Characteristics of pulse plasma enhanced atomic layer deposition of tungsten nitride diffusion barrier for copper interconnect

摘要

We have deposited the W-N diffusion barrier with pulse plasma enhanced atomic layer deposition (PPALD) method by using WF{sub}6 and NH{sub}3. It is very difficult to deposit W-N film with ALD method by using WF{sub}6 and NH{sub}3 due to the fast Si catalytic reaction with WF{sub}6 since the deposition rate is as low as 0.5 A/cycle. However, using PPALD method the N content is uniformly distributed into the W-N film. The deposition rate per cycle is ～2.2 A/cycle in the ALD temperature window of 350～400℃. As a diffusion barrier for the Cu interconnect, high resolution-TEM reveals that 22 nm thick W-N successfully prevents Cu diffusion after annealing at 600℃ for 30 min.