Asymmetric bipolar pulsed power: a new power technology

There is increasing commercial interest in processes involving reactive PVD deposition of insulating films, including deposition of wear resistant coatings; insulating films for microcircuits (including devices such as thin films heads) or electronic devices such as capacitors; sophisticated architectural glass coatings; coatings on polyester him for architectural glass laminates or oxygen barriers for food packaging; heat reflecting coatings for high efficiency lamps or induction furnace heat shields; deposition of barrier and functional layers for flat panel displays, including the ITO glass used in LCD displays; and myriad other similar functional and decorative applications. Reactive sputtering using single cathodes and pulsed de power has been used, and satisfactory results obtained. An intrinsic problem with single targets, however, is related to the coating of the anode with the deposited insulator, a problem solved by using dual sources. Dual target systems can use sinusoidal power, but increased flexibility is obtained using pulsed power and multiple cathodes. This article describes the power supply technology required for pulsed multiple cathode sputtering, and describes a new pulsed power supply which has been developed for dual cathode sputtering. (C) 1998 Elsevier Science S.A.