【作者】 胡振江；

【导师】 董申；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2007， 博士

【摘要】 随着纳米技术的发展,微纳米系统、微纳米尺度零件及相关产品的需求越来越多。无论是微机电系统零件加工,还是微纳米器件制造,都离不开微纳米尺度的微结构加工技术。传统的微结构加工技术,普遍存在某一维度精确自动控制能力差的问题,只能实现二维或准三维的微结构加工。并且它们都不具备加工检测一体化的能力。因此亟需研究一种具备加工检测一体化功能的三维微结构加工技术。扫描探针显微技术的发明,极大地促进了纳米技术的发展。随着科学技术的不断进步,人们越来越多地将其应用于微观世界的改造方面:将AFM(Atomic Force Microscope)金刚石探针模拟为一个尖锐的单点金刚石车刀,以机械刻划去除材料的方式在扫描探针显微镜的高精密操控下对样品进行微纳米尺度下的微结构加工。应用现有的AFM扫描成像功能进行微结构刻划加工,只能实现平面二维加工量的精确控制。在刻划深度方向,目前还不具备精确的自动控制能力:现有的AFM系统在对样品进行刻划加工时,刻划驱动与刻划深度之间的控制方式是开环的,刻划深度不仅与驱动有关,还与样品材料性质、微悬臂等效弹性系数等有关。这种控制方式对刻划深度是无法实现精确自动控制的。弹性微悬臂探针系统是AFM进行微观三维形貌检测的根本;同时,正是由于微悬臂探针系统的弹性性质,造成了刻划加工深度精确控制方面的困难。如何解决这一矛盾,实现具备加工检测一体化能力的三维微结构加工系统,是基于AFM进行微结构机械刻划加工过程中摆在我们面前的一个全新课题。基于AFM系统,设计相应的辅助控制单元,并深入研究AFM弹性微悬臂探针在微结构刻划加工中的刻划深度形成规律,进而实现刻划深度的实时检测与闭环自动控制,是解决这一矛盾的有效途径。本文从相应理论、刻划加工系统组建及刻划加工实验等方面入手,深入研究了基于AFM的微结构机械刻划加工过程中刻划深度控制技术,以多学科交叉应用的手段初步建立起基于AFM可控三维微结构刻划加工技术应用体系。具体研究内容包括如下几个方面:从AFM三维微结构刻划加工过程分析入手,辅助其它驱动控制单元,应用材料力学的相关理论,深入分析微悬臂探针系统在刻划加工时刻划深度与AFM相应系统的对应关系,找到刻划加工过程中刻划深度的实时检测方法,为刻划深度的闭环控制奠定基础;应用微纳米塑性力学相关理论,对微悬臂探针压入材料样品形成压入深度的过程进行分析,研究压入深度对应于压入驱动的形成规律,建立压入驱动与压入深度之间的对象模型。并应用自动控制相应理论,设计优化相应的控制器及控制算法,实现压入深度的闭环控制。应用有限元仿真手段,研究微悬臂探针对样品刻划加工时刻划深度的变化规律,由此制定出刻划过程中刻划深度的控制方案,最终实现刻划加工全过程的刻划深度闭环精确控制;结合AFM及三维微动工作台,应用计算机及微处理器技术研制相应辅助控制装置,组成刻划深度自动闭环控制的三维微结构加工检测一体化加工系统。应用该加工系统,实现设定深度的三维微结构加工,并进一步研究三维连续曲面及复杂曲面的三维微结构刻划加工。更多还原

【Abstract】 With the development of nanotechnology, the requirements for micro/nano system, micro/nano scale components and associated products have become more and more. Either the fabrication of MEMS (Micro Electro Mechanical Systems) components, or the manufacturing of micro/nano devices, the machining techniques in micro/nano scale are necessary for these fabrications. However, the conventional methods always are restricted by the control accuracy in some dimension during constructing the microstructure. As a result, only the two-dimensional or quasi-three-dimensional structures can be realized. Moreover, these fabrication methods all have no on-line or on-site measuring abilities. Thus, to construct an ideal method including fabrication and measuring to fabricate the three dimensional microstructure is significant urgent. The invention of scanned probe microscopy technology leads to the considerable progress of nanotechnologies. And now this technology is extensively used to modify the micro world, i.e. that the scanning tip is used as a tool to fabricate the micro structure under the control of the high accuracy AFM(Atomic Force Microscope) system. Moreover, due to the measuring capability for 3D topographies and no special limitations to work piece material and machining condition, this technology is therefore a perfect method to fabricate 3D microstructures.However, based on the commercial AFM system, the fabricated structures are always 2D. This is because there is no precision controlling in the scratching depth. When the scratching is carried out on the AFM system, the control mode between the scratching activation and scratching depth is open loop. As well known, the scratching depth is dependent on the activation, the properties of sample and the equivalent elastic coefficient. And thus, this mode has no access to control the scratching depth accurately.AFM works through an elastic cantilever which can undergo the elastic deformation freely corresponding to the surface topographies. The elasticity enabling of the cantilever results in the difficulty in depth controlling. Therefore, how to realize the scratching and measuring integrated system has been a challenging subject for the fabrication of 3D microstructure via AFM. In terms of the application state based on AFM, a promising way is to design the associated assistant controller and discover the forming rule of scratching depth so as to provide the real time inspection and closed-loop control for the scratching depth. From the viewpoint of the related theory, construction of scratching system and scratching experiments of this technique, the control technology of scratching depth during fabrication of microstructure with AFM is studied in-depth in this thesis. Then the control-enable scratching machining system based on AFM is established by using the means from multi-disciplines. The detailed contents are listed as follows:Through the analyses for the machining process of 3D microstructures by AFM scratching and the application of the theory of material mechanics, the relationship between the scratching depth of the tip and AFM system is analyzed. Resultantly, the executing method about real time detection during scratching is determined, which acts as a foundation for the closed loop control of scratching depth.By application of the micro/nano plastic mechanics, the indenting and depth forming processes using the diamond tip of AFM cantilever on the sample’s surfaces are analyzed. And then the forming rule of scratching depth corresponding to the scratching driving is investigated to set up the object model. And in terms of the automatic control theory and the optimized design of controller and control algorithm, the automatic and accurate closed-loop control for scratching depth is realized. Moreover, the variation rule of scratching depth is investigated through finite element simulations, in which the control scheme for scratching depth is determined. Finally, the accurate and closed loop control system for scratching depth is realized.The associated assistant control equipments are developed by using the computer and microprocessor techniques. The machining system integrated with AFM and 3D high precision stage, is established, which can perform the fabrication and measuring procedures and enables the scratching depth to be controlled automatically and accurately. Based on this setup, the fabrication of 3D microstructures with a design depth is carried out. Moreover, the 3D microstructures characterized with the continuous curved faces or other complicated faces all can be fabricated.更多还原