Effects of Scaling on Analog FoMs of UTBB FD-SOI MOS Transistors: A Detailed Analysis

Abstract

In this article, the combined effect of BOX thickness (TBOX) and ground-plane (GP) doping (NGP) on channel carrier mobility and analog figures of merit (FoMs) is investigated. It is reported that the thin BOX along with higher NGP will limit the electron/hole mobility of ultrathin body and BOX fully depleted silicon-on-insulator (UTBB FD-SOI) MOS transistors. The physics responsible for this observation is discussed in detail. The contrasting behavior of different GPs, the effect of TBOX scaling, and gate-length scaling on device behavior is also analyzed. It is also shown that in advanced UTBB FD-SOI MOS transistors, a tradeoff exists between transistor intrinsic gain, cutoff frequency, and non-linearity. In nMOS transistors, the best intrinsic gain and cut-off frequency can be achieved with ultrathin BOX and n-type GP (or with no GP), whereas the best linearity can be achieved with ultrathin BOX and p-type GP implant.