Influence of deposition parameters in PACVD-SiO2 preparation on resulting film properties
Silicon oxide thin films are used in several products serving from optical to electrical function. For use in sensors, especially directly applied sensors on technical surfaces, e.g. sputter strain gauges, SiO2 is a common material as insulator. Besides CVD application at high temperature, plasma enhanced CVD (PECVD) offers the potential to deposit coatings with good insulating properties at low substrate temperatures and high deposition rates. For improved electrical insulation a PECVD process using TMS and oxygen was developed using a small industrial box coater. The working pressure, TMS:O2 gas mixture, also adding argon and the applied bias voltage were varied. The prepared samples were analyzed regarding chemical composition, deposition rate, and breakdown voltage. The insulating properties were characterized by using a specific tester in a soaked sodium chlorite solution, and for close to application test samples with additional metallization. The deposition rate could be increased up to 1.5 µm/h. The maximum breakdown voltage for the metallized samples was exceeding 1 kV for films of approximately 4 µm thickness.