Evaluation of silicon nitride and silicon carbide as efficient polysilicon grain-growth inhibitors

Abstract

A technique to improve the smoothness of the floating polysilicon layer of non-volatile memory devices is proposed. Via low-energy N2 + and Ar+ ion implantation onto exposed deposited-polysilicon film, SixNy and SiC are formed at the top surface of the film. These silicon impurities act as additional nucleating centers in the film, promoting growth of small surface grains in the event of a following high-temperature process step. Better planarity of the film is achieved and this implies the generation of a good interface with the subsequently deposited or thermally grown interpoly dielectric. Overall, the results are promising for the control of surface roughness by Low-Energy Ion Implantation.