Apparatus for obtaining planarity measurements with respect to a probe card analysis system

Abstract

A system and method of mitigating the effects of component deflections in a probe card analyzer system may implement three-dimensional comparative optical metrology techniques to model deflection characteristics. An exemplary system and method combine non-bussed electrical planarity measurements with fast optical planarity measurements to produce “effectively loaded” planarity measurements.

1 . A probe card analysis system, comprising:
 a probe card;   a probe card fixture supporting the probe card;   a fiducial plate; and   a stage providing relative movement of the probe card and fiducial plate; and   a data processing component executing instructions including:
 measuring a planarity of a probe card; 
 computing planarity effects due to fiducial plate deflection and probe card fixture deflection; and 
 calculating a load compensated planarity for said probe card by applying to the measured planarity of the probe card the computed planarity effects due to fiducial plate deflection. 
   
     
     
         2 . The system of  claim 1  wherein the instructions further comprise accounting for planarity effects due to stage deflection and wherein said calculating is further responsive to said accounting. 
     
     
         3 . The system of  claim 2 , wherein said accounting comprises utilizing a distance sensor proximate to said stage deflection. 
     
     
         4 . The system of  claim 1  wherein said computing comprises utilizing an optical metrology technique. 
     
     
         5 . The system of  claim 4  wherein said utilizing an optical metrology technique comprises:
 acquiring image data of a fiducial on said fiducial plate; 
 responsive to said acquiring, identifying deflection data values representative of a deflection of said fiducial plate; and 
 responsive to said identifying, providing correction data values enabling a first order correction of said deflection. 
 
     
     
         6 . The system of  claim 5  wherein said utilizing an optical metrology technique further comprises:
 further identifying rate data values representative of a rate of deflection of said fiducial plate; and 
 responsive to said further identifying, providing additional correction data values enabling a second order correction of said deflection. 
 
     
     
         7 . The system of  claim 1  wherein said combining comprises:
 obtaining measurements of optical planarity and electrical planarity for said probe card; 
 measuring fiducial plate deflection at first electrical contact; and 
 responsive to said obtaining and said measuring, computing a combined deflection value for said probe card and said probe card fixture. 
 
     
     
         8 . A probe card analysis system, comprising:
 a probe card;   a probe card fixture supporting the probe card;   a fiducial plate;   an optics assembly obtaining measurements of optical planarity;   a component obtaining measurements of electrical planarity for all non-bussed probes by providing relative movement of the probe card and the fiducial plate; and   a data processing component executing instructions comprising:
 identifying fiducial plate deflection at first electrical contact at all non-bussed probe locations; 
 calculating planarity effects due to fiducial plate deflection and, responsive to said obtaining and said identifying, calculating a load compensated planarity for said probe card by applying to the measured planarity of the probe card the planarity effects due to fiducial plate deflection. 
   
     
     
         9 . The system of  claim 8  wherein the instructions further comprise acquiring stage deflection measurements at proximal sensor locations and wherein calculating is further responsive to said acquiring. 
     
     
         10 . The system of  claim 9  wherein said stage deflection measurements are assumed to be zero. 
     
     
         11 . The system of  claim 8  wherein said identifying fiducial plate deflection comprises:
 selectively positioning an imaging apparatus to acquire optical data at a selected non-bussed probe location; 
 acquiring said optical data when a non-bussed probe makes contact with said fiducial plate at said selected non-bussed probe location; and 
 responsive to said acquiring, measuring said fiducial plate deflection at said selected non-bussed probe location. 
 
     
     
         12 . The system of  claim 11  wherein said identifying fiducial plate deflection further comprises selectively repeating said selectively positioning, said acquiring, and said measuring for a different selected non-bussed probe location. 
     
     
         13 . The system of  claim 8  wherein said identifying fiducial plate deflection comprises computing said fiducial plate deflection as a function of full overtravel plate deflection at a particular probe location and of optical planarity. 
     
     
         14 . The system of  claim 13  wherein said computing comprises utilizing a two dimensional interpolation calculation. 
     
     
         15 . A computer readable medium encoded with data and instructions for obtaining planarity measurements with respect to the tips of an array of probes on a probe card under inspection by an inspection apparatus, said data and said instructions causing said inspection apparatus executing said instructions to:
 inspect the tips of the array of probes to obtain a planarity measurement;   quantify a deflection of at least one of a fiducial plate, the probe card, and a probe card fixture;   compute an effect the at least one deflection quantity has on the planarity measurement of the tips of the array of probes; and   calculate a load compensated planarity by combining the planarity measurement of the tips of the array of probes with the computed effect of the at least one quantified deflection.   
     
     
         16 . The computer readable medium of  claim 15  further encoded with data and instructions causing the apparatus executing said instructions to quantify deflection of a stage to which the probe card is coupled and to compute the effect said deflection has on the planarity measurement of the tips of the array of probes. 
     
     
         17 . The computer readable medium of  claim 15  further encoded with data and instructions causing the apparatus executing said instructions to quantify deflection of the fiducial plate utilizing an optical metrology data processing technique. 
     
     
         18 . The computer readable medium of  claim 17  further encoded with data and instructions causing the apparatus executing said instructions to execute said optical metrology data processing technique by:
 acquiring image data of a fiducial on said fiducial plate; 
 responsive to said acquiring, identifying deflection data values representative of a deflection of said fiducial plate; and 
 responsive to said identifying, providing correction data values enabling a first order correction of said planarity measurement. 
 
     
     
         19 . The computer readable medium of  claim 18  further encoded with data and instructions causing an apparatus executing said instructions to execute said optical metrology data processing technique by:
 identifying rate data values representative of a rate of deflection of said fiducial plate; and 
 responsive to said further identifying, providing additional correction data values enabling a second order correction of said planarity measurement.