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Noncontact conductivity measuring instrument

  • US 7,309,995 B2
  • Filed: 11/05/2004
  • Issued: 12/18/2007
  • Est. Priority Date: 11/10/2003
  • Status: Expired due to Fees
First Claim
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1. A measuring instrument for noncontact measurement of conductivity of a silicon wafer using a microwave, the measuring instrument comprising:

  • an oscillator operating at a frequency not more than 100 GHz for oscillating the microwave;

    a circulator connected to the oscillator;

    a horn antenna connected to the circulator, the horn antenna transmitting the microwave to an upper surface of the silicon wafer and receiving a reflected wave from the upper surface of the silicon wafer;

    a detector connected to said circulator, the detector outputting a voltage proportional to a square of magnitude of the wave from the upper surface of said silicon wafer; and

    a computer for computing conductivity of said silicon wafer from said voltage.

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