Monitored vacuum deposition of dielectric coatings over surface acoustic wave devices

• We describe in-situ monitoring of SAW device electrical response during deposition.
• This method is a valuable technological addition for achieving higher yield.
• It helps to study thin film electrical, mechanical and acoustical properties.
• It is an important tool for verification of physical models.
• Results can help in understanding properties and in designing SAW devices.

We report on our experience in the control of magnetron sputtering process by in-situ monitoring of a surface acoustic wave (SAW) device (resonator or delay line) electrical response during the deposition of dielectric layers on the SAW device surface. While the electrical response changes with the growth of different layers, the response monitoring provides a useful feedback for layer thickness control in a multiple layer system. The monitoring approach is reproducible and gives physical insight into the SAW propagation changes occurring during the fabrication. It serves as a good tool for obtaining acoustic wave dispersion curves and helps in verifying theoretical and design principles of building multiple layer microwave acoustics devices.