Characterization of the RD50-MPW4 HV-CMOS pixel sensor

TL;DR

The RD50-MPW4 HV-CMOS pixel sensor, developed by CERN-RD50, demonstrates enhanced radiation hardness, spatial resolution, and noise performance through architectural improvements and advanced fabrication techniques.

Contribution

This paper introduces the RD50-MPW4 sensor with novel design features that improve radiation hardness and performance over previous models.

Findings

Enhanced radiation hardness up to 500V biasing

Improved spatial resolution and efficiency

Reduced noise and crosstalk

Abstract

The RD50-MPW4 is the latest HV-CMOS pixel sensor from the CERN-RD50-CMOS working group, designed to evaluate the HV-CMOS technology in terms of spatial resolution, radiation hardness and timing performance. Fabricated by LFoundry using a 150nm process, it features an improved architecture to mitigate crosstalk, which has been an issue with the predecessor RD50-MPW3, allowing more sensitive threshold settings and full matrix operation. Enhancements include separated power domains for peripheral and in-pixel digital readout, a new backside-biasing step, and an improved guard ring structure supporting biasing up to 500V, significantly boosting radiation hardness. Laboratory measurements and test beam results presented in this paper show significant improvements over its predecessor regarding noise behavior, spatial resolution, and efficiency.