Etch stop layer for use in a self-aligned contact etch

摘要

A self-aligned contact, and a method for fabricating the same, are provided. A conductive element having an overlying hydrogen silsesquioxane (HSQ)-based dielectric cap is formed over a semiconductor substrate. Dielectric sidewall spacers are then formed adjacent to sidewalls of the conductive element and the HSQ-based dielectric cap. A HSQ-based dielectric layer is formed over the resulting structure, and an inter-layer dielectric layer, such as TEOS, is formed over the HSQ-based dielectric layer. The inter-layer dielectric layer is then etched through a mask having an opening located over a sidewall spacer, a portion of the HSQ-based dielectric cap and a portion of the substrate. The etch (which may be a C₅F₈ based etch) has a high selectivity (e.g., about 20:1) with respect to the HSQ-based dielectric layer, thereby enabling the etch to stop on the HSQ-based dielectric layer. Another etch removes the exposed HSQ-based dielectric layer to expose the substrate.