Study On Chemical Mechanical Polishing Of Hard And Brittle Crystal Substrates

In chapter one, the application of the hard and brittle crystal substrates?A plane sapphire and ceramic glass substrates? was summarized. The surface of the hard and brittle crystal substrates should be smoother. The smoother surface can be obtained by polished, but chemical mechanical polishing?CMP? is the only way to provide global planarization.In chapter two, chemical mechanical polishing was done on A plane sapphire by using nano-Al₂O₃ as abrasive. The effects of the concentration of Al₂O₃, the particle size of Al₂O₃, polishing time, polishing pressure and the concentration of NH₄ F on the material removal rate?MRR? and the surface roughness?Ra? of A plane sapphire were studied. The surface roughness was measured by Atomic Force Microscopy?AFM?. The results showed that the following condition: the particle size of Al₂O₃ is 50 nm, 1wt.% Al₂O₃, polishing time is 40 min, polishing pressure is 16.39 kPa, 0.6wt.%NH₄F, pH=4.0, MRR=18.2nm/min, Ra=22.3 nm.In chapter three, F-doped ?-Al₂O₃ was successfully synthesized by aluminum nitrate as raw materials by the sol-gel method. The effect of the fired temperature and the amount of fluoride on the phase composition of the prepared powders were investigated by X-ray diffraction?XRD?. It was found that the gel can be transformed into ?-Al₂O₃ completely at 1100?, and no weak phase was found in the alumina powders, the high purity ?-Al₂O₃ could be obtained. On the other hand, the characteristic peaks of ?-Al₂O₃ shift to the left while adding NH₄ F which can certify that the fluoride was doped into the crystalline phase of ?-Al₂O₃. Furthermore, fluorine was detected in the alumina powders by XRF. Chemical mechanical polishing experiments were done on glass ceramics substrates by using the F-doped ?-Al₂O₃ as abrasive. The results showed that the material removal rate and the surface roughness could attain 89.3 nm/min and 1.9 nm, respectively.In chapter four, the effects of the concentration of abrasive, pH, the flow rate of polishing slurry, the rotate speed, the kinds of surfactant and the concentration of NH₄ F on the material removal rate and the surface roughness of the ceramic glass were investigated by CeO₂ slurry. The surface roughness of the glass ceramics substrates before and after being polished was characterized by atomic force microscope. The experimental results showed that the MRR could reach 183.57 nm/min and the Ra could reach 0.70 nm when the concentration of CeO₂ is 3%, the flow rate of slurry is 25 m L/min, the rotate speed is 100 r/min, pH=8.0, the concentration of SDS is 0.01%, the concentration of NH₄ F is 0.7%.In chapter five, The effects of the species and the concentration of complexing agent, the kinds of oxidant, the species and the concentration of lubricant on the material removal rate and the surface roughness of the glass ceramics substrates were investigated. The surface roughness of the glass ceramics substrates before and after being polished was characterized by atomic force microscope. The experimental results reveal that the MRR could reach 72.8 nm/min and the Ra could reach 0.12 nm under the following CMP conditions: polishing rotation speed is 100 r/min, polishing liquid is 25 m L/min, the down pressure force is 9.4 kPa, pH=8, the mass fraction of SiO₂ is 8%, the mass fraction of EDTA is 0.2%, the mass fraction of glycerol is 0.2%, and the mass fraction of oxidant??NH₄?2S2O8? is 0.2%.