【作者】 刘方；

【导师】 于军；

【作者基本信息】 华中科技大学 ， 半导体芯片系统设计与工艺， 2007， 硕士

【摘要】 准确地对流体中的剪切应力进行测量,在微流控系统、工业流程控制、生物医学应用等许多领域里都有着重要的意义。基于MEMS技术的剪切应力传感器技术是最有前景的一种技术,其中,热剪切应力传感器最易于加工并集成化。本文应用有限元分析软件,模拟和分析四种不同(硅片、玻璃、空气腔及真空腔)基底的热场分布,得出结论,采用玻璃基底真空腔结构时,绝热效果最好;并用ANSYS对热剪切应力传感器的流体热场、压力场、速度场以及剪切应力本身进行模拟分析。设计了适合实验室加工的硅基热剪切应力传感器以及玻璃基热剪切应力传感器,提出了采用背面开口制作真空腔,并用铂取代多晶硅作电阻,采用铝作牺牲层,改进了剥离工艺,制作出铂电极最小线宽50μm,厚度100nm的基于玻璃和硅基底的热剪切应力传感器。对完成制作的器件进行了电阻温度系数的标定,测得其值为0.00257/℃,并测试了它们的稳态电热特性,其V-I、P-T曲线表明,在相同工作条件下,玻璃基底的热剪切应力传感器向基底传输的热量明显小于硅基底,更适合于加工热剪切应力传感器,这一结论很好的验证了前面的模拟结果。更多还原

【Abstract】 The accurate measurement of wall shear stress is of vital importance to a broad application spectrum, such as micro-fluidic control, industrial process control and biomedical applications. As one kind of MEMS-based sensors, which are considered as the most promising techniques for measuring wall shear stress, thermal shear stress sensor can be fabricated and integrated easily.This paper used FEA (finite element analysis) method to simulate thermal field of four different (silicon, glass, air cavity and vacuum cavity) substrates, and concluded that the glass substrate with a vacuum cavity has the most effective characteristic of thermal insulation. Meanwhile, the thermal field, pressure field, velocity field, and shear stress of the flow was analyzed using ANSYS. The process for the fabrication of silicon-based shear stress sensor and glass-based shear stress sensor were designed to fit with the conditions of our lab well; the scheme of back-side vacuum cavity and substituting poly-silicon resister with Pt were proposed; Using aluminum as the sacrifice layer, the Lift-Off process was improved; Finally, the glass-based and silicon-based thermal shear stress sensor, whose Pt electrodes had the minimum width 50μm and thickness 100μm, were fabricated successfully. The TCR (temperature coefficient of resistance) of Pt film was tested at 0.00257/℃, and their steady electro-thermal characteristics were also studied. Their V-I and P-T curves showed that the sensor with glass substrate had greatly reduced the heat transferred to the substrate, which testified the above simulation results.更多还原