Nitridation of High‐Purity Silicon

The kinetics and morphology of the growth of nitride on spec-trographically pure Si were investigated in the range 1250° to 1370°C for N2 pressures of 20 to 760 torr. A model is presented which explains all the observations. The initial linear kinetics are associated with the growth of individual nitride nuclei. As the nuclei coalesce, the reaction rate steadily decreases, finally falling effectively to zero when the Si is completely covered with nitride. The model indicates how the microstructure of reaction-sintered Si3N4 may be controlled.