Imaging and Characteristics of a Bimaterial Microcantilever FPA Fabricated using Bulk Silicon Processes

For a focal plane array (FPA) fabricated with a surface sacrificial layer process, the IR flux must transmit through the silicon substrate and the air gap before it reaches the cantilever pixels. Part of the IR radiation energy is therefore lost owing to the reflection and absorption caused by the silicon substrate. We fabricate an infrared FPA consisting of 128×128 microcantilever pixels by using a novel bulk micro−electro-mechanical-system process. Thermal images of persons at room temperature are captured to demonstrate the IR imaging capability of the FPA. For the proposed device, the thermal response is calculated to be 4.03×10^-3, the thermo−mechanical sensitivity is measured to be 0.273 µm /K, the noise equivalent temperature difference is measured to be 200 mK by a gray level change method and the time constant is calculated to be 15 ms under a 10 mTorr pressure.