Geometric Design of Microbolometers Made From CMOS Polycrystalline Silicon

In this paper, microbolometers with different geometric designs were fabricated using polycrystalline silicon (polysilicon) films from TSMC 0.35 μm (D35 type) and 0.18 μm (T18 type). D35 microbolometers with high-resistance films showed negative temperature coefficient of resistance (TCR) values, whereas T18 microbolometers with low-resistance films showed positive TCR values. Results indicate that conventional designs with large areas of infrared absorbers can be optimized using uniform suspended arms throughout the microbolometer in the two types of devices. Finite element modeling indicates that the heat flux of microbolometers with uniform beams is evenly distributed and thus results in improved TCR values.