Feasibility of Nitrogen (or Oxygen)-Incorporated Ruthenium Titanium Ternary Diffusion Barrier Suggested by a New Design Concept for Future High-Density Memory Capacitors

Abstract

A new design concept for diffusion barriers in high-density memory capacitors was suggested, and both the RuTiN (RTN) and the RuTiO (RTO) films, as sacrificial oxygen diffusion barriers, were proposed. The newly developed RTN and RTO barriers showed much lower sheet resistance, as reported by others, than various barriers including binary and ternary nitrides up to 800°C, without a large increase in resistance. For both the channel layer/Si and the channel layer/Si contact structures, contact resistance, the most important electrical parameter for the diffusion barrier in the bottom electrode structure of capacitors, exhibited as low as 5 kΩ, even after annealing up to 750°C. Moreover, when the RTN film was inserted as a glue layer between the bottom electrode Pt layer and the TiN barrier film in the chemical vapor deposited- simple stack-type structure, the thermal stability of the RTN glue layer was observed to be 150°C higher than that of the TiN glue layer. Correspondingly, new RTN and RTO films, as diffusion barriers for oxygen, are very promising materials for achieving the high-density capacitors. © 2002 The Electrochemical Society. All rights reserved.