Depleted Fully Monolithic Active CMOS Pixel Sensors (DMAPS) in High Resistivity 150~nm Technology for LHC

Depleted monolithic CMOS 1 1 Complementary metal-oxide-semiconductor. active pixel sensors (DMAPS) have been developed to demonstrate their suitability as pixel detectors in the outer layers of the ATLAS Inner Tracker (ITk) pixel detector in the High-Luminosity Large Hadron Collider (HL-LHC). Two prototypes have been fabricated using a 150 nm CMOS technology on high resistivity ( ≥ 2 k Ω cm) wafers. The chip size of 10 mm × 10 mm is similar to that of the current FE-I3 ATLAS pixel detector readout chip. One of the prototypes is used for detailed characterization of the sensor and analog front end circuitry of the DMAPS. The other one is a fully monolithic DMAPS, including fast readout digital logics that handle the required hit rate. To yield a strong homogeneous electric field within the sensor volume, back-side process of the wafer was tested. The prototypes were irradiated with X-rays up to a total ionization dose (TID) of 50 Mrad(SiO 2 ) and with neutrons up to a 1 MeV neutron equivalent fluence of 10 15 n eq /cm 2 to test non-ionizing energy loss (NIEL) effects. The analog front end circuitry maintained its performance after TID irradiation, and the hit efficiency at < 10 −7 noise occupancy was as high as 98.9% after NIEL irradiation.