Papers by Author: Sheng Li Wang

Abstract: Chemical mechanical polishing (CMP) has been a widely applied process for hard disk substrates with nickel–phosphorous (Ni–P) plated. In this paper, the effects of abrasive and surfactant on the polishing performance of hard disk substrates using prepared colloidal silica-based alkaline slurry were investigated. The experimental results indicate that the material removal rate (MRR) strongly depends on the abrasive concentration and nonionic surfactant have little influence on the material removal rate. Under the testing conditions, smaller SiO₂, moderate SiO₂ concentration and higher surfactant concentration can obtain high surface quality in the prepared slurry. These results have been explained by which the abrasive particles move through the cover layer caused by surfactant adsorption on the disk substrates surface being polished.

Abstract: Chemical mechanical polishing (CMP) is the effective technology which obtains high accuracy surface of hard disk substrate with nickel-phosphorus (Ni-P) coating. The slurry is significant factor in hard disk substrate CMP. Colloidal silica-based alkaline slurry was prepared based on negative pressure vortex method. The effects of slurry parameters such as abrasive concentration, organic alkali concentration and oxidant concentration on material removal rate and surface characteristics were investigated. The experimental result indicated that the abrasive concentration was 20wt%, the slurry pH value was 11.2, the oxidant concentration was 15ml/L, improved surface roughness and polishing efficiency of hard disk substrates, a smooth surface was obtained and micro scratches could hardly be observed.

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: Chemical mechanical polishing (CMP) has become an essential technique in advanced ULSI process. The mechanism of Ta CMP is discussed in this paper. According to the physical and chemical properties of Ta, the alkaline polishing slurry and proper process parameters for Ta CMP are prepared. The paper optimized four key parameters-abrasive concentration, organic alkali, oxidant and surfactant concentration, obtained the comprehensive optimized slurry used in evaluating the removal rate using Taguchi method. The results indicate that: abrasive concentration is 10%, the organic alkali concentration is 15ml/L, the oxidant concentration is 10ml/L and the surfactant concentration is 10ml/L, higher removal rate can be obtained.

Abstract: Chemical mechanical polishing (CMP) of copper films in alkaline slurries was investigated. In the copper CMP, the slurry was made by adding colloidal silica abrasive to de-ionized water.The organic alkali was added to adjust the pH, H2O2 was used as an oxidizer.The effects of varying polishing temperature, polishing pressure, slurry flow rate, organic alkali concentration and oxidizer concentration on removal rate were investigated in order to determine the optimum conditions for those parameters. It is shown the chemical composition of the slurry was 2%~3% oxidizer concentration, 3% organic alkali concentration and proper amount surfactant is reasonable. The solid concentration of the polishing slurry was fixed at 20% by weight. The removal rate of copper could reach 700nm/min and the surface roughness after CMP was 0.49nm.