Monolithic Pixel Sensors for Fast Silicon Vertex Trackers in a Quadruple Well CMOS Technology

Apsel4well is a monolithic active pixel sensor (MAPS) chip intended for application to fast and low material silicon vertex trackers for future experiments at high intensity machines. The design is based on a 180 nm CMOS process with quadruple well option called INMAPS. This technology makes it possible to increase the in-pixel intelligence as compared to standard three transistor MAPS and their variants. Moreover, the availability of a high resistivity epitaxial layer is confirmed to lead to further improvements in terms of charge collection performance and radiation resistance. This paper, after providing some details on the INMAPS process, focuses on the analog front-end section of the pixel readout chain. Measurement results on the main analog channel parameters, like charge sensitivity and equivalent noise charge, are given along with charge collection properties evaluation through ⁹⁰Sr/ ⁹⁰Y spectrum measurements and laser stimulation. Characterization data were also used for validating a TCAD model of the device. Finally, selected results from a neutron irradiation campaign with fluences up to 2.7 × 10¹³ 1 MeV neutron equivalent/cm ² will be shown.