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Method and reference standards for measuring overlay in multilayer structures, and for calibrating imaging equipment as used in semiconductor manufacturing

  • US 5,617,340 A
  • Filed: 02/03/1995
  • Issued: 04/01/1997
  • Est. Priority Date: 04/28/1994
  • Status: Expired due to Fees
First Claim
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1. A method for calibrating an imaging instrument with respect to measurements of distance between features of a structure formed in a sequence of steps on a substrate, measurements made by said imaging instrument being susceptible to one or both of tool-induced shift (TIS) and wafer-induced shift (WIS), comprising the steps of:

  • forming a structure comprising components formed in a sequence of steps on a substrate, said components of said structure each comprising first artifacts the spacing of which is measurable using said imaging instrument, and also comprising second artifacts the spacing of which is analyzable using electrical measurement techniques not susceptible to TIS or WIS, said first and second artifacts being in defined physical relation to one another;

    measuring the spacing of said first artifacts employing said imaging instrument;

    analyzing the spacing of said second artifacts employing said electrical measurement technique; and

    calibrating said imaging instrument responsive to comparison of said measurements and analyses.

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