Method of forming a semiconductor device having self-aligned contact

Abstract

At the surface of a semiconductor substrate a conductor film over a silicon comprising insulating film, and the first aluminium oxide film are formed. These films are patterned to form a plurality of lines and an aluminium oxide film mask covering the top faces of the lines. Over the whole surface, the second aluminium oxide film is formed and etched back to form aluminium oxide film spacers covering the side faces of the lines. Over the whole surface a silicon oxide comprising dielectric film is formed. Anisotropic dry etching of the dielectric film and the insulating film is performed with fluorocarbon comprising gas to form self-aligned contact holes extending down to the surface of diffused layers formed at the surface of the semiconductor substrate. The self-aligned contact holes can be formed to be self-aligned with two adjacent lines because silicon-comprising dielectric films have a high etching selectivity to anisotropic dry etching with fluorocarbon-comprising gas, compared with aluminium oxide film. Isolation between the self-aligned contact hole and the interconnect is made only by aluminium oxide film spacers, resulting in suitably minimized area of the self-aligned contact holes. Besides isolation between the lines and the interconnects filling the self-aligned contact holes, and between two interconnects each filling the neighboring self-aligned contact holes, respectively, can be well secured.