Automation of an electron cyclotron resonance plasma system for the manufacturing of inhomogeneous optical coatings for sensor applications

The control system for an electron cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD) reactor was developed for the growth of inhomogeneous dielectric filters for optical applications. The system is intended to supervise the growth of films of a required refractive index profile on different substrates including fibre ends. It controls the gas flow rates, microwave power, RF substrate bias and the ECR and extraction magnet power supplies. All controlled parameters are displayed in real time as graphs and tables. The system also tunes the microwave generator to minimize reflected power during deposition. This is required because the varying gas flow rates and gas composition change the plasma conditions. The control system consisting of software and hardware, is implemented on an ECR-PECVD system that was designed and built in our laboratory. The characteristics of the ECR-PECVD-system and the automation of the deposition process is discussed using the growth of a complex rugate optical filter as an example.