Analysis of local lattice strain around oxygen precipitates in silicon crystals using CBED technique

Oxygen precipitates SiO.in Czochralski-grown silicon single crystals CZ-Si.have been used for the ‘getter’ sink for x impurities introduced during the LSI wafer manufacturing process. In order to understand the ‘gettering’ phenomena, lattice strain fields around the precipitates have been measured quantitatively using convergent beam electron diffraction CBED.. The local lattice strain can be measured from higher order Laue zone HOLZ.patterns since the HOLZ pattern in the bright field disk is sensitive to the lattice displacement. As a result, a tetragonal distortion of silicon lattices was found in the vicinity of a platelet of an oxygen precipitate. That is, the strain due to the displacement of 001.Si planes is compressive along the direction normal tow001xSi and is tensile along the direction parallel tow001xSi. The normal strain is estimated to be about 0.3% near the flat plane of the platelet and 0.1% near the edge of the platelet whose edge length is about 500 nm. The results are discussed and compared to those from the finite element method FEM.simulation. q1998 Elsevier Science B.V. All rights reserved