Thin Solid Films, Vol.351, No.1-2, 27-31, 1999
TwinMag (TM) II: attempts to improve an excellent sputter tool
A new mid frequency powered double magnetron cathode with higher target utilization has been developed. The width of its single target has been expanded from 100 to 240 mm. This enables a higher stock of target material and allows more flexibility on the design of the magnet field to increase its utilization. Both targets are inclined to face each other in the chamber, thus forming a roof which enables a smaller mounting width, a better collection efficiency and improved film growth conditions. A simple modification of the magnetic field creates two race tracks (ToraMag(TM)) on the surface of the target resulting in wider erosion profiles. The material utilization is in a range within 45 and 50%. The stabilization of the reactive plasma discharge at the operation point offers excellent film properties (structure, density, optics) at high deposition rates. A simple new strategy to control the oxygen partial pressure has been developed based on a reliable gas sensor. This involves the use of a constant oxygen flow at a constant level, while the cathode power is adjusted to fix an operation point close to the 'metallic mode' of the plasma discharge.