US4635343A
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Method of manufacturing GaAs semiconductor device
Assignee: Fujitsu Ltd
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Filing: 1984-03-09
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Granted: 1987-01-13
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Expires: 2004-03-09
Abstract
Abstract A method of manufacturing a GaAs semiconductor device of an E/D construction having a GaAs/AlGaAs heterojunction and utilizing two-dimensional electron gas, which includes the steps of forming a heterojunction semiconductor substrate and etching a portion of the substrate to provide a gate portion of a depletion-mode FET. When the substrate of a semi-insulating GaAs layer, an undoped GaAs, an N-type AlGaAs layer providing an electron-supply layer, and a GaAs layer is formed, the GaAs layer is composed of a first GaAs layer, an etching stoppable AlGaAs layer, and a second GaAs layer, the first GaAs layer being formed on the N-type GaAs layer. The etching for provision of the gate portion is carried out by a dry etching method using an etchant of CCl2F2 gas, so that the second GaAs layer can be etched but the AlGaAs layer cannot be etched. Thus, the thickness of the layers between a gate electrode of the depletion-mode FET and the GaAs/AlGaAs heterojunction plane is determined by the formation of the heterojunction substrate, and consequently a better uniformity of the threshold voltage of depletion-mode FETs is obtained.
Inventors
- 👤 Shigeru Kuroda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:23
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/80; H10D30/40; H10D30/47; H10D30/471; H10D30/475; H10D30/4755; H10D30/801; H10D84/00; H10D84/01; H10D84/02; H10D84/05; H10P; H10P50/00; H10P50/20; H10P50/24; H10P50/246; H10W; H10W10/00; H10W10/01; H10D84/80; H10D84/82; H10D84/83; H10D84/84; H10D84/86; Y; Y10; Y10S; Y10S438/00; Y10S438/97
Claims Analysis
Total Claims: 53
Claim 1
Independent Claim
174 words
A method of manufacturing a GaAs semiconductor device comprising an enhancement-mode GaAs FET having a heterojunction and utilizing a two-dimensional electron gas and a depletion-mode GaAs FET, comprising the steps of: forming an undoped GaAs layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs layer on said undoped GaAs layer; forming a first GaAs layer on said N-type AlGaAs layer; forming an AlGaAs layer serving as an etching stoppable layer on said first GaAs layer; forming a second GaAs layer on said etching stoppable AlGaAs layer; selectively etching said second GaAs layer, said etching stoppable AlGaAs layer, and said first GaAs layer at a position for a gate of the enhancement GaAs FET; and a further etching step of selectively etching the GaAs of said first GaAs layer remaining at the position for the gate of the enhancement-mode GaAs FET and of said second GaAs layer at a position for a gate of the depletion-mode GaAs FET, the etching being stopped at said N-type AlGaAs layer and said etching stoppable AlGaAs layer, respectively.
Claim 2
Independent Claim
174 words
A method of manufacturing a GaAs semiconductor device comprising an enhancement-mode GaAs FET having a heterojunction and utilizing a two-dimensional electron gas and a depletion-mode GaAs FET, comprising the steps of: forming an undoped GaAs layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs layer on said undoped GaAs layer; forming a first GaAs layer on said N-type AlGaAs layer; forming an AlGaAs layer serving as an etching stoppable layer on said first GaAs layer; forming a second GaAs layer on said etching stoppable AlGaAs layer; selectively etching said second GaAs layer, said etching stoppable AlGaAs layer, and said first GaAs layer at a position for a gate of the enhancement GaAs FET; and a further etching step of selectively etching the GaAs of said first GaAs layer remaining at the position for the gate of the enhancement-mode GaAs FET and of said second GaAs layer at a position for a gate of the depletion-mode GaAs FET, the etching being stopped at said N-type AlGaAs layer and said etching stoppable AlGaAs layer, respectively.
Claim 3
Dependent Claim
37 words
A method according to claim 1, wherein said undoped GaAs layer, said N-type AlGaAs layer, said first GaAs layer, said etching stoppable AlGaAs layer, and said second GaAs layer are formed by a molecular beam epitaxy method.
Claim 4
Dependent Claim
38 words
A method according to claim 1, wherein said undoped GaAs layer, said N-type AlGaAs layer, said GaAs layer, said etching stoppable AlGaAs layer, and said second GaAs layer are formed by a metal organic chemical vapor deposition method.
