Varian Semiconductor Equipment Associates, Inc.

Varian Associates, Inc.

Charles E Van Wagoner

Matthew J Goeckner

Susan Benjamin Felch

Terry T Sheng

Charles B Cooper, Iii

In a plasma processing system, displacement current is removed from a current measurement by providing a secondary capacitor connected in parallel with a primary capacitor defined by an anode and a cathode spaced from one another within the plasma doping chamber. The secondary capacitor is chosen or adjusted to have a same or nearly the same capacitance as the primary capacitor. When a voltage pulse is applied to both the primary and secondary capacitors, the respective currents through the capacitors are measured. In order to remove the effects of the displacement current that is present at the leading and falling edges of the voltage pulse, and in order to measure the ion current within the doping chamber, the secondary current through the secondary capacitor is subtracted from the primary current through the primary capacitor.

Method and apparatus for eliminating displacement current from current measurements in a plasma processing system

A charge measuring system for determining implantation dose in a PI.sup.3 system with means to compensate for current in the charge sensor which does not arise from positive ions arriving on the wafer.

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San Jose, CA, United States of America

Charles E Van Wagoner