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.