Patent ID: 6201208
Filing Date: 2001-03-13
Classification: B23K,H01J,H01L

Abstract:
A method of plasma ion treatment of a substrate comprising:(a) enclosing the substrate in a plasma reactor with a plasma forming gas;(b) forming a plasma in the reactor by exciting the plasma forming gas; and(c) applying a periodic bias voltage to the substrate through a DC blocking capacitor, each cycle of which has a waveform comprised of a voltage pulse peak followed by a ramp down of voltage from a first level lower than the pulse peak to a second lower level, the period of the bias voltage waveform applied to the DC blocking capacitor and the ramp down of voltage in each cycle selected to compensate for and substantially cancel the effect of ion accumulation on the substrate so as to maintain a substantially constant DC self-bias voltage on the substrate between the voltage pulse peaks, the waveform of each cycle of the bias voltage appearing on the substrate comprising a narrow pulse of voltage during which electrons are attracted from the plasma to the substrate followed by a substantially constant DC bias voltage level resulting from a self-bias of the substrate.