EPR AND RBS STUDY OF DEFECTS PRODUCED BY MEV ION-IMPLANTATION INTO SILICON

Electron paramagnetic resonance and Rutherford backscattering have been used to investigate the damage produced by implanting (100) silicon wafers with either 3 MeV Au+ of 2 MeV Si+ ions at liquid nitrogen temperature, 300 or 500 K (Au only). For samples implanted at liquid nitrogen temperature the EPR spectra include those of the neutral 4-vacancy (Si-P3), the silicon di-interstitial (Si-P6), the D centre (indicative of amorphous silicon) and a broad anisotropic resonance; their concentration in these samples is determined as a function of dose in the range 10(13)- 10(15) Si+ cm-2 and 10(12) - 10(14) Au+ cm-2. The EPR spectrum for any dose of Au+ ions at the low implantation temperature is very similar to the equivalent spectrum for an approximately 20 times larger dose of Si+ ions. At the lowest doses there is no measurable D centre concentration. For implants at 300 K of 5 x 10(13) - 5 x 10(15) Au+ cm-2 and of 3 x 10(15) Si+ cm-2 an amorphous layer is produced and the EPR spectrum reveals only D centres. However, no such layer is present and point defects are revealed by EPr for an implant of 5 x 10(14) Si+ cm2 at 300 K or 5 x 10(14) - 5 x 10(15) Au+ cm2 at 500 K.