White X-ray beam topography and radiography of Si1-xGex crystals bonded to silicon

The defect structure of Si1-xGex. wafers with 4% of germanium and their interfaces with Si wafers were studied using white radiation topography and phase-sensitive radiography. The heterostructures were manufactured by direct bonding of Si1-xGex. and Si crystalline wafers made of bulk crystals that were grown by the Czochralski technique. In Si1-xGex. crystals, the segregations of Ge act as dislocation nucleation sites. In Si1-xGex/Si bonded structures, the segregation of Ge as well as the accumulation of dislocations induce elastic strain and plastic deformation during high-temperature bonding annealing. With the topography-radiography combination, we are able not only to detect microcracks, indicating nonbonded areas, by radiography, but also to reveal dislocations and long-range strain fields by topography at the same time. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.