Super Smooth Modification of Al2O3 Ceramic Substrate by High Temperature Glaze of CaO–Al2O3–SiO2 System

The rough surface of ceramic substrate is an obstacle for the scale down of line-width for thin film passive integrated devices (PID). In this paper, a modification method for Al 2 O 3 ceramic substrate with super smooth in surface was proposed. Coating a layer of CaO–Al 2 O 3 –SiO 2 (CAS) glass was performed to flat the rough surface of alumina substrate by sol–gel method. It was found that addition of 0.06% V 2 O 5 can inhibit the recrystallization of the glaze. The root-mean-square (RMS) roughness of the glazed substrates reached a surprising flatness as small as 0.5 nm, and its melting temperature is higher than 1300 °C. This substrate with super flatness and high temperature endurance may be promising for high performance thin film devices.