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Plasma density, energy and etch rate measurements at bias power input and real time feedback control of plasma source and bias power

  • US 20040226657A1
  • Filed: 05/16/2003
  • Published: 11/18/2004
  • Est. Priority Date: 05/16/2003
  • Status: Active Grant
First Claim
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1. An instrument for measuring at least one of:

  • (a) etch rate, (b) plasma ion density, (c) wafer voltage, in a plasma reactor 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 instrument comprising;

    an input phase processor connected to sense voltage, current and power at said impedance match network for computing, from said voltage, current and power, an input impedance, an input current and an input voltage to said transmission line;

    a transmission line processor for computing 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 for providing shunt electrical quantities of a shunt capacitance between said grid and a ground plane;

    a grid-to-wafer transformation unit for providing load electrical quantities of a load capacitance between said grid and said wafer; and

    a combined transformation processor for computing the at least one of said etch rate, plasma ion density and wafer voltage from said junction admittance, said shunt electrical quantities, said load electrical quantities and a frequency of said RF power generator.

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