MEMS气体传感器微热板芯片热均匀性设计及性能

Thermal Uniformity Design and Performance of MEMS Gas Sensor Micro-Hotplate Chip

基于微电子机械系统(MEMS)技术的气体传感器具有灵敏度高、尺寸小、响应速度快、功耗低等优点,成为下一代半导体气体传感器的重要发展方向,其中敏感氧化物材料的温度均匀性对其探测灵敏度、选择性和可靠性均有重要影响。聚焦MEMS气体传感器中的核心微热板芯片的设计,通过热学分析和物理场有限元仿真,设计了一种等温热区占比90%的微热板芯片,有效解决了MEMS气体传感器中微小芯片内大面积均匀加热问题。在此理论基础上,设计了两款微热板芯片结构并进行了表征。实际测试结果显示温度-功耗曲线与仿真结果一致,在372℃工作温度下,方形薄膜结构的微热板芯片单位面积功耗仅为2.8×10^(-4)mW/μm^(2),但圆形薄膜结构的微热板芯片温度分布更均匀,两种设计的工作温度均可以达到370℃以上。受限于低温成膜工艺,该微热板芯片薄膜的最大应力仅为1500 MPa左右,这为后续优化设计提升工作温度和降低功耗提供了一定参考。

Gas sensors based on micro-electromechanical system(MEMS)technology have the advantages of high sensitivity,small size,fast response speed and low power consumption,and become an important development direction of the next generation semiconductor gas sensors.The temperature uniformity of sensitive oxide materials has an important effect on its detection sensitivity,selectivity and reliability.By focusing on the design of the core micro-hotplate chip for MEMS gas sensor,a micro-hotplate chip with isothermal hot zone accounting for 90%was designed through thermal analysis and physical finite element simulation,effectively solving the problem of large area uniform heating within the micro-chip in MEMS gas sensors.Based on the theory,two kinds of micro-hotplate chip structures were designed and characterized.The actual test results show that the temperature-power consumption curves are consistent with the simulation results.At 372℃working temperature,the power consumption per unit area of the micro-hotplate chip with a square thin film structure is only 2.8×10^(-4)mW/μm^(2),while the temperature distribution of the micro-hotplate chip with a circular thin film structure is more uniform,and the working temperature of the two designs is higher than 370℃.Limited by low temperature thin film forming process,the maximum stress of the micro-hotplate chip thin film is only about 1500 MPa.This provides a certain reference for the subsequent optimization design to increase working temperature and reduce power consumption.