US4859253A
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Method for passivating a compound semiconductor surface and device having improved semiconductor-insulator interface
Assignee: International Business Machines Corp
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Filing: 1988-07-20
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Granted: 1989-08-22
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Expires: 2008-07-20
Abstract
Abstract A method for passivating the surface of a compound semiconductor comprises annealing the substrate to form an anion rich surface layer containing cationic and anionic oxides and stripping the oxides to leave only a very thin anionic layer on the surface. The substrate is then subjected to an H 2 plasma cleaning to remove chemisorbed oxygen. An N 2 plasma cleaning is then performed to form an anionic nitride layer that is free of any cationic nitride. A layer of insulating material, such as, a native or other oxide, or a nitride, is deposited. The resulting structure has a very low interface state density such that the Fermi level may be swept through the entire band gap.
Inventors
- 👤 Douglas A. Buchanan
- 👤 Alessandro C. Callegari
- 👤 Peter D. Hob
- 👤 Dianne L. Lacey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:02
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/69; H10P14/692; H10P14/6921; H10P14/69215; H10P14/63; H10P14/6326; H10P14/6328; H10P14/6332; H10P14/65; H10P14/6502; H10P14/6504; H10P14/6506; H10P14/6512; H10P14/6514; H10P14/6516; H10P14/6518; H10P14/6524; H10P14/6526; H10P14/6529; H10P14/6532; H10P14/68; H10P14/694; H10P14/6943; H10P14/69433; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6312; H10P14/6322; H10P14/6938; H10P14/6939; H10P14/69391
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
36 words
A method for passivating the surface of a compound semiconductor comprising the step of: forming an anionic nitride layer free of a detectable amount of a cationic nitride on the surface of a compound semiconductor substrate.
Claim 2
Independent Claim
36 words
A method for passivating the surface of a compound semiconductor comprising the step of: forming an anionic nitride layer free of a detectable amount of a cationic nitride on the surface of a compound semiconductor substrate.
Claim 3
Dependent Claim
77 words
The method according to claim 1 wherein the step of forming an anionic nitride includes the steps of: annealing said substrate to form an anion rich surface layer containing cationic and anionic oxides; stripping said cationic and anionic oxides from said surface leaving an anionic layer on said surface; cleaning said surface in a hydrogen plasma; and nitriding said anionic layer in a nitrogen plasma to form an anionic nitride layer on the surface of said substrate.
Claim 4
Dependent Claim
19 words
The method according to claim 2 wherein the substrate is annealed at a temperature range of 300°14 500° C.
Claim 5
Dependent Claim
14 words
The method according to claim 3 wherein the substrate is annealed at 470° C.
Claim 6
Dependent Claim
15 words
The method according to claim 4 wherein the substrate is annealed in an inert atmosphere.
Claim 7
Dependent Claim
26 words
The method according to claim 5 further including the step of forming a metallic contact to an opposing surface of said substrate during the annealing step.
Claim 8
Dependent Claim
18 words
The method according to claim 2 wherein the stripping step comprises subjecting the surface to a wet etch.
Claim 9
Dependent Claim
19 words
The method according to claim 7 wherein the wet etch includes cleaning the surface in a solution containing HCL.
Claim 10
Dependent Claim
24 words
The method according to claim 2 wherein the hydrogen plasma cleaning step includes an H 2 RF plasma at low pressure and low voltage.
Claim 11
Dependent Claim
44 words
The method according to claim 9 wherein the H 2 RF plasma is at a pressure in the range of 1-10 mTorr, at a voltage in the range of -50 to -250 volts dc and at a temperature in the range of 150°-300° C.
Claim 12
Dependent Claim
30 words
The method according to claim 10 wherein the H 2 RF plasma is at a pressure 5 mTorr, a voltage of -150 volts dc and a temperature of 200° C.
Claim 13
Dependent Claim
23 words
The method according to claim 2 wherein the nitrogen plasma step includes an N 2 RF plasma at low pressure and low temperature.
Claim 14
Dependent Claim
43 words
The method according to claim 12 wherein the N 2 RF plasma is at a pressure in the range 1-10 mTorr, at a voltage in the range of -50 to -200 volts dc and at a temperature in the range of 150°-300° C.
Claim 15
Dependent Claim
30 words
The method according to claim 13 wherein the N 2 RF plasma is at a pressure of 5 mTorr, a voltage of -150 volts, and a temperature of 200° C.
