发明名称 |
CMOS integrated circuit devices and substrates having buried silicon germanium layers therein and methods of forming same |
摘要 |
CMOS integrated circuit devices include an electrically insulating layer and an unstrained silicon active layer on the electrically insulating layer. An insulated gate electrode is also provided on a surface of the unstrained silicon active layer. A Si<SUB>1-x</SUB>Ge<SUB>x </SUB>layer is also disposed between the electrically insulating layer and the unstrained silicon active layer. The Si<SUB>1-x</SUB>Ge<SUB>x </SUB>layer forms a first junction with the unstrained silicon active layer and has a graded concentration of Ge therein that decreases monotonically in a first direction extending from a peak level towards the surface of the unstrained silicon active layer. The peak Ge concentration level is greater than x=0.15 and the concentration of Ge in the Si<SUB>1-x</SUB>Ge<SUB>x </SUB>layer varies from the peak level to a level less than about x=0.1 at the first junction. The concentration of Ge at the first junction may be abrupt. More preferably, the concentration of Ge in the Si<SUB>1-x</SUB>Ge<SUB>x </SUB>layer varies from the peak level where 0.2<x<0.4 to a level where x=0 at the first junction. The Si<SUB>1-x</SUB>Ge<SUB>x </SUB>layer also has a retrograded arsenic doping profile therein relative to the surface. This retrograded profile may result in the Si<SUB>1-x</SUB>Ge<SUB>x </SUB>layer having a greater concentration of first conductivity type dopants therein relative to the concentration of first conductivity type dopants in a channel region within the unstrained silicon active layer. The total amount of dopants in the channel region and underlying Si<SUB>1-x</SUB>Ge<SUB>x </SUB>layer can also be carefully controlled to achieve a desired threshold voltage.
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申请公布号 |
US6914301(B2) |
申请公布日期 |
2005.07.05 |
申请号 |
US20030685116 |
申请日期 |
2003.10.14 |
申请人 |
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发明人 |
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分类号 |
H01L21/336;H01L21/337;H01L21/762;H01L27/12;H01L29/10;H01L29/786;H01L29/80;(IPC1-7):H01L27/01 |
主分类号 |
H01L21/336 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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