Design And Fabrication Of A Novel Triaxial Micro-accelerometer

Acceleromer, as one type of the inertial sensors, plays a very important role ininertial measurement and navigation systems. And accelerometers have found widelyapplications in various fields of aerospace, marine, aviation, land navigation, etc.Recently, triaxial micro accelerometers have gained more and more attention andbecome one of the hottest research topics, due to some special advantages. Because itcan not only detect different oriention input acceleration, but also has the virtures ofsmall size, low price and so on.In this paper, a new capacitive triaxial micro-accelerometer was proposed which isbased on the groundwork of study about the micro-gyroscope and micro-accelerometer.Based on what we have done, the research work mainly focuses on the optimized designof the sensitive structure, the fabrication process and the detect circuit technology. Theexperiment result shows that the micro-accelerometer is exsert. Subsequent researchcontents are included in this dissertation.1. Structure design. Starting from the basics theory of micro-accelerometer design,the materials of the production, the detection methods, as well as the theoretical modelof the accelerometer are introduced. Thereout the overall structure of themicro-accelerometer is designed and then the ralation between sensitivity, frequencyand structure parameters of the micro-accelerometer is analyzed. In this paper, theresearch work mainly focuse on structure optimised design, anchors distribuction andthe fabrication of on-chip capacitors. In order to achive design goal, the key structureparameters of the micro-accelerometerthe are determined and theoretical analysis andFinite-Element-Modeling (FEM) are carried out.2. Fabrication techniques. According to the technics level of laboratory and thestructural characteristics of the accelerometer, wet etching technology is uesd tomanufacture the accelerometer. The entire fabrication flow includes wafer procedure,glass procedure, bonding, and packaging technology.3. Circuitry design. The basic principle and implementing method of lowcapacitance measuring are studied. In order to detect the variation of the capacitanceinduced by input acceleration, the capacitive detective circuit aer performed, whichmainly contains the hardware and software based on the core chips of C8051F411、andcapacitive detect chip AD7745. Furthermore, the program of collectting data iscompiled using the software LabWindows.4. Capability testing. The better micro-accelerometer sample is selected out afterthe primary testing, and then the choosen micro-accelerometer is testing farther whichincludes sensitivity detection、stability detection and precision detection. The testingoutcome shows that the micro-accelerometer is so good that can detect the acceleration of gravity with the biggest error3.5%.