EP0045181A2
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High electron mobility heterojunction semiconductor device and method of manufacturing
Assignee: Fujitsu Ltd
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Filing: 1981-07-23
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Granted: —
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Expires: 2001-07-23
Abstract
Abstract In a high electron mobility heterojunction semiconductor device a heterojunction is formed between an n-type AlGaAs layer 5 and an undoped GaAs layer 4. An undoped AlGaAs layer 3 is formed between layer 6 and the device substrate 1. The layer 3 prevents migration of impurities from the substrate 1 during heat treatment in the manufacture of the device, acts as a buffer layer, and provides a test layer for setting up optimum manufacturing conditions before formation of n-type AlGaAs layer 5.
Inventors
- 👤 Satoshi Hiyamizu
- 👤 Toshio Fujii
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 14:10
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/20; H10P14/29; H10P14/2901; H10P14/2907; H10P14/2911; H10D; H10D30/00; H10D30/40; H10D30/47; H10D30/471; H10D30/473; H10D30/4732; H10P14/22; H10P14/32; H10P14/3202; H10P14/3214; H10P14/3221; H10P14/34; H10P14/3402; H10P14/3414; H10P14/3421
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
101 words
A high electron mobility heterojunction semi- conductor device, for example a HEMT, comprising: a n-type ternary or quaternary semiconductor layer, an elementary or binary semiconductor layer, below the n-type ternary or quaternary semiconductor layer, a substrate, below the elementary or binary semiconductor layer, characterised in that an undoped layer, of the same ternary or quaternary semiconductor as the said n-type ternary or quaternary semiconductor layer, is provided between the elementary or binary semiconductor layer and the substrate, and in that the elementary or binary semiconductor layer is undoped,or doped to a lesser degree than the n-type ternary or quaternary semiconductor layer.
Claim 2
Dependent Claim
101 words
A high electron mobility heterojunction semi- conductor device, for example a HEMT, comprising: a n-type ternary or quaternary semiconductor layer, an elementary or binary semiconductor layer, below the n-type ternary or quaternary semiconductor layer, a substrate, below the elementary or binary semiconductor layer, characterised in that an undoped layer, of the same ternary or quaternary semiconductor as the said n-type ternary or quaternary semiconductor layer, is provided between the elementary or binary semiconductor layer and the substrate, and in that the elementary or binary semiconductor layer is undoped,or doped to a lesser degree than the n-type ternary or quaternary semiconductor layer.
Claim 3
Dependent Claim
27 words
A device as claimed in claim 1, characterised in that the n-type ternary or quaternary semiconductor layer is formed directly uponthe elementary or binary semi- conductor layer.
Claim 4
Dependent Claim
36 words
A device as claimed in claim 1, characterised in that an undoped region of the ternary or quaternary semiconductor is provided between the n-type ternary or quaternary semiconductor layer and the elementary or binary semiconductor layer.
Claim 5
Dependent Claim
34 words
A device as claimed in claim 1, 2 or 3, characterised in that a further elementary or binary semiconductor layer, undoped, is provided between the undoped ternary or quaternary semiconductor layer and the substrate.
Claim 6
Dependent Claim
32 words
A device as claimed in claim 1, 2, 3 or 4, characterised in that the elementary or binary semi- conductor is GaAs , and the ternary or quaternary semiconductor is AlGaAs. -
Claim 7
Dependent Claim
23 words
A device as claimed in claim 5, wherein the substrate is a semi-insulating substrate, for example of GaAs, or is of Cr-doped GaAs.
Claim 8
Independent Claim
27 words
A device as claimed in any preceding claim, comprising a gate electrode on top of the n-type ternary or quaternary semiconductor layer, and source and drain electrodes.
Claim 9
Independent Claim
137 words
A method of manufacturing a high electron mobility heterojunction semiconductor device, for example a HEMT, comprising:- growing, above a substrate, an elementary or binary semiconductor layer, growing, above the elementary or binary semiconductor layer, an n-type ternary or quaternary semiconductor layer, characterised by growing an undoped layer, of the same ternary or quaternary semiconductor as the said n-type ternary or quaternary layer, above the substrate, before the elementary or binary semiconductor layer is grown, so that the elementary or binary semiconductor layer is grown above the undoped ternary or quaternary semiconductor layer, the elementary or binary semiconductor consisting of one or two of the elements making up the ternary or quaternary semi- conductor, and the layer of the elementary or binary semiconductor being undoped,or doped to a lesser degree than the n-type ternary or quaternary semiconductor layer.
Claim 10
Independent Claim
137 words
A method of manufacturing a high electron mobility heterojunction semiconductor device, for example a HEMT, comprising:- growing, above a substrate, an elementary or binary semiconductor layer, growing, above the elementary or binary semiconductor layer, an n-type ternary or quaternary semiconductor layer, characterised by growing an undoped layer, of the same ternary or quaternary semiconductor as the said n-type ternary or quaternary layer, above the substrate, before the elementary or binary semiconductor layer is grown, so that the elementary or binary semiconductor layer is grown above the undoped ternary or quaternary semiconductor layer, the elementary or binary semiconductor consisting of one or two of the elements making up the ternary or quaternary semi- conductor, and the layer of the elementary or binary semiconductor being undoped,or doped to a lesser degree than the n-type ternary or quaternary semiconductor layer.
Claim 11
Dependent Claim
25 words
A method as claimed in claim 8, wherein the n-type ternary or quaternary semiconductor layer is grown directly upon the elementary or binary semiconductor layer.
Claim 12
Dependent Claim
36 words
A method as claimedin claim 8, wherein an undoped region of the ternary or quaternary semiconductor is grown on the elementary or binary semiconductor layer and the n-type ternary or quaternary semiconductor layer is grown thereon.
Claim 13
Dependent Claim
37 words
A method as claimed in claim 8, 9 or 10, wherein a buffer layer, of the elementary or binary semiconductor, is grown on the substrate, and then the undoped ternary or quaternary semiconductor layer is grown thereon.
Claim 14
Dependent Claim
29 words
A method as claimed in claim 8, 9, 10 or 11, wherein each layer is grown either by a molecular beam epitaxy process or an ion beam epitaxy process.
Claim 15
Dependent Claim
106 words
A method as claimed in claim 12, wherein, in the growth of the elementary or binary semiconductor layer, the beam or beams from the or those beam sources providing the element or elements of the ternary or not of the elementary or-binary semiconductor quaternary semiconductor / are cut off by means of a shutter or shutters, but intensity of the beam or beams from the beam sources are maintained during the growth of the elementary or binary semiconductor layer, and for the subsequent growth of the n-type ternary or quaternary semiconductor layer, the shutter or shutters are opened to allow the previously cut-off beams to pass.
Claim 16
Independent Claim
34 words
A method as claimed in any one of claims 8 to 13, further comprising:- growing a gate electrode on top of the n-type ternary or quaternary semiconductor layer, and growing source and drain electrodes.
Claim 17
Dependent Claim
40 words
A method as claimed in claim 14, wherein an ion implantation process is employed for at least one of the following steps :- growing a ternary or quaternary semiconductor layer, growing the gate electrode, growing the source and drain electrodes.
Claim 18
Independent Claim
28 words
A method as claimed in any one of claims 8 to 15, wherein the ternary or quaternary semiconductor is AlGaAs and the elementary or binary semiconductor is GaAs.
References Cited (Backward Citations)
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