Study of MOS-gated strained-Si Buried Channel Field Effect Transistors

Abstract

MOS-gated strained-Si modulation doped Field Effect Transistors (MOSMODFETs) traditionally suffer from parallel conduction causing degradation of the device performance below that of the Si control fabricated in the same batch. We present a MOSMODFET in which parallel conduction is avoided through the use of ultra-thin modulation doped layers and TMAH etching to remove the top Si parasitic layer. A low thermal budget and deposited oxides are used to conserve material integrity. This approach has lead to MOSMODFETs that show RF performance improvement over the Si control MOSFET and improved DC operation over a temperature range from 10K to 300K. The influence of the low temperature processing on the characteristics is an increase from 0.3 to 1.2 Ω mm of the contact resistance, and the deposited oxide increases the interface state density.

Indexing terms:

• Strained-Si
• SiGe virtual substrate
• Buried channel FET
• MOS-gating