Sputtering system using cylindrical rotating magnetron electrically powered using alternating current

A sputtering system for forming a dielectric layer on a substrate comprising:

• an alternating current power supply having a first and a second pole and adapted to produce a power signal with a frequency of less than a megahertz;
• a chamber;
• a transformer having two output terminals and two input terminals, the two input terminals connected between the first and second pole;
• a cylindrical tubular target of an electrically conductive material with associated magnet assembly located in said chamber electrically connected by a first electrical path to the first output terminal of the transformer;
• an electrically conductive member in the chamber electrically connected by a second electrical path to the second output terminal of the transformer;
• and
• an impedance-limiting capacitor connected in series in the electrical path between the target and the electrically conductive member through the transformer, the capacitance of the impedance-limiting capacitor being sufficiently large that the impedance-limiting capacitor prevents arcing in the system.

A method for depositing a dielectric layer on a substrate by reactive sputtering comprising the steps of:

• providing a cylindrical target of a conductive material in a chamber;
• applying an alternating current signal to the cylindrical target to produce a plasma, said signal having positive and negative portions;
• producing a magnetic field to produce an erosion zone about the cylindrical target such that ions strike the erosion zone when a negative portion of the signal is applied to the cylindrical target;
• providing in the chamber a gas which reacts with the target material to form a dielectric;
• depositing a dielectric layer on the substrate;
• cleaning portions of the target by rotating the cylindrical target so that portions of the cylindrical target away from the erosion zone defined by the magnetic field have deposited material removed by the bombarding ions of the erosion zone;
• and
• attracting electrons in the plasma to the cleaned portions away from the erosion zone when the positive portion of the signal is applied to the target.