CMOS monolithic sensors in a homogeneous 3D process for low energy particle imaging

A 3D, through silicon via microelectronic process, capable of face-to-face assembling two 130 nm CMOS tiers in a single bi-layer wafer, has been exploited for the design of monolithic active pixels (MAPS), featuring a deep N-well (DNW) collecting electrode. They are expected to improve on planar CMOS DNW MAPS in terms of charge collection efficiency since most of the PMOS transistors in the front-end electronics, with their N-wells, can be moved to a different layer from that of the DNW sensor. The vertical integration process also requires that one of the two CMOS tiers be thinned down to a mere 6 μm to expose the through silicon vias and contact the sandwiched circuits. In this work, results from device simulations of 3D MAPS will be presented. The aim is to evaluate the potential of such a thin sensitive substrate in the detection of low energy particles (in the tens of keV range), in view of possible applications to biomedical imaging.