Robert John Stephenson

Comparative Study of Uniform Versus Supersteep Retrograde MOSFET Channel Doping and Implications for 6-T SRAM Yield

The benefit of supersteep retrograde (SSR) channel doping for suppressing short-channel effects in planar bulk MOSFET performance is studied via technology computer-aided design simulation of devices with gate length Lg = 28 nm. It is found that drain-induced barrier lowering is reduced by more than 40%, and variation in saturation threshold voltage (σ VT,Sat), caused by random dopant fluctuation, is reduced by ~50%, with SSR channel doping. However, degraded drive current is observed for SSR channel doping due to enhanced body effect. Estimations of six-transistor static random access memory (SRAM) cell yield indicate that 33% reduction in the minimum operating voltage (VMIN,SRAM) can be achieved with SSR channel doping.

Extension of Planar Bulk n-Channel MOSFET Scaling With Oxygen Insertion Technology

An experimental and simulation study of short-channel planar bulk nMOSFET performance enhancement achieved with oxygen insertion technology is presented. The benefits of this technology for low-power digital logic circuits make it a promising evolutionary approach to extend bulk MOSFET scaling.

Electron mobility enhancement in (100) oxygen-inserted silicon channel

High performance improvement (+88% in peak Gm and >30% in linear and saturation region drain currents) was observed for N-MOSFETs with Oxygen-Inserted (OI) Si channel. From TCAD analysis of the C-V measurement data, the improvement was confirmed to be due to electron mobility enhancement of the OI Si channel (+75% at Ninv = 4.0 × 1012 cm−2 and +25% at Ninv = 8.0 × 1012 cm−2). Raman and high-resolution Rutherford backscattering measurements confirmed that negligible strain is induced in the OI Si layer, and hence, it cannot be used to explain the origin of mobility improvement. Poisson-Schrodinger based quantum mechanical simulation was performed, taking into account phonon, surface roughness and Coulomb scatterings. The OI layer was modeled as a “quasi barrier” region with reference to the Si conduction band edge to confine inversion electrons. Simulation explains the measured electron mobility enhancement as the confinement effect of inversion electrons while the formation of an super-steep retrograde we...

Oxygen-inserted SegFET: A candidate for 10-nm node system-on-chip applications

An oxygen-inserted quasi-planar segmented channel MOSFET design is proposed and studied for monolithic system-on-chip applications. Projections indicate that it will provide for higher performance than bulk FinFET technology at the 10 nm node, due to higher field-effect carrier mobility, lower source/drain series resistance, and the benefit of super-steep retrograde well punchthrough-stopper doping.