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Test System Control Technique Detecting Potential Short Circuit Defects by Use of a Voltage Screen

IP.com Disclosure Number: IPCOM000059743D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

VanHorn, J: AUTHOR

Abstract

Redeposited, oxidized aluminum from the lift-off process can become a short between device conductors if a high voltage breaks the oxide down and welds the aluminum in place. By programming a device tester appropriately, a high-voltage screen is applied to silicon gate devices, thereby inducing this type of failure at final test. These failures otherwise would occur in the field and become reliability detractors. The device tester is programmed to perform the voltage screen function prior to performing normal tests. The high voltage condition is applied to the device under test for a time duration short enough that device life is not affected, but long enough to exceed time of high voltage application in normal use. The high voltage is applied to the highest possible number of switching gates on the device.

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Test System Control Technique Detecting Potential Short Circuit Defects by Use of a Voltage Screen

Redeposited, oxidized aluminum from the lift-off process can become a short between device conductors if a high voltage breaks the oxide down and welds the aluminum in place. By programming a device tester appropriately, a high- voltage screen is applied to silicon gate devices, thereby inducing this type of failure at final test. These failures otherwise would occur in the field and become reliability detractors. The device tester is programmed to perform the voltage screen function prior to performing normal tests. The high voltage condition is applied to the device under test for a time duration short enough that device life is not affected, but long enough to exceed time of high voltage application in normal use. The high voltage is applied to the highest possible number of switching gates on the device. During application of the high voltage screen, off- chip drivers are put into a high impedance mode, and voltage clamp circuitry is set above the high- voltage screen value. The program also suspends device measurement during the high voltage screen portion of the test. The program resets to normal conditions immediately after the voltage screen is completed and normal tests are run. This method provides protection for the device under test during set-up, application of the voltage screen, and the transition to normal testing. Since it is simply a small addition...