SEL-Sensitive Area Mapping and the Effects of Reflection and Diffraction From Metal Lines on Laser SEE Testing

Laser and heavy-ion data reveal the areas and shapes of single-event latchup (SEL)-sensitive regions in CMOS test structures and their positions relative to the affected p-n-p-n paths. Contrary to previous two-dimensional studies, this three-dimensional study shows that the position of maximum SEL sensitivity in these structures is not centered on a p-n-p-n region, but between two neighboring p-n-p-n regions, suggesting that synergistic triggering increases SEL sensitivity. The SEL-sensitivity maps suggest that laser light scattered from metal lines toward the silicon can contribute to the SEE response, for both back-side-incident two-photon absorption and front-side-incident single-photon absorption laser tests. We describe the metallization configurations and laser pulse energies for which reflected and/or diffracted laser light may contribute to the single-event effect (SEE) response.