MAPPING OF 2-DIMENSIONAL LATTICE-DISTORTIONS IN SILICON-CRYSTALS AT SUBMICROMETER RESOLUTION FROM X-RAY ROCKING-CURVE DATA

Lattice distortions perpendicular to the surface in thin surface layer s of ion-implanted (111) silicon crystals have been mapped as a functi on of depth and lateral position with resolutions of 0.05 and 0.65 mum , respectively. X-ray triple-crystal diffractometry data were collecte d 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 l attice distortions in a very thin layer of 0.15 mum thickness at 1.05 mum depth below the surface, with interplanar lattice spacings normal to the surface increased by several parts in 10(4). The distortions ar e appreciably extended in the lateral direction, suggesting diffusion of the ions. A 0.5 mum-thick thermaloxide strip is found to contract t he interplanar spacing of substrate silicon crystal under the strip re gion by a few parts in 10(4), while the strain field created by the pa rallel oxide edges extends beyond a depth of 3 mum. A practical proced ure is also described for arriving at a solution of the phase problem in the case of a strain field involving heavily distorted layers.