Study On SPM-Based Nanomachining Related Processing Theory And Techniques

Nanotechnique is one of the novel fields among current techniques, which aims to manufacture products with specific functions in nanometer. Advances in nanomachining technique can lead to significantly improvements in research fields such as micromachine, information storage, microelectronic technique and biotechnique. Scanning probe microscope (including Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AFM)) are becoming regarded as the manipulation technique in nanomachining technique due to its atomic and nanoscaled analytical and nanomachining efficient.Nanomachining mechanism is the key issue in nanomachining technique.Existing results of nanomachining studies based on SPM could fulfill both nanoscaled material removal and nanoscaled machining accuracy, however, there are still problems about the instinct principle of nanomachining mechanism. When the objects are scaled down to the nanometer scale, there are many significant changes in the physics and properties of nanomachining process. It's inaccuracy using the continuum mechanics to describe the nanomachining mechanism ignoring the quantum effect of SPM probe-sample interaction. Quantum physics approach is advantageous to disclosure the nature of nanomachining mechanism. In addition, studyies on material deformation, surface-sbusurface properties and cutting tool-sample interaction of nanomachining process are scarce. To better understand the nanomachined surface accuracy and nanomechanism, more investigations on chip formation and nanomachined surface formation mechanisms are necessary. To solve these problems, density-functional theory is used to simulate the transport mechanism in nanoscale process with first-principle calculation, to disclosure the basic principle of nanomachining process. In addition, nanomachining experiments using scanning probe microscope have been carried out to study the nanomachining mechanism, give theoretical explanation of current namomachining tehnciques, and provide theoretical promotion of novel naomachining methods. The detailed contents of this thesis contain:First-principle calculation of density-functional theory was carried out to simulate SPM scanning process and probe-sample interaction during nanomachining process. The simulations took into account the quantum efforts and analyzed the probe-sample micro-pattern and distributions of their electron clouds. The results provide a basic principle of SPM nanomachining process, and theorticial foundation for future experimental studies.To study the interaction of probe-sample atomics during nanomachining process, STM nanofabrication system using electric-field method was established. And nanofabrication experiments were conducted on Au thin film and crystal silicon to study the STM probe-sample interaction mechanism in the state of atmosphere, to investigate the influences of impulse quantities, current feedback control, current distance on stability of nanofabricated microstructures.Nanoscratching experiments were performed using AFM and Nanoindenter to obtain minimum thickness of scratching data and to determine the critical loads at which scratching tracks initiated. The influences of loading rate and maximum normal load on scratching process and critical load were studied by analyzing the scratching process from elastic recovery to plastic deformation.To further stuy nanoscratching process, scratch resistance of carbon nanotube-typical one-dimension material, was studied using Nanoindenter scratching mode. The radial structure of carbon nanotube was proved to be scratched breakage. The revolution of friction coefficient as a function of normal load helped in identifying the deformation process of carbon nanotubes, from elastic recovery, plastic deformation and finally scratched breakage, and helped in determine the scratch critical load of carbon nanotube. This experimental study brings a new method to study carbon nanotube mechanical properties.Nanomachining experiments using AFM diamond probe were conducted furrowed surfaces to investigate the influences of normal loads, speed, lateral feed, multiple scratching, probe feed direction, sample mechanical properties on removal material, chip formation. The nanomachined surface roughness and chip behaivour were detected by SEM and AFM. The experiment results helped a better understanding to increase the reliability, stability and controllability of this nanomachining technique.