Claim 5
Dependent Claim
22 words
A method according to claim 1, wherein said N-type AlGaAs layer has a thickness in the range from 25 to 60 nm.
Claim 6
Dependent Claim
23 words
A method according to claim 1, wherein said etching stoppable AlGaAs layer has a thickness in the range from 1 to 10 nm.
Claim 7
Dependent Claim
23 words
A method according to claim 5, wherein said etching stoppable AlGaAs layer has a thickness in the range from 3 to 6 nm.
Claim 8
Dependent Claim
23 words
A method according to claim 1, wherein said further step of selectively etching said GaAs is carried out by a dry etching method.
Claim 9
Dependent Claim
35 words
A method according to claim 7, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising at least one of a chlorine system gas and a fluorine system gas.
Claim 10
Dependent Claim
16 words
A method according to claim 8, wherein said etchant gas comprises CCl 2 F 2 .
Claim 11
Dependent Claim
22 words
The method of claim 7, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising chlorine.
Claim 12
Dependent Claim
23 words
A method according to claim 7, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising fluorine.
Claim 13
Dependent Claim
30 words
A method according to claim 1 comprising the step of forming an undoped AlGaAs layer on said undoped GaAs layer, prior to said step of forming said N-type AlGaAs layer.
Claim 14
Dependent Claim
37 words
A method according to claim 1, comprising the step of forming source and drain electrodes for said enhancement-mode and depletion-mode GaAs FETs on said second GaAs layer, prior to said further step of selectively etching the GaAs.
Claim 15
Dependent Claim
33 words
A method according to claim 1, further comprising the step of forming gate electrodes for said enhancement-mode and depletion-mode GaAs FETs on said N-type AlGaAs layer and said AlGaAs etching stoppable layer, respectively.
Claim 16
Dependent Claim
28 words
The method of claim 1, comprising forming a buffer layer of undoped AlGaAs on said undoped GaAs layer and forming said N-type AlGaAs layer on said buffer layer.
Claim 17
Dependent Claim
22 words
The method of claim 1, comprising forming source and drain electrodes for said GaAs FETs in contact with said first GaAs layer.
Claim 18
Dependent Claim
30 words
The method of claim 1, further comprising the step of forming an undoped AlGaAs layer on said undoped GaAs layer, prior to said step of forming said electron-supply AlGaAs layer.
Claim 19
Dependent Claim
56 words
The method of claim 1, comprising forming a plurality of devices each having said enhancement-mode FET and said depletion-mode FET so that the absolute value of the ratio of the standard deviation of the threshold voltage of said depletion-mode FETs to the average threshold voltage is at least 0.056 V/0.50 V=0.13 for 144 of said devices.
Claim 20
Independent Claim
232 words
A method of manufacturing a GaAs semiconductor device comprising an enhancement-mode GaAs FET having a heterojunction and utilizing a two-dimensional electron gas and a depletion-mode GaAs MESFET, comprising the steps of: forming an undoped GaAs layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs layer as an electron-supply layer on said undoped GaAs layer; forming an N-type GaAs layer as an active layer of the depletion-mode GaAs MESFET on said N-type AlGaAs layer; forming an AlGaAs layer serving as an etching stoppable layer on said active GaAs layer; forming a GaAs layer as a contact layer on said etching stoppable AlGaAs layer; forming an isolation region for the depletion-mode GaAs MESFET; selectively etching said contact GaAs layer, said etching stoppable AlGaAs layer, and the active GaAs layer at a position for a gate of the enhancement mode GaAs FET to make the thickness of the remaining active GaAs layer similar to that of said contact layer; forming source and drain electrodes of both the GaAs FETs on said contact GaAs layer; a further etching step of selectively etching the GaAs of said active GaAs layer remaining at the position for the gate of the enhancement-mode GaAs FET and of said contact GaAs layer at a position for a gate of the depletion-mode GaAs MESFET, the etching being stopped at said electron-supply AlGaAs layer and said etching stoppable AlGaAs layer, respectively; and
Claim 21
Independent Claim
232 words
A method of manufacturing a GaAs semiconductor device comprising an enhancement-mode GaAs FET having a heterojunction and utilizing a two-dimensional electron gas and a depletion-mode GaAs MESFET, comprising the steps of: forming an undoped GaAs layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs layer as an electron-supply layer on said undoped GaAs layer; forming an N-type GaAs layer as an active layer of the depletion-mode GaAs MESFET on said N-type AlGaAs layer; forming an AlGaAs layer serving as an etching stoppable layer on said active GaAs layer; forming a GaAs layer as a contact layer on said etching stoppable AlGaAs layer; forming an isolation region for the depletion-mode GaAs MESFET; selectively etching said contact GaAs layer, said etching stoppable AlGaAs layer, and the active GaAs layer at a position for a gate of the enhancement mode GaAs FET to make the thickness of the remaining active GaAs layer similar to that of said contact layer; forming source and drain electrodes of both the GaAs FETs on said contact GaAs layer; a further etching step of selectively etching the GaAs of said active GaAs layer remaining at the position for the gate of the enhancement-mode GaAs FET and of said contact GaAs layer at a position for a gate of the depletion-mode GaAs MESFET, the etching being stopped at said electron-supply AlGaAs layer and said etching stoppable AlGaAs layer, respectively; and
Claim 22
Dependent Claim
24 words
forming respective gate electrodes for said enhancement-mode and depletion-mode GaAs FETs on said electron-supply AlGaAs layer and on said etching stoppable AlGaAs layer, respectively.
