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

Depleted monolithic CMOS active pixel sensors (DMAPS) have been developed in order to demonstrate their suitability as pixel detectors in the outer layers of a toroidal LHC apparatus inner tracker (ATLAS ITk) pixel detector in the high-luminosity large hadron collider (HL-LHC). Two prototypes have been fabricated using 150 nm CMOS technology on high resistivity (> 2 k$\Omega$ $cm^2$) wafers. The chip size is equivalent to that of the current ATLAS pixel detector readout chip. One of the prototypes is used for detailed characterization of the sensor and the analog readout of the DMAPS. The other is a fully monolithic DMAPS including fast readout digital logic that handles the required hit rate. In order to yield a strong homogeneous electric field within the sensor volume, thinning of the wafer was tested. The prototypes were irradiated with X-ray up to a total ionization dose (TID) of 50 Mrad and with neutrons up to non-ionizing energy loss (NIEL) of $10^{15}$ $n_{eq}/cm^2$. The analog readout 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.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