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US 5,241,197 AGranted
Transistor provided with strained germanium layer
AssigneeHitachi, Ltd.
InventorsEiichi Murakami, Kiyokazu Nakagawa, Takashi Ohshima, Hiroyuki Eto, Masanobu Miyao
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Abstract
A transistor having a high carrier mobility and suited for a high-speed operation can be formed by utilizing a fact that the carrier mobility in a strained germanium layer is large. A strain control layer is provided beneath the germanium layer to impose a compressive strain on the germanium layer, and the composition of the strain control layer in a predetermined range is used to generate the compressive strain surely.
Claims22
A semiconductor device comprising:
- a substrate;
- a first layer, having a crystalline structure;
- a charge carrier transport region, constituted by a crystalline germanium layer formed on said first layer;
- and
- a third layer formed on said germanium layer, wherein said first layer has a sufficiently large thickness, of at least 5000 .ANG., such that the first layer imposes a compressive strain on the germanium layer, so as to increase a valence-band discontinuity between said crystalline germanium layer and said third layer as compared to a valence-band discontinuity between a layer of crystalline germanium and a layer of material of the third layer in a case that no compressive strain is applied to the layer of crystalline germanium.
2 more elements
A semiconductor device, comprising:
- a substrate;
- a first layer, made of a Si.sub.1-x.sbsb.s Ge.sub.x.sbsb.s alloyed crystal (where 0<x.sub.x <1), formed on said substrate;
- a second layer, made of germanium, formed on said first layer;
- and
- a third layer, made of a Si.sub.1-x Ge.sub.x alloyed crystal (where 0<x<1), formed on said second layer;
- wherein said first layer has a sufficiently large thickness, of at least 5000 .ANG., so as to impose a compressive strain on said second layer, such that a valence-band discontinuity between said strain-imposed second layer and the third layer is increased, as compared to a valence-band discontinuity between a layer of material of the second layer and a layer of material of the third layer in a case that no compressive strain is applied to the layer of material of the second layer.
3 more elements
A field effect transistor, comprising:
- a substrate;
- a first layer, made of a Si.sub.1-x.sbsb.s Ge.sub.x.sbsb.s alloyed crystal (where 0<x.sub.s <1), formed on said substrate;
- a second layer, made of germanium, formed on said first layer;
- and
- a third layer, made of a Si.sub.1-x Ge.sub.x alloyed crystal (where 0<x<1), formed on said second layer;
- a source region and a drain region, each of which is formed in said third layer and said second layer;
- a source electrode on said source region;
- a drain electrode on said drain region;
- a gate insulating film formed on a surface region of said third layer between said source region and said drain region;
- and
- a gate electrode on said gate insulating film;
- wherein said first layer has a sufficiently large thickness, of at least 5000 .ANG., so as to impose a compressive strain on said second layer, such that a valence-band discontinuity between said strain-imposed second layer and the third layer is increased, as compared to a valence-band discontinuity between a layer of material of the second layer and a layer of material of the third layer in a case that no compressive strain is applied to the layer of material of the second layer.
9 more elements
A bipolar transistor comprising:
- a substrate;
- a collector layer, made of a Si.sub.1-x.sbsb.s Ge.sub.x.sbsb.s alloyed crystal (where 0<x.sub.s <1), formed on said substrate;
- a base layer, made of germanium, formed on said collector layer;
- an emitter layer, made of a Si.sub.1-x Ge.sub.x alloyed crystal (where 0<x<1), formed on said base layer;
- a collector electrode connected with said collector layer;
- a base electrode connected with said base layer;
- and
- an emitter electrode connected with said emitter layer;
- wherein said collector layer has a sufficiently large thickness, of at least 5000 .ANG., so as to impose a compressive strain on said base layer, such that a valenced-band discontinuity between said strain-imposed base layer and said emitter layer is increased, as compared to a valence-band discontinuity between a layer of material of the base layer and a layer of material of the emitter layer in a case that no compressive strain is applied to the layer of material of the base layer.
6 more elements
Dependencies are inferred from the claim text.