Claim 23
Dependent Claim
24 words
forming respective gate electrodes for said enhancement-mode and depletion-mode GaAs FETs on said electron-supply AlGaAs layer and on said etching stoppable AlGaAs layer, respectively.
Claim 24
Dependent Claim
37 words
A method according to claim 19, wherein said undoped GaAs layer, said electron-supply AlGaAs layer, said active GaAs layer, said etching stoppable AlGaAs layer, and said contact GaAs layer are formed by a molecular beam epitaxy method.
Claim 25
Dependent Claim
38 words
A method according to claim 19, wherein said undoped GaAs layer, said electron-supply AlGaAs layer, said active GaAs layer, said etching stoppable AlGaAs, and said contact GaAs layer are formed by a metal organic chemical vapor deposition method.
Claim 26
Dependent Claim
20 words
A method according to claim 19, wherein said electron-supply GaAs layer has a thickness of from 25 to 60 nm.
Claim 27
Dependent Claim
21 words
A method according to claim 19, wherein said etching stoppable AlGaAs layer has a thickness of from 1 to 10 nm.
Claim 28
Dependent Claim
21 words
A method according to claim 23, wherein said etching stoppable AlGaAs layer has a thickness of from 3 to 6 nm.
Claim 29
Dependent Claim
23 words
A method according to claim 19, wherein said further step of selectively etching the GaAs is carried out by a dry etching method.
Claim 30
Dependent Claim
30 words
A method according to claim 25, wherein said dry etching method is a reactive ion etching method using an etchant comprising a chlorine system gas and a fluorine system gas.
Claim 31
Dependent Claim
16 words
A method according to claim 26, wherein said etchant gas comprises CCl 2 F 2 .
Claim 32
Dependent Claim
23 words
A method according to claim 26, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising fluorine.
Claim 33
Dependent Claim
22 words
The method of claim 25, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising chlorine.
Claim 34
Dependent Claim
31 words
A method according to claim 19, further comprising the step of forming an undoped AlGaAs layer on said undoped GaAs layer, prior to said step of forming said electron-supply AlGaAs layer.
Claim 35
Dependent Claim
36 words
The method of claim 19, comprising etching respective portions of said GaAs contact layer and said AlGaAs etching stoppable layer and forming source and drain electrodes for said GaAs FETs on said N-type GaAs active layer.
