Speaker
Description
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 $\mu$m 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 up to 500 V.
This contribution will discuss the design and latest results of the MPW4, where tests with unirradiated samples showed > 99.9% efficiency, 16 $\mu$m spatial resolution and 10 ns timing resolution. Efficiencies of more than 99% were achieved for samples irradiated with fluences of 1 x 10$^{15}$ 1 MeV n$_{\mathrm{eq}}$/cm$^2$. 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.