Characterization of pixel sensors for the CMS Tracker upgrade at HL-LHC.

The High-Luminosity phase of the CERN Large Hadron Collider (HL-LHC) calls for an extensive upgrade of the CMS Tracker System requiring, for the Inner Tracker detector, high-radiation tolerant silicon pixel sensors to cope with fluences up to about 2E16 $n_{eq}/{cm^{2}}$. CMS has recently chosen thin planar and 3D pixel sensors to instrument the upgraded Inner Tracker. The results obtained with FBK planar and 3D sensors interconnected with prototype read-out chip RD53A will be shown. First modules are also being assembled with the final CMS chip prototype, also known as C-ROC (CMS Read Out Chip). Both RD53A and C-ROC compliant sensors have $25\times$ 100 $\mu m^{2}$ cell size and $150 \mu m$ of silicon active thickness. The sensors were also irradiated and then tested in different test beam facilities in order to validate them up to the fluence figures foreseen for HL-LHC. The analysis of collected data shows very high hit detection efficiencies and excellent spatial resolutions before and after irradiation.