Papers by Keyword: Polishing Mechanism

Abstract: Single sapphire crystal is an important optical element and semiconductor substrate material, widely used in industry, national defense and scientific research, etc. But, high hardness and good chemical stability of the sapphire make it hard to be polished by applying mechanical chemical polishing and other contact methods. Therefore, laser polishing will be one of polishing methods which are supposed to replace contact method polishing sapphire. This essay, based on the summary of the study on laser polishing mechanism and technique of processing sapphire by laser, from the perspective of the interaction mechanism of the laser and the substance, analyzes in theory the interaction of laser and sapphire during the sapphire is polished by the short-wavelength laser. Experiments proved that under the cases of 20mJ and 40mJ laser energy when green laser polishes sapphire, the main material removal mechanism is fracture, at the same time, light melt mechanism exists.

Abstract: This paper studies the polishing mechanism of SiC optic surface; it also introduces the grinding mechanism of ceramic material – indentation fracture model. In this paper, the model of SiC polishing in ideal condition is analyzed and the mechanism of SiC polishing in real state is studied.

Abstract: Chemical mechanical polishing (CMP) has been a widely applied process for nickel-phosphorus (Ni-P) coating hard disk substrate polishing. In this study, colloidal silica-based alkaline slurry was prepared for polishing Ni-P plated substrates and its CMP mechanism was studied with alkali slurry. Effects of the various process parameters such as polishing pressure and plate speed on hard disk substrate were investigated. The results show that the polishing pressure and plate speed have a strong influence on the material removal rate and surface roughness of the hard disk substrate. The oxidization layer formed on hard disk substrate surface after polishing. The nickel ions were bounded with amidocyanogen to form stable and soluble macromolecular amidocyanogen-complex agent, improved selectivity of convex region and concave region, enhanced the chemical reaction uniformity and the mass transfer velocity, and thus high removal rate and low surface roughness could be realized.

Abstract: Sapphire (α-Al2O3) single crystal, as an important photoconducting device substrate material, stringent surface quality requirements, i.e. surface finish and flatness, are required. The use of chemical mechanical polishing (CMP) technique can produce high quality surface finishes at low cost and with fast material removal rates. The polishing mechanism was studied in this paper, and it was pointed that there were chemical and mechanical kinetics process respectively. The chosen polishing temperature was 40 oC. SiO2 sol was chosen as abrasive and the particle size is 40nm. The pH value was determined at 11.5~12. During CMP process C6382I-W/YJ single side polisher and SUBA 600 pad were used. After polishing and cleaning of sapphire surface, the measured removal rate was above 183.3nm /min and the surface roughness by using AFM was lower than Ra 0.3 nm. From the results, it was found that using such method, the optimal sapphire surface can be gotten, which is advantaged for epitaxial growth and device making-up.

Abstract: A gelatin stone having a new polishing mechanism that can polish a free-form surface is proposed in this study. The gelatin based stone can easily control the hardness and the melting point by changing the density, the cooling condition and the kinds of additives. The main conclusions obtained in this study are as follows. The proposed gelatin stone can polish the surface of various materials. The high density of gelatin is suited for a gelatin stone. Surface roughness improves as the polishing time gets longer. Polishing by gelatin stone needs a high-speed relative motion.