Chapter 6 - Physics and Modeling of Submicron Insulated-Gate Field-Effect Transistors. I

Abstract

Publisher Summary This chapter discusses physics and modeling of submicron insulated-gate field-effect transistors. The concept of space-charge effects at the surface of a semiconductor has been well known for a considerable period of time. In the past several years, the integration density of silicon circuits has increased steadily and, when compared to the medium-scale integration of a decade ago, dramatically. A significant part of this steady increase lies in the reduction of channel lengths of the individual devices, and this reduction has been supported by several technological developments such as more accurate process control and fine-pattern lithography by optical, electron-beam, and ion-beam techniques. However, as the channel length is reduced, many effects, which heretofore were of second-order importance, become of primary importance and dominate device and circuit performance. The traditional approach to the modeling problem of semiconductor device operation is to divide the device into several areas for which several different, but linear, approximations hold. Then, the one-dimensional transport problem is solved consistently within these areas, such as with the gradual-channel approximation. Attempts to go beyond the gradual-channel approximation are driven by the need to treat more fully the short-channel effects, such as drain-voltage-induced shifts of threshold, general sensitivity to threshold shifts, and actual channel-mobility variations.