Phosphorus Diffusion in Silicon Oxide and Oxynitride Gate Dielectrics

Abstract

Evidence is presented that silicon oxynitride gate dielectrics suppress phosphorus diffusion, as compared to pure silicon dioxide dielectrics. Furthermore, the implantation of fluorine into the polycrystalline silicon gate enhances phosphorus diffusion. Both effects are similar to what has been observed with boron diffusion in silicon oxide and oxynitride. These results suggest a general model for diffusion in oxynitrides, in which network-forming cations (A = B, P, As, Si, Ge) diffuse substitutionally for Si as AOx, and the role of nitrogen is to block diffusion by impeding the rearrangement of SiO4 tetrahedra. © 1999 The Electrochemical Society. S1099-0062(99)04-105-X. All rights reserved.