A NEUTRON BACKSCATTERING STUDY OF LATTICE DEFORMATIONS IN SILICON DUE TO SIO2 PRECIPITATION

Czochralski-grown dislocation free silicon crystals containing approximately 7.5, 9.9, and 18×1017 cm -3 oxygen atoms have been annealed at 750, 1050, and 1200 °C for times varying between 20 and 216 h. Neutron transmission spectra measured at reflection 111 in backscattering geometry reveal mean lattice contractions of the order of 5×10-5 and lattice parameter fluctuations up to Δd/d≊5×10-4. The measuring time for one spectrum is 15 min and an on-line characterization of the defects produced during annealing is feasible. A combination of this technique with neutron small angle scattering, γ-ray diffractometry, and diffraction experiments with high-energy synchrotron radiation opens new possibilities for investigations of oxygen precipitation in silicon crystals as used in very-large-scale integration semiconductor device technology.