Speaker
Description
During the testing of pre-production and production of ATLAS ITk pixel modules the readout of modules can fail. These failures are due to issues in core columns causing the trigger processing inside the ITkPix chip to deadlock. This can be mitigated by disabling one or more core columns within the ITkPix chips. Disabling a core column results in a loss of 2% of the active area of a chip and 0.5% of a module.
A range of studies has been made to determine the characteristics and the origin of the core column issue by mining the ATLAS ITk production database, electrical tests at wafer and module level, and investigations of mechanical damage. No definitive cause has been identified but the evidence indicates that it is due to mechanical damage introduced during the flip-chip process.
This contribution will describe the core column issue and its impact on performance of the detector. The investigations to determine the causes will be described and mitigations discussed.
