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Process for etching a transparent workpiece including backside endpoint detection steps

  • US 20080099432A1
  • Filed: 10/30/2006
  • Published: 05/01/2008
  • Est. Priority Date: 10/30/2006
  • Status: Active Grant
First Claim
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1. A method of defining a pattern on a mask comprising a transparent substrate having top and bottom surfaces, comprising:

  • defining a photoresist pattern on said top surface of said mask, said pattern including a periodic structure having a periodic spacing between elements of the structure;

    placing said mask on a support pedestal in a plasma reactor chamber and generating a plasma in said chamber to etch said top surface of said mask through openings in said photoresist pattern;

    transmitting light through said pedestal and through said bottom surface of said mask;

    viewing through said support pedestal light reflected from said periodic structure and detecting an interference pattern in said reflected light; and

    determining from said interference pattern a depth to which periodic structure has been etched in said top surface.

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