Characterization of Passive CMOS Strip Detectors After Proton Irradiation

TL;DR

This study demonstrates the feasibility of fabricating large-area passive CMOS strip detectors using stitching techniques in commercial foundries, with successful proton irradiation tests showing no stitching effects.

Contribution

It introduces a new method for manufacturing large-area passive CMOS strip detectors with stitched reticles, validated through proton irradiation testing.

Findings

Stitched CMOS strip detectors show no adverse effects after proton irradiation.

Fabrication in commercial foundries is feasible for large-area detectors.

Different geometries were tested successfully with no stitching issues.

Abstract

Strip detectors are populating outer trackers of high-energy particle experiments. They are convenient for covering large areas of sensitive material since they use less power and have fewer readout channels compared to pixels sensors. Nevertheless, they are typically manufactured with a mask set that covers the full wafer, otherwise when using smaller reticles the strip implants have to be stitched. For this project, strip detectors were fabricated in a CMOS commercial foundry using different reticles to be stitched several times, proving the feasibility of this technology. LFoundry produced the passive CMOS strip detector with a production line of 150 nm node technology, using a 150 um thick FZ wafer. Those strip sensors have three different geometries to study different impacts of the CMOS technology. The strips have lengths of 2.1 cm and 4.1 cm, stitching 3 or 5 reticles respectively. This work shows results of 24 GeV proton irradiated passive CMOS strip detectors. The detectors were irradiated at CERN and were tested with different set-ups, not showing any effect from the strips stitching. Proving that this technology is feasible for detecting high-energy particles opens the door to future large productions of passive strip detectors and also to produce active strip sensors in commercial CMOS foundries.