Investigation by high resolution X-ray diffraction of the local strains induced in Si by periodic arrays of oxide filled trenches

High Resolution X-ray Diffraction allows for the measurement of periodic strain fields in monocrystalline silicon and is non-destructive. In this study a periodic strain field is induced in Si by SiO2 filled trenches (Shallow Trench Isolation process). The strain in Si is evaluated for different periods of the trench arrays namely from 2 μm to 0.2 μm. The periodic strain field gives rise to satellites in reciprocal space maps around the Si substrate peak. The intensity and envelope of these satellites depend on the local strain. The experimental reciprocal space maps are qualitatively compared with those computed from the elastic displacement field calculated with finite element modeling. When the array period decreases, a strong increase in local strain is observed. From 0.58 μm period and below, in addition to the Si substrate diffraction peak, a secondary diffraction peak representative of the strain in Si lines can be distinguished on reciprocal space maps. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)