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Fast sample height, AOI and POI alignment in mapping ellipsometer or the like

  • US 7,872,751 B2
  • Filed: 11/25/2008
  • Issued: 01/18/2011
  • Est. Priority Date: 03/21/2000
  • Status: Expired due to Term
First Claim
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1. A method of aligning a sample in an ellipsometer system, which ellipsometer system comprises:

  • a source of a beam of electromagnetic radiation;

    a polarizer;

    a stage for supporting a sample;

    an analyzer;

    a data detector;

    means for adjusting the relative “

    height”

    positioning between said stage for supporting a sample and, as a unit, said source of a beam of electromagnetic radiation and data detector;

    as well as means for translating relative positioning of said sample with respect to said source of an ellipsometer beam of electromagnetic radiation and said data detector, along two orthogonal axes, and optionally means for adjusting the relative orientation of the ellipsometer systems with respect to said sample to set the angle and plane of incidence of said ellipsometer beam with respect to a surface of said sample;

    said ellipsometer system optionally comprising at least one compensator and/or focusing means between said source of a beam of electromagnetic radiation and said data detector;

    such that in use a beam of electromagnetic radiation from said source thereof approaches said sample at an oblique angle-of-incidence and reflects therefrom into said data detector;

    said method comprising the steps of;

    a) functionally mounting a sample alignment system to said ellipsometer system, which sample alignment system comprises;

    an alignment source of an alignment beam of electromagnetic radiation;

    a first alignment beam focusing means for focusing an alignment beam of electromagnetic radiation provided from said source thereof onto a sample on said ellipsometer system stage for supporting a sample;

    a second alignment focusing means for focusing alignment beam electromagnetic radiation which reflects from said sample onto a two dimensional detector array; and

    said two dimensional detector array;

    such that in use an alignment beam of electromagnetic radiation from said source thereof is focused onto said sample at an oblique angle-of-incidence and reflects therefrom and is focused onto said two dimensional detector array;

    said sample alignment system optionally further comprising;

    between said second alignment focusing means and said two dimensional detector array a beam splitter which diverts a portion of the alignment beam electromagnetic radiation which reflects from said sample to a secondary two dimensional detector array, and said secondary two dimensional detector array;

    said ellipsometer and alignment system being mounted with respect to one another such that the ellipsometer beam of electromagnetic radiation and said alignment beam of electromagnetic radiation impinge on said sample at substantially the same location;

    said method further comprising;

    prior to step e, performing steps b and c at least once, in which steps b and c are;

    b) while monitoring output intensity from said data detector causing a beam of electromagnetic radiation from said source thereof to approach said sample at an oblique angle-of-incidence and reflect therefrom into said data detector, adjusting the means for adjusting the relative “

    height”

    positioning between said stage for supporting a sample, and, as a unit, said source of a beam of electromagnetic radiation and data detector, until output from said data detector is of a desirable intensity; and

    c) causing the source of an alignment beam of electromagnetic radiation from said source thereof to approach said sample at an oblique angle-of-incidence and reflect therefrom onto said two dimensional detector array and identifying the location on said two dimensional detector array as an aligned position;

    said method further comprising performing steps d, e and f a plurality of times, wherein steps d, e and f are;

    d) using said means for translating relative positioning of said sample with respect to, as a unit, said source of an ellipsometer beam of electromagnetic radiation and said data detector, along two orthogonal axes, causing relative translation of said sample along at least one of said orthogonal axes so that a new spot on said sample is investigated by said ellipsometer beam, and such that the location at which the alignment beam reflected from said sample surface in step c appears on the two dimensional detector array, possibly at a different location than said aligned position;

    e) if necessary, adjusting the means for adjusting the relative “

    height”

    positioning between said stage for supporting a sample and, as a unit, said source of a beam of electromagnetic radiation and data detector, until said alignment beam reflected from said sample surface in step c appears on the two dimensional detector array at said aligned position;

    f) with the above adjustment set, acquiring ellipsometric data from said data detector.

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