Effects of N Doping in Ru-Ta on Barrier Property and Reliability Performance for Cu Interconnects

摘要

The effects of N doping in Ru-Ta alloy on film property, barrier property against Cu diffusion and reliability performance in Cu interconnects were investigated. RuTa(N) film which was doped with N in Ru-Ta alloy was applied as a diffusion barrier layer in Cu interconnects, and barrier property and reliability performance with RuTa(N) barrier were mainly evaluated. As RuTa(N) film was annealed, N desorbed easily from RuTa(N) film due to its low thermal stability and the crystal size became larger because of the recrystallization. RuTa(N) film had the poor barrier property against Cu diffusion due to the structure of high-angle grain boundaries despite the crystal size of RuTa(N) increases and the density of grain boundaries decreases after annealing. Reliability performance of via electromigration could be improved by using Ru-Ta based alloy barrier. However, there was remarkable difference of reliability performance between RuTa and RuTa(N) barrier, and RuTa(N) had inferior reliability performance of via electromigration. On the other hand, RuTa had both good barrier property and superior reliability performance. It was found that doping N in Ru-Ta alloy degraded barrier property and reliability performance. Consequently, it is appropriate to apply RuTa single film as the diffusion barrier layer for Cu interconnects. (C) The Author(s) 2016. Published by ECS. All rights reserved.