【作者】 王璐；

【导师】 温殿忠；

【作者基本信息】 黑龙江大学 ， 微电子学与固体电子学， 2010， 博士

【摘要】 脉诊是中医学中最具特色的诊断方法,具有简便、可靠、无创伤等优点。随着现代科学技术的飞速发展,用科学的方法采集、处理脉象信息,成为脉诊为患者提供疾病客观信息的重要手段,而脉象传感器的设计和制作是脉诊客观化研究的基础。本文采用MEMS技术、CMOS工艺和激光加工技术,设计并制作了硅杯和悬臂梁两种结构的以纳米硅／单晶硅异质结为源极和漏极的MOSFETs脉象传感器,该脉象传感器具有体积小,重量轻、灵敏度高、温度特性好等优点,能够实现对微小脉象信号的准确检测。作为脉象传感器的应用,本文研制了纳米硅／单晶硅异质结MOSFETs脉象检测系统,并阐述了采用人工神经网络处理脉象检测结果的方法。在理论分析的基础上,本文设计了纳米硅／单晶硅异质结MOSFETs脉象传感器的力敏结构,确定了衬底材料、硅膜厚度、MOSFET沟道电阻在硅膜和悬臂梁上的位置。在硅杯的长方形硅膜上和悬臂梁上分别设计四个纳米硅／单晶硅异质结p-MOSFET,以p-MOSFET的沟道电阻做为力敏电阻,并将四个p-MOSFET沟道电阻构成惠斯通电桥结构。当硅膜和悬臂梁受到脉搏压力作用时,其内部MOSFET沟道电阻的改变使惠斯通电桥输出电压发生变化,可以实现对脉搏压力的检测。本文在n型<100>晶向双面抛光单晶硅片上,分别制作了硅杯和悬臂梁结构的纳米硅／单晶硅异质结MOSFETs脉象传感器芯片,给出了制作工艺和MOSFETs脉象传感器芯片照片。为了解决现有硅悬臂梁刻蚀工艺中存在的刻蚀速度和刻蚀质量等问题,本文研究了激光加工技术与MEMS技术相结合制作硅悬臂梁的方法,使硅悬臂梁的制备更加简洁、快速、精准,有效克服了传统悬臂梁释放时存在的削角问题,也为其他微结构的制备提供了高质量的激光刻蚀方法。本文对制备的纳米硅／单晶硅异质结p-MOSFET的特性、硅杯式纳米硅／单晶硅异质结MOSFETs脉象传感器的静态特性、悬臂梁式纳米硅／单晶硅异质结MOSFETs脉象传感器的特性,以及硅杯式纳米硅／单晶硅异质结MOSFETs脉象传感器的温度特性等四个方面,给出实验结果如下：在不受外加压力作用时,对纳米硅／单晶硅异质结p-MOSFET的电学特性进行测试分析,并对纳米硅／单晶硅异质结p-MOSFET在-20℃-60℃的温度范围内进行高低温实验。实验结果表明,纳米硅／单晶硅异质结p-MOSFET的沟道电流IDS随温度变化很小,而且随着温度的升高沟道电流IDS的变化量减小。四个纳米硅／单晶硅异质结p-MOSFET的沟道电阻都随着温度的增加而略有变小。分别采用恒压源和恒流源两种供电方式对硅杯式纳米硅／单晶硅异质结MOSFETs脉象传感器进行标定,传感器外加压力量程0～160kPa。实验结果给出,采用恒压源供电时,纳米硅／单晶硅异质结MOSFETs脉象传感器的灵敏度随着供电电压的增加而增加,当供电电压为-5.0V时,灵敏度为0.6517mV/kPa,准确度为2.343%F.S；采用恒流源供电时,纳米硅／单晶硅异质结MOSFETs脉象传感器的灵敏度随着供电电流的增加而增加,当供电电流为1.000mA时,灵敏度为0.6381mV/kPa,准确度为2.281%F.S。对悬臂梁式纳米硅／单晶硅异质结MOSFETs脉象传感器的特性进行测试,实验结果给出,在一定的振动频率下,悬臂梁的加速度越大,传感器的输出电压越大；在一定的加速度下,振动频率越高,传感器的输出电压越大。在不同温度下,对硅杯式纳米硅／单晶硅异质结MOSFETs脉象传感器的温度特性进行测试。实验结果表明,在恒压和恒流两种供电方式下,纳米硅／单晶硅异质结MOSFETs脉象传感器的灵敏度都随着温度的降低而升高。本文给出纳米硅／单晶硅异质结MOSFETs脉象传感器的应用实例,介绍了纳米硅／单晶硅异质结MOSFETs脉象检测系统的总体设计方案和各功能模块的设计方法,并给出MOSFETs脉象检测系统的实测结果。本文还阐述了利用人工神经网络中的误差反向传播神经网络和概率神经网络对脉象检测结果进行分析,判别妇女是否怀孕的方法。这种方法有别于单纯对脉形进行分类的分析方法,其优势在于只凭借妇女的脉形特征参量,就能够准确判断该妇女是否怀孕,为今后采用科学方法分析人体脉象信息的研究奠定了基础。综上所述,基于MEMS技术研制硅脉象传感和检测系统的方案可行,同时具有集成化和大批量生产的特点,对脉诊客观化研究具有重要意义。更多还原

