Effect of silicon oxide, silicon nitride and polysilicon layers on the electrostatic pressure during anodic bonding

Abstract

The quality of the anodic bonding between glass and silicon wafers coated with silicon oxide, silicon nitride and polysilicon layers has been investigated. We have used an electrostatic test to study the effect of these layers on the quality of the bond. The electrostatic test shows how the electrostatic pressure decreases with the increase of the thickness of the silicon oxide layer. In the bonds with silicon wafers coated with silicon nitride layers, electrostatic pressure problems are not observed but the uniformity of the bond is very bad. The deposition of a polysilicon layer over the silicon oxide and silicon nitride layers increases the electrostatic pressure and, in consequence, gives a high-quality bond.