Method and apparatus for preparing and metallizing high aspect ratio silicon semiconductor device contacts to reduce the resistivity thereof

A CVD apparatus is equipped with a cleaning gas source, selectively connectable to a gas inlet of the chamber of the apparatus, structure, to supply a gas mixture of hydrogen and argon in which the hydrogen content is between 20 percent and 80 percent by volume. A selectively operable 450 MHz MF energy source is coupled to the chamber to energize a plasma in gas. A selectively operable 13.56 MHz HF energy source, controllable independently of the MF energy source and connected between the wafer support and a chamber anode biases a wafer on the support to less than 100 volts, preferably 15 to 35 volts, negative. A heater heats the wafer to temperature about 550 DEG C. Preferably, a turbo molecular pump is used to pump the cleaning gas while maintaining a pressure of between 1 mTorr and 10 Torr and at a rate of from 3 to 12 sccm.