一种两级微桥结构快速测温微型传感器的研制

Investigation on Two-Stage Micro-Bridge Structure of Fast Temperature Measurement Microsensors

设计了一种新型薄膜热电阻温度传感器.传感器感温结构由基片(Si)/绝缘层(SiO_2)/感温部(Pt)组成,Pt薄膜片以悬空的微桥连接方式搭接在SiO_2片上,SiO_2片也以同样的方式搭接在Si片上,以此构成两级微桥机构.较之传统温度传感器,该感温部件采用悬空布置结构可使测温过程中的热损失大为减少,并能保证温度传感器热响应的线性度和可靠性.通过ANSYS有限元软件仿真Pt薄膜片在不同厚度SiO_2片下的温度分布情况.当SiO_2片厚度为2μm,该传感器热响应时间常数达到最小的10 ms,与SiO_2片厚度为5μm和10μm相比其时间常数减小了50%以上.研究结果表明:在温度测量过程中,SiO_2片厚度对感温的Pt薄膜片热损失影响很大,在设计中应尽可能减小SiO_2片厚度.

A thin film temperature sensor of micro electro mechanical systems was constructed. The sensor consists of three parts：substrate（Si）,insulating layer（SiO2）and the temperature sensing unit（Pt）. The Pt thin film sits on the SiO2 layer and the latter sits on the Si substrate by a free-standing micro-bridge strucrure. Thus,a two-stage micro-bridge structure was formed. Compared with the traditional temperature sensor,the temperature sensing unit can greatly reduce heat loss in the process of measuring temperature by using vacant layout structure,and it can ensure the linearity and reliability of thermal response of the temperature sensor. We use the finite element software of ANSYS to simulated the temperature distribution of Pt thin film under different thicknesses of SiO2 film. The time constant of thermal response of the sensor reaches 10 millisecond when the thickness of SiO2 film is 2μm,decreasing by more than 50% compared with that of 5μm and 10μm. The results prove that the thickness of SiO2 film has a great influence on the thermal loss of Pt thin films in the process of temperature measurement. So the thickness of SiO2 film should be reduced as much as possible in the design work.