Downscaling Study of Uncooled a-Si Infrared Microbolometer Cell based on Simulation

This study analyzes the response time, that is, thermal time constant of an uncooled amorphous silicon (a-Si) infrared (IR) microbolometer cell based on simulation when the device is downscaled for higher resolution. For accurate analysis, an 80x80 array of a-Si microbolometer was fabricated with a 35 mu m pixel size. The real device was used to extract the external environmental parameter for the simulation where temperature coefficient of resistance (TCR) of a-Si is also modeled to include temperature-dependence. It is known qualitatively that the cell geometries like as the length of the resistance layer and width of the leg are key factors for the time constant of the device. When the pixel is downscaled to 17 mu m, the time constant is found to increase as the length of the resistance layer becomes narrower, but this tendency is reversed for the width of the leg. This is because the influence of each component on the total resistance is changed according to the cell area, which is efficiently optimized by the simulation analysis.