Phosphorus diffusion in silicon oxide and oxynitride gate dielectrics

Evidence is presented that silicon oxynitride gate dielectrics suppress pho sphorus diffusion, as compared to pure silicon dioxide dielectrics. Further more, the implantation of fluorine into the polycrystalline silicon gate en hances phosphorus diffusion. Both effects are similar to what has been obse rved with boron diffusion in silicon oxide and oxynitride. These results su ggest a general model for diffusion in oxynitrides, in which network-formin g cations (A = B, P, As, Si, Ge) diffuse substitutionally for Si as AO(x), and the role of nitrogen is to block diffusion by impeding the rearrangemen t of SiO4 tetrahedra. (C) 1999 The Electrochemical Society. S1099-0062(99)0 4-105-X. All rights reserved.