QUANTITATIVE KINETIC-ANALYSIS OF SILICON NITRIDATION

Kinetic analysis of silicon nitridation requires intrinsic single-particle behaviour to be isolated from global or compact effects that typically manifest during the reaction-bonding process. These effects arise from the influence of adjacent particles, which modify the macropore structure as the reaction proceeds. Much of the variation in the published kinetic data can be attributed to compact effects, particle shape, and size distribution, resulting in a myriad of models being reported, each only applicable to the nitridation conditions in which the data were obtained. Our work clearly demonstrates that the intrinsic single-particle nitridation behaviour is well described by a sharp-interface model, with diffusion control (E(a) = 301.5-31 0.0 kJ mol-1) through an expanding Si3N4 product layer developing on the individual grains. For the nitridation of silicon compacts, the reaction-bonding process can be divided into three fundamental stages- (1) initial devitrification/nucleation, (2) massive nitridation, and (3) termination by further sintering, densification, and coarsening of the Si3N4 product. Factors influencing and controlling each stage are summarized.