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Apparatus and methods for resistivity testing

  • US 4,703,252 A
  • Filed: 02/22/1985
  • Issued: 10/27/1987
  • Est. Priority Date: 02/22/1985
  • Status: Expired due to Term
First Claim
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1. In an automatic sheet resistance mapping system for semiconductor wafers having a capability of taking multiple test readings in both contour scan and diameter scan modes, in combination:

  • a rotatable wafer stage for carrying a semiconductor wafer thereon with a center of said wafer positioned substantially at an axis of rotation of said wafer stage;

    a probe head assembly including a linear array of at least four equally spaced probe tips projecting from one surface thereof;

    mounting means for mounting said probe head assembly with said one surface facing said wafer stage and for moving said array of probe tips alternately into and out of contact with the surface of a wafer carried on said wafer stage;

    first positioning means for rotating said wafer stage to accurately registered angular test positions; and

    second positioning means for producing translation between said wafer stage and said probe head assembly to position said array of probe tips at accurately registered radial test positions relative to the center of said wafer;

    said first and second positioning means being operable in said diameter scan mode to locate said probe tips at a multiplicity of successive closely spaced test positions along a diameter line of said wafer and being operative in said contour scan mode to locate said probe tips at a two-dimensional array of different test positions across an area of said wafer;

    said mounting means including means for mounting said probe head in a prearranged alignment position with said linear array of probe tips oriented at a prearranged small acute angle to said diameter line of said wafer as said second positioning means move said probe tips along said diameter line such that said probe tips each define a track of separated test probe footprints on said wafer in said diameter scan mode.

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