热应力对非制冷红外焦平面微桥的影响及控制研究

Study on Effect of Thermal Stress on Microbridges of Uncooled IRFPA and Controlling Methods

非制冷红外焦平面阵列的微桥结构在微加工工艺中,由于温度的剧烈变化,在薄膜中产生热应力而引起微桥的变形,将对器件产生不利影响。利用有限元分析方法,对微桥在热应力作用下产生的变形进行了分析,提出了两种控制热应变的途径:1)选择一种低热膨胀系数、低杨氏模量的电极材料;2)在电极材料的表面沉积一层SiNx薄膜。仿真结果表明,两种途径使微桥的最大形变值从1.4740μm分别减小到0.4799μm和0.0704μm,达到了减小热应变的目的。

In the micro-fabrication process of microbridges of uncooled infrared focal plane arrays（IRFPA）,the microbridges are deformed by the thermal stress in thin films due to the acute temperature changes.Such deformation is harmful to the devices.The deformation of the microbridges is analyzed and two ways to control the deformation are presented： 1） choosing a better electrode material which has a lower thermal expansion coefficient and smaller Young modulus;2） adding another SiNx thin film on the surface of electrode.Results indicate that by using above two ways,the deformation can be efficiently reduced from 1.4740 μm to 0.4799 μm and 0.0704 μm respectively,the aim of controlling the deformation is achieved.