Anodic Bonding

Anodic bonding is a key technology for silicon glass wafer bonding. A very similar thermal expansion coefficient of the two wafers is required to realize a low-stress wafer bond. Furthermore, a sufficient high concentration of alkali ions is required. These requirements can be fulfilled with borosilicate glasses like Borofloat® and Pyrex®. Nearly defect free bonds can be realized with the aid of special cleaning techniques. Careful tuning of the wafer warpage enables further cleanroom processing. Despite the requirement of a polished surface, even prestructured wafers can be processed.