Three mechanisms by which edges induce stress relaxation in GeSi strained stripes are described and their relative importance is discussed. Relaxation of stresses in the middle of the layers with I/h( =half-width/thickness) varying from 3 to 100 is calculated including the efFect of the two mechanisms which are important in this range. The values calculated in this manner agree with our recent finite element calculations. Since the stresses in the stripes in the two orthogonal directions are not

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We investigated in detail the strain relaxation behaviour of metastable tensile-strained Si 1−y C y epilayers on Si(001) by comparing the layers before and after an annealing step using a variety of different diagnostic methods. The dominant strain-relieving mechanism is the formation of carbon-containing interstitial complexes and/or silicon carbide nanoparticles, similar to the behaviour of carbon in silicon under thermodynamical equilibrium conditions (concentrations below the solid bulk solubility limit). We did not observe any carbon out-diffusion. To grow material suitable for device applications, all carbon atoms should be incorporated substitutionally. There is only a very narrow temperature window for perfect epitaxial growth of such layers, limited on one side by the possible formation of interstitial carbon complexes and on the other side by the deterioration of epitaxial growth at low temperatures. The carbon concentration should not exceed a few per cent to avoid strain-driven precipitation.

Changes in the densities of dislocations on distinct slip systems during stress relaxation in thin aluminium layers: The interpretation of xray diffraction line broadening and line shift

10-nm-thick germanium layers have been grown on Si(100) with and without antimony as a surfactant, and investigated by RHEED, TEM, and XPS. We obtained smooth epitaxial germanium layers with the antimony surfactant by passing through an island formation stage. These islands, formed below 400 °C, are of different structure than the islands obtained without surfactants. A possible mechanism for the "smoothing out" of islands developed in the beginning stage of surfactant-controlled solid phase epitaxy is proposed.

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Micro-Raman spectroscopy allows one to measure stress in crystalline materials. The method is nondestructive and provides microscopic lateral resolution. In this paper we show that resonance excitation using an ultraviolet (UV) laser line strongly enhances the depth resolution in micro-Raman spectroscopy. The Raman line shift becomes a true picture of the stress-field in a 12 nm thick surface layer, whereas visible light averages over a depth of some hundreds of nanometers. We review the effects of defocusing and inhomogeneous scattering, and present results obtained from a processed wafer. Measurements of stress fields in a sample taken from a typical silicon integrated circuit process prove the strongly enhanced resolution. The UV light, therefore, allows one to resolve stress components averaged out by longer wavelength light, giving a much better way to pinpoint areas of critical stress levels that would likely lead to defects in subsequent processes in silicon microelectronic production.

We present measurements of mechanical stress in silicon device structures by ultraviolet (UV) micro-Raman spectroscopy. The shorter wavelength of the UV light (364 nm) is the basis for two major improvements over conventionally used blue light (458 nm): The smaller penetration depth of only 15 nm (vs 300 nm for blue light) probes the stress very close to the surface, and a smaller laser spot on the sample (0.7 μm vs 0.9 μm) results in higher spatial resolution. A comparison of stress patterns obtained in the same sample with 364 nm (UV) and 458 nm (blue) light demonstrates that areas of high stress, which are averaged out by longer wavelength light, can be detected with UV light.