Simultaneous determination of the thermal expansion coefficient and the elastic modulus of Ta2O5 thin film using phase shifting interferometry

摘要

This paper reports on the application of a phase shifting interferometry technique for the concurrent measurement of the thermal expansion coefficient alpha(f) and the elastic modulus E-f/1 nu(f) of Ta2O5 thin film. The Ta2O5 films were prepared by ion beam sputter deposition. The stresses in the thin films were measured with the phase shifting interferometry technique using two types of circular discs with known thermal expansion coefficients, Young's moduli and Poisson's ratios. The temperature-dependent stress behaviour of Ta2O5 films was obtained by heating samples in the range from room temperature to 70 degrees C. The internal stresses of Ta2O5 thin films deposited on the BK-7 and Pyrex glass substrates were plotted against the stress measurement temperature, showing a linear dependence. From the slopes of the two lines in the stress versus temperature plot, the thermal expansion coefficient and the elastic modulus of Ta2O5 thin film are then calculated. [References: 36]