim 8
Dependent Claim
19 words
A method of claim 3 wherein said semiconductor materials have the same III-V chemical composition except for dopant characteristics.
Claim 9
Dependent Claim
18 words
A method of claim 2 wherein said semiconductor materials have the same chemical composition except for dopant characteristics.
Claim 10
Dependent Claim
19 words
A method of claim 2 wherein said semiconductor materials have the same III-V chemical composition except for dopant characteristics.
Claim 11
Dependent Claim
12 words
A method of claim 9 wherein each of said materials is GaAs.
Claim 12
Dependent Claim
24 words
A method of claim 2 wherein each of said materials is of the same type, n- or p-, but have different primary carrier concentrations.
Claim 13
Dependent Claim
37 words
A method of claim 11 wherein each of said materials is of n-type, said first material having a lower n-concentration than said second material, and said bias voltage having a negative polarity in the second semiconductor material.
Claim 14
Dependent Claim
19 words
A method of claim 12 wherein said semiconductor materials have the same III-V chemical composition except for dopant characteristics.
Claim 15
Dependent Claim
37 words
A method of claim 11 wherein each of said materials is of p-type, said first material having a lower p-concentration than said second material, and said bias voltage having a positive polarity in the second semiconductor material.
Claim 16
Dependent Claim
18 words
A method of claim 11 wherein said semiconductor materials have the same chemical composition except for dopant characteristics.
Claim 17
Dependent Claim
19 words
A method of claim 11 wherein said semiconductor materials have the same III-V chemical composition except for dopant characteristics.
Claim 18
Dependent Claim
12 words
A method of claim 16 wherein each of said materials is GaAs.
Claim 19
Dependent Claim
21 words
A method of claim 11 wherein the carrier concentrations of the two materials differ by a factor of 3 or less.
Claim 20
Dependent Claim
12 words
A method of claim 11 wherein each of said materials is silicon.
Claim 21
Dependent Claim
19 words
A method of claim 2 wherein said photon flux is initiated on said materials in a preselected, imaged pattern.
Claim 22
Dependent Claim
16 words
A method of claim 2 wherein said semiconductor materials are part of the same semiconductor device.
Claim 23
Dependent Claim
16 words
A method of claim 2 wherein said semiconductor materials have binary, ternary or quaternary chemical compositions.
References Cited (Backward Citations)
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