Self-aligned metal process for field effect transistor integrated

Abstract

A process is described which achieves self-aligned metal to silicon contacts and submicron contact-to-contact and metal-to-metal spacing for field effect transistors. The insulation between the contacts and the metal is dielectric material having a thickness dimension about a micron or less. The structure is substantially planar. The method for forming this structure involves providing a silicon body and then forming a first insulating layer on the silicon body. A layer of polycrystalline silicon is formed thereover. Openings are made in the layer by reactive ion etching which results in the structure having horizontal surfaces and vertical surfaces. The openings can be in either the areas designated to be the gate regions or a PN junction region of the field effect transistors in the integrated circuit. A second insulating layer is then formed on both the horizontal surfaces and vertical surfaces. Reactive ion etching of this second insulating layer moves the horizontal layers and provides a narrow dimensioned dielectric pattern of regions on the major surface of the silicon body. The gate dielectric is either formed hereat or PN junctions are fabricated by diffusion or ion implantation. The remaining polycrystalline layer is removed to leave the narrow regions on the major surface of the silicon body. A conductive layer is blanket deposited over the narrow dimensioned regions and areas in between to make contact to source/drain PN regions and form the gate electrodes.