多尺度硅悬臂梁吸附的理论模型

发布时间：2018-07-02 22:16

本文选题：NEMS + 多尺度　；参考：《东南大学》2015年博士论文

【摘要】：纳电子机械系统(NEMS)是纳米科技的一个分支。由于纳米技术的特征,纳电子机械系统相较于微电子机械系统有以下几个主要的优点：品质因数高,频率高,功率低以及尺寸和质量很小,因而纳米悬臂梁在传感器的应用方面有着很好的发展前景,得到了国内外的广泛重视。单晶硅是微电子机械系统中的重要材料,硅具有优质的力学特性和热学特性,并且具有极好的集成电路制造兼容性,因而以硅为衬底的纳米悬臂梁是纳电子机械系统中最具有代表性的悬臂梁之一。当硅悬臂梁表面吸附粒子时,吸附效应会使得硅悬臂梁本身的特性发生改变。当硅悬臂梁在宏观尺度范畴内时,可以用经典的连续介质理论来进行特性分析,而当硅悬臂梁在纳米尺度范畴内时,连续介质理论不再适用,从头算方法和第一原理模型的计算量大,就现阶段而言很难实现,因此,建立一种相对简单精确的理论模型是十分必要的。本论文以半连续体理论为基础,运用能量法,从基本的粒子间作用力出发,建立了多尺度硅悬臂梁吸附的理论模型。本论文的主要内容如下：(1)发展了水分子吸附多尺度硅悬臂梁的理论模型。首次考虑了本征氧化层对多尺度硅悬臂梁特性的影响,以半连续体理论为基础,运用能量法,从基本的粒子间作用力出发,为多尺度硅悬臂梁的特性分析提供了简单有效的理论基础。运用分子动力学模拟的方法对多尺度硅悬臂梁吸附的理论模型进行分析,将理论值和模拟值相比较,验证了该理论模型的正确性。(2)建立了不同分子吸附多尺度硅悬臂梁的理论模型,首次研究了吸附分子不同对多尺度硅悬臂梁特性的影响。建立了甲烷分子吸附多尺度硅悬臂梁的理论模型,并和水分子吸附多尺度硅悬臂梁的理论模型进行了比较,进一步探索了不同分子吸附多尺度硅悬臂梁的理论模型。(3)建立了吸附层不同时多尺度硅悬臂梁的理论模型,讨论了吸附层不同对多尺度硅悬臂梁特性的影响。建立了金吸附层多尺度硅悬臂梁的理论模型,并和铝吸附层多尺度硅悬臂梁的理论模型进行了比较,进一步探索了吸附层不同时多尺度硅悬臂梁的理论模型。(4)考虑了不同的吸附分子和吸附层对多尺度硅悬臂梁特性的影响,建立了多尺度硅悬臂梁吸附的理论模型,并讨论了硅层厚度和本征氧化层厚度对多尺度硅悬臂梁特性的影响。本论文建立的理论模型可以得到多尺度硅悬臂梁吸附分子后的曲率半径、自由端位移量、表面应力等物理参数,运用分子动力学模拟的结果验证了本文模型的正确性。本文建立的多尺度硅悬臂梁吸附的理论模型对硅基NEMS的研究和设计有一定的参考价值。
[Abstract]:Nanoelectronic mechanical system (NEMS) is a branch of nanotechnology. Because of the characteristics of nanotechnology, nanoelectromechanical systems have the following main advantages over microelectromechanical systems: high quality factor, high frequency, low power, and small size and mass. Therefore, nano-cantilever beam has a good prospect in the application of sensors, and has been widely paid attention to at home and abroad. Monocrystalline silicon is an important material in microelectromechanical system. Silicon has excellent mechanical and thermal properties and excellent compatibility of integrated circuit manufacturing. Therefore, the nanocrystalline cantilever beam with silicon substrate is one of the most representative cantilever beams in nanoelectromechanical systems. When the particles are adsorbed on the surface of the silicon cantilever beam, the adsorption effect will change the characteristics of the silicon cantilever beam itself. When the silicon cantilever beam is in the macro scale, it can be analyzed by the classical continuum medium theory, but when the silicon cantilever beam is in the nanometer scale, the continuum medium theory is no longer applicable. The ab initio method and the first principle model have a large amount of computation, so it is very difficult to realize at the present stage. Therefore, it is necessary to establish a relatively simple and accurate theoretical model. Based on the semicontinuous theory and the energy method, a theoretical model for the adsorption of silicon cantilever beams with multi-scale is established based on the basic interparticle forces. The main contents of this thesis are as follows: (1) the theoretical model of multi-scale silicon cantilever beam adsorbed by water molecules is developed. The effect of intrinsic oxide layer on the characteristics of multi-scale silicon cantilever beam is considered for the first time. Based on the semi-continuum theory, the energy method is used to analyze the basic interparticle force. It provides a simple and effective theoretical basis for the characteristic analysis of multiscale silicon cantilever beam. The theoretical model of multi-scale silicon cantilever adsorption was analyzed by molecular dynamics simulation, and the theoretical value was compared with the simulated value. The validity of the theoretical model is verified. (2) the theoretical model of different molecular adsorbed multi-scale silicon cantilever beam is established, and the influence of different adsorbed molecules on the characteristics of multi-scale silicon cantilever beam is studied for the first time. The theoretical model of multi-scale silicon cantilever for methane adsorption was established and compared with that for water molecule adsorption. The theoretical model of multi-scale silicon cantilever beam adsorbed by different molecules is further explored. (3) the theoretical model of multi-scale silicon cantilever beam with different adsorption layers is established, and the influence of different adsorption layers on the characteristics of multi-scale silicon cantilever beam is discussed. The theoretical model of gold adsorption layer multi-scale silicon cantilever beam is established and compared with that of aluminum adsorption layer multi-scale silicon cantilever beam. The theoretical model of multiscale silicon cantilever beam with different adsorption layers is further explored. (4) considering the influence of different adsorption molecules and adsorption layers on the characteristics of multi-scale silicon cantilever beam, a theoretical model of multi-scale silicon cantilever beam adsorption is established. The effects of the thickness of silicon layer and the thickness of intrinsic oxide layer on the characteristics of multiscale silicon cantilever beam are discussed. The theoretical model established in this paper can obtain the physical parameters such as radius of curvature, displacement at free end, surface stress and so on. The results of molecular dynamics simulation verify the correctness of the model. The theoretical model of multi-scale silicon cantilever beam adsorption has some reference value for the research and design of silicon based NEMS.
【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1;O647.3

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