Patent ID: 7247218
Filing Date: 2007-07-24
Classification: H01J

Abstract:
1. A plasma reactor having an instrument for measuring at least one of: (a) etch rate, (b) plasma ion density, (c) wafer voltage, during processing of a semiconductor wafer on a workpiece support within a chamber of the plasma reactor containing a plasma, said reactor including an RF power generator coupled from an impedance match circuit through a transmission line to a conductive grid within the workpiece support, said impedance match circuit including sensing circuitry, said instrument comprising: an input phase processor connected to said sensing circuitry and configured to compute from outputs of said sensing circuitry an input impedance, an input current and an input voltage to said transmission line; a transmission line processor configured to compute a junction admittance of a junction between said transmission line and said conductive grid from said input impedance, input current and input voltage and from parameters of said transmission line; a grid-to-ground transformation unit configured to provide shunt electrical quantities of a shunt capacitance between said grid and a ground plane; a grid-to-wafer transformation unit configured to provide load electrical quantities of a load capacitance between said grid and said wafer; and a combined transformation processor configured to compute the at least one of said etch rate, plasma ion density and wafer voltage from all of the following: said junction admittance, said shunt electrical quantities, said load electrical quantities and a frequency of said RF power generator.