硼掺杂工艺对微加速度计性能的影响

发布时间：2018-03-05 19:57

本文选题：微加速度计　切入点：硼掺杂　出处：《电子科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：微加速度计作为微惯性测量组合(MIMU)的核心元件,具有小型化、低能耗、高精度、高集成度等优点。本文所研究的叉指式加速度传感器是各类加速度计产品中的代表,在强势的市场需求牵引和高新技术推动下,叉指式加速度计的设计和研制已经成为MEMS领域研究热点之一。为了提高硅片的电学性能以及提供腐蚀的高选择性,微加速度计的加工采用基于浓硼掺杂的自停止腐蚀技术,硼原子代替硅原子的掺杂工艺会产生晶格失配现象,导致表芯结构发生翘曲现象,梳齿之间的间距和正对面积会产生变化,从而改变微加速度计的检测电容。此外,深反离子刻蚀(DRIE)工艺的工艺误差会使折叠梁的实际宽度小于设计宽度,梁的刚度会发生改变,从而影响微加速度计的输出。当同时考虑掺杂工艺引起的结构变形以及DRIE刻蚀工艺引起的结构误差,微加速度计的静电刚度、灵敏度、零位等性能指标的分析将变得更加复杂。本文主要研究内容有:1.建立微加速度计表芯结构的多层等效模型,计算出每一个可动梳齿在敏感方向上的收缩量以及厚度方向的翘曲值。并根据结构变性特点,推导硼掺杂表芯的电容表达式以及微加速度计的灵敏度随掺杂深度的变化趋势。2.考虑硼掺杂和DRIE工艺误差的共同作用,建立质量块平移的力学模型,求出质量块的整体位移并推导出两种非理想因素共同作用下微加速度计的静电刚度、灵敏度和零位的解析表达式。结果表明:质量块的平移随折叠梁误差的增大而增大,当梁误差e最大值为0.3μm时,质量块平移达到最大值7.93nm。3.利用有限元分析软件COMSOL MUTIPHYSICS,仿真分析了硼掺杂的微加速度计梳齿电容和灵敏度;随后建立硼掺杂与梁误差同时作用的表芯模型,仿真分析差分电容以及灵敏度、零位输出等性能指标,同时与理论计算结果对比。
[Abstract]:As the core component of MIMUU, micro accelerometer has the advantages of miniaturization, low energy consumption, high precision and high integration. The cross finger accelerometer studied in this paper is the representative of all kinds of accelerometers. In order to improve the electrical properties of silicon wafers and provide high selectivity for corrosion, the design and development of cross finger accelerometers have become one of the research hotspots in the field of MEMS due to the strong market demand and high technology. The micro-accelerometer is fabricated by self-stopping etching technology based on concentrated boron doping. The doping process of boron atoms instead of silicon atoms will produce lattice mismatch and lead to the warping of the surface core structure. The distance between carding teeth and the positive area will change, which will change the detection capacitance of the micro-accelerometer. In addition, the error of deep counterion etching technology will cause the actual width of the folded beam to be smaller than the design width, and the stiffness of the beam will change. Therefore, the output of microaccelerometer is affected. The structural distortion caused by doping process and the structural error caused by DRIE etching process, the static stiffness and sensitivity of microaccelerometer are considered. The analysis of zero position and other performance indexes will become more complicated. The main contents of this paper are: 1. To establish a multi-layer equivalent model of micro-accelerometer core structure. The shrinkage of each movable comb in the sensitive direction and the warping value in the thickness direction are calculated. The capacitance expression of boron doped table core and the variation trend of sensitivity of micro-accelerometer with doping depth are derived. Considering the interaction of boron doping and DRIE process error, the mechanical model of mass block translation is established. The integral displacement of mass block is obtained and the analytical expressions of electrostatic stiffness, sensitivity and zero position of micro-accelerometer under the action of two kinds of non-ideal factors are deduced. The results show that the translation of mass block increases with the increase of the error of folding beam. When the beam error e is 0.3 渭 m, the mass block translation reaches the maximum value of 7.93 nm.3.The combing capacitance and sensitivity of boron doped micro-accelerometer are simulated and analyzed by using the finite element analysis software COMSOL MUTIPHYSICSs. Then the core model of boron doping and beam error is established, and the differential capacitance, sensitivity, zero output and other performance indexes are simulated and analyzed, and the results are compared with the theoretical results.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH824.4

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