Importance

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Abstract

An apparatus for making and verifying electrical contact with the backside of a semiconductor wafer having a bulk portion covered with an insulating layer of oxide includes a contact probe, a wafer chuck having at least one probe vacuum groove and a probe aperture and a probe cylinder having a low pressure and a high pressure portion. The low pressure portion communicates with the probe vacuum groove and the probe aperture. The apparatus further includes a piston movably located between the low pressure and high pressure portions. The contact probe is attached to the piston and adapted to be protrudable from the probe aperture. The groove, aperture and low pressure portion are adapted to form a low pressure chamber with the wafer. The probe is urgeable to pierce the oxide and make electrical contact with the bulk portion of the wafer. The apparatus further includes a time-varying voltage source connectable between the chuck and the probe, and a current measuring device for measuring a current between the chuck and the probe. The probe is in electrical contact with the wafer if the current corresponds at least to a capacitive coupling between the chuck and the wafer.

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First Claim