An investigation was made of the effect of plasma-processing upon the transient enhanced diffusion of implanted B. Thermally oxidized wafers were first processed using CHF3/CF4 plasma, and were then implanted with B to a dose of 1013/cm2 using energies which ranged from 3 to 20keV. The profiles were measured by means of secondary-ion mass spectrometry, while lattice extended defects which were introduced by the plasma processing were characterized by using transmission electron microscopy. The secondary-ion mass spectrometry measurements revealed that the transient enhanced diffusion of B after rapid thermal annealing was strongly reduced in plasma-processed samples as compared with unprocessed samples. The defects which were introduced by plasma processing caused the reduction by acting as very efficient traps for the interstitial atoms which were generated during implantation. The trapping efficiency was critically dependent upon the projected range of the implanted B. This was very evident at low energies but was less marked as the energy was increased; that is, when the interstitials which were generated by the implanted B were far from the trapping sites. By changing the plasma conditions (Ar instead of CHF3/CF4), it was possible to establish a general correlation between trapping defect centers and reductions in transient enhanced diffusion. Spreading resistance measurements revealed that the amount of electrically active B in plasma-processed pure epitaxial material was almost equal to that obtained in samples which were not exposed to plasma bombardment. This demonstrated that plasma processing had no detrimental effect upon B electrical activation.

Plasma Processing of the Silicon Surface. G.Mannino, F.Priolo, V.Privitera, V.Raineri, C.Spinella, E.Napolitani, A.Carnera, G.Arena, A.Messina, C.Rapisarda: Journal of Applied Physics, 1998, 84[12], 6628-35