New radiation-tolerant thin planar and 3D columnar n$^+$ on p silicon pixel sensors

The High Luminosity upgrade of the CERN Large Hadron Collider (HL-LHC) calls for new high radiation-tolerant solid-state pixel sensors, capable of surviving irradiation fluences up to a few $10^{16}\\$\,n$_{\rm eq}$/cm$^2$ at $\sim3$\,cm from the interaction point. The INFN ATLAS-CMS joint research activity, in collaboration with Fondazione Bruno Kessler, is aiming at the development of thin n$^+$ on p type pixel sensors to be operated at the HL-LHC. The R\&D covers both planar and 3D pixel devices made with the Direct Wafer Bonding technique. The active thickness of the planar sensors studied in this paper is 100\,$\mu$m or 130\,$\mu$m, that of 3D sensors 130\,$\mu$m. First prototypes of hybrid modules, bump-bonded to the present CMS readout chips, have been characterized in beam tests. First results on their performance before and after irradiation are reported in this article