3D trenched-electrode pixel sensors: Design, technology and initial results

3D sensors have already been proven as a viable and inherently radiation hard technology. While encouraging timing results have been obtained from small-pitch 3D test structure, new approaches are also being investigated to meet the challenges of the coming years. One such approach, pursued in the framework of the INFN TIMESPOT project, is the development of 3D sensors with trenched electrodes. The trench geometry will provide more uniform electric and weighting fields than in current devices, allowing for good timing resolution, while also maintaining or improving upon the usual advantages of a 3D geometry. We report the fabrication of the first batch of devices, consisting of TIMEPIX compatible pixel sensors, as well as a number of test devices that have been used to study the performance of different pixel geometries. Results highlighted good intrinsic properties, with leakage current of the order of 10 pA per pixel and opposite electrode pixel capacitance of approximately 70-75 fF per pixel, in good agreement with previous simulations of these devices.