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Substrate monitoring method and apparatus

  • US 6,824,813 B1
  • Filed: 04/06/2000
  • Issued: 11/30/2004
  • Est. Priority Date: 04/06/2000
  • Status: Expired due to Fees
First Claim
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1. A substrate processing apparatus comprising:

  • a process chamber capable of processing a substrate, the substrate having overlying and underlying materials;

    a radiation source outside the process chamber, the radiation source capable of providing non-polarized radiation that is at least partially reflected from the substrate in the chamber;

    an interferometric radiation detector to detect the reflected radiation and generate an interferometric signal; and

    a controller to (i) receive the interferometric signal, (ii) calculate a dynamic variance within a predefined time period of the interferometric signal by subtracting an intensity value at a minimum point from an intensity value at a maximum point, and (iii) determine a property of the overlying or underlying material on the substrate in the chamber based on the calculated dynamic variance of the interferometric signal.

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