Mechanical stresses in silicon carbonitride films obtained by PECVD from hexamethyldisilazane

Silicon carbonitride films were obtained by PECVD method from hexamethyldisilazane at different deposition temperatures. Mechanical stresses in the films were studied by laser beam deflection method. It was found that the films deposited at low temperatures (below 400 °C) are in compressive internal stresses because of the volume expansion of the growing film. Meanwhile, the films deposited at high temperatures (above 400 °C) have tensile stresses due to volume contraction during deposition. In addition, the dependences of coefficient of thermal expansion and Young's modulus of the films on deposition temperature are obtained. The results are discussed in the light of known features of the deposition process and also chemical and phase composition of the films.