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

TL;DR

CMOS pixel sensors offer a promising, cost-effective technology for high-energy physics detectors, combining small pixel size, low material budget, and potential for high radiation hardness and fast readout, driven by advances in commercial CMOS processes.

Contribution

This paper reviews recent developments in CMOS pixel sensors, highlighting their advantages and potential for future high-energy physics tracking and vertexing applications.

Findings

CMOS sensors enable small pixels and low material budget.

Advances in CMOS processes improve radiation hardness and readout speed.

Applications include upgrades for LHC and FAIR experiments.

Abstract

CMOS pixel sensors (CPS) represent a novel technological approach to building charged particle detectors. CMOS processes allow to integrate a sensing volume and readout electronics in a single silicon die allowing to build sensors with a 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 for vertexing and tracking systems of high energy physics experiments. Moreover, thanks to the mass production industrial CMOS processes used for the manufacturing of CPS the fabrication construction cost can be significantly reduced in comparison to more standard semiconductor technologies. However, the attainable performance level of the CPS in terms of radiation hardness and readout speed is mostly determined by the fabrication parameters of the CMOS processes available on the market rather than by the CPS intrinsic potential. The permanent evolution of commercial CMOS processes towards smaller feature sizes and high resistivity epitaxial layers leads to the better radiation hardness and allows the implementation of accelerated readout circuits. The TowerJazz $0.18 \mu m$ CMOS process being one of the most relevant examples recently became of interest for several future detector projects. The most imminent of these project is an upgrade of the Inner Tracking System (ITS) of the 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 as one of the viable options for flavour tagging and tracking sub-systems.