Abstract
In this paper, we numerically explore electrical characteristics of a simple device called the π-shaped source/drain (π-S/D) MOS transistor. Some techniques such as Si/SiGe epitaxial growth and selective SiGe etch process are implemented for the fabrication of quasi-SOI devices with an S/D tie. More importantly, a new method presented here for fabricating π-S/D MOSFETs does not require any additional mask step due to self-alignment process being exploited. The isolation technique is carried out only after S/D annealing, resulting in only four extra process steps introduced in this new quasi-SOI technology. According to numerical simulations, the new π-S/D structure has better control on the short-channel and thermal effects compared with the conventional (conv.) π-S/D structure. Despite Miller capacitance sacrifice behaviour owing to the absence of the conv. isolation approach before gate definition, which causes an increase in the body area under the gate, NMOSFET intrinsic delay τ and cutoff frequency f T are within acceptable limits for this new structure.
Acknowledgments
This work was supported in part by the National Science Council of Taiwan, R.O.C., under Contact No. NSC98-2221-E-110-075. The authors would like to thank the National Center for High-performance Computing for computer time and facilities.