GAAS LOW-TEMPERATURE FUSION BONDING

High strength, low temperature fusion bonding of GaAs has been achieve d at annealing temperatures between 400 and 420-degrees-C in an ambien t H2 atmosphere. The reducing effect of H2 on the oxide interlayer is believed to play an important role. The fracture surface energy of the strongest bonds (0.8 J/m2) is close to that of the bulk material. The tensile fracture strength measured (sigmaf greater-than-or-equal-to 1 0 MPa) is of the same order as that measured for silicon fusion bondin g, hence yielding sufficient strength for most micromechanical devices . Resistivity measurements as well as XTEM analyses indicate the exist ence of a thin, insulating layer of unrecovered oxide in the bond zone . Also, the anisotropy dependence of the fracture surface energy is th eoretically described. The bonding technique could be useful in GaAs-b ased sensor applications and micromechanical devices, as well as in 3D -integration.