一种用于薄膜热容测量的微热量计的设计与制作

Design and fabrication of microcalorimeter for measuring heat capacity of thin films

目前已发现并证实薄膜的热导率和热扩散率存在着尺寸效应。本文为了研究薄膜的另一个热学性质比热是否也具有尺寸效应 ,提出了一种用于薄膜热容测量的新方法 ,其相应的实验器件为一悬膜结构。从理论上阐述了其测量原理 ,结合ANSYS热学模拟设计并利用微机械加工技术制作出SiO2 悬膜结构 ,悬膜由两个悬臂支撑 ,在悬膜上制作了Pt薄膜电阻同时用于加热和测温。这种结构加快了样品、悬膜和加热 /测温电阻之间的热传递 ,减小了悬膜的热损失 ,提高了测量精度。

The size effects on the thermal conductivity and the thermal diffusivity of thin films have been discovered and proved by many experiments. In order to investigate the specific heat of thin films, a new ac method for measuring heat capacity of thin films is proposed in this paper, using a floating membrane as the measurement structure. The measurement method was theoretically analyzed. The floating membrane structure was designed according to the thermal simulation results of ANSYS. The membrane of silicon oxide supported with two arms was fabricated by surface and bulk micromachining, with platinum thin film made as the heater as well as the thermometer on the floating membrane. The measurement structure has high precision for the quick heat transfer among sample, floating membrane and platinum thin film and slow heat transfer between membrane and substrate.