Strain effects in thin film/Si substrates revealed by X-ray microdiffraction

Abstract

The local variation in strain and rotation of the Si substrate due to overlying Ni thin film features has been observed using X-ray microdiffraction. Residual tensile stress in 1 μm thick, 190 μm diameter Ni dots of 990 MPa imparted an average compressive stress in the underlying Si substrate. Ni Kα fluorescence scans, acquired simultaneously with Si (333) diffraction data, allow for a precise determination of the Ni feature edge location relative to the observed shift in Si (333) peak position. Rocking curve mesh scans, in which the sample was translated perpendicular and parallel to the diffraction plane, were used to deconvolute the effects of substrate strain due to d-spacing shifts and rotation of the local Si surface. In addition, shear strains at the dot edge imparted a significant shift in the Si (333) diffraction peak, producing a secondary diffraction peak in modified reciprocal space scans.