Multi-cell upset probabilities of 45nm high-k + metal gate SRAM devices in terrestrial and space environments

Abstract

Multi-cell soft errors are a key reliability concern for advanced memory devices. We have investigated single-bit (SBU) and multi-cell upset (MCU) rates of SRAM devices built in a 45 nm high-k + metal gate (HK+MG) technology under neutron, proton and heavy-ion radiation. Our data highlight the excellent soft error reliability scaling properties of HK+MG. MCU rates were kept at 10% or less of SBU ones and bit-level SBU rates continue to decrease 2times per technology generation for terrestrial applications. SRAM upset rates in orbit are projected to be 2 to 4 orders of magnitude higher than at sea-level. A dramatic increase in MCU rates relative to SBU is projected for geosynchronous orbits, where direct ionization by heavy-ions dominates. No indication of charge amplification by parasitic bipolar devices has been observed for all investigated radiation environments. The observation that SBU error rates and small MCU error rates are elevated at locations in close proximity to well contacts for high LET values is speculated to be the result of the formation of a funnel between well contacts and sensitive drains.