A 2.5 µm pitch CMOS active pixel sensor in 65 nm technology for Electron Microscopy

This work presents the design and characterization of a monolithic active pixel sensor manufactured in a commercial 65 nm CMOS process. The chip is the first prototype of our third generation development of CMOS pixel sensors as direct detectors for Transmission Electron Microscopy, and follows previous designs manufactured in 0.35 μm and 0.18 μm processes. The sensor features square pixels of 2.5 μm pitch, arrayed on a 400×400 pixel matrix and subdivided in four sections implementing different layouts for the charge collecting diode and the readout transistors. The paper will present results from the characterization performed in the laboratory and in an electron microscope, including the evaluation of the sensor performance after irradiation to a 200 Mrad dose, and compare them to those obtained on the previous sensors.