He implantation in Si for B diffusion control

✍ Scribed by E. Bruno; S. Mirabella; E. Napolitani; F. Giannazzo; V. Raineri; F. Priolo

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 176 KB
• Volume: 257
• Category: Article
• ISSN: 0168-583X
• DOI: 10.1016/j.nimb.2007.01.034

✦ Synopsis

A definitive method to prevent undesired phenomena related to B implantation in crystalline Si is still lacking. In fact, B undergoes enhanced diffusion, clustering and electrical deactivation as a consequence of interaction with implantation related damage. In this work we investigated the effect of He and B co-implantation in Si on point-defect population. We implanted Si wafers with B 12 keV, 5 • 10 14 ions/cm 2 and/or He 25-80 keV, 0.5-3 • 10 16 ions/cm 2 . By means of B diffusion and Cu gettering experiments, we studied the effectiveness of He induced nanovoids on controlling self-interstitials generated by implantation. We demonstrated that nanovoids strongly affect B diffusion, producing a B box-like shape, and that their efficiency increases with increasing He fluence. Moreover, this beneficial effect is still present increasing the annealing temperature from 700 to 1000 °C, leading to a reduction of B clustering, while maintaining a strong confinement of the implanted B profile.