The objective of this research is to study the effect of sputter pressure on thin zinc oxide film deposited by RF magnetron sputtering technique on Si and glass substrates using ZnO disk with 99.99% purity. In order to avoid the effect of the thickness of the layers on the physical properties, we worked on samples of comparable thickness, from 0.8 to 1.1 μm. The deposition is done with heating the substrate at very low temperature, which is currently the most favorable conditions for integration into a MEMS process. X-ray diffraction spectra showed that ZnO thin films are hexagonal wurtzite and exhibited a c-axis orientation of below 0.32° full width at half maximum of X-ray rocking curves. The preferential orientation is along the (002) direction reported for all ZnO samples deposited by sputtering RF magnetron. The general observation indicates that the parameters of the microstructure such as grain size, intrinsic stresses, dislocation density and the full width at half maxima (FWHM) dependent on the sputter pressure of the film. Sample deposited 3.35mTorr gives the best results. In addition, the transmission is more than 90% in the visible region. Ellipsometry data have been fitted with a Cauchy-Urbach model. From this fitting the refraction index (n), extinction coefficient (k) and thickness (d) of the sputtered ZnO films were determined. As a result of the combined spectroscopic ellipsometry, structural properties and transmission analysis, there was a good correlation in comparison. The network analyzer shows losses are -5dB at a k33 = 0.26 experimental.