X-ray diffraction study of thermal stress relaxation in ZnO films deposited by magnetron sputtering
Résumé
X-ray diffraction stress analyses have been performed on two different thinfilms deposited onto siliconsubstrate: ZnO and ZnO encapsulated into Si3N4layers. We showed that both as-deposited ZnOfilms are in ahigh compressive stress state. In situ X-ray diffraction measurements inside a furnace revealed a relaxationof the as-grown stresses at temperatures which vary with the atmosphere in the furnace and change withSi3N4encapsulation. The observations show that Si3N4films lying on both sides of the ZnOfilm play animportant role in the mechanisms responsible for the stress relaxation during heat treatment. The differenttemperatures observed for relaxation in ambient and argon atmospheres suggest that the thermallyactivated stress relaxation may be attributed to a variation of the stoichiometry of the ZnOfilms. The presentobservations pave the way tofine tuning of the residual stresses through thermal treatment parameters