  The High Luminosity upgrade of the CERN Large Hadron Collider will be able to
reach a peak instantaneous luminosity of 5E34/cm2 s. The innermost detectors of
the CMS and ATLAS experiments will have to cope with unprecedented requirements
on radiation hardness. At the end of the operation period, radiation levels are
expected to reach values above 2.6E16 neq/cm2. Sensors based on 3D pixel
technology, with intrinsic radiation tolerance, are the baseline option for the
innermost layers of the vertex detectors of several HL-LHC experiments. This
article gives an overview of the ongoing characterization of the pixelated 3D
sensor technology, their performance and their current development status for
tracking on radiation harsh environments.
