Layout and process improvements to double-sided silicon 3D detectors fabricated at FBK

In the past few years, very important progress has been made in the development of silicon 3D detectors, passing from the R&D phase with performance demonstration of a few prototypes to an industrialization phase, which led to the first production of 3D sensors to cover 25% of the ATLAS Insertable B-Layer (IBL) staves. Double-side 3D sensor technology developed at FBK (Trento, Italy) in collaboration with INFN proved successful to yield good quality detectors for the IBL. In spite of the good performance of the IBL sensors, it is possible to further improve the electrical characteristics of these devices while reducing the fabrication complexity and therefore the time required for a medium volume production. To this purpose, with the aid of TCAD simulations, we have investigated some modifications at both the layout and fabrication level aimed at improving the sensor breakdown voltage, both before and after irradiation, while reducing the number of lithographic steps required during fabrication. This paper reports on simulation results and preliminary experimental results from a new batch of 3D sensors implementing the proposed improvements.