Development of Advanced Silicon 3D Sensors at FBK Using Stepper Lithography

We are developing a new generation of 3D pixel sensors, based on columnar electrodes and trenched electrodes, and aimed at the upgrades of the major detector experiments at the High Luminosity LHC. These 3D sensors have small pixel size with downscaled geometries, and their layout is much denser than in previous devices, that is a challenge for lithography equipment. Mask aligners are not favored to be used in these conditions, so we have started to use stepper lithography, which yields a much smaller minimum feature size and higher alignment accuracy. We report on the initial results obtained from the first stepper batches, which confirm the feasibility of advanced 3D sensors with a good fabrication yield.