System and method of mitigating effects of component deflection in a probe card analyzer
View Patent ↗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 method of obtaining a combined deflection measurement for deflections of a probe card and a probe card fixture; said method comprising:
obtaining measurements of optical planarity and measurements of electrical planarity for all non-bussed probes;
identifying fiducial plate deflection at first electrical contact at all non-bussed probe locations; and
responsive to said obtaining and said identifying, computing a combined deflection attributable to deflection of said probe card and deflection of said probe card fixture.
2. The method of claim 1 further comprising acquiring stage deflection measurements at proximal sensor locations and wherein said computing is further responsive to said acquiring.
3. The method of claim 2 wherein said stage deflection measurements are assumed to be zero.
4. The method of claim 1 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.
5. The method of claim 4 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.
6. The method of claim 1 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.
7. The method of claim 6 wherein said computing comprises utilizing a two dimensional interpolation calculation.