Deep-Trench Vertical Si Photodiodes for Improved Efficiency and Crosstalk

摘要

The advancement of deep reactive-ion etching (DRIE) technology has enabled many 3-D structures, and are widely employed in microelectromechanical systems (MEMS). From an electrical point of view, however, those structures have been used as passive components such as capacitors and resistors. To further evolve the utility of future MEMS devices, the authors propose to integrate “active electrical devices” into 3-D MEMS. As an example, vertical trench photodiodes were fabricated on an n-type bulk silicon wafer using DRIE and thermal diffusion of boron. A photocurrent increase from 25% to 70%, and 20% smaller crosstalk was seen in 40-mm deep-trench diodes, as compared to a planar diode made on the same wafer.