In-situ nitride and oxynitride deposition process in the same chamber

Abstract

A method for insitu forming a SiN layer and an overlying Silicon oxynitride layer in one chamber. A substrate is loaded into a chamber. The substrate has thereover a polysilicon layer and a overlying metal layer. In a first in-situ step, a nitride layer is deposited using a LPCVD process over the substrate. The nitride layer is preferably formed at a temperature between 650 and 800.degree. C. and flowing SiH.sub.2 Cl.sub.2 and NH.sub.3. In a second in-situ step, an oxynitride layer is deposited over the nitride layer. The oxynitride layer acts as a bottom anti-reflective coating (BARC). The oxynitride (SiON) layer can be formed by a LPCVD process. Second, the LPCVD oxynitride can be formed a temperature between 600 and 800.degree. C. with a SiH.sub.4 flow and a N.sub.2 O flow. The substrate is removed from the chamber. A photoresist layer is formed over the oxynitride layer. The photoresist layer is exposed using the oxynitride layer as a bottom anti-reflective coating (BARC). The photoresist layer is developed. The oxynitride layer, the nitride layer, the metal layer and the polysilicon layer are etched to form a gate structure. The gate structure has sidewalls. Spacers are formed on the sidewalls of the gate structure. An ILD layer is formed over the gate structure. A contact hole is etched through the ILD layer using the gate structures and spacers as a mask to expose the substrate to form a self aligned contact (SAC) opening.