Stacked spacer structure and process

摘要

A stacked spacer structure and process adapted for a stacked layer on a semiconductor substrate is described. The stacked spacer structure is formed on the sidewalls of the stacked layer which comprising a conductive layer and a cap layer thereon. A dielectric layer made of a material with low dielectric constant lower than that of silicon nitride is formed on the semiconductor substrate. A first silicon nitride layer is then formed over the substrate. The first silicon nitride layer and dielectric layer are etched sequentially to form an inner spacer on the sidewalls of the stacked layer. A second silicon nitride layer is formed over the substrate, and etched to form an outer spacer on the sidewalls of the inner spacer. By forming the stacked spacer structure of the present invention embedded low dielectric material, the coupling capacitance produced therein will be greatly reduced.