Method for forming a high quality chemical oxide on a freshly cleaned silicon surface as a native oxide replacement

Abstract

A continuous and integrated cleaning/preparation process is described to condition a silicon surface for the formation of a high quality ultra thin gate oxide described. The process is conducted with the wafer surface immersed in an aqueous solution the composition of which is varied continuously according to the steps of the process. The process includes the initial removal of contaminants and particulates followed by the removal of a native oxide. Next the silicon surface is dressed in the present of both HF and ozone by removing a thin surface layer. Any interfacial contamination or surface structural defects which lay under the native oxide are thereby removed. Next a high quality chemical oxide is grown by the action of the ozone in the aqueous bath. The chemical oxide is found to be of higher purity and structural quality than native oxide and provides a superior passivation of the active surface prior to gate oxidation. The chemical oxide is incorporated into the final gate oxide and, because of it's high quality, results in improved device performance of the final gate oxide.