SIMS study of rapid thermal nitridation of silicon dioxide thick films in ammonia ambient

Abstract Thick silicon dioxide layers (1.5 μm) have been nitrided in a lamp-heated furnace in an ammonia ambient. Temperatures of 700–1100°C were used for the nitridation for times of 5 to 300 s at atmospheric pressure. The distribution of the nitrogen in the nitrided samples was obtained using SIMS. The exponential shapes of the nitrogen profiles have been interpreted by a mechanism involving diffusion of the nitriding groups (NH 3 ) with a reaction with the network. We obtained the values of the effective diffusivity D ∗ = D NH 3 C 0 N i and of the reactivity k ∗ = k cn C 0 N i correlated by the length of exchange x 0 = ( D ∗ k ∗ ) 1 2 . It appears that the increase of k ∗ with the temperature is larger than the increase of D ∗ . This finding implies a shorter length of exchange at high temperature than at low temperature.