A secondary ion mass spectroscopic study was made of the redistribution of  in situ  doped or implanted N in polycrystalline material, and of N segregation at Si/SiO2 interfaces during heat treatment at 700 to 1000C. When N-doped samples were subjected to heat treatment at temperatures above 800C, the N diffused to the Si/SiO2 interface and surface and piled up there. Some of the N was immobile when the concentration was above a threshold value. This immobile N became mobile and diffused during annealing. The threshold concentration for N diffusion depended upon the grain size. There was a limit on how much N segregated to the interface. This limit did not depend upon the initial N content, but only upon the annealing temperature. A comparison of data for polycrystalline films, with data on bulk material, suggested that the redistribution of N in the former was limited by the transformation process via which immobile N became mobile.

Redistribution of in situ Doped or Ion-Implanted Nitrogen in Polysilicon. S.Nakayama, T.Sakai: Journal of Applied Physics, 1996, 79[8], 4024-8