A BiCMOS active substrate probe card technology for digital testing

An active substrate silicon probe card employs a polyimide membrane formed on a silicon substrate. The probe card combines tungsten probe tips and aluminum interconnects in the polyimide membrane with active test circuitry integrated in the silicon substrate. The card is potentially capable of providing more than 1000 probe tips in an array format. The choice of the active circuitry included in the substrate depends on the application of the probe card. If the probe card is intended for use with conventional digital testers, linear buffers can be integrated into the substrate to isolate the device under test (DUT) outputs from the 50/spl Omega/ transmission lines in the test system and drive those lines from matched impedances. Alternatively, by integrating the front-end circuits of a digital tester into the substrate, timing measurements can be made at distances less than 1cm from the probe tips, resulting in a significant improvement in testing accuracy. In this work, experimental circuits for both approaches are explored. An experimental prototype of an active substrate probe card employing linear buffers is integrated in a 2/spl mu/m BICMOS technology.