Review of radiation damage studies on DNW CMOS MAPS

Monolithic active pixel sensors fabricated in a bulk CMOS technology with no epitaxial layer and standard resistivity ( 10 Ω cm ) substrate, featuring a deep N-well as the collecting electrode (DNW MAPS), have been exposed to γ - rays , up to a final dose of 10 Mrad (SiO2), and to neutrons from a nuclear reactor, up to a total 1 MeV neutron equivalent fluence of about 3.7 · 10 13 cm − 2 . The irradiation campaign was aimed at studying the effects of radiation on the most significant parameters of the front-end electronics and on the charge collection properties of the sensors. Device characterization has been carried out before and after irradiations. The DNW MAPS irradiated with 60Co γ - rays were also subjected to high temperature annealing (100 °C for 168 h). Measurements have been performed through a number of different techniques, including electrical characterization of the front-end electronics and of DNW diodes, laser stimulation of the sensors and tests with 55Fe and 90Sr radioactive sources. This paper reviews the measurement results, their relation with the damage mechanisms underlying performance degradation and provides a new comparison between DNW devices and MAPS fabricated in a CMOS process with high resistivity ( 1 k Ω cm ) epitaxial layer.