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A study on phenemona induced by nano-particle motion upon work surface¡Geffects of particle rigidity and geometryCheng, Chih-jen 19 July 2005 (has links)
The surface phenemona in polishing process induced by nano-particle was studied in this thesis. The properties of particle, rigidity and geometry, are forced. A perfect polished surface includes lower roughness and thinner damage layer. Besides a perfect surface, how we get higher rate of remove is also an important thing. The goal is to get the relation between induced surface phenomena and properities of nano-particle. The M.D. (Molecular Dynamic) simulation is uesed in this thesis. The specicaly lowered integral timestep is second for simulating the rigidity of nano-particle with saving simulation time and geting accurate in simulation results. In order to simuate the nano-particle rigidity and adhesive effects between nanoparticle and work surface, the modified potential function is used. Considering the types of nano-particle motion which are pure rolling and sliding, the different geometric shapes are used .
In the results of simulation about the rigidity of particles, the phenomena induced by rolling particles and rigidity don¡¦t have apparent correlation. For sliding particles, the lower rigidity and lower thick damage layer was. However, if the rigidity is too weak to hold the particle geometric shape, the damage layer thickness is larger. In the results of simulation about particle shapes, the sliding particle with larger front angle will indcue deeper damager layer. It¡¦s because the more workpiece atoms could move to the bottom or rear of the particles to make more damaged atoms. If the length of particle bottom be increased, the interactive behavior between particle and work surface would become more violently to make deeper damaged layer. The rolling particle with scraggy surface can cohere more atoms than the ball particle even in the lower adhesive coefficient, but induced roughness will be higher .
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The Damage Layer Produced in Ion Bombarded SiliconReid, Ian 08 1900 (has links)
In this thesis a study is made of the damage layer (as defined by its solubility in a HF-H2o2, or concentrated HF solution) produced by ion bombardment of Si. This thesis is concerned with not only the layer but also its usefulness in the study of radiation damage itself. The layer is examined with respect to the adverse effects it has upon the anodic oxidation and stripping technique, to the dose of incident ions required to produce it (ie the threshold dose), and to its relationship to the amorphous layer which has been observed with ion bombardment of Si. Annealing of the damage has been approached from two points of view. First the temperature dependence of the threshold dose is used to obtain information about the annealing of the damage that occurs between the formation of a discrete damage zone and the formation of a layer. Secondly using gas release of the radioactive Kr85 the annealing of the fully formed amorphous damage layer is followed. The solubility of the damage layer in a HF-H2o2 solution is shown to be a very useful tool in the study of radiation damage. Firstly it provides a convenient means of obtaining the mean range of the damage distribution as a function of incident ion energy. Secondly it is used to obtain the threshold dose for the formation of the damage layer, and thirdly it is used in the gas release experiments to give more detailed information about the Kr85 motion. / Thesis / Master of Science (MS)
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