Claim 16
Dependent Claim
16 words
The method according to claim 2 wherein the cleaning and nitriding steps are performed in situ.
Claim 17
Dependent Claim
19 words
The method according to claim 2 further including the step of depositing an insulator on said anionic nitride layer.
Claim 18
Dependent Claim
15 words
The method according to claim 16 wherein said insulator is deposited by electron beam evaporation.
Claim 19
Dependent Claim
20 words
The method according to claim 17 wherein said electron beam evaporation is a low voltage, low pressure O 2 plasma.
Claim 20
Dependent Claim
45 words
The method according to claim 18 wherein the plasma is at a pressure in the range of 1 to 10 mTorr, the voltage is in the range of -50 to -250 volts dc and the temperature is in the range of 24° to 260° C.
Claim 21
Dependent Claim
25 words
The method according to claim 19 wherein the plasma pressure is 2 mTorr, the voltage is -100 volts dc, and the temperature is 200° C.
Claim 22
Dependent Claim
18 words
The method according to claim 16 wherein the cleaning, nitriding at insulator depositing steps are performed in situ.
Claim 23
Dependent Claim
19 words
The method according to claim 1 wherein the compound semiconductor is GaAs and the anionic nitride layer is AsN.
Claim 24
Dependent Claim
19 words
The method according to claim 22 further including the step of depositing an insulator on said anionic nitride layer.
Claim 25
Dependent Claim
32 words
The method according to claim 23 wherein the insulator is one of Ga 2 O 3 , SiO 2 , Al 2 O 3 , AlN, and Si 3 N 4 .
Claim 26
Independent Claim
105 words
A method for passivating the surface of a substrate of a compound semiconductor comprising the steps of: annealing said substrate in an inert atmosphere at a temperature sufficient to form a cationic oxide of said compound semiconductor having anions and anionic oxides of said compound semiconductor included therein, removing said oxides leaving said anions on said substrate surface in the form of a thin layer, removing any chemisorbed oxygen from said thin layer, and converting said layer of anions to a layer of anionic nitride in a plasma of-nitrogen, said anionic nitride being free of detectable amounts of the cationic nitride of said compound semiconductor.
Claim 27
Independent Claim
105 words
A method for passivating the surface of a substrate of a compound semiconductor comprising the steps of: annealing said substrate in an inert atmosphere at a temperature sufficient to form a cationic oxide of said compound semiconductor having anions and anionic oxides of said compound semiconductor included therein, removing said oxides leaving said anions on said substrate surface in the form of a thin layer, removing any chemisorbed oxygen from said thin layer, and converting said layer of anions to a layer of anionic nitride in a plasma of-nitrogen, said anionic nitride being free of detectable amounts of the cationic nitride of said compound semiconductor.
Claim 28
Dependent Claim
21 words
The method according to claim 25 wherein said oxides are removed by subjecting the substrate to a dilute HCl wet etch.
Claim 29
Dependent Claim
21 words
The method according to claim 26 wherein the chemisorbed oxygen is removed by an RF plasma cleaning in H 2 .
Claim 30
Independent Claim
20 words
The method of claims 27 wherein the converting step is performed by an RF plasma cleaning in N 2 .
Claim 31
Dependent Claim
18 words
The method of claim 28 further including the step of depositing an insulator on said anionic nitride layer.
Claim 32
Dependent Claim
48 words
A passivated compound semiconductor structure comprising: a substrate of a compound semiconductor material having first and second major surfaces; and a layer of anionic nitride of said semiconductor disposed on said first major surface, said layer being free of detectable amounts of cationic nitride of said compound semiconductor.
Claim 33
Dependent Claim
48 words
A passivated compound semiconductor structure comprising: a substrate of a compound semiconductor material having first and second major surfaces; and a layer of anionic nitride of said semiconductor disposed on said first major surface, said layer being free of detectable amounts of cationic nitride of said compound semiconductor.
Claim 34
Dependent Claim
17 words
The structure according to claim 30 further including insulating material disposed on said layer of anionic nitride.
Claim 35
Dependent Claim
20 words
The structure according to claim 31 further including a metallic contact disposed on the second major surface of said substrate.
Claim 36
Dependent Claim
18 words
The structure according to claim 30 wherein said substrate is GaAs and said anionic nitride layer is AsN.
Claim 37
Dependent Claim
33 words
The structure according to claim 33 wherein said insulating material is one of Ga 2 O 3 , SiO 2 , Al 2 O 3 , AlN and Si 3 N 4 .
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