物理尺寸对MEMS皮拉尼真空计性能的影响

发布时间：2018-05-02 13:12

  本文选题：MEMS皮拉尼真空计 + 硅电阻温度关系　； 参考：《中北大学》2014年硕士论文

【摘要】：真空封装是很多MEMS器件正常工作和提高器件性能的必要保障，因此微型真空腔体的气压值测量和检测就成为一项重要的研究课题。MEMS皮拉尼真空计不仅具有灵敏度高和测量范围宽等优越性能，而且体积小、重量轻、热响应迅速等优点，并且采用标准体硅工艺，便于与其它MEMS器件相集成。本研究小组提出了一种体硅微热缝隙式MEMS皮拉尼真空计，具有高深宽比、双热沉结构等结构特点。本论文设计并制备了具有不同物理尺寸的MEMS皮拉尼真空计，包括不同电阻条长度、宽度、厚度以及电阻条和热沉间隙。基于气体热传导的微观原理和详细测试实验，系统分析研究了这些物理尺寸对器件性能的影响。 本文分析研究了物理尺寸对加热体电阻的影响。随着长度的增加、宽度和厚度的减小，实测电阻均大幅度地增加。大长度、小宽度和厚度以及大间隙结构的实测电阻值与设计值偏差较显著，这主要是由于光刻、深刻蚀等因素引起的结构尺寸偏差造成的。采用四线法测量电阻，测试分析了硅加热体的电阻温度特性。结果显示，在室温至215℃范围，电阻随温度上升不断上升，其中在120℃以上，表现出良好的线性。 本文测量了器件在不同真空度下的温度响应时间。在1.275mA的小电流下，在全气压范围内，除宽度为10μm和15μm的器件，其它器件的加热体温度在10秒内即可稳定。宽度为10μm和15μm的器件，仅在10-3Pa下需要30s达到温度稳定，而在其它气压下，也仅需10s以内。说明MEMS皮拉尼真空计具有快速响应的特点。 本文对标准结构器件的真空度传感性能进行了详细测试分析。在2Pa至55.14Pa区间，电阻随气压降低而显著增加，形成高灵敏传感区，其灵敏度SmH为259.23Ω/In(Pa)。在0.021Pa至2Pa区间，电阻随气压降低而持续增加，形成低灵敏传感区，其灵敏度SmL为125.00Ω/In(Pa)。当气压小于0.021Pa时，电阻值增长缓慢，但仍具有一定的线性度，此段的平均灵敏度为19.87Ω/In(Pa)。当气压高于100Pa时，灵敏度很低。因此，标准结构器件的测量范围为0.021Pa至55.14Pa。 本论文系统研究了不同物理尺寸对于器件真空度传感性能的影响。结果显示，增加长度、减小宽度和厚度均可显著提升器件在测量范围内的灵敏度，其中减小宽度和厚度的提升效果更加明显。与标准结构器件相比，将宽度减小40%，器件的SmL和SmH分别增加了198.5%和165.5%；将厚度减小50%，器件的SmL和SmH分别增加了118.8%和101.0%。随着电阻条与热沉间隙的改变，，器件测量范围基本没有变化。但是可以通过缩短长度和增大加载功率来获得更宽的传感范围。
[Abstract]:Vacuum packaging is the necessary guarantee for many MEMS devices to work properly and improve their performance. Therefore, the measurement and detection of pressure value of micro vacuum cavity has become an important research topic. MEMS Pilani vacuum gauge not only has the advantages of high sensitivity and wide measurement range, but also has the advantages of small volume, light weight, rapid thermal response and so on. The standard bulk silicon process is used to facilitate the integration with other MEMS devices. In this paper, a new type of bulk silicon micro-heat gap MEMS Pilani vacuum gauge with high aspect ratio and double heat sink structure is proposed. In this paper, a MEMS Pilani vacuum gauge with different physical dimensions is designed and fabricated, including the length, width, thickness, resistance strip and heat sink gap of the resistor strip. Based on the microscopic principle of gas heat conduction and the detailed testing experiments, the effects of these physical dimensions on the performance of the device are systematically analyzed and studied. In this paper, the effect of physical size on the resistor of heating body is analyzed and studied. With the increase of length and the decrease of width and thickness, the measured resistance increases greatly. The large length, small width and thickness, and the deviation between the measured resistance value and the design value of the large gap structure are significant, which is mainly caused by the structure dimension deviation caused by lithography, deep etching and other factors. The resistance temperature characteristics of silicon heater were measured by four-wire method. The results show that from room temperature to 215 鈩

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