Method of making borderless contact having a sion buffer layer

Abstract

Borderless contacts are used in integrated circuits in order to conserve chip real estate. As part of the process for manufacturing borderless contacts, an etch-stopping layer of silicon nitride is first laid over the area that is to be contacted. Investigation has now shown that this can lead to damage to the silicon at the edges of the via. The present invention eliminates this damage by introducing a buffer layer between the silicon surface and said sidon nitride layer. Suitable materials for the buffer layer that have been found to be infective include silicon oxide and silicon oxynitride with the latter offering some ditional advantages over the former. Experimental data confirming the effectiveness of the buffer layer are provided, together with a process for its manufacture.

Dependencies are inferred from the claim text.