The New Fence Mosfet Modeling And Simulation Research

The conventional planar MOSFETs are approaching their physical limits, due to the ever increasing small size effects caused by feature length scaling down. To better suppress the short channel effect (SCE), more and more novel device structures have been explored, such as Double/Surrounding-Gate MOSFET, FinFET, etc. These dual gate device can significantly enhance the capability of gate against channel region, improve the device characteristics, and ultimately enable integrate circuits go on scaling down according to Moore’s Law. However, with the decrease of device feature length, quantum effect will become more serious. In this paper, we talk about the device characteristics and application of quantum mechanical effects based on the surrounding gate device.This paper is consisted of three parts. First of all, we investigate the SG MOSFET with evenly doped silicon body. We firstly obtain the electric potential model by solving analytically a two-dimensional (2-D) Poisson equation (PE) in cylindrical coordinates. Then, based on the potential model, we present2-D models for the threshold voltage, the sub-threshold current and the sub-threshold swing. After that, we analyze the short-channel effects and sub-threshold characteristics of the device. The model accuracy is proved to be quite high by comparing model results with3D TCAD simulation. We have studied the device parameters and applied bias voltage on the device characteristics such as the electric potential, the threshold voltage and current, by both modeling and simulation.As the device goes into nanometer scale, space confinement and field confinement are becoming important, and quantum mechanical effects (QME) need to be explored. In the second part, we show how threshold voltage is influenced with QME with the considerations of (110)-silicon (Si) orientation and (100)-Si orientation. The analytical results of the undoped model are compared with those obtained. the threshold voltage shift will be significant with an extremely small silicon body radius.Eventually, the ellipse surrounding gate device characteristic is especially studied. The process deviation for the surrounding gate device usually results in a ellipse surrounding gate. To get a better understanding of its impact, we introduce our equivalent radius model for the ellipse gate device. The model is then compared to the surrounding gate model to analyses the fluctuation bought by radius variability.In this paper, the characteristics of new surrounding gate devices are systematically analyzed by modeling and simulation. As the radius gradually decreases, the transport mechanism will transverse to be quantized for surrounding gate devices; at the same time, ellipse surrounding gate device caused by process deviation is more sensitive to quantum effects. Surrounding gate devices have become a an irresistible trend of next generation IC. This paper has proposed a promising method in modeling and simulation for surrounding gate.