Elastic stiffness and thermal expansion coefficients of various refractory silicides and silicon nitride films

Abstract

The elestic stiffness parameter Ef/(1−νf) and the thermal expansion coefficient αf were obtained for four different silicides (TiSi2, TaSi2, MoSi2 and WSi2) and for two different nitrides (chemically vapor-deposited Nitrox Si3N4 and r.f. plasma SiN) from stress-temperature measurements on identical films deposited on two different substrate materials. The values determined for αf and Ef/(1−νf) were quite similar for all silicides and averaged 15 ppm °C−1 and 1.1 × 1012 dyncm−2 respectively. The thermal mismatch of these silicides is such that, once safely formed, the silicide film should be able to withstand high temperature processing steps without cracking. For the nitrides the α values were essentially the same (approximately 1.5 ppm°C-1), although the larger value of Ef/(1−νf) chemically vapor-deposited Si3N4 film (3.7 × 1012 as opposed to 1.1 × 1012 dyn cm-2) indicates that it is somewhat stiffer than the SiN film. © 1980, All rights reserved.