Development of CMOS pixel sensors for tracking and vertexing in high energy physics experiments

摘要

CMOS pixel sensors (CPS) represent a novel technological approach to buildingcharged particle detectors. CMOS processes allow to integrate a sensing volumeand readout electronics in a single silicon die allowing to build sensors witha small pixel pitch ($\sim 20 \mu m$) and low material budget ($\sim 0.2-0.3\%X_0$) per layer. These characteristics make CPS an attractive option forvertexing and tracking systems of high energy physics experiments. Moreover,thanks to the mass production industrial CMOS processes used for themanufacturing of CPS the fabrication construction cost can be significantlyreduced in comparison to more standard semiconductor technologies. However, theattainable performance level of the CPS in terms of radiation hardness andreadout speed is mostly determined by the fabrication parameters of the CMOSprocesses available on the market rather than by the CPS intrinsic potential. The permanent evolution of commercial CMOS processes towards smaller featuresizes and high resistivity epitaxial layers leads to the better radiationhardness and allows the implementation of accelerated readout circuits. TheTowerJazz $0.18 \mu m$ CMOS process being one of the most relevant examplesrecently became of interest for several future detector projects. The mostimminent of these project is an upgrade of the Inner Tracking System (ITS) ofthe ALICE detector at LHC. It will be followed by the Micro-Vertex Detector(MVD) of the CBM experiment at FAIR. Other experiments like ILD consider CPS asone of the viable options for flavour tagging and tracking sub-systems.