The first fully functional 3D CMOS chip with Deep N-well active pixel sensors for the ILC vertex detector

This work presents the characterization of Deep N-well (DNW) active pixel sensors fabricated in a vertically integrated technology. The DNW approach takes advantage of the triple well structure to lay out a sensor with relatively large charge collecting area (as compared to standard three transistor MAPS), while the readout is performed by a classical signal processing chain for capacitive detectors. This new 3D design relies upon stacking two homogeneous tiers fabricated in a 130 nm CMOS process where the top tier is thinned down to about 12 μ m to expose through silicon vias (TSV), therefore making connection to the buried circuits possible. This technology has been used to design a fine pitch 3D CMOS sensor with sparsification capabilities, in view of vertexing applications to the International Linear Collider (ILC) experiments. Results from the characterization of different kind of test structures, including single pixels, 3×3 and 8×8 matrices, are presented.