Citation

Lin MH, Chiou SY. Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 2004; 43(6 A): 3340-3345.

Copyright

(Copyright © 2004)

DOI

10.1143/JJAP.43.3340

PMID

unavailable

Abstract

Hafnium (Hf) and hafnium nitride (Hf-N) flims were deposited on silicon wafers using a magnetron sputtering system. The as-deposited Hf film has a hexagonal close packed structure and a low resistivity of 101 μΩcm. The phases form in the order of α-Hf → HfN0.4 → ε-Hf3N2 → fcc-HfN with increasing nitrogen concentration in the Hf-N film. The thermal stabilities of Cu/Hf-N/Si contact systems are evaluated by thermal stressing at various annealing temperatures. In Cu/Hf/Si, a reaction between the Hf barrier layer and the Cu layer is observed, and copper-hafnium compounds form after annealing at 550°C. Moreover, highly resistive copper suicide is found after 600°C annealing. No copper-hafnium or copper suicide compounds are found in the Cu/HfN 0.47/Si contact system even after annealing at 650°C. Incorporating nitrogen into the hafnium diffusion barrier can suppress the formation of copper-hafnium compounds and copper penetration, thus improving the barrier's thermal stability.

Language: en

Keywords

Copper; Annealing; Thermodynamic stability; Thin films; Silicon wafers; Sputtering; Diffusion barriers; Atomic force microscopy; Magnetron sputtering; Hafnium; Nitrides; Hafnium compounds; Columnar barrier; Ion polishing system (PIPS); Nitrogen flow ratio