Mapping of two-dimensional lattice distortions in silicon crystals at submicrometer resolution from X-ray rocking-curve data

Lattice distortions perpendicular to the surface in thin surface layers of ion-implanted (111) silicon crystals have been mapped as a function of depth and lateral position with resolutions of 0.05 and 0.65 μm, respectively. X-ray triple-crystal diffractometry data were collected near the fundamental 111 and satellite reflections from samples with periodic superstructure modulations in the lateral direction. 300 keV B+ ions implanted through surface mask windows are found to produce lattice distortions in a very thin layer of 0.15 μm thickness at 1.05 μm depth below the surface, with interplanar lattice spacings normal to the surface increased by several parts in 104. The distortions are appreciably extended in the lateral direction, suggesting diffusion of the ions. A 0.5 μm-thick thermal-oxide strip is found to contract the interplanar spacing of substrate silicon crystal under the strip region by a few parts in 104, while the strain field created by the parallel oxide edges extends beyond a depth of 3 μm. A practical procedure is also described for arriving at a solution of the phase problem in the case of a strain field involving heavily distorted layers. (orig.)