Sensor Quality Control and Annealing Studies of HGCAL Silicon Sensors

Abstract

We summarise Sensor Quality Control (SQC) results of non-irradiated silicon sensors for the CMS HGCAL detector, as well as the first detailed annealing campaign with a wafer-scale 120\,\textmu m (Epitaxial) sensor exposed to \(2\times10^{15}\)\,\si{n_{eq}/cm^2} at the Rhode Island Nuclear Science Center (RINSC). For the non-irradiated sensors, we present an overview of the QC workflow developed for HGCAL, including automated handling of vendor data, validation of electrical measurements, and cross-checking of wafer-level characteristics. The study investigates, for the first time, the isothermal annealing behaviour at 60\,\si{\celsius} after annealing periods ranging from 10 to 5000 minutes. Hamburg-model parameters for effective doping concentration changes with annealing time, extracted from full-sensor data, are presented. The post-irradiation behaviour of sensors with hot regions in the pre-irradiation leakage current measurements, as well as epitaxial sensors with stacking faults in individual cells, is also investigated.