Characterization and analysis of Total Ionizing Dose Effects in a 28 nm PolarFire FPGA

This paper presents an experimental and analytical investigation of the Total Ionizing Dose (TID) effects on a commercial 28 nm PolarFire Field Programmable Gate Array (FPGA). The device, which employs a SONOS (Silicon-Oxide-Nitride-Oxide-Silicon) flash architecture, was exposed to a cumulative gamma dose of 34.97 krad(Si) using a Cobalt-60 source. Experimental findings indicate that the PolarFire FPGA maintains its functional integrity up to a cumulative dose of 34.97 krad(Si). Notably, there was a significant increase in supply current, rising from an initial 1.93 mA to 17.6 mA, which provides compelling evidence of TID-induced leakage. Throughout the exposure, the FPGA demonstrated full functional integrity; however, there were observable increases in supply current and a moderate rise in propagation delay. The 7% increase in propagation delay observed on the rising edge of the inverter chain is consistent with anticipated TID effects on the performance of CMOS logic. This paper offers an in-depth discussion of the physical mechanisms underlying these effects and outlines critical design considerations for deploying these devices in space applications.