Electrostatic force detection during anodic wafer bonding

This paper proposes a novel in situ monitoring method for anodic wafer bonding by measuring the evolving electrostatic force between the wafers during the bonding process. The genuine principle of the developed method is based on the direct detection of the electrostatic force compressing the wafers by measuring the resultant displacement of a proper silicon membrane structure. The membrane deformation is to be determined from the capacitance change of the structure formed by the flexible silicon and the fix metal electrode. In contrast to other experimental methods not only the resulted bonding strength could be studied posterior, but the entire process by this continuous in situ measurement. The methodology could significantly facilitate the comprehension of physical phenomena of the bonding process in correlation to the parameters (temperature, voltage bias, time) and establishing optimal conditions for particular structure development.