(Invited) Plasma Activation as a Pretreatment Tool for Low-Temperature Direct Wafer Bonding in Microsystems Technology

Abstract

Dynamic measurements of interfacial fracture surface energies γ have been carried out during the annealing of pairs of silicon, fused silica and borosilicate glass wafers, resp. Pronounced maxima of the resulting γ(t) curves could be detected in several cases, especially for plasma activated wafer pairs. In the present article the different phases of the bonding process are discussed and an interpretation is given for the formation of the γ(t) maxima. Moreover, influences of plasma activation at atmospheric pressure and at low pressure on the increase in surface energy during annealing are compared. Based on AFM roughness measurements, power spectral densities were determined for two debonded wafer pairs and the influence of the bond strength is discussed here.