Alteration for a diffusion barrier design concept in future high-density dynamic and ferroelectric random access memory devices

The barrier properties and failure mechanisms for many diffusion barriers in high-density volatile and non-volatile capacitors were reviewed. Based on failure mechanisms of these barriers reported by others, we suggested the new design concept for a diffusion barrier and developed the new Ta + CeO₂ and Ta + RuO₂ barriers. Although both barriers were shown to exhibit good diffusion barrier properties, however, oxide-incorporated barriers result in the surface oxidation of the under-layer during deposition and/or post-thermal budgets, resulting in the degradation of capacitor performance. The design concept for a diffusion barrier should be changed to sacrificial oxygen diffusion barrier concept, and both the RuTiN and the RuTiO films, as new sacrificial oxygen diffusion barriers, were proposed. New RuTiN and RuTiO barriers showed the higher oxidation resistance and cell capacitance and the lower contact resistance up to high temperatures. Therefore, the design concept of a sacrificial diffusion barrier should be emphasized to achieve high-density dynamic and ferroelectric random access memory devices.