Patent ID: 6156164
Filing Date: 2000-12-05
Classification: C23C

Abstract:
A method of physical vapor deposition onto areas of gallium arsenide wafers comprising the steps of:providing a PVD apparatus having a vacuum processing chamber therein equipped with a DC magnetron sputtering cathode, the apparatus being configured to perform physical vapor deposition on a substrate in the chamber with process gas maintained therein at a vacuum processing pressure level upon the application of power at a sputtering power level to the sputtering cathode;placing a gallium arsenide wafer on a substrate holder in the chamber and sealing the chamber from outside atmosphere;injecting a burst of ignition gas species into the chamber and producing therewith an ignition vacuum pressure level in the chamber that is higher than the vacuum processing pressure level;igniting a plasma in the ignition gas species at the ignition gas pressure level in the chamber by applying electrical power thereto without applying power at the sputtering power level to the cathode; thenreducing the pressure in the chamber to the vacuum processing pressure level while maintaining process gas in the chamber and sustaining the plasma in the process gas; thenapplying power at the sputtering power level to the sputtering cathode and sputtering material from the sputtering cathode and onto the wafer to form a film of the sputtered material on the wafer; andperforming at least one parameter controlling step selected from the group of parameter controlling steps consisting of:selecting an ignition gas species that is different from the species of the process gas and performing the ignition gas species injecting step and the plasma igniting step therewith then exhausting the ignition gas species from the chamber while reducing the pressure in the chamber to the vacuum processing pressure level and maintaining process gas in the chamber and sustaining the plasma in the process gas, before applying the power at the sputtering power level to the sputtering cathode and sputtering material from the sputtering cathode and onto the wafer to form the film of the sputtered material on the wafer,changing the DC magnetron of the PVD apparatus to increase magnetic field strength adjacent the sputtering cathode while performing the plasma igniting step then reducing said magnetic field strength when applying the power at the sputtering power level to the sputtering cathode and sputtering material from the sputtering cathode and onto the wafer to form the film of the sputtered material on the wafer,increasing the distance from the wafer to the sputtering cathode from a lesser distance when sputtering material from the sputtering cathode onto the wafer to a greater distance when igniting the plasma and then decreasing said distance to said lesser distance when sputtering material from the sputtering cathode onto the wafer to form the film of the sputtered material on the wafer, andlimiting the electrical potential of the wafer when igniting the plasma with a zener diode connected between the wafer and a system ground.