Study Of Stick-slip Precision Positioner For Micro/Nano-manipulation In SEM

The breakthrough development of the nanotechnology is inspiring people to make it industrialized. Only nanomanufacturing technology can pave the way for nanotechnology applied in practice and benefit the people’s daily life. The industrialization process of nanotechnology is hindered by the difficulties and limits in nanoscale manufacturing, so it is badly in need of the researches in basic field of nanomanufacturing. As1D nanomaterials, the nanowires with significant electrical, mechanics and thermal properties have shown a great potential for application in industry. In recent years, there emerged numerous nanomanipualtion equipments where employed the scanning probe microscope and/or electrical microscope as the manipulation platform. Since the scanning electrical microscope (SEM) is capable of providing real-time observation and spacious working space, integrating kinds of positioners and detection devices, the micro/nano manipulation system based on SEM has become an idea equipment for3D nano manipulation and fabrication.Supported by The National High Technology Research and Development Program of China (863Program) titled “Key issues in typical micro/nano-scale component manipulation”(No.2007AA04Z315), The Major Research Plan of the National Natural Science Foundation of China titled “Cross-scale3D manipulation and interaction techniques for nanostructures and components”(No.90923041), three kinds of stick-slip positioners are developed, with which a micro/nano manipulation system for nano-scale components in SEM is established and3D manipulation methods for nanowires are proposed and achieved. This dissertation focuses on the stick-slip positioner design, dynamics modeling and driving control system.In design of the stick-slip positioners, three kinds of precision positioners are proposed with the principle of the stick-slip driving and the concept of modularization in SEM. The horizontal, vertical and rotary positioning can be achieved by the three positioners with piezoelectric actuators as driving units. For the horizontal and vertical positioners, a plate flexure hinge structure is proposed to generate displacement, with the advantages of miniaturized shape. A symmetrical cross flexure hinge is employed to yield the displacement in the rotary positioner, and it eliminates the motion of rotating axis while improving the load bearing capacity.In dynamics modeling and analysis of stick-slip positioners, three dynamics models of the positioners are proposed. The piezoelectric actuator is identified by the combination of an electric model and a mechanical model which describe the electrical effects and mechanical effects respectively. An equivalent mass and elastic damping are adopted to describe the mechanical effects. A new multistate friction model based on saturation function is proposed to capture some important properties of friction phenomena in the presliding regime. The new model can produce presliding hysteresis with nonlocal memory and cannot produce unbounded positional drift. On three dynamics models, a simulation analysis for precise positioning and step positioning has been conducted. The trend as well as the degree of the parameters’ influence on the displacement loss is obtained and also utilized as the reference to optimize the positioner structures.In design of the driving control system, the driver, the controller as well as the human-machine interface have been investigated. A hybrid controlled driver incorporating with voltage-control mode and current-control mode is proposed, where the fine positioning or step positioning can be achieved by switching two control modes. The stability and thermal diffusion of the driver are calculated and analyzed. A DSP based controller, which integrates a high-speed serial D/A converter module with14-bit resolution, is proposed to generate stick-slip driving signals. The module can have an extension to supply at most6parallel outputs by using the daisy chains between the6extended modules. The human-machine interface of the driving control system is also designed to improve the operating efficiency. The operator can control the stick-slip positioner either by software or by joystick under different conditions.The performance test for the driving control system and stick-slip positioners, as well as fabrication of the needle-shape manipulation tool and nanomanipualtion of nanowires, are carefully carried out and validated. The test for the driving control system is focused on resolution, accuracy, degree of linearity, step response time and full power sawtooth wave response. The test for the proposed stick-slip positioners concentrates on the displacement resolution, minimum step, maximum velocity and load bearing capacity as well. Also, a fabrication system based on electrochemical corrosion method for nanomanipulation probe is achieved. The micro-nano manipulation system in SEM is established by integration of stick-slip positioner and driving control system. After an investigation of the2D and3D manipulation approaches for a single nanowire, a valid3D manipulation method of picking-releasing a single nanowire by the aid of the residual impurity deposit induced by the electron beam in SEM is proposed. The corresponding experiments validate the practicability of stick-slip positioners.