Speaker
Description
A new generation of 3D pixel detectors with high granularity and thin active substrates is being developed for the upgrade of the ATLAS Inner Tracker (ITk) at HL-LHC. The new sensors will have to fulfil the requirements for the innermost pixel layers in terms of radiation hardness and rate capabilities.
Two productions of 3D sensors compatible with the new RD53A chip (the prototype of the future ITk chip) have been carried out at CNM, Barcelona. Both feature a single side process in which all columns are etched from the top-side. This allows the use of support wafers to keep the structure rigidity and achieve thin active substrates.
The first CNM production used Silicon-on-Insulator (SOI) wafers which needed to be etched in order to provide bias to the backside. The second production instead uses Silicon-on-Silicon (Si-Si) wafers where the bias can be provided directly through the conductive silicon support avoiding further stress of the structure.
Both productions include 3D silicon pixel sensors with two pixel cell sizes, 50x50 µm$^2$ and 25x100 µm$^2$, and active thicknesses of 150 µm which are compatible with the baseline of the ITk innermost pixel layer.
Full modules with sensors from the SOI production have been assembled at IFAE and characterised at beam tests before and after proton irradiation at the KIT Cyclotron.
Results of these studies and very first measurements of the new Si-Si production will be presented.
