The interface of bonded hydrophobic Si pairs was found to be a strong gettering layer. By thinning one wafer of the pair, the location of the gettering layer with respect to the defect-free Si surface layer could be varied from more than 500 to less than a micron. Secondary ion mass spectrometry and simulation results suggested that F atoms at the interface were mainly responsible for the gettering effect, via Au-F ion pairing. Significant segregation of Au to the hydrophobic bonding interface was observed during annealing at 900C.

Q.Y.Tong, S.Hsia, U.Gösele, H.Zimmermann, M.Reiche: Materials Chemistry and Physics, 1996, 45[3], 223-7