Use of process and 2-D MOS simulation in the study of doping profile influence on S/D resistance in short channel MOSFET's

Abstract

At small V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</inf> , g <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</inf> reduction in MOSFET's is often attributed to mobility degradation due to increased vertical electric field with increasing V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</inf> . This is correct for long channel devices; however, for short channel devices the parasitic series resistance of source/drain, R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> , has a similar effect in reducing the g <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</inf> value. In this paper, simulation is used to show how the lateral subdiffusion regions of S/D represent a dominant, V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</inf> -dependent portion of the total resistance, since the doping profile there is steeply decreasing and the carrier concentration can be modulated by the gate voltage.