Self-aligned metal process for integrated circuit metallization

Abstract

A method of forming on a substrate a pattern of structures having a thickness on the order of one micron or less. A first insulating layer is formed on a major surface of a substrate, for example, a silicon body. A polycrystalline silicon layer is formed thereover and openings are formed therein by reactive ion etching to provide substantially horizontal surfaces and substantially vertical sidewalls. The vertical sidewalls of the openings are formed at the desired locations of the narrow dimensioned structures. A second, conformal insulating layer is then formed followed by a reactive ion etching step which substantially removes the horizontal portions of the second insulating layer. The remaining polycrystalline silicon layer is removed to leave a pattern of self-supporting narrow dimensioned dielectric regions on the major surface of the substrate. The narrow dimensioned dielectric regions can be used as a mask to form narrow structures in the substrate. Alternatively, a self-aligned pattern of metallization can be formed using the narrow dimensioned dielectric regions to provide sub-micron metal-to-metal spacing.