Research On Replication Mechanism Of Diamond Micro-machine Components

Micro-machine with small size,high precision,stable performance and mass production could be applied in the field of industrial automation,biomedical,information and aerospace.Due to the high friction coefficient and low thermal conductivity of silicon material,micro-machine with silicon-based material could not be used in the hard environments with high-speed,corrosion resistance,wear resistance and bio-compatibility.In these hard environments,diamond has been considered to be the ideal micro-machine material for replacing the silicon because of their unique properties of low friction coefficient,high thermal conductivity,corrosion resistance and bio-compatibility.Hence,the fabrication technology of diamond micro-machine component becomes an important topic of concern in industry and science.In this dissertation,an research idea about the fabrication of diamond micro components by the replicas from silicon microstructure molds and CVD.At first,the masks of micro-hole array,cross array,groove array and gear have been designed by standard photolithographic process.Then,the corresponding silicon microstructure molds have been fabricated by Bosch deep silicon etching in ICP system.Finally,the diamond micro components have been deposited in the corresponding silicon mold cavity by HFCVD.Based on the fabrication mechanism research of silicon microstructure molds,the preparation technology and mechanism of several typical diamond micro components were focused on.The size consistency of component were discussed,a new way on the industry production of diamond micro components was explored.The main work and the results obtained in this dissertation are as follows:(1)The mechanism of Bosch etching was analyzed at first,then the dimension manufacturing errors of silicon micro hole and cross arrays were investigated,finally,mass fabrication technology of silicon microstructure mold was explored.It is showed that the silicon micro hole and cross arrays with fine morphology are achieved by the optimal etching process and the undercut and footing effect is not observed obviously.(2)The mechanism of diamond deposition and filling the mold cavity was analyzed at first,and the corresponding processes were explored.The diamond micro hole and cross arrays without hollow structure defect and completely filling the silicon mold are fabricated successfully by the optimal depositing process.The investigation of SEM,XRD and Raman shows that the micro and nano diamond component could be achieved by adjusting the deposition process.(3)Based on the successful fabrication of diamond micro cylinder and cross arrays,the diamond micro beam array were fabricated by the same process.The formation mechanism of diamond micro beam residual stress was analyzed,and the corresponding processes of residual stress were explored.It is showed that the macro strain and stress of diamond components can be reduced effectively by controlling the deposition condition of HFCVD and the cooling process of multiple annealing stages,reducing the deformation of diamond micro beam.(4)The research on the fabrication process of the double layer complex shape components was carried out.Diamond single micro gear and double-linked micro gear are successfully prepared,which is the research and technical basement of diamond micro mechanical transmission component preparation in the future.The thickness of each layer of the diamond double-linked gear is more than 10 μm.(5)The size consistency between the diamond micro cylinder,cross,beam,gear and the corresponding silicon microstructure molds was investigated in depth.It is showed that the relative size error between diamond component and silicon mold is less than 2%.Therefore,the diamond micro components could keep good size consistency quality with the silicon microstructure molds through effective controlling the deposition process,although the deformation of components should be caused by diamond growth stress,induced by the difference of thermal expansion coefficient between the silicon and diamond the component.