High Power Processes: Power Delivery and Discharge Management

Magnetron sputtering persists as a dominant technique for deposition of intrinsic target material and reactive compounds on large areas, notably architectural and automotive glass, flexible webs and photovoltaics. These large area applications require effective delivery of high average power for economic industrial use. The power system must also monitor the deposition process, and in particular detect transitions from the desired glow discharge to the cathodic arc mode and respond to return to a glow discharge. Arc detection methods have evolved, and some have been developed especially to manage the characteristics of various equivalent output characteristics. Power supplies configured as current sources are well posed for stable delivery of high power with characteristics that work with the plasma to result in a stable discharge. When a process arc occurs, a current source enables very rapid arc detection, with inherent potential low arc energy. Consequently, stable processes are possible at lower frequencies due to faster arc handling, reduced arc energy and prompt restoration of process power. This may enable reduced energy consumption by operation at the minimum frequency consistent with assessed process stability. Power delivery and discharge management at high power will be discussed, including perspective on evolution of arc detection methodologies.