High-Voltage 12.5-V Backside-Illuminated CMOS Photovoltaic Mini-Modules

In this paper, we employed a one-step localized substrate removal (LSR) process to fabricate a backside-illuminated CMOS photovoltaic (PV) mini-module suitable for high-voltage and low-power applications. LSR can be considered an upgrade of multichip module technology, by providing a 50-μm physical gap between on-chip PV cells for electrical isolation, while avoiding the need for time-consuming pick-and-place steps. A proof-of-concept PV module achieved open-circuit voltage of 12.5-V and μA-scale short-circuit current within a small form factor (3.13 V/mm
²
). The fabrication of this PV mini-module is based on standard microelectronics manufacturing/packaging processes, thereby ensuring easy integration with other microelectronics for self-powered systems.