【Abstract】 Pulse diagnosis is the most characteristic diagnosis method in traditional chinese medicine, which has the advantages of convenient, reliable and non-invasion. With the rapid development of the modern science and technology, collecting and processing information by scientific methods is an important means of pulse diagnosis providing objective information of diseases for patients. The design and fabrication of the pulse sensor is the objective research foundation of pulse diagnosis.The pulse sensors of the silicon cup and the cantilever beam structures have been designed and fabricated by using MEMS, CMOS and laser processing technologies, in which the nc-Si/c-Si heterojunction has been used as the source and drain of the MOSFETs. The pulse sensors can detect the tiny pulse signal accurately, which is small size, light weight, high sensitivity and good temperature characteristics. As the application of the pulse sensors, the nc-Si/c-Si heterojunction MOSFETs pulse detecting system has been fabricated. The methods of processing the pulse detecting results by using artificial neural network have been presented.On the basis of theoretical analysis, the force-sensitive structures of the nc-Si/c-Si heterojunction MOSFETs pulse sensors have been designed. The substrate material, the thickness of the silicon film, the position of the MOSFET channel resistance on the silicon film and cantilever beam have been determined. Four nc-Si/c-Si heterojunction p-MOSFETs have been designed on the rectangular silicon film of the silicon cup and the cantilever beam. The p-MOSFETs whose channel resistance has been used as force-sensitive resistance have been designed in a Wheatstone bridge configuration. When the silicon film and the cantilever beam are stimulated by the pulse pressure, the MOSFET channel resistance on the silicon film and the cantilever beam changes, and the output voltage of the Wheatstone bridge changes with the MOSFET channel resistance. Therefore, the pulse sensors can detect the human pulse.The nc-Si/c-Si heterojunction MOSFETs pulse sensor chips based silicon cup and cantilever beam have been fabricated on the n-type,<100> crystal orientation, double-side polished silicon wafer. The fabrication process and the photographs of the MOSFETs pulse sensors chips have been presented. To solve some problems of etching rate and quality in the etching technology for silicon cantilevers, a method which combines laser processing technology and MEMS technology is adopted to fabricate silicon cantilevers. The method makes the fabrication of silicon cantilevers simple, rapid and accurate, which avoiding the convex corner undercutting in etching of cantilevers. This study also provides a laser etching method for the fabrication of other microstructures.The characteristics of the fabricated nc-Si/c-Si heterojunction p-MOSFET, the static characteristics of the nc-Si/c-Si heterojunction MOSFETs pulse sensor based silicon cup, the characteristics of the nc-Si/c-Si heterojunction MOSFETs pulse sensor based cantilever beam and the temperature characteristics of the nc-Si/c-Si heterojunction MOSFETs pulse sensor based silicon cup have been studied, and the experimental results are as following.The electrical characteristics of the nc-Si/c-Si heterojunction p-MOSFET has been studied under the conditions of the applied pressure P=0, and the high and low temperature experiments of the nc-Si/c-Si heterojunction p-MOSFET in temperature range from-20℃to 60℃have been studied. The experimental results show that the channel current IDS of the nc-Si/c-Si heterojunction p-MOSFET has little change with temperature, and the variable quantity of channel current IDs decreases with increasing temperature. The channel resistance of the four nc-Si/c-Si heterojunction p-MOSFET slightly decreases with increasing temperature.The nc-Si/c-Si heterojunction MOSFETs pulse sensor based silicon cup has been experimentized using the constant voltage and the constant current power supply respectively, and the applied pressure range of the sensor is 0-160kPa. The experimental results show that the sensitivity of the nc-Si/c-Si heterojunction MOSFETs pulse sensor increases with the increasing of the supply voltage under the conditon of constant voltage power supply, the sensitivity is 0.6517 mV/kPa and the precision is 2.343 %F.S with-5.0V power supply; the sensitivity of the nc-Si/c-Si heterojunction MOSFETs pulse sensor increases with the increasing of the supply current under the conditon of constant current power supply, the sensitivity is 0.6381 mV/kPa and the precision is 2.281% F.S with 1.000mA current supply.The characteristics test of the nc-Si/c-Si heterojunction MOSFETs pulse sensor based cantilever beam has been studied. The experimental results show that the output voltage of sensor increases when the acceleration of the cantilever beam increases at a constant vibration frequency; the output voltage of sensor increases when the vibration frequency increases at a constant acceleration.The temperature characteristics test of the nc-Si/c-Si heterojunction MOSFETs pulse sensor based silicon cup has been studied at different temperatures. The experimental results show that the sensitivity of the nc-Si/c-Si heterojunction MOSFETs pulse sensor increases with decreasing temperature under the conditions of constant voltage and constant current power supply.The application example of the nc-Si/c-Si heterojunction MOSFETs pulse sensor has been presented. The general scheme of the nc-Si/c-Si heterojunction MOSFETs pulse detecting system and the design methods of the function modules have been presented. The detecting results of the MOSFETs pulse detecting system has been presented.The error back propagation neural network and the probabilistic neural network in artificial neural network have been used to process the detecting results of pulses, which can distinguish the pregnant woman. The method is different from the classification of pulse, whose advantage is accurately distinguishing the pregnant woman by the pulse characteristic parameters of the woman. The research will establish the foundation for the study on the human pulse information by scientific methods.To sum up, the fabrication method of the silicon pulse sensing and detecting system by MEMS technology is feasible. It is easy to be integrated and produced in a large scale. The study has great significance for the objective research of pulse diagnosis.更多还原