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PROBE ALIGNMENT METHOD AND APPARATUS FOR USE IN PARAMETRIC TESTING

IP.com Disclosure Number: IPCOM000008783D
Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2002-Jul-12
Document File: 2 page(s) / 112K

Publishing Venue

Motorola

Related People

Stephen Traynor: AUTHOR [+2]

Abstract

Initial set up of a batch of wafers for automatic probing is a manual process, in which the operator must establish a good electrical contact between the probe pins of a probe card and probe pads of the first wafer of the batch. This is achieved by careful- ly raising the wafer while aligning the bond pads onto the pins of the probe card.

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@ MOTOROLA Technical Developments

PROBE ALIGNMENT METHOD AND APPARATUS FOR USE IN PARAMETRIC TESTING

by Stephen Traynor and Phil Walker BACKGROUND SOLUTION

  Initial set up of a batch of wafers for automatic probing is a manual process, in which the operator must establish a good electrical contact between the probe pins of a probe card and probe pads of the first wafer of the batch. This is achieved by careful- ly raising the wafer while aligning the bond pads onto the pins of the probe card.

  The normal procedure, as described briefly above, is used to set up the wafer batch. When pin to pad connection is established, an initial series of tests is done to confirm connection. Only if all these tests are passes will the prober then be instructed to automatically perform the main production test rou- tine. Otherwise a new set up attempt is required.

  Poor quality alignment of multiple probe pins to electrical pad connections can arise through a vati- ety of sources, such as poor pin to pin alignment on the probe card, poor pin planarisation and/or poor initial set up. This always results in producing bad on-wafer electrical test data.

  Often the difficulty is not in achieving good contact with one pad, but ensuring that all pins make a sound electrical contact to all pads (Figure I illus- trates 'good' electrical connections on the first, third and fifth pads, but 'marginal' on the second and fourth). This may lead to a compromise, compensat- ing an accurate set up on some pads, with a margin- al set up on others (Figure 2 illustrates the probe marks left on the pads after the above set up is per- formed).

  One typical way to address these concerns is to perform simple tests once the probe tips have con- nected to the pads, while the prober is still in a man- ual state. If there is electrical contact between probe and pad, the main test program is initiated. However, this method only detects gross misalign- ment and does not detect marginal misalignment on the first wafer (such as that shown on pads 2 and 4 of Figures I and 2), which is then subject to the inherent tolerances of the prober mechanics as sub- sequent wafers in the batch are tested. It is the accu- mulation of such tolerances that can force a mar- ginal set up on the first wafer into a misalignment in respect of subsequent wafers in the batch.

  In the initial series of tests, the prober is instructed (through a routine coded into the test pro- gram) to...