The Study of Micro-Electro-Mechanical System (MEMS) Technology for Sensor and RF Inductor Applications

• Main Authors: Ming-Chun Hsieh, 謝明君
• Other Authors: Yean-Kuen Fang
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/67463795207585154449

博士 === 國立成功大學 === 電機工程學系碩博士班 === 92 === 　　In this dissertation, we report the study of Micro-electro-mechanical system (MEMS) technology for sensors, including, shear-stress sensor, far infrared sensor and RF inductor applications. The Finite Element Method (FEM) package ANSYS has been employed for the thermal isolation, stress distribution, impact force and temperature distribution analysis. 　　Firstly, we study the preparation of prototype contact type micro piezoresistive shear-stress sensor that can be utilized to measure the shear stress between skin of stump and socket of Above-Knee (AK) prosthesis. MEMS technology has been chosen for the design because of the low cost, small size and adaptability to this application. The Finite Element Method (FEM) package ANSYS has been employed for the stress analysis of the micro shear-stress sensors. The sensor contains two transducers that will transform the stresses into an output voltage. The piezoresistive strain gauges were implanted with boron ions. Static characteristics of the shear sensor were determined through a series of calibration tests. In addition, the results simulated by FEM are validated by comparison with experimental investigations. 　　Next, we report the design, fabrication and performance of a novel crystal SiGeC infrared sensor with wavelength 8-14mm for portable far infrared ray (FIR) in rehabilitation system application. The operation principle of the sensor is based on the change of thermistor’s resistance under the irradiation FIR light. The thermistor in the IR detector is made of Si0.68Ge0.31C0.01 thin films for its large activation energy and the temperature coefficient. Finite Element Method (FEM) package ANSYS has been employed for analyze of the thermal isolation and stress distribution in the IR detector. In addition, a comparison between the detectors both with and without the micro-bridge structure has been made in order to verify the improvement of the thermal isolation and lowering of the thermal conductance owing to the micro-bridge structure. The complete process and measured thermal conductance, thermal time constant and the heat capacity of developed FIR sensor have been described in detail. 　　Finally, we study the design, fabrication and comparison various geometry of deep sub-micron high Q suspended spiral on chip inductors. In the design, finite element program, ANSYS, were used for electrical-characteristics, maximum endurable impact force and thermal conduction simulations, respectively. Based on the design, suspended 10-turns spiral inductor with different air cavity structures, i.e., diamond opening, circle opening, triangle opening and full suspended with pillar supports were developed for different applications. Among these structures, the suspended inductor with pillar support possesses the highest Qmax (maximum of quality factor) of 6.6 at 2 GHz, the least effective dielectric constant of 1.06, and the lowest endurable impact force 0.184 Newton. On the other hand, the spiral inductor with diamond opening has a lowest Qmax of 4.3, the largest effective dielectric constant of 3.44 and highest endurable impact force 4 Newton. The former is suitable for station telecommunication applications in which the mechanical vibration is not a serious concern, while the latter can be used for mobile telecommunication applications subject to strong mechanical vibrations. Additionally, the conventional on-chip spiral inductor embraced by SiO2 with a dielectric constant of 4 was prepared for comparison and found its Qmax is 3.8 at 1.2 GHz. 　　Moreover, the impact force, the maximum allowable operating current of inductors with various structures, including planar spiral inductor, square solenoid inductor, inclined solenoid inductor, and stacked spiral inductors have been simulated and compared.