A plasma processing system for ULSI device manufacturing using energy clean technology is proposed that is capable of subtle control of ion impact energy under very low pressure and magnetron enhancement. Careful and extensive probe measurements were carried out to determine the effects of magnetic field, plasma excitation frequency, DC-biasing of plasma confining cylinder (shield), DC-biasing of electrodes and secondary RF excitation on spatial distribution of potential. It was found that the substrate DC potential can be effectively controlled by DC-biasing or RF-biasing using an external DC power source or a secondary RF excitation, respectively. As a consequence, the wafer-surface damage induced by the high energy ions can be minimized by directly controlling the potential difference between plasma and substrate. The study also found that DC-biasing of the shield is very effective in minimizing the chamber material contamination, i.e., the contamination levels of both iron and copper atoms measured by total reflection X-ray fluorescence spectroscopy.
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