Microstructures in directly bonded Si substrates

We have investigated using X-ray microdiffraction (XRMD) and transmission electron microscopy (TEM) the microstructures of Direct Silicon Bonding (DSB) substrates which were prepared by bonding a Si(0 1 1) wafer to a Si(0 0 1) wafer. XRMD was performed to measure the local lattice spacing and tilting in the samples before and after the interface oxide out-diffusion annealing. Diffraction analyses for (0 2 2) lattice planes with two orthogonal in-plane directions of X-ray incidence revealed anisotropic domain textures in the Si(0 1 1) layer. Such anisotropy was also confirmed by TEM in the morphology at the Si(0 1 1)/Si(0 0 1) bonded interface. The anisotropic crystallinity is discussed on the basis of interfacial defect structures which are proper to the DSB substrate.