Effects of dissolved nitrogen in improving barrier properties of ruthenium

Abstract

Diffusion barrier properties of 10nm Ru sputtered in N and Ar atmospheres have been assessed. N was found to be dissolved in the Ru film deposited in N atmosphere making it amorphous with ten times higher sheet resistance. Annealing caused effusion of N resulting in crystallization of Ru and a sharp decrease in sheet resistance. The incorporation of N delayed the Ru silicide formation and reduced Cu and Ru diffusion into the SiO2 dielectric layer. These beneficial performances are attributed to dissolved N in the amorphous films and to N grain boundary stuffing in crystallized films.

Fabrication and diffusion barrier properties of nanoscale Ta/Ta-N bi-layer

“…This may be attributed to that the addition of "N" makes the Ta grain thin, and makes the Ta-N tends to be nano-crystalline or amorphous-like (Damayantia et al, 2006). So the surface of Ta-N is smoother than the others.…”

Improved diffusion barrier performance of Ru/TaN bilayer by N effusion in TaN underlayer

“…Unfortunately, RuN is known to be very unstable. Most of the N in RuN is released upon annealing at 275 C, inducing some unfavorable phenomenon [14,15,32]. Wu et al and Ihara et al reported that there were a large amount of nitrogen vacancies formed by N effusion in RuN after annealing [15,33].…”

“…Damayanti et al reported that these advantages can be attributed to the N atoms dissolved and stuffed in the grain boundaries (GBs) of Ru films. Unfortunately, RuN is known to be decomposed after annealing at 275 C [14,15]. Consequently, enhancing thermal stability of RuN becomes critical for improving the barrier performance of Ru film.…”

Low-Resistivity Ru-Ta-C Barriers for Cu Interconnects

“…5 To prevent formation of Ru x Si y , multilayers of ruthenium nitrides have been used to impart superior barrier properties. [6][7][8][9] In these previous studies, 10-nm-thick amorphous RuN thin film was shown to block Cu diffusion after annealing at 350°C for 30 min. 6 RuN, RuTa, and Ru-TaN thin films with thickness of 15 nm have failure temperatures of 600°C, 700°C, and 900°C, respectively.…”

“…[6][7][8][9] In these previous studies, 10-nm-thick amorphous RuN thin film was shown to block Cu diffusion after annealing at 350°C for 30 min. 6 RuN, RuTa, and Ru-TaN thin films with thickness of 15 nm have failure temperatures of 600°C, 700°C, and 900°C, respectively. 7,8 Such barrier films are attractive due to their compatibility with direct Cu electroplating.…”