Mechanical Robustness of FPA in a-Si Microbolometer with Fine Pitch

Abstract

Microbolometer array sensors with fine pitch pixel arrays have been implemented using amorphous silicon supported by two contact pads. Simple beam test structures were fabricated and characterized for the purpose of designing a focal plane with geometrical flatness. As the beam length decreased, the effect of beam width on the bending was minimized. Membrane deformation of focal plane in a real pixel showed downward curvature by residual stress of a-Si and Ti layer. The tilting deformation was caused by the misalign effect of contact pad and confirmed by FEA (Finite Element Analysis) simulation results. The electro-optical properties of bolometer have been measured to be noise equivalent temperature difference (NETD) = 145 mK, temperature Coefficient of Resistance (TCR) = −2 %/K, and thermal time constant = 1.99 ms.

Keywords

• Microbolometer
• Amorphous silicon
• IR sensor
• Residual stress