Microscopic Structure of Directly Bonded Silicon Substrates

Using X-ray microdiffraction (XRMD) and transmission electron microscopy (TEM) techniques, we have investigated the microscopic structure of Si(011)/Si(001) direct silicon bonding (DSB) substrates. XRMD was performed to measure the local lattice spacing and tilting in the samples before and after oxide out-diffusion annealing. Diffraction analyses for (022) lattice planes with two orthogonal in-plane directions of X-ray incidence revealed anisotropic domain textures in the Si(011) layer. Such anisotropy was also confirmed by TEM in the morphology at the Si(011)/Si(001) bonded interface. The anisotropic crystallinity is discussed on the basis of interfacial defect structures which are proper to the DSB substrate.