Characterization of a hydrogenated amorphous silicon microbolometer array

Abstract

We present the characterization of a boron doped hydrogenated amorphous silicon (a-Si:H) thermosensor bolometer array for far infrared detection. The array was fabricated over a silicon wafer on a 0.4 μm silicon-nitride (Si3N4) layer. Wet bulk micromachining was used to create pixels of suspended nitride film by removing the silicon underneath. On this film, a boron doped a-Si:H layer was deposited using a low frequency PECVD system at 540 K. Conventional lithography was used to define the bolometers on the nitride windows, and the 5 x 5 microbolometer array was fabricated and characterized at 77 K. A 1.17 x 10-2 mA/W responsivity, with a temperature coefficient of resistance (TCR) of 4.25%, were obtained.