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 transistor integrated circuits. The method for forming integrated circuits with this structure includes forming openings in a first polycrystalline silicon layer overlying an insulator by reactive ion etching which results in the structure having substantially horizontal surfaces and substantially vertical surfaces. The openings are in those areas designated to be the gate regions of the field effect transistors. A second insulating layer is then formed on both the substantially horizontal surfaces and substantially vertical surfaces. Reactive ion etching of this second insulating layer substantially removes the horizontal layers and provides a narrow dimensioned dielectric pattern of regions on the major surface of the silicon body. The gate dielectric is formed hereat. A second polycrystalline silicon gate electrode is formed over the gate dielectric and between certain of said narrow dimensioned regions. The remaining first polycrystalline silicon layer is then removed by etching to leave the narrow dimensioned 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. A blanket layer of a plastic material is used to planarize the surface by reactive ion etching the plastic material and the conductive layer until the tops of the narrow dimensioned regions are reached. The plastic material is then removed leaving the structure of patterns of metal or polycrystalline silicon filling the regions between the pattern of dielectric material having a thickness dimension in the order of a micron or less. The source and drain electrodes are thusly formed.