EP0056904A2
Expired / Lapsed
EP
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High electron mobility single heterojunction semiconductor devices and methods of production of such devices
Assignee: Fujitsu Ltd
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Filing: 1981-12-21
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Granted: —
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Expires: 2001-12-21
Abstract
Abstract A high electron mobility semiconductor device has a channel layer (7) and a source layer (8). For example, the source layer (8) contains a sufficient amount of n-type impurity to permit the accumulation of a quasi-two-dimensional electron gas (9) in proximity to a heterojunction (10) of the device formed between the layers (7 and 8). p-type impurity is selectively introduced into selected areas (12) of the source layer (8). In relation to those selected areas (12) the availability of electrons in the source layer is decreased, so that the quasi-two-dimensional gas cannot accumulate in proximity to regions of the heterojunction (10) corresponding to those areas (12). Thereby, the selected areas (12) function as isolation areas. In general, by controlling impurity concentration and/or impurity type in selected areas of the source layer (8) the appearance of the quasi-two-dimensional electron gas (9) can be inhibited or permitted selectively in correspondence with those areas.
Inventors
- 👤 Hidetoshi Nishi
- 👤 Satoshi Hiyamizu
- 👤 Shigeru Okamura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 12:46
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/01; H10D84/02; H10D84/05; H10D30/00; H10D30/40; H10D30/47; H10D30/471; H10D30/475; H10D30/4755; H10W; H10W10/00; H10W10/01; H10W10/031; H10W10/30; H10W20/00; H10W20/20; H10D84/0123
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
71 words
A method of manufacturing a high electron mobility semiconductor device having first and second layers, of semiconductors having lesser and greater electron affinities respectively, to provide a heterojunction in the device, wherein impurity concentration and/or impurity type in the first layer is selectively controlled, thereby to regulate the sheet concentration of electrons accumulated in proximity to the heterojunction in consequence of the different electron affinities of the first and second layers.
Claim 2
Independent Claim
71 words
A method of manufacturing a high electron mobility semiconductor device having first and second layers, of semiconductors having lesser and greater electron affinities respectively, to provide a heterojunction in the device, wherein impurity concentration and/or impurity type in the first layer is selectively controlled, thereby to regulate the sheet concentration of electrons accumulated in proximity to the heterojunction in consequence of the different electron affinities of the first and second layers.
Claim 3
Dependent Claim
65 words
A method as claimed in claim 1, wherein, in selected areas of the first layer impurity concentration and/or impurity type is so controlled that the accumulation of electrons in proximity to regions of the heterojunction corresponding to those selected areas is inhibited, whereby, the selected areas can provide isolation regions, for example for isolating high electron mobility transistors, formed in the device, from one another.
Claim 4
Dependent Claim
65 words
A method as claimed in claim 1, wherein, in selected areas of the first layer impurity concentration and/or impurity type is so controlled that the accumulation of electrons in proximity to regions of the heterojunction corresponding to the selected areas is encouraged, whereby the selected areas can provide conductive pathways, for example for connecting high electron mobility transistors, formed in the device, to one another.
Claim 5
Dependent Claim
45 words
A method as claimed in claim 1, wherein, in selected areas of the first layer impurity concentration and/or impurity type is so controlled that high electron mobility transistors of the device, formed so as to employ those selected areas , have respective different pinch-off voltages.
Claim 6
Dependent Claim
42 words
A method as claimed in claim 4, wherein impurity concentration and/or impurity type is so controlled in those selected areas that some of the high electron mobility transistors are formed as depletion mode transistors, and others are formed as enhancement mode transistors.
Claim 7
Independent Claim
74 words
A method as claimed in any preceding claim, wherein impurity concentration and/or impurity type in the first layer is so controlled by the selective introduction into selected areas of the first layer, provided previously in an initial impurity condition, of impurities of a type or types or in an amount or amounts such as to regulate the sheet concentrations of electrons accumulated in proximity to regions of the heterojunction corresponding to the selected areas.
Claim 8
Dependent Claim
117 words
A method as claimed in claim 6, wherein, when, in an initial impurity condition,the first layer contains a sufficient amount of n-type impurities to permit accumulation of electrons in proximity to the heterojunction, p-type impurities are -selectively introduced to inhibit such accumulation; when, in an initial impurity condition,the first layer contains an insufficient amount of n-type impurities to permit accumulation of electrons in proximity to the heterojunction, n-type impurities are selectively introduced to encourage such accumulation ; when, in an initial impurity condition,,the first layer contains an intermediate amount of n-type impurities, or substantially no impurities, n-type and/or p-type impurities are selectively introduced respectively to encourage and to inhibit accumulation of electrons in proximity to the heterojunction.
Claim 9
Dependent Claim
39 words
A method as claimed in claim 6 or 7, wherein the selective introduction of impurities into selected areas of the first layer is effected by ion implantation, a diffusion process, or molecular beam epitaxy accompanied by ion beam doping.
Claim 10
Dependent Claim
16 words
A high electron mobility semiconductor device made by a method as claimed in any preceding claim.
Claim 11
Dependent Claim
19 words
A device as claimed in claim 10, being an integrated circuit including a plurality of high electron mobility transistors.
References Cited (Backward Citations)
No citation records indexed.
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