Via sidewall sog nitridation for via filling

Abstract

A new method of forming the dielectric layer of an integrated circuit is described. A thick insulating layer is formed over semiconductor device structures in and on a semiconductor substrate. A first metal layer is deposited over the thick insulating layer. The first metal layer is etched using conventional photolithography and etching techniques to form the desired metal pattern on the surface of the thick insulating layer. The intermetal dielectric layer is formed by first covering the patterned first metal layer with a layer of silicon oxide. The silicon oxide layer is covered with a layer of spin-on-glass material which is baked and cured. A second layer of silicon oxide completes the intermetal dielectric layer. Via openings are formed through the intermetal dielectric layer to the underlying patterned first metal layer. A silicon nitride cap is formed on the exposed surfaces of the spin-on-glass layer within the via openings to prevent outgassing from the intermetal dielectric layer, and thus to prevent poisoned via metallurgy. A second metal layer is deposited overlying the intermetal dielectric layer and within the via openings and fabrication of the integrated circuit is completed.