Analysis of anisotropic in-plane strain behavior in condensed Si_1-xGe_x fin epitaxial layer using X-ray reciprocal space mapping

Epitaxial Si_1-xGe_x fin layers with x = 0.50 and 0.63 were selectively grown on trench patterned Si (001) substrates with trench widths of 65 and 90 nm. Using a dry oxidation process for the Si_1-xGe_x fin layers, the Ge was condensed by up to ca. 90% while anisotropic in-plane strain was induced. To analyze the anisotropic in-plane strain behavior, reciprocal space mapping measurements were performed in the directions parallel and perpendicular to the fins. After the condensation, a compressive strain of ca. 1% was induced in the direction parallel to the fin. We discuss the uniaxial stress factor influencing the anisotropic in-plane strain of the condensed Si_1-xGe_x fin layer in the two trench patterns.