In-situ gamma irradiation testing of radiation hardened chips till 1 MGy

Ten samples of a custom tailored Mega-Gray hardened resolver/LVDT-to-digital converter, a resistive base sensor-to-digital converter and a RS485 communication application specific integrated circuit (ASIC) were combined in 1 irradiation campaign for Fusion for Energy (Barcelona, Spain). Radiation resistance of these ASICs, developed by Magics Instruments (Geel, Belgium) for Fusion for Energy, was assessed for a total ionizing dose (TID) above 1 MGy using the Co-60 gamma underwater irradiation test facility at SCK CEN (Mol, Belgium). The 3 different ASICs were irradiated at an average dose rate of 484 Gy/h and their performance was continuously measured (in-situ) during 97 irradiation days. A fully autonomous and modular test setup was developed to perform these measurements and ensure continuous operation by implementing a recovery and warning system in case of failure to restrict measurement data loss to minimum. An in-situ post-irradiation assessment was performed afterwards to observe recovery from the irradiation in a socalled annealing phase. Annealing was done for seven days at room temperature followed by another 7 days of high temperature annealing at 100 °C to accelerate the recovery effect. During the full test campaign all data was saved in a database, post-processed with Python into readable plots to deduct possible performance shifts due to the irradiation and afterwards during recovery. During the complete testing campaign of these ASICs the ESCC22900 (Total Dose Steady-State Irradiation Test Method) standard was followed. Key words: Rad hard ASIC / 1MGy TID / In-situ measurements