In order to investigate the role which is played by H in the anomalous diffusion of P in non mass-separation type plasma doping, a study was made of the effects of pre-hydrogenation upon P diffusion in crystalline samples. Secondary-ion mass spectrometric measurements indicated that pre-hydrogenated samples with a -200V radio-frequency bias exhibited a much greater P penetration depth than did samples without pre-hydrogenation, after PH3 plasma treatment, thus indicating that the diffusion of P was enhanced by pre-hydrogenation. The use of Fourier transformation infra-red spectroscopy revealed that the Si-H bonds increased after the plasma treatment. On the basis of these results, the mechanism of enhanced diffusion was explained in terms of negatively charged mono-hydrogen and metastable di-hydrides.

H.Kakinuma, M.Mohri: Japanese Journal of Applied Physics, 1995, 34[2-10B], L1325-8