Microbolometer based on a porous silicon fabrication process with a plasmonic absorber

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Low-cost microbolometers are crucial for expanding the market for uncooled thermal imaging sensors, which are now utilized in various commercial applications like thermal building inspections and automotive night vision. Current microbolometer arrays often rely on exotic materials, such as vanadium oxide (VOx), that are not compatible with CMOS technology. This dissertation introduces a novel approach by fabricating a distinct micro-electro-mechanical-system (MEMS) microbolometer chip and a separate read-out circuit (ROIC) chip, which are then combined using wafer-level bonding. In this design, infrared (IR) radiation is directed onto the pixels from behind through the substrate. The MEMS chip is designed to create thermally insulated microbolometer pixels, with temperature-sensitive devices (TSDs) that detect heat from IR radiation using PN-junction diodes. A significant aspect of this work is the fabrication design of a plasmonic absorber for the microbolometer pixels. The comparison between pixels with and without a plasmonic absorber reveals that the former absorb long-wave infrared (LWIR) radiation 18 percent more effectively, indicating that peak absorption aligns closely with the designed wavelength.