Oxidation of CVD Si 3 N 4 at 1550° to 1650°C

A thermo gravimetric study of the oxidation behavior of chemically vapor‐deposited amorphous and crystalline Si 3 N 4 (CVD Si 3 N 4 ) was made in dry oxygen (0.1 MPa) at 1550° to 1650°C. The specimens were prepared under various deposition conditions using a mixture of SiCl 4 , NH 3 , and H 2 gases. The crystalline CVD Si 3 N 4 indicated a parabolic oxidation kinetics over the whole temperature range, whereas the amorphous CVD Si 3 N 4 changed from a parabolic to a linear law with increased temperature. The oxidation mechanism is discussed in terms of the activation energy for the oxidation and the microstructure of the formed oxide films.