Patent ID: 7446351
Filing Date: 2008-11-04
Classification: H01L

Abstract:
1. A transistor structure comprising: a first undoped channel layer consisting of compositionally graded SiGe, the first channel layer being over a substrate; a buried channel consisting of germanium and, optionally, a dopant, the buried channel being over the first channel layer, the SiGe having a higher Ge content at an interface with the buried channel in comparison to all other portions of the first channel layer; a second undoped, silicon-comprising channel layer over the buried channel; a gate dielectric layer having a K greater than 3.9 on and in contact with the second channel layer, a distance from a gate dielectric layer/second channel layer interface to the germanium buried channel being from greater than 50 to about 100 Angstroms; a gate over the gate dielectric layer; and a source and a drain in electrical connection with the buried channel.