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Method and apparatus for in-situ monitoring of thickness during chemical-mechanical polishing

  • US 6,108,091 A
  • Filed: 05/28/1997
  • Issued: 08/22/2000
  • Est. Priority Date: 05/28/1997
  • Status: Expired due to Fees
First Claim
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1. In a chemical mechanical polishing device of the type comprising:

  • least two rollers, a belt comprising a layer of polishing material and mounted to extend between the rollers such that rotation of the rollers drives the belt, and a substrate carrier positioned adjacent the belt to press a substrate against the belt during a polishing operation;

    the improvement comprising;

    the belt having at least one opening formed therein, the opening positioned to move into intermittent alignment with the substrate during the polishing operation;

    the belt further comprising a monitoring window secured to the belt to close the opening and to create a monitoring channel in the belt, the window comprising a flexible material adapted to flex with the belt as the window moves around and between the rollers in use; and

    said device further comprising a film thickness monitor, said film thickness monitor comprising an ellipsometer responsive to optical radiation reflected from the substrate through the monitoring channel during the polishing operation to provide an indication of thickness of a film carried by the substrate.

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