Abstract: A high selectivity etch-stop layer comprising oxynitride is disclosed for forming damascene structures in the manufacturing of semiconductor substrates. Because of its relatively high selectivity to oxides, the oxynitride etch-stop can be made thinner than the conventionally used nitride layer. Therefore, the disclosed oxynitride etch-stop layer makes it possible to avoid the cracking problems of thicker etch-stop layers as well as the associated problems of poor definition of contact or via holes in the damascene structure.

Abstract: A self-aligned structure and method of etching contact holes in the self-aligned structure are described. The dielectric materials, etching methods, and etchants are chosen to provide high selectivity etching. The structure comprises an electrode with a silicon oxy-nitride cap and silicon oxy-nitride spacers on the sidewalls of the electrode and the cap. An etch stop layer of silicon nitride is deposited over the substrate covering the spacers and cap. A layer of silicon oxide is deposited over the etch stop layer. Etching methods and etchants are used which provide a ratio of the etching rate of silicon oxide to the etching rate of silicon nitride or silicon oxy-nitride of at least eight and a ratio of the etching rate of silicon nitride to the etching rate of silicon oxy-nitride of at least two.