Summary of quality control (QC) of ATLAS18 production ITk strip sensors

Le résumé fourni par la source

To address the demanding operational requirements of the High-Luminosity upgrade of the Large Hadron Collider (HL-LHC), the ATLAS experiment is replacing its current Inner Detector with a new all-silicon Inner Tracker (ITk). The ITk will feature an active sensor area of 165 m 2 , with its outer tracking layers populated by approximately 18,000 ATLAS18 n + -in-p silicon strip sensors. The silicon sensors, available in eight geometries tailored to two barrel and six endcap module types, respectively, are designed to tolerate fluences of up to 1.6 × 10 15 neq/cm 2 and ionizing doses of 66 Mrad. A comprehensive, multi-year Quality Control (QC) program is underway across multiple international institutes to evaluate these ITk strip sensors for mechanical and electrical conformity. The QC process includes IV/CV characterization, full strip tests, long-term current stability monitoring, visual inspection, and metrology tests. To manage the high throughput of about 500 sensors per month, the collaboration has implemented standardized test procedures, software packages for data monitoring and integrity checks, unified data formats, and automated analysis tools. The standardization ensures consistent pass/fail evaluation and centralized data handling that enables effective identification of trends and anomalies at all sites during multi-year production. This contribution presents an overview of the ITk strip sensor production and QC framework, along with key findings throughout the whole production, such as charge-up of sensors, stability of the leakage currents, nonrecoverable IV breakdown, and low inter-strip isolation within wafers. It provides insights into sensor yield, quality trends, and reviews specific case studies, such as p-stop doping non-uniformity. Over 91% of the production, totaling over 590 batches, were tested and accepted as-is. Six batches were rejected: two due to instability and non-recoverable IV breakdown found in QC, and four due to non-uniform p-stop doping found during Quality Assurance (QA) testing. These account for 2.8% of the total tested sensors. Additionally, 1.8% of individual sensors are rejected after visual inspection, non-recoverable IV breakdown, and other issues.

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