Testing and characterisation of the readout chip of the CMS Inner Tracker for High-Luminosity LHC

This thesis is part of the ongoing work for the CMS Inner Tracker upgrade for High-Luminosity LHC. The complete replacement of the Inner Tracker during the Long Shutdown 3 of the LHC is a crucial part of the CMS upgrade. The pixel readout electronics of the Inner Tracker has been completely redesigned in order to comply with the more stringent pixel size, hit rates, radiation hardness, buffering, and readout requirements. The CMS Readout Chip (CROC) is the result of 10 years of development and testing carried out by the RD53 collaboration. Three ASIC iterations have been produced by the collaboration using the CMOS 65nm technology (RD53A demonstrator, RD53B prototypes, RD53C production chips). Given the different experimental requirements, two production chip flavours have been implemented: ITkPix for the ATLAS experiment and CROC for CMS. The first wafers of the production ASICs have been received in July 2023 (ITkPixV2) and in January 2024 (CROCv2). The first results obtained with the production chips have confirmed the suitability of these ASICs for operation in the High-Luminosity LHC environment. Wafer-level testing of approximately 300 CROCv2 wafers is an important aspect of detector construction. During waferprobing, chip selection and calibration is performed in order to discard defective electronics and to obtain the necessary information for constructing detector modules with either two or four readout chips. The CMS waferprobing setup for CROC production testing has been developed and successfully commissioned in the two waferprobing centres located in Turin (Italy) and Manhattan (Kansas, USA). In this thesis, the upgrade of the Inner Tracker electronics will be outlined. The development of the CROC waferprobing setup, in its hardware and software components, will be described in detail. The most important results obtained after setup commissioning, including waferprobing results of production chips (CROCv2), will be reported.