Claim 36
Independent Claim
133 words
A method of manufacturing a GaAs semiconductor device comprising an enhancement-mode GaAs FET and a depletion-mode GaAs FET which have a heterojunction and utilize a two-dimensional electron gas, comprising the steps of: forming an undoped GaAs layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs layer as an electron-supply layer on said undoped GaAs layer; forming a first GaAs layer on said electron-supply AlGaAs layer; forming an AlGaAs layer serving as an etching stoppable layer on said first GaAs layer; forming a second GaAs layer on said etching stoppable AlGaAs layer; selectively etching said second GaAs layer, said etching stoppable AlGaAs layer, and said first GaAs layer at a position for a gate of the enhancement-mode GaAs FET; forming source and drain electrodes of both the FETs on said second GaAs layer;
Claim 37
Independent Claim
133 words
A method of manufacturing a GaAs semiconductor device comprising an enhancement-mode GaAs FET and a depletion-mode GaAs FET which have a heterojunction and utilize a two-dimensional electron gas, comprising the steps of: forming an undoped GaAs layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs layer as an electron-supply layer on said undoped GaAs layer; forming a first GaAs layer on said electron-supply AlGaAs layer; forming an AlGaAs layer serving as an etching stoppable layer on said first GaAs layer; forming a second GaAs layer on said etching stoppable AlGaAs layer; selectively etching said second GaAs layer, said etching stoppable AlGaAs layer, and said first GaAs layer at a position for a gate of the enhancement-mode GaAs FET; forming source and drain electrodes of both the FETs on said second GaAs layer;
Claim 38
Dependent Claim
83 words
a further etching step of selectively etching the GaAs of said first GaAs layer remaining at the position for the gate of enhancement-mode GaAs FET and of said second GaAs layer at a position for a gate of the depletion-mode GaAs FET, the etching being stopped at said electron-supply AlGaAs layer and said etching stoppable AlGaAs layer, respectively; and forming respective gate electrodes for said enhancement-mode and depletion-mode GaAs FETs on said electron-supply AlGaAs layer and on said etching stoppable AlGaAs layer, respectively.
Claim 39
Dependent Claim
83 words
a further etching step of selectively etching the GaAs of said first GaAs layer remaining at the position for the gate of enhancement-mode GaAs FET and of said second GaAs layer at a position for a gate of the depletion-mode GaAs FET, the etching being stopped at said electron-supply AlGaAs layer and said etching stoppable AlGaAs layer, respectively; and forming respective gate electrodes for said enhancement-mode and depletion-mode GaAs FETs on said electron-supply AlGaAs layer and on said etching stoppable AlGaAs layer, respectively.
Claim 40
Dependent Claim
37 words
A method according to claim 32, wherein said undoped GaAs layer, said electron-supply AlGaAs layer, said first GaAs layer, said etching stoppable AlGaAs layer, and said second GaAs layer are formed by a molecular beam epitaxy method.
Claim 41
Dependent Claim
38 words
A method according to claim 32, wherein said undoped GaAs layer, said electron-supply AlGaAs layer, said first GaAs layer, said etching stoppable AlGaAs, and said second GaAs layer are formed by a metal organic chemical vapor deposition method.
Claim 42
Dependent Claim
20 words
A method according to claim 32, wherein said first GaAs layer has a thickness of from 25 to 200 nm.
Claim 43
Dependent Claim
20 words
A method according to claim 32, wherein said electron-supply AlGaAs layer has a thickness of from 25 to 60 nm.
Claim 44
Dependent Claim
21 words
A method according to claim 32, wherein said etching stoppable AlGaAS layer has a thickness of from 1 to 10 nm.
Claim 45
Dependent Claim
21 words
A method according to claim 37, wherein said etching stoppable AlGaAs layer has a thickness of from 3 to 6 nm.
Claim 46
Dependent Claim
23 words
A method according to claim 32, wherein said further step of selectively etching the GaAs is carried out by a dry etching method.
Claim 47
Dependent Claim
30 words
A method according to claim 39, wherein said dry etching method is a reactive ion etching method using an etchant comprising a chlorine system gas and a fluorine system gas.
Claim 48
Dependent Claim
25 words
A method according to claim 39, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising chlorine and fluorine.
Claim 49
Dependent Claim
22 words
The method of claim 39, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising chlorine.
Claim 50
Dependent Claim
22 words
The method of claim 39, wherein said dry etching method is a reactive ion etching method using an etchant gas comprising fluorine.
Claim 51
Dependent Claim
16 words
A method according to claim 32, wherein said etchant gas comprises CCl 2 F 2 .
Claim 52
Dependent Claim
31 words
A method according to claim 32, further comprising the step of forming an undoped AlGaAs layer on said undoped GaAs layer, prior to said step of forming said electron-supply AlGaAs layer.
Claim 53
Dependent Claim
37 words
The method of claim 32, comprising etching respective portions of said second GaAs layer and said AlGaAs etching stoppable layer and forming source and drain electrodes for said GaAs FETs in contact with said first GaAs layer.
References Cited (Backward Citations)
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