Use of a Pulsed Laser as an Aid to Transient Upset Testing of I2L LSI Microcircuits

Pulsed lasers operating at infrared wavelengths can act as convenient sources for excitation of excess carriers in silicon devices. It is shown that a pulsed GaAs laser effectively simulates the effects caused by high energy ionizing radiation on integrated circuit devices. Experimental data is presented on several LSI complexity level devices manufactured with I2L technology. The data shows excellent correlation of failure modes between LINAC and laser tests. Good quantitative agreement has been obtained between LINAC and laser upset levels. This is desirable, but not necessary since the laser test is not considered to be a replacement for LINAC or Flash X-ray testing. The laser has been used in conjunction with an optical microscope and a micromanipulator to observe voltage waveforms at internal circuit nodes and to selectively shadow small areas of the chip during the transient event. This provides a powerful diagnostic tool for analysis of basic failure mechanisms.