Comparison of different sensor thicknesses and substrate materials for the monolithic small collection-electrode technology demonstrator CLICTD

TL;DR

This study investigates how varying sensor thicknesses and substrate materials affect the charge collection and performance of monolithic CMOS sensors with small collection electrodes, demonstrating that thicker high-resistivity substrates significantly enhance detection efficiency and resolution.

Contribution

It provides experimental insights into how substrate material and thickness influence the active volume and performance of monolithic CMOS sensors, highlighting the benefits of high-resistivity Czochralski substrates.

Findings

Thicker high-resistivity substrates double the sensitive volume.

Enhanced detection efficiency with increased sensor depth.

Improved spatial and time resolution observed.

Abstract

Small collection-electrode monolithic CMOS sensors profit from a high signal-to-noise ratio and a small power consumption, but have a limited active sensor volume due to the fabrication process based on thin high-resistivity epitaxial layers. In this paper, the active sensor depth is investigated in the monolithic small collection-electrode technology demonstrator CLICTD. Charged particle beams are used to study the charge-collection properties and the performance of devices with different thicknesses both for perpendicular and inclined particle incidence. In CMOS sensors with a high-resistivity Czochralski substrate, the depth of the sensitive volume is found to increase by a factor two in comparison with standard epitaxial material and leads to significant improvements in the hit-detection efficiency and the spatial and time resolution.