Oxygen '96

Early Stages of Oxygen Precipitation in Silicon

---

LUMINESCENCE INVESTIGATIONS OF THE INTERACTION OF OXYGEN WITH DISLOCATIONS IN CZ Si

V. Higgs

Department of Physics, Kings College London, London, WC2R 2LS, U
Present address, Bio-Rad Microscience Ltd, Hemel Hempstead, HP2 7TD, UK

Keywords: oxygen, silicon, dislocations, luminescence.

The control of oxygen precipitation and generation of oxygen related lattice defects in Si can lead to improved device characteristics and performance. To optimise intrinsic gettering processes it is important to understand the interaction of oxygen related defects with other residual impurities in Si, such as hydrogen and transition metals. Photoluminescence (PL) and Cathodoluminescence (CL) imaging measurements have been carried out to characterise the interaction of an oxygen with dislocations in CZ Si.

The CL and PL spectra recorded from the CZ Si samples ([O]=10¹⁷-10¹⁹ cm^-3) deformed at 700 degrees C for 15 minutes contained the characteristic D-band features (D1-D4). As the deformation time increased ( > 2 hours) the D-band luminescence features were quenched. the quenching of the D-band features for the CZ Si samples containing more oxygen. In the CZ Si where the D-band luminescence is quenched, transition metal contamination produced a marked increase in the non-radiative recombination processes (as measured by EBIC). CL spectra recorded from the FZ control samples deformed under the same conditions contained no D-band features. In addition, CL spectra recorded from CZ Si samples deformed in the flowing hydrogen contained no D-band features.

Infrared absorption measurements showed that there was no detectable changes in the bulk oxygen levels for deformation treatments at T=700 degrees C, TEM investigations did not reveal any changes in the dislocation structure or precipitation. In the samples where the D-band features were quenched EBIC measurements showed the dislocations exhibited deep level recombination. CL imaging measurements and oxidation experiments suggest that the origin of D1 and D2 are point defect related, possibly related to interstitial Si clusters trapped at carbon or oxygen. After extended deformation treatments (T=750-800 degrees C) and aging annealing to simulate intrinsic gettering processes the intensity of the D1 and D2 bands vary with the amount of precipitated oxygen. This effect is believed to be caused by the segregation of oxygen atoms producing point defects.

It is suggested that the effects that are observed are due to atomically dispersed oxygen atoms interacting with the dislocation core. The dislocation-oxygen interactions produce predominately deep level states and non-radiative processes dominate the recombination process and quench the radiative processes.

Last modified: Mon Feb 19 17:21:00 GMT 1996 JG