An improved anodic bonding process using pulsed voltage technique

In this study, we report a pulsed-voltage technique that is commonly employed in the electroplating industry to achieve a more efficient Si-glass anodic bonding process than the conventional constant electric field process. This technique features a less stringent voltage requirement and a shortened bonding time without compromising the tensile strength of the bonded structure. A square waveform voltage profile is used to investigate the effects of pulsed-voltage profile on the bonding time. In particular, the effects of magnitude of the base voltage and duration of the peak and base voltages are investigated. With peak and base voltages set to 400 and 300 V, respectively, and the duration of each voltage pulse fixed at 10-30 s, the bonding time is reduced to 30% of that required by a constant field process (400 V). Tensile strength of all completely bonded Si-glass pairs prepared by this technique is greater than 15 MPa. A postulated bonding mechanism based on the experimental results is presented.