基于热电堆结构的微型热传导真空传感器

Thermopile-Structured Micro Thermal Conductivity Vacuum Sensor

本文描述了一种与CMOS工艺完全兼容的热电堆微型热传导真空传感器。该传感器可在商业化的标准CMOS生产流水线上进行流片,配合后续的无掩模体硅各向异性腐蚀工艺,即可完成全部制造程序。器件敏感部分为124μm×100μm的多层复合薄膜架空结构,其上制作了n型多晶硅加热器、20对由p型多晶硅条和铝条构成的热电堆。利用加热器对复合薄膜加热,在不同的真空状态下,薄膜呈现不同温度,温度值由热电堆转换为温差电动势输出。本文在以下方面进行详细描述:1.器件的结构设计和制造工艺;2.器件的稳态和瞬态有限元分析;3.测试结果与理论分析的对照。结果表明,在加热器1.5V恒压驱动条件下,器件的气压敏感范围为0.1Pa^105Pa(空气),此时热电堆输出电压范围为26mV^50mV,最大响应时间预计为1.4ms。

A novel type of micro-thermal conductivity vacuum sensor has been developed, on the basis of the thermopile structure, and fabricated with commercially standardized complementary metal oxide semiconductor （CMOS） processes. The device consists of the composite sensing multi-layers, 124μm×100μm, in the form of a micro-bridge suspend- ed over the cavity etched on the silicon substrate, a n-type poly-silieon heater,and a thermopile made up of 20 pairs of poly-silicon-aluminum thermocouples. The discussions focused on the following： i） the design and fabrication process; ii） the finite element analysis （FEA） of the steady and transient states of the device;and iii） comparison of the experimental and theoretical results. When resistively heated at 1.5V the experimental results show the pressure sensing ranges from 0.1Pa to 10^5Pa （of air） with a thermopile output of 26mV to 50mV,and a response time around 1.4ms.