【作者】 刘丽；

【导师】 陈维友；

【作者基本信息】 吉林大学 ， 微电子学与固体电子学， 2008， 博士

【摘要】 本文提出和设计了一种硅基共平面型微结构气体传感器,它具有与硅平面工艺和传统厚膜工艺均能实现兼容的特点,采用理论模拟和实验相结合的方法对该种微传感器的结构和版图进行了优化和验证。首先,利用有限元分析软件Ansys对微型气体传感器中的一个重要的组成部分--微热板进行了设计与分析,通过对微气体传感器的版图进行模拟,初步设计了尺寸均为3.6×1.2mm2的Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型结构版图。其次,通过实验研究了分别以Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型结构版图制作的传感器对乙醇的敏感特性,发现它们的功耗较高,进而对微传感器进行了优化,设计出了尺寸分别为2×1mm2和2×0.5mm2两种新结构的微型传感器版图,分别称为Ⅴ型和Ⅵ型结构版图。再次,实验研究了以La0.7Sr0.3FeO3为敏感材料基于Ⅴ型结构的Ⅴ型乙醇气体传感器,对于500ppm乙醇气体,元件的响应与恢复时间约为1.5秒和2.5秒,灵敏度约是8.2,加热功耗为261mW。实验研究了以掺杂的SnO2为敏感材料分别制作了Ⅴ型和Ⅵ型CO气体传感器,对50ppm CO,Ⅴ型CO微传感器的响应与恢复时间分别为5秒和22秒,灵敏度约是8.6,加热功耗约为82mW;Ⅵ型CO微传感器响应与恢复时间分别为17秒和30秒,灵敏度约是11.2,加热功耗约为39mW。本文还,设计制作了一种利用光功率计测量微热板表面温度的系统,该系统能够精确地完成微区(50×50um2)温度的测量,解决了微热板及其它微小器件表面温度的测量难题。更多还原

【Abstract】 Gas sensors play important roles in air quality control, industry and healthcare as well as security, and they are also very important to measure the flammable and poisonous gases. Recently, microstructure gas sensors, which are based on“Micro-Electro-Mechanical Systems (MEMS)”, have gain special interesting due to their compact size, low power consumption, ease of use, and low cost, et al. And they have also proved to be propitious to the integration, intelligentize, multimode function, reliability, and stability of the gas sensors.In this paper, we report the design of micro-heating plate (MHP), which is a part and parcel of microstructure sensor. MHP is simulated by using a finite element analysis method using the software of Ansys. The materials, layouts are studied in detail to improve our microstructure sensor.There are two structures of MHP: membrane-structure and suspending-structure. The suspending-structure MHP owns better stabilization due to the low heat-convection below the MHP. However, the distance between central area and the substrate must be less than the thickness of the chip, thus high technics need to spend on it. In contract, membrane-structure MHP owns our focus due to its easy achievement. In our studies, MHP has been simulated through a finite element analysis method using the software of Ansys. Si and SiO2 are chosen as the substrate and the insulated layer respectively, because of the benefit of heat-convergence and consumption-reduction of the sensor. The heater, signal electrodes are designed on the same plane to avoid the signal cross-talk of the current.We simulated the width, the space between, and the layout of our samples. The idle state is the temperature in the center of MHP is uniformity, which is very import for sensing materials to work. The temperature on the edge of MHP should be low, for the low power consumption of the sensor.Based on our simulations, the performance of sensor, whose width of heater Pt strip, signal Pt strip, space between heater and signal strip is separate 50μm, 50μm, and 25μm, is superior to the other designs. Its central temperature distribution is comparatively even and the power consumption is comparatively lower.We have designed four abecedarian layouts (Ⅰ,Ⅱ,Ⅲ, andⅣ) in our studies. However, the resistance of the heater and the power consumption are found to be high. Subsequently, two new layouts are designed based on our experimental results, the size of them are 2×1×0.253mm and 2×0.5×0.25mm3, respectively. And they are designated as layoutⅤand layoutⅥin this paper.LayoutⅤhas been studied by loading La0.7Sr0.3FeO3 as the sensitive material. The sensor show high sensitivity towards to ethanol: the sensitivity can reach 8.2 to 500 ppm ethanol, the response time and recovery time are 1.5 and 2.5 s, respectively. The power consumption of the sensor is 261 mW, which is 2/3 of the consumption of the sintered sensor.LlayoutⅤandⅥhave also been studied by loading the CO sensing material of doped SnO2. The sensitivity of typeⅤsensor is 8.6 to 50 ppm CO (2.5 times larger than that of sintered sensor), the response time and recovery time are 5 and 22 s, respectively. The power consumption is 82 mW (1/4 of sintered sensor). The sensitivity of typeⅥCO sensor is 11.2 to 50 ppm CO (3.2 times larger than that of sintered sensor), the response time and recovery time are 17 and 30 s, respectively. The power consumption is 39 mW (1/5 of sintered sensor).In conclusion,these novel microstructure gas sensor possess some good gas sensing properties, such as low power consumption, high sensitivity, quick response-recovery. Also, it can avoid the parasitic electric field between heat and signal electrode that are called“sandwich”structure, makes the process technique simple, and enhances the whole performance.Additionally, a temperature measurement based on radialization power for micro-hotplate is designed in our studies. By means of comparing the relation between the radialization power and the temperature, sample surface temperature can be accurately discerned. The experimental result based on this method is quite similar to that of simulation results obtained by Ansys in theory. This measurement is very useful for measuring temperature for these micro samples prone to be untouchable.更多还原