EFFECT OF SUBSTRATE POTENTIAL ON PLASMA PARAMETERS OF MAGNETIC MULTICUSP PLASMA SOURCE

The effect of substrate potential on plasmas produced in a magnetic mu lticusp plasma source has been studied experimentally. Plasma paramete rs such as electron temperature and plasma potential are estimated fro m electron energy distribution function numerically calculated from pr obe current-voltage characteristics. For a substrate potential of -150 V with respect to the source chamber, which is much lower than substr ate Heating potentials, the plasma parameters are not affected by the application of the potential. However, for the case where the substrat e is shorted with the source chamber, the high energy component of ele ctrons significantly decreases in comparison with the floating case le ading to the reduction of electron temperature. In this case, plasma p otential is positive with respect to the substrate to suppress electro n loss but its absolute value is only of the order of electron tempera ture in eV, which is much lower than the potential between the plasma and the substrate in the floating case. This discharge mode could be a dvantageous in significantly reducing the ion impact energy to the sub strate plate.