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Pilsl, B., Bergauer, T., Casanova, R., Handerkas, H., Irmler, C., Kraemer, U., et al. (2025). Enhancing radiation hardness and granularity in HV-CMOS: The RD50-MPW4 sensor. Nucl. Instrum. Methods Phys. Res. A, 1080, 170752–5pp.
Abstract: The latest HV-CMOS pixel sensor developed by the former CERN-RD50-CMOS group, known as the RD50-MPW4, demonstrates competitive radiation tolerance, spatial granularity, and timing resolution – requirements for future high-energy physics experiments such as the HL-LHC and FCC. Fabricated using 150 nm CMOS process by LFoundry, it introduces several improvements over its predecessor, the RD50-MPW3, including separated power domains for reduced noise, a new backside biasing scheme, and an enhanced guard ring structure, enabling operation at bias voltages up to 800 V. Tests with non-irradiated samples achieved hit detection efficiencies exceeding 99.9 % and a spatial resolution around 16 μm. Neutron-irradiated sensors were characterized using IV measurements and beam campaigns, confirming the sensor's robustness in high-radiation environments. The results highlight ability of HV-CMOS technology to restore hit detection efficiency post-irradiation by increasing the applied bias voltage. Details of these measurements and timing performance are presented in this paper.
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Sonneveld, J., Bergauer, T., Casanova, R., Handerkas, H., Irmler, C., Jimenez-Sanchez, J., et al. (2027). The RD50-MPW4: A radiation hard HV CMOS sensor for future colliders. Nucl. Instrum. Methods Phys. Res. A, 1093, 172091–5pp.
Abstract: The former CERN RD50 collaboration develops monolithic active pixel high voltage (HV) CMOS sensors for future colliders with the aim of high radiation tolerance, good time resolution, and high granularity pixel detectors. The most recent prototype, the RD50-MPW4, was produced by LFoundry in December 2023 using a 150 nm CMOS process. It features a matrix of 64x64 pixels with a 62 μm pitch and employs a column-drain readout architecture. Compared to its predecessor, it now has separate analog and digital power domains and a new biasing scheme with a guard ring structure that supports bias voltages over 600 V. This contribution will discuss the design and latest results of the MPW4, where tests with unirradiated samples showed more than 99.9% efficiency, 16 μm spatial resolution and 10 ns timing resolution. Efficiencies of over 99% were achieved for samples irradiated to fluences of 1 & times;1015 1 MeV neq/cm2. A 3D map of the charge collection efficiency from a measurement with two-photon absorption laser is presented that nicely outlines the depletion depth of this radiation hard, high granularity monolithic active pixel sensor.
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