Suppression of Boron Diffusion by Fluorine Implantation in Preamorphized Silicon

Abstract

ABSTRACTWe have investigated the role of fluorine in the reduction of transient enhanced diffusion (TED) and thermal diffusion (TD) of B in preamorphized Si layers implanted with F. For this purpose, we have employed B delta-doped layers, grown by molecular beam epitaxy (MBE), as markers for silicon self-interstitials (Is). We have shown that boron TED decreases with increasing amount of incorporated F up to the complete TED suppression. Furthermore, we have clearly demonstrated that the physical mechanism that suppresses the boron TED is not a B-F chemical bonding, but a strong interaction between F atoms and Is. In addition, we have seen that fluorine strongly reduces B diffusion also under Is thermal equilibrium concentration. Our results clearly show that the presence of F lowers the Is density very effectively, reducing the boron TED as well as the dopant diffusion under equilibrium conditions.