Method of Equivalent Electrical Circuit for Point Cathode Electric Field Assisted Anodic Bonding

Electric field assisted anodic bonding is one of the most frequently used techniques in the field of MEMS,but the physical and chemical mechanism involved in it is not clear yet,and papers concerning this are few.Deep understanding of the mechanism of the anodic bonding process will be helpful to the improvement of the technique.In this paper,effects of point cathode anodic bonding are theoretically investigated by using electrical circuit analog.The bonding current,incubation period and intimate contact area are calculated.By taking into account the influence of the depth of glass in the anodic bonding,Anthony's result is improved and formula for the incubation period proposed.The results show that the current decays rapidly at early stage during anodic bonding and then decreases slowly; there is generally an incubation period for the anodic bonding,and the incubation period falls off exponentially as the bonding temperature is raised; the intimate contact area spreads nonlinearly with time.The front of intimate contact area spreads more and more slowly,and the intimate contact area increases faster and faster with bonding time,until 100% intimate contact is achieved.