Strain relaxation of epitaxial CoSi ₂ and SiGe layers in cap-Si/Si _0.83 Ge _0.17 /Si(0 0 1) and epi-CoSi ₂ /Si _0.83 Ge _0.17 /Si(0 0 1) structures

Strain relaxation behaviors of the epitaxial CoSi ₂ (epi-CoSi ₂ ) and Si _0.83 Ge _0.17 layers in epi-CoSi ₂ /Si _0.83 Ge _0.17 /Si(0 0 1) and cap-Si/Si _0.83 Ge _0.17 /Si(0 0 1) structures were investigated by high-resolution X-ray diffraction (HR-XRD) analyses. Samples were treated at the temperature, T _A = 650-900 °C by rapid thermal annealing. Comparative measurements showed a different strain relaxation behavior in the SiGe layers with and without CoSi ₂ layer. And Ge content and lattice mismatch in the SiGe film of the epi-CoSi ₂ /Si _0.83 Ge _0.17 /Si(0 0 1) are smaller than those in the SiGe layer in cap-Si/SiGe/Si(0 0 1) possibly due to the diffusion of Ge into the tensile-stressed epi-CoSi ₂ layer to reduce the compressive stress in the SiGe layer at elevated temperature. The analyses of high-resolution ω-2θ scan spectra and reciprocal space mapping showed that epi-CoSi ₂ layer is under tensile residual stress and a significant strain relaxation starts at T _A = 900 °C indicating of thermal stability up to T _A = 850 °C.