Spatially Resolved X-ray Diffraction Technique for Crystallographic Quality Inspection of Semiconductor Microstructures

Spatially resolved X-ray diffraction is introduced and applied for microimaging of strain in GaAs and GaSb layers grown by epitaxial lateral over-growth on GaAs substrates. We show that laterally overgrown parts of the layers (wings) are tilted towards the underlying mask. By spatially resolved X-ray diffraction mapping the direction of the tilt and distribution of tilt magnitude across the width of each layer can be readily determined. This allows measuring of the shape of the lattice planes in individual epitaxial stripes. In GaSb/GaAs heteroepitaxial laterally overgrown layers local mosaicity in the wing area was found. By spatially resolved X-ray diffraction the size of microblocks and their relative misorientation were analyzed. Finally, microscopic curvature of lattice planes confined between two neighboring slip bands in thermally strained Si wafers is measured. All these examples show advantages of spatially resolved X-ray diffraction over a standard X-ray diffraction when applied for analysis of crystalline microstructures.