THE USE OF OPTICAL-EMISSION SPECTROSCOPY FOR PROCESS-CONTROL IN TRIODE ION PLATING WITH ZRN

In ion plating one effective way to enhance ionization is to use a negatively biased hot filament. The use of an electron emitting filament brings an extra variable to be taken into account in process control. However, in practice the most influential factor to be controlled is the evaporation rate. Simultaneous monitoring of the evaporation rate and a closed loop control of the evaporation source should therefore be the preferred method. There exist a great variety of different methods available for process control. These include mass spectroscopy (MS), absorption spectroscopy (AS) and optical emission spectroscopy (OES). The only way to control the coating process without disturbing the glow discharge is to use emission spectroscopy.