Depletion depth studies with the MALTA2 sensor, a depleted monolithic active pixel sensor

MALTA2 is a depleted monolithic active pixel sensor (DMAPS) developed in the Tower 180 nm CMOS imaging process. Monolithic CMOS sensors offer advantages over current hybrid imaging sensors both in terms of increased tracking performance due to lower material budget but also in terms of ease of integration and construction costs due to the monolithic design. Current research and development efforts are aimed towards radiation-hard designs up to 100 Mrad in Total Ionizing Dose and 3 × 1015 1 MeV neq / cm2 in Non-Ionizing Energy Loss. One important property of a sensor’s radiation hardness is the depletion depth at which efficient charge collection is achieved via drift movement. Grazing angle test-beam data was taken during the 2023 SPS CERN test beam with the MALTA telescope and Edge Transient Current Technique studies were performed at DESY in order to develop a quantitative study of the depletion depth for un-irradiated, epitaxial MALTA2 samples. The study is planned to be extended for irradiated and Czochralski MALTA2 samples

Radiation hardness of MALTA2, a monolithic active pixel sensor for tracking applications

MALTA is a depleted monolithic active pixel sensor (DMAPS) developed in the Tower Semiconductor 180 nm CMOS imaging process. Monolithic CMOS sensors offer advantages over current hybrid imaging sensors both in terms of increased tracking performance due to lower material budget but also in terms of ease of integration and construction costs due to the integration of read-out and active sensor into one ASIC. Current research and development efforts are aimed towards radiation hard designs up to 100 Mrad in Total Ionizing Dose (TID) and 1 × 10 15 1 MeV n eq /cm 2 in Non-Ionizing Energy Loss (NIEL). The design of the MALTA sensors was specifically chosen to achieve radiation hardness up to these requirements and satisfy current and future collider constraints. The current MALTA pixel architecture employs small electrodes which provide less noise, higher signal voltage and a better power to performance ratio. To counteract the loss of efficiency in pixel corners, modifications to the Tower process have been implemented. The MALTA sensors have been tested during the 2021 and 2022 SPS CERN Test Beam in the MALTA telescope. The telescope ran for the whole duration of the beam time and took data in order to characterize the novel MALTA2 variant and the performance of irradiated samples in terms of efficiency and cluster size. These campaigns show that MALTA is an interesting prospect for HL-LHC and beyond collider experiments, providing both very good tracking capabilities and radiation hardness in harsh radiation environments

Radiation hardness of MALTA2, a monolithic activepixel sensor for tracking applications

MALTA is a depleted monolithic active pixel sensordeveloped in the Tower Semiconductor 180 nm CMOS imagingprocess. Monolithic CMOS sensors offer advantages over currenthybrid imaging sensors both in terms of increased trackingperformance due to lower material budget but also in terms ofease of integration and construction costs due to the integration ofread-out and active sensor into one ASIC. Current research anddevelopment efforts are aimed towards radiation hard designsup to 100 Mrad in Total Ionizing Dose (TID) and 1 × 10$^{15}$ 1MeV n$_{eq}$ /cm$^2$ in Non-Ionizing Energy Loss (NIEL). The designof the MALTA sensors was specifically chosen to achieve radiationhardness up to these requirements and satisfy current and futurecollider constraints. The current MALTA pixel architectureemploys small electrodes which provide less noise, higher signalvoltage and a better power to performance ratio. To counteractthe loss of efficiency in pixel corners, modifications to the Tower process have been implemented. The MALTA sensors have beentested during the 2021 SPS CERN Test Beam in the MALTAtelescope. Additional characterization of MALTA2 samples tookplace during the 2022 campaign. The telescope ran for thewhole duration of the beam time and took data in order tocharacterize the novel MALTA2 variant and the performance ofirradiated samples in terms of efficiency and cluster size. Thesecampaigns show that MALTA is an interesting prospect for HL-LHC and beyond collider experiments, providing both very goodtracking capabilities and radiation hardness in harsh radiationenvironments

MALTA-Cz: A radiation hard full-size monolithic CMOS sensor with small electrodes on high-resistivity Czochralski substrate

Depleted Monolithic Active Pixel Sensor (DMAPS) sensors developed in the Tower Semiconductor 180 nm CMOS imaging process have been designed in the context of the ATLAS ITk upgrade Phase-II at the HL-LHC and for future collider experiments. The ``MALTA-Czochralski (MALTA-Cz)'' full size DMAPS sensor has been developed with the goal to demonstrate a radiation hard, thin CMOS sensor with high granularity, high hit-rate capability, fast response time and superior radiation tolerance. The small pixel size ($36.4\times 36.4$~$\mu$m$^2$) provides high spatial resolution. Its asynchronous readout architecture is designed for high hit-rates and fast time response in triggered and trigger-less detector applications. The readout architecture is designed to stream all hit data to the multi-channel output which allows an off-sensor trigger formation and the use of hit-time information for event tagging. The sensor manufacturing has been optimised through process adaptation and special implant designs to allow the manufacturing of small electrode DMAPS on thick high-resistivity p-type Czochralski substrate. The special processing ensures excellent charge collection and charge particle detection efficiency even after a high level of radiation. Furthermore the special implant design and use of a Czochralski substrate improves the sensor's time resolution. This paper presents a summary of sensor design optimisation through process and implant choices and TCAD simulation to model the signal response. Beam and laboratory test results on unirradiated and irradiated sensors have shown excellent detection efficiency after a dose of $2\times10^{15}$ 1 MeV n$_{eq}$/cm$^{2}$. The time resolution of the sensor is measured to be $\sigma=2$~ns