Rohit Shenoy - Ph.D. Oral Examination - Friday Oct 1 2pm

Rohit S. Shenoy rohits at
Tue Sep 28 00:55:31 PDT 2004

Stanford University Ph.D. Oral Examination

"Technology and Scaling of Ultrathin Body Double-Gate FETs"

Rohit S. Shenoy
Department of Electrical Engineering
Stanford University

CIS-X Auditorium
Friday, Oct 1, 2004
2:00 pm - 3:00 pm
(Refreshments at 1:45 pm)


As silicon CMOS technology advances into the sub-50 nm regime, 
fundamental and manufacturing limits impede the traditional scaling 
of transistors. Innovations in materials and device structures will 
be needed for continued transistor miniaturization with commensurate 
performance improvements. The ultrathin body double-gate (DG) FET is 
a leading candidate for replacing bulk CMOS transistors in future 
technology generations. Multiple gates and the ultrathin body enable 
better electrostatic gate control over the channel, allowing DG FETs 
to be scaled to smaller dimensions than their conventional bulk 
counterparts. This research is focused on some of the major issues 
in the design and fabrication of high performance scaled DG FETs.

The first part of the talk deals with extrinsic factors that limit 
the overall performance of ultrathin body DG FETs. The impact of 
parasitic capacitance and resistance is studied and quantified by 
device simulation. In particular, the importance of optimizing the 
lateral doping profile in the thin source/drain extension regions to 
minimize series resistance is discussed in detail.

Next, a novel process is proposed to fabricate the ideal planar DG 
FET with the following attributes: 1) deposition controlled uniform 
ultrathin body, 2) fully self-aligned gates for low parasitic 
capacitance, and 3) flared-out low resistance source/drain regions. 
Experimental work on the unit process development verifies the 
feasibility of the key steps. As proof of concept, functional 
transistors with very good turn-off characteristics are demonstrated.


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