Radiation hard DMAPS pixel sensors in 150nm CMOS technology for operation at LHC

TL;DR

This paper presents the development of radiation-hard, fully depleted monolithic pixel sensors in 150nm CMOS technology, capable of operating in the high-radiation environment of the LHC and HL-LHC experiments.

Contribution

The work introduces a novel fully depleted MAPS design with high resistivity substrates and deep n-wells, achieving significant radiation tolerance improvements.

Findings

Radiation hardness up to 10^15 n_eq/cm^2 and 50 Mrad TID demonstrated.

Successful operation in particle rates comparable to LHC inner detectors.

Development from prototypes to large, fully integrated readout matrices.

Abstract

Monolithic Active Pixel Sensors (MAPS) have been developed since the late 1990s employing silicon substrate with a thin epitaxial layer in which deposited charge is collected by disordered diffusion rather than by drift in an electric field. As a consequence the signal is small and slow, and the radiation tolerance is below the requirements for LHC experiments by factors of 100 to 1000. We developed fully depleted (D)MAPS pixel sensors employing a 150 nm CMOS technology and using a high resistivity substrate as well as a high biasing voltage. The development has been carried out in three subsequent iterations, from prototypes to a large pixel matrix comprising a complete readout architecture suitable for LHC operation. Full CMOS electronics is embedded in large deep n-wells which at the same time serve as collection nodes (large electrode design). The devices have been intensively characterized before and after irradiation employing lab tests as well as particle beams. The devices can cope with particle rates seen by the innermost pixel detectors of the LHC pp-experiments or as seen by the outer pixel layers of the planned HL-LHC upgrade. They are radiation hard to particle fluences of at least $10^{15}~\mathrm{n_{eq}/cm^2}$ and total ionization doses of at least 50 Mrad.