Transient radiation response of VLSI circuits: shadowing effects and pulse widths dependence in laser measurements

Transient radiation responses on VLSI-circuits of various complexities were studied for different pulse widths using both laser and accelerator sources. The shadowing effects of the incident laser light due to the metallization were also investigated. The results were in good agreement with the results from the accelerator measurements. The transmission studies show that the metal cover at the most sensitive latch-up areas on the circuits compared to the reference circuit IDT 6116 follows the VdG/laser ratio latch-up threshold values well. The large divergence (>or=20%) from 1.0 for some circuits' VdG/laser-ratio indicates, however, that the use of only one calibration circuit for radiation assessment with a laser is unsatisfactory. The big difference in metal cover and complexity between circuits requires the use of a reference circuit with similar metal coverage as the circuit under test.<
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