Thickness optimization of AlN thin films deposited by RF Magnetron Sputtering

Aluminium nitride (AlN) which has a wurtzite crystal structure is highly suitable material for applications in a wide range field of ultrasonic transducers, non-destructive testing and MEMS-Micro-Electro-Mechanical Systems because of AlN´s good piezoelectric properties. We are interested in investigation of the suitability of piezoelectric AlN for thin film based devices for MEMS applications. Since the good functionality of piezoelectric devices is highly dependent on the quality of the thin film, our first aim is to improve the quality of the deposited film and eventually to build an optimised deposition parameters by using design of experiments method (DoE). Thin films produced by RF Magnetron Sputtering were characterized to analyze its crystallographic structure by using X-ray diffraction, Scanning Electron Microscope (SEM), and Spectrophotometer. The structural and mechanical characterization results showed that AlN thin film has highly (002) c-axis orientation. The optical characterization supported the thickness of the films were in the range of micron. The optimization process pointed out that the input parameters did not have a significant effect on the output parameters.