Strain Relaxation in Surface Nano-Structures Studied by X-Ray Diffraction Methods

We study the lattice strain relaxation in pseudomorphic surface gratings using high resolution X-ray diffraction (XRD), grazing incidence diffraction and elasticicty theory. Ba means of grazing incidence diffraction we determine the grating shape and detect a depth dependent lattice strain rlaxation in the grating. Symmetrical and asymmetrical XRD gives evidence of a non-uniform strain relaxation in the etched structures and the creation of a periodic strain field deep in the substrate. The experimental findings are confirmed by an elasticity model which describes the interaction of the different crystalline media. Comparing the measured diffraction maps with calculated ones, we determine the actual strain distribution in the trapezoidal grating and in the substrate