X-RAY
DIFFUSE SCATTERING FROM OXYGEN-BASED DEFECTS IN CZOCHRALSKI SILICON
P. Klang1 ,
V. Holư1,2
1Institute of Condensed Matter
Physics,
2Faculty of Mathematics and Physics,
klang@physics.muni.cz
Silicon
single crystals grown by the Czochralski method contain oxygen impurities in
the concentration of about 1018 cm-3. Annealing at high temperatures leads to
the formation of amorphous SiO2 precipitates, which create traps for fast
diffusing metallic contaminants [1]. The understanding of the formation and
growth of these oxygen-based defects plays an important role in fabrication of
integrated circuits.
Czochralski
grown silicon wafers (111) were studied using triple-axis high resolution X-ray
diffraction. We have measured reciprocal space maps of intensity distribution
from the scattering on defects in silicon wafers after annealing processes (see
Fig. 1(a)). The samples were annealed at 1000 °C for different periods in order
to study the growth of oxygen-based defects. In the radial cross-section of the
measured map we can find different types of scattering - Huang scattering (HS)
for small q, Stokes-Wilson scattering (SWS) for middle q and thermal diffuse
scattering (TDS) for large q (see Fig. 1(b)).
Figure 1. (a) Measured symmetrical reciprocal space map
(111) of the sample annealed at 1000 °C for a period of 16 h, (b) radial
cross-section of this map along the qx direction with the different
types of the scattering.
We have
also modelled the reciprocal space maps of intensity distribution using the
Krivoglaz theory [2] and a continuum model of the defect deformation field.
From the comparison, we have determined the size, symmetry and concentration of
the defects, as well as the deformation field in their neighbourhood.
References
1. C.
Newman, J.Phys.: Condens. Matter 12, (2000), R335
2. M. A. Krivoglaz in Diffraction of X-rays and Neutron in Nonideal Crystals (Springer,