3D trenched-electrode sensors for charged particle tracking and timing

The INFN CSN5 "TIMESPOT" project aims at the development and implementation of a complete integrated tracking system featuring very high precision both in space and in time for every pixel. Within this framework we are developing 3D pixel sensors optimized for timing, while retaining their usual advantages of low depletion voltage, extreme radiation hardness, and active edges. The pixel geometries are being optimized in terms of size, electrode configuration and shape. In particular, trenched electrodes are used instead of columns, so as to achieve more uniform electric and weighting field profiles. No established technology exists for 3D sensors with trenched electrodes, so we have developed and tested the necessary process steps. In this paper we report the main design and fabrication issues and selected results from TCAD simulations.