Strain near SiO2-Si interface revealed by X-ray diffraction intensity enhancement

For the system of polycrystalline Si/SiO2(thermal)/Si(001), the strain fiel d introduced into the Si substrate was studied with the asymmetric X-ray di ffraction method. Polycrystalline Si layers with a thickness of 10.0 nm wer e grown on 4.5-nm thick thermally grown oxide layers. To study the strain f ields, the rocking curves for Si {113} planes of the bulk films were measur ed. The intensity of the rocking curves increased for polycrystalline Si-gr own films, whereas the intensity must be decreased by the absorption of X-r ays in the polycrystalline Si layer. This indicates that the strain is intr oduced into the substrate. The Darwin dynamical calculation for a distorted crystal indicates that the intensity enhancement of a rocking curve can oc cur as a compressive strain. From a comparison of the measured and calculat ed curves, we conclude that the compression of the {001} spacing near the s ubstrate surface occurs during the growth of the polycrystalline Si layer. (C) 2000 Elsevier Science S.A. All rights reserved.