Realization of ultrafast and high-quality anodic bonding using a non-contact scanning electrode

The anodic bonding technique, which is primarily used in glass to silicon wafer bonding, has been extensively used in microelectromechanical systems (MEMS) for the packaging of microsensors and microactuators. When the bonding voltage is applied, the bonded region instantly occurs at the contact point of the cathode with the glass. The geometric shape or arranged pattern of the cathode electrode significantly affects the bonding quality, particularly the gas-trapping at the bonded interface and the bonding time. This paper presents a novel anodic bonding process, in which the non-contacting and rotating electrode with radial lines is used as the cathode for scan bonding with arc-discharge assistance. The experimental results show that a bonding ratio of 99.98% and an average bonding strength of 15.45 MPa for a 4-inch silicon/glass bonded pair can be achieved in a 17 s bonding time by using a cathode electrode with eight 45 included-angle radial lines at a rotation speed of 0.45 rpm, a non-contact gap of 120 μm, a bonding voltage of 900 V and a bonding temperature of 400 °C. This ultrafast and high-quality anodic bonding has been synchronously realized under this scan bonding technique.