Development of a radiation hard CMOS monolithic pixel sensor

This paper presents the design and experimental test results of a CMOS monolithic pixel sensor prototype with an optimized layout of the pixel cell aimed at a superior radiation tolerance. The chip implements transistors designed both with and without Enclosed Layout Transistor (ELT) rules, and different optimizations of the charge collecting diodes. Irradiations up to a total dose of 1.1 MRad and single particle detection tests have been performed with 200 keV electrons in view of the utilization of such a sensor in Transmission Electron Microscopy (TEM) applications. The sensor response to high-momentum particles was tested on a 1.5 GeV electron beam. The chip radiation tolerance was also assessed against a 2 MRad total dose of 29 MeV protons and against 1–14 MeV neutron fluences in excess of 10¹³ neq cm⁻². These tests show an improved performance of pixels with ELT transistors, a thinner oxide on top of the diode surface and guard-rings around the diodes.