The analysis of oxygen plasma pretreatment for improving anodic bonding

The oxygen plasma surface treatment of silicon and glass was studied for improving the characteristics of anodic bonding. By contact-angle measurements, we calculated the surface energy which is the sum of polar and dispersion components. The results showed that oxygen-plasma-induced distinctive high-polar and low-dispersion characteristics and caused the total surface energy to increase even at low power or short plasma exposure times for both silicon and glass surfaces. The highly polar-component-induced surface was maintained for over 100 days. On increasing plasma power and exposure time, it was observed that surface roughness increased. The oxygen plasma treatment was significantly efficient to reduce the contaminants on the surface, which was the main factor in degrading bonding strength and electrical properties of the interface. In the tensile test, the oxygen plasma treatment led to higher bonding strength than a conventional anodic bonding method. (C) 2001 The Electrochemical Society.