X-Ray Residual Stress Measurement of Aluminum Thin Films with [111] Fiber Texture

Abstract

A new method of X-ray stress measurement was applied to the measurement of residual stress in aluminum thin films sputtered on (100) oriented silicon single-crystal wafers. The film has the [111] fiber texture perpendicular to the film surface. The strain was measured from Al 222 and 311 diffractions obtained by Cr-Kα radiation. The values of in-plane residual stresses σ₁₁, σ₂₂ and σ₁₂, and out-of-plane normal residual stress, σ₃₃ were determined from the measured strains by using the fundamental formulae derived on the basis of Reuss and Voigt models. The residual stress in the thin films was nearly equi-biaxial tension, and its magnitude decreased with increasing film thickness. The residual stress determined by the curvature method was nearly equal to the value determined by the X-ray method.