A Novel Step-Doping Fully-Depleted Silicon-on-Insulator Metal–Oxide–Semiconductor Field-Effect Transistor for Reliable Deep Sub-micron Devices

Abstract

For first time, we report a novel deep sub-micron fully-depleted silicon-on-insulator metal-oxide-semiconductor field-effect-transistor (FD SOI MOSFET) where the channel layer consists of two sections with a step doping (SD) region in order to increase performance and reliability of the device. This new structure that called SD FD SOI structure (SDFD-SOI MOSFET), were used for reaching suitable threshold voltage upon device scaling and reliability improvement. We demonstrate that the electric field was modified in the channel and common peak near the source junction have been reduced in the SDFD-SOI structure. The device demonstrates large enhancements in performance areas such as current drive capability, output resistance, hot-carrier reliability and threshold voltage roll-off. It was found that the device performance is very much dependent upon the SD region parameters. Simulation results show that the proposed structure improved on/off current ratio, and saturated output characteristics compared with conventional SOI structure (C-SOI MOSFET). Also, it was shown that substrate current of SDFD-SOI MOSFET is much lower than the C-SOI MOSFET which presented the lower hot-carrier degradation in proposed MOSFET. Results show that the most short-channel problems in very large scale integrated circuits (VLSI) could be solved and the proposed SDFD-SOI MOSFETs can work very well in deep sub-micron and nanoscale regime.

Minimization of leakage current through horizontal step doping in SOI MOSFETs

“…This figure 2.1 illustrates the minimum surface potential shifts downward with increases in horizontal high source side doping gradients in channel region. Channel Electric field: Fig.2.2 shows the electricfield of the proposed, uniform doping, HHSS &HHDSstructures along the lateral position atVG=0.2 V andVD=0.1 V. The electricfield enlargement near the source junction leads to its peakreduction near the drain region at afixed drain voltage [8,9]. So, when electricfield enhance near the source region, device carriers get accelerated which causes saturation velocity, carriers mobility and drain current growth.…”

“…On the other hand, hot carriers are generated near the drain region due to the electric field peak which accelerates them for injection into the gate oxide. So, because of theelectricfield peak value reduction near the drain region, the electron temperature, gate and substrate currents of the proposed structure get decreased [8,9]The built-in electric field improves the on current of device that accelerates the channel carriers and easestheir transportation. Electron velocity: Fig: 2.3 shows variation of Electron velocity along the channel length for different channel doping in uniform doping, Horizontal high source side doping (HHSS)&Horizontal high drain side doping(HHDS) .…”