Precipitation processes in materials synthesis by high-dose ion implantation of semiconductors

Abstract

High dose ion implantation for materials synthesis in semiconductors is receiving increasing attention with the commercialization of medium and high current ion implanters. Surface and buried dielectric layers in silicon are being fabricated by high-dose implantation of oxygen, nitrogen, and carbon. Metallic silicides are being synthesized by implantation of metals such as cobalt and nickel. The evolution of a new phase or phases from a supersaturated solid solution during implantation occurs in a zone with increasing concentration which is also in a concentration gradient. Because of this, and the dynamic phenomena occurring, the whole process is quite complex. Additionally, a final, high temperature anneal to remove damage and to consolidate and stabilize the new phase(s) further complicates any analysis. There is no standard approach to analyze structural changes during high dose implantation and subsequent annealing, but it should be possible to approximate the phenomena based on traditional models for precipitation processes in solids. These processes include precipitate nucleation, growth, coarsening, coalescence, and dissolution. The most heavily studied process of materials synthesis by implantation is formation of a buried oxide layer in silicon (often referred to as SIMOX material).