Residual stress analysis of anodic aluminum oxide thin films for infrared emitter device application

Abstract

Infrared scene projector (IRSP) is a tool for evaluating IR sensors by projecting virtual IR images from the IR mitter array. IR sensor assessment using IRSP is time and cost-effective, and it is safer than field-testing conducted by observing the actual weapon system in operation. Two important performance parameters of the IRSP are maximum apparent temperature and operating speed. While the apparent temperature can be increased by increasing the input power, the operating speed of the IRSP is limited by the thermal rising time, which is determined by the structural dimension and constituent material of the IR emitter device. To improve the operating speed of the device, materials with higher thermal conductivity and low heat capacity must be used. The emitter device has a suspended structure; therefore, a suitable material should be chosen. In this paper, the application of anodic aluminum oxide (AAO) is proposed as a material for the emitter device. The proposed AAO is suitable for high temperature operation owing to its mechanical strength and high melting point (~2345 K).Its higher thermal conductivity and porous structure, which lead to heat capacity reduction, can shorten the thermal rising time and operate in high speed. Before applying AAO to the IR emitter device, the residual stress of AAO thin film is analyzed by changing the fabrication conditions of the thin film to solve membrane deformation problem in the device fabrication process based on the FEA simulation.