In-plane strain and shape analysis of Si/SiGe nanostructures by grazing incidence diffraction

Surface-sensitive X-ray grazing incidence diffraction (GID) was used to inv estigate the elastic strain relaxation in laterally periodic Si/SiGe wires, oriented along the [(1) over bar 1 0] direction, fabricated by holographic lithography and reactive ion etching from a 10-period multilayer. Using tr ansverse and longitudinal scans, i.e. with the diffraction vector parallel and perpendicular to the wire direction information on the shape and the st rain status were obtained from measurements at different incidence and exit angles. For the simulation a modified effective refractive index profile, i.e. a different average electron density for the etched and the non-etched a ire pattern was taken into account. Using data from finite element calcu lations of the strain fields. a simulation based on DWBA is in good agreeme nt with the experimental data. (C) 2000 Published by Elsevier Science B.V. All rights reserved.