Agere Systems Inc.

Brian Lee Buss

Wayne Rademacher

Robert Dale Ickes, Jr

A cantilever probe method of parametrically testing wafers extends the probe tip cleaning interval, maintains relatively low contact resistance, and reduces contact resistance variability. In one embodiment of our invention, a method of testing electronic circuits formed in a wafer having lead-free terminals, comprises the steps of exposing the terminals to a plasma containing oxygen; providing a test apparatus having cantilevered probes for contacting the terminals; each probe having a cantilevered probe arm and a BeCu probe tip extending from the arm at an acute angle &#x3b1;; the angle &#x3b1; being designed to essentially eliminate sliding movement of the probe tip when in contact with a terminal; and bringing the probe tips into contact with selected ones of the terminals, so as to perform electrical tests on the wafer; and, during the contacting step, exposing the probe tips to a flow of a non-oxidizing gas (e.g, nitrogen, argon). In a preferred embodiment, the terminals are Sn-based solder bumps. In another preferred embodiment the angle &#x3b1; is approximately 87&#xb0;&#x2013;90&#xb0;.

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Emmaus, PA, United States of America

Brian Lee Buss