Plasma immersion ion implantation as an alternative deep trench buried-plate doping technology

Plasma immersion ion implantation (PIII) has been developed as an alternative deep trench capacitor buried-plate doping technology and compared to a conventional solid-state diffusion technique using arsenosilicate glass (ASG). Novel top-down (or vertical) SIMS measurements demonstrated the conformal doping capability of PIII along the trench sidewall. The doping level by PIII was almost one order of magnitude higher than that by a conventional technique. As a consequence, PIII provided better depletion characteristics than conventional technique. Furthermore, PIII processing did not degrade node-to-buried plate leakage current characteristics. From these results, it was demonstrated that PIII is a promising technology as an alternative deep trench capacitor buried-plate doping technique for future deep trench-based DRAM processing development.