Black alumina, which has a dense microstructure, was successfully fabricated using various additives. For the application of black alumina to LCD photo device material, a low reflectivity with a dense microstructure is required as well as proper insulation resistivity. In particular, a high light absorption coefficient showing low reflectivity of below 10% is necessary for the commercial use of black alumina in photolithography. In this study, TiO2, Fe2O3, and MnO2 were used as coloring agents, and MgO and SiO2 were used for densification through liquid phase sintering. The effects of the sintering temperature and atmosphere were investigated with the influence of additive content. MnO2 had a strong influence on the black color of the alumina, and SiO2 worked as an effective additive for liquid phase sintering with liquid formation by the eutectic reaction with Fe2O3 and Al2O3. The fabricated black alumina showed an 8% reflectivity and 3.94 g/cm(3) sintering density. Other properties such as flexural strength, thermal expansion coefficient, and insulation resistivity were also approached to the suitable properties of the material for chuck plate in LCD photo process.

Keywords: Black alumina; Reflectivity; Microstructure; MnO2; Liquid phase sintering