Determination of thermal expansion coefficient of thermal oxide

An accurate thermal expansion coefficient (a) of a thin film is important in the design of microelectronic devices and microsystems. In this research, we present the use of inicrobridge buckling deformation caused by residual stresses to determine the a of a thermal oxide (SiO2) film. The determination of a is supported through experimental means and the analysis by finite-element method (FEM) of the buckling profiles of a microbridge. Moreover, to obtain the a of a thermal SiO2 film accurately, a nanoindentation system and an optical microscope with a high-resolution gauge were used to determine the elastic modulus of the thermal SiO2 film and the a of the silicon substrate, respectively. By combining micro-electro-mechanical systems (MEMS) technologies and FEM with thermomechanical analysis, the a of the thermal SiO2 film was calculated. The measured a of the thermal SiO2 film at roorn temperature is 0.24 x 10(-6)/degrees C with a standard deviation of 0.02x 10(-6)/degrees C.