Method of making self-aligned field-effect transistor

Abstract

A self-aligned gate (SAG) transistor or FET is described which transistor overcomes several disadvantages of the prior art for making SAG field-effect transistors. The disadvantages noted above result from the fact that current SAG FET's have a symmetrical structure, with n+ regions on either side of the gate electrode. This invention provides a means of masking off a region on the drain side of the gate electrode before performing an n+ implant, so that the n+ implanted region is asymmetrical on the two sides of the gate electrode. This has the desired beneficial effect of reducing the parasitic source resistance, without the deleterious effects on gate-drain breakdown voltage, gate-drain capacitance, and output resistance that invariably accompany a high doping level on the drain side of the gate. Using this technique, substantially increased performance can be obtained from a self-aligned FET.