Field effect transistor with mixed-crystal-orientation channel and source/drain regions

Abstract

Hybrid orientation substrates allow the fabrication of complementary metal oxide semiconductor (CMOS) circuits in which the n-type field effect transistors (nFETs) are disposed in a semiconductor orientation which is optimal for electron mobility and the p-type field effect transistors (pFETs) are disposed in a semiconductor orientation which is optimal for hole mobility. This invention discloses that the performance advantages of FETs formed entirely in the optimal semiconductor orientation may be achieved by only requiring that the device's channel be disposed in a semiconductor with the optimal orientation. A variety of new FET structures are described, all with the characteristic that at least some part of the FET's channel has a different orientation than at least some part of the FET's source and/or drain. Hybrid substrates into which these new FETs might be incorporated are described along with their methods of making.