Characteristics of polysilicon oxides combining N ₂O nitridation and CMP processes

This paper present a high-quality polysilicon oxide combining N ₂O nitridation and chemical mechanical polishing (CMP) processes. Experimental results indicate that polyoxide grown on the CMP sample exhibits a lower leakage current, higher dielectric breakdown field, higher electron barrier height, less electron trapping rate, higher charge-to-breakdown (Q _bd), and lower density of trapping charge than those of non-CMP samples. In addition, the CMP process enhances nitrogen incorporation at the interface by the N ₂O nitridation, ultimately improving the polyoxide quality. Moreover, the CMP process smooths the surface of polysilicon and this planar surface reduces the out-diffusion of the phosphorous during thermal oxidation.