Uv resist curing as an indirect means to increase sin corner selectivity

Abstract

A method of forming a self-aligned contact in the fabrication of an integrated circuit is described. Semiconductor device structures are formed on a semiconductor substrate wherein their top and side surfaces are covered by a silicon nitride layer. A diagonal width of the silicon nitride layer on the side surfaces is a critical dimension. A layer of silicon oxide is deposited over the device structures and contacting the substrate adjacent to at least one of the semiconductor device structures where the self-aligned contact is to be formed. The substrate is covered with a layer of photoresist which is patterned to provide an opening over the planned self-aligned contact. Thereafter, the photoresist is exposed to ultraviolet light whereby the photoresist layer is cured. The silicon oxide is etched away at a high temperature to provide an opening to the silicon substrate using the patterned and cured photoresist and the silicon nitride layer on the side surfaces as a mask wherein the high temperature provides high selectivity of the silicon nitride layer to the silicon oxide layer and wherein the critical dimension is maintained at a thickness sufficient to prevent a short between the semiconductor device structure and a conducting layer to be deposited within the opening. A conducting layer is deposited within the opening to complete the formation of the self-aligned contact.