Residual stress and texture in poly-SiC films grown by low-pressure organometallic chemical-vapor deposition

We present a study of the stress state of polycrystalline 3C-SiC thin films grown on a-SiO2/Si(100) substrates by low-pressure chemical-vapor depositi on using an organometallic precursor, tetramethylsilane (TMS), that contain s both Si and C atoms. Substrate curvature and x-ray stress measurements in dicate a change from compressive to tensile stress with increasing depositi on temperature. Film thickness and TMS flow also influence the total stress of the films. The different microstructure of the films with growth temper ature and the presence of impurities are at the origin of the observed diff erences in the stress. While samples grown below 1100 degrees C have a colu mnar structure, are highly oriented along [111], and show compressive stres s, those grown at 1130 degrees C are randomly oriented, with an equiaxial g rain shape, and are tensile stressed. The thermal stress is tensile and rel atively constant over the temperature range investigated. We speculate the observed intrinsic stress is composed of a tensile and a compressive compon ent. Within the grain-boundary relaxation model we calculate the intrinsic stress variations with temperature due to differences in grain size and den sity of grain boundaries. The compressive component originates from the pre sence of oxygen impurities within the film. Peak broadening analysis of the x-ray signal reveals the existence of important microstresses due to low a datom mobility during the deposition process. (C) 2000 American Institute o f Physics. [S0021-8979(00)07704-5].