Vertical distribution of lattice strain in polycrystalline silicon films grown on silicon dioxide

The vertical distribution of lattice strains in low-pressure chemical-vapor -deposited polycrystalline silicon (poly-Si) films grown on SiO2 was studie d by energy-dispersive grazing-incidence X-ray diffraction with synchrotron radiation white X-rays. The results revealed that a 5 nm thick poly-Si fil m consisting of nanometer-scale islands had tensile strain originating from poly-Si/SiO2. interface stress. Thicker films indicated not only strain re laxation but also compressive strain at thicknesses greater than 20 nm. Tra nsmission electron microscopy showed lattice defects including dislocations . This leads one to conclude that compressive strain is caused by insertion -type dislocations induced by grain-boundary formation and subsequent bendi ng in these boundaries. (C) 2001 The Electrochemical Society. [DOI: 10.1149 /1.1381391] All rights reserved.