Probe skates for electrical testing of convex pad topologies

Abstract

A probe for engaging a conductive pad is provided. The probe includes a probe contact end for receiving a test current, a probe retention portion below the contact end, a block for holding the probe retention portion, a probe arm below the retention portion, a probe contact tip below the arm, and a generally planar self-cleaning skate disposed perpendicular below the contact tip. The self-cleaning skate has a square front, a round back and a flat middle section. The conductive pad is of generally convex shape having a granular non-conductive surface of debris and moves to engage the skate, whereby an overdrive motion is applied to the pad causing the skate to move across and scrub non-conductive debris from the pad displacing the debris along the skate and around the skate round back end to a position on the skate that is away from the pad.

Description

[0001]Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 7,436,192. The reissue applications are application Ser. No. 12 / 903,566, filed on Oct. 13, 2010 (now U.S. Pat. No. Re. 43,503) and Ser. No. 13 / 545,571 (the present application), filed on Jul. 10, 2012, which is a divisional of application Ser. No. 12 / 903,566.CROSS-REFERENCE TO RELATED APPLICATIONS[0002]This application is a divisional reissue application of U.S. application Ser. No. 12 / 903,566 (now U.S. Pat. No. Re. 43,503), filed Oct. 13, 2010, which is a reissue of U.S. Pat. No. 7,436,192 issued Oct. 14, 2008, which is a continuation-in-part application of the inventor's prior U.S. application Ser. No. 11 / 480,302 (U.S. Pat. No. 7,759,949) filed Jun. 29, 2006, for PROBES WITH SELF-CLEANING SKATES FOR CONTACTING CONDUCTIVE PADS, to which claims the benefit of U.S. application Ser. No. 10 / 850,921 filed on May 21, 2004, now U.S. Pat. No. 7,148,709, U.S. application Ser. No. 10 / 888,347 filed...

AI Technical Summary

Benefits of technology

The present invention is a method for improving the cleaning of semiconductor wafers during processing. The method involves using a self-cleaning skate with a conductive pad and a non-conductive layer of debris. A conductive probe engages the conductive pad and removes debris from it by applying overdrive motion to the pad. The skate has a unique design with a square front end, round back end, and flat middle section, which allows it to easily engage and disengage with the pad while scrubbing the debris from it. The method can be used on irregularly shaped conductive pads and provides better control during overdrive motion. Its use reduces the time between failures of the probe and improves the reliability of pad testing on silicon wafers before dicing.

Problems solved by technology

A problem exists with a non-conductive layer of debris on the pad such as a non-conductive oxide layer impeding the conductive pad from receiving the test signal, where the debris is an artifact of the fabrication process.

Numerous problems arise from this method such as controlling the probe scrubbing action, managing undesirable debris accumulation on the probe tip, and the added need for a complicated and invasive probe cleaning processes to remove the debris from the probe tips.

A probe is often too sensitive to the overdrive motion from the pad, causing a scrub depth that is too deep that not only removes a portion of the non-conductive layer, but also damages or breaches the conductive pad, thus rendering the wafer unusable.

Debris accumulation on the probe tip degrades the electrical continuity between the probe and conductive pad, often times restricting the test signal and providing erroneous test results, where implementation of an undesirable test redundancy may then become necessary.

Such a technique not only disrupts the fabrication throughput, but also degrades the probe tip, resulting in shortened utility of the probes and requiring premature replacement.

While such an alloy lends itself for creating a tip that is more robust for scrubbing, the need to disrupt fabrication throughput for a probe tip cleaning process still exists.

Further, the geometry of the contact bump made from the alloy nub lends itself for undesirable accumulation of debris, thus necessitating relatively frequent cleaning.

Unfortunately, such geometry has been shown to lack scrubbing control and damage the pad due to the probe having a hypersensitivity to overdrive motion.

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