Processing of Czochralski silicon (Cz-Si, semiconductor in microelectronics and optoelectronics) at high temperature (HT) leads to clustering of oxygen always present in Cz-Si (oxygen content, c_o, can reach > 1.1 x10¹⁸ cm^-3 ), with a creation of Si0_2-x precipitates exhibiting tensile stress on the matrix. Oxygen precipitation, the stress mentioned and so the defect structure of Cz-Si are affected by hydrostatic pressure (HP) exerted by inert medium at HT. The effect of HT - HP treatment (typically for 5 h) at 1230 /1400 K under HP up to 1.2 GPa on structural transformations in Cz-Si was investigated by microhardness, photoluminescence (PL), ellipsometric, and related measurements.
To create nucleation centres for precipitation (NC's), Cz-Si was subjected to one step pre-annealing at 720 K (samples A, resulting c_o = 1 x10¹⁸ cm^-3 ) or to 4 steps pre-annealing at up to 1000 K (samples B, c_o = 3.6x10¹⁷ cm^-3 ).
Pre-annealing of Cz-Si at 720 K for up to 20 h affects its microhardness (H) only slightly while the B samples are less hard (H equals to 15.9 and 14.4 GPa, respectively). The HT - HP treatment of A samples results in decreased c_o (after the treatments at 1230 K under 0.01 GPa and 1.2 GPa, c_o equals to 7.3x10¹⁷ cm^-3 and 5.8x10¹⁷ cm^-3, respectively). The treatment of B samples at 1230/1400K under HP results in increased H (up to 16.6 GPa) while the density of dislocations (evidenced by the presence of PL lines at 0.81 eV and 0.87 eV) decreases with HP in the case of treatment at 1230 K but increases after the treatments at 1400 K.
Structural transformations in treated Cz-Si are related to the effect of HP on the creation and stability of NC's as well as on diffusivity of oxygen and of Si interstitial.