Alpha-emitter induced soft-errors in CMOS 130nm SRAM: Real-time underground experiment and Monte-Carlo simulation

This work reports a long-duration (> 2 years) realtime characterization study of SRAM memories at the underground laboratory of Modane (LSM) to quantify alpha emitter radioactive impurities present in the circuit materials and responsible of soft-errors detected in absence of atmospheric neutrons. Experimental data have been obtained using ~3.5 Gbit of SRAMs manufactured in CMOS 130 nm technology. In a second part of this work, the underground experiment is simulated using a Monte-Carlo code to extract the contamination level related to the disintegration chain of uranium in silicon at secular equilibrium. Results are finally compared to data obtained from experimental counting experiments using an ultra low background alpha-particle gas proportional counter.