Design, simulation and validation of a novel uncooled infrared focal plane array

This paper describes a novel single-layer bi-material cantilever microstructure without silicon (Si) substrate for focal plane array (FPA) application in uncooled optomechanical infrared imaging system (UOIIS). The UOIIS, responding to the radiate infrared (IR) source with spectral range from 8 to 14 μm, may receive an IR image through visible optical readout method. The temperature distribution of the IR source could be obtained by measuring the thermal-mechanical rotation angle distribution of every pixel in the cantilever array, which is consisted of two materials with mismatching thermal expansion coefficients. In order to obtain a high detection to the IR object, gold (Au) film is coated alternately on silicon nitride (SiN_x) film in the flection beams of the cantilevers. And a thermal-mechanical model for such cantilever microstructure is proposed. The thermal and thermal-mechanical coupling field characteristics of the cantilever array structure are optimized through numerical analysis method and simulated by using the finite element simulation method. The thermal-mechanical rotation angle simulated and thermal-mechanical sensitivity tested in the experiment are 2.459 × 10^-3 and 3.322 × 10^-4 rad/K, respectively, generally in good agreement with what the thermal-mechanical model and numerical analysis forecast, which offers an effective reference for FPA structure parameters design in UOIIS.