International Business Machines Corporation

Nathaniel W Bowe

Ronald DeSales Rossi

A method has been found to check contact to chips having inputs lacking a diode to substrate, such as silicon on insulator (SOI) chips. A mid level voltage, such as Vdd/2, is applied to each receiver sequentially to partially turn on both complementary devices of a CMOS inverter receiver or to partially turn on a current switch receiver. The overall chip standby leakage current is measured while a receiver is at the mid level voltage. These measurements are compared to the overall chip standby leakage current in normal operation when a logical high or logical low level is applied to all I/O pads. A mid level voltage is enough to partially turn on both complementary devices of an inverter receiver or to partially turn on a current switch receiver and the current going through that one receiver is sufficient to provide a significant increase in the overall chip standby current. Thus by measuring an overall chip Idd current, probe contact is checked for each receiver pad individually without directly accessing a current at each receiver pad.

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Colchester, VT, United States of America

Nathaniel W Bowe