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为了简化制作工艺,使温度分布均匀以及降低功耗,设计了一种基于MEMS制造工艺的悬臂共面式SnO2气体传感器.使用有限元法对这种传感器及膜结构堆积于硅基底上的封闭膜式气体传感器进行了稳态热分析,结果表明悬臂共面式传感器拥有更均匀的温度分布和更低的功耗.当最高温度为383℃时功耗仅为7mW,敏感薄膜上的温差低于14℃.为解决悬臂易碎的问题,提出了一种新的制造工艺,该过程在正面刻蚀SiO2层形成悬臂结构前沉积SnO2敏感薄膜,并采用深反应离子刻蚀的方法对硅基底进行体刻以避免湿法刻蚀对传感器表面的化学污染.整个过程总共需要4块掩模板.采用旋涂法溶胶凝胶法将掺有Fe离子的SnO2薄膜沉积于基底上作为敏感元件.该器件对氢气表现出了良好的气敏性能,随着氢气浓度从50×10-6上升到2000×10-6,灵敏度逐渐提高,在2000×10-6时的灵敏度为30.
In order to simplify the manufacturing process, make the temperature distribution more uniform and reduce the power consumption, a cantilever coplanar SnO2 gas sensor based on MEMS manufacturing process was designed.The finite element method was used to simulate the sensor and membrane structure deposited on the silicon substrate The steady state thermal analysis of the gas sensor showed that the cantilever coplanar sensor has a more uniform temperature distribution and lower power consumption.When the maximum temperature is 383 ℃, the power consumption is only 7mW, the temperature difference on the sensitive film is less than 14 ℃ .To solve the problem of the cantilever friability, a new manufacturing process was proposed, in which a SnO2 sensitive thin film was deposited before the SiO2 layer was etched to form a cantilever structure, and the silicon substrate was subjected to deep reactive ion etching In order to avoid chemical contamination of the sensor surface by wet etching, a total of 4 masks are required for the whole process, and the SnO2 thin film doped with Fe ions is deposited on the substrate as a sensitive element by a spin-on method sol-gel method. Hydrogen gas showed good gas sensitivity, with the hydrogen concentration from 50 × 10-6 to 2000 × 10-6, the sensitivity gradually increased, at 2000 × 10-6 when the sensitivity of 30.