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Proceedings Paper

Behavior of Ta thin film as a diffusion barrier in the Cu/barrier/SiO2 system
Author(s): Ji Sheng Pan; Andrew Thye Shen Wee; C. H. Alfred Huan; Jian Wei Chai
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Paper Abstract

Tantalum (Ta) thin films of 35 nm thickness were investigated as diffusion barriers as well as adhesion- promoting layers between Cu and SiO2 using x-ray diffractometry (CRD), Scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). After annealing at 600 degrees C for 1h in vacuum, no evidence of interdiffusion was observed. However, XPS depth profiling indicates that elemental Si appears at the Ta/SiO2 interface after annealing. In- situ XPS studies show that the Ta/SiO2 interface was stable until 500 degrees C, but about 32 percent of the interfacial SiO2 was reduced to elemental Si at 600 degrees C. Upon cooling to room temperature, some elemental Si recombined to form SiO2 again, leaving only 6.5 percent elemental Si. Comparative studies on the interface chemical states of Cu/SiO2 and Ta/SiO2 indicates that the stability of the Cu/Ta/SiO2/Si system may be ascribed to the strong bonding of Ta and SiO2 due to the reduction of SiO2 through Ta oxide formation.

Paper Details

Date Published: 24 October 2000
PDF: 5 pages
Proc. SPIE 4227, Advanced Microelectronic Processing Techniques, (24 October 2000); doi: 10.1117/12.405381
Show Author Affiliations
Ji Sheng Pan, Institute of Materials Research and Engineering (Singapore)
Andrew Thye Shen Wee, National Univ. of Singapore (Singapore)
C. H. Alfred Huan, National Univ. of Singapore (Singapore)
Jian Wei Chai, Institute of Materials Research and Engineering (Singapore)

Published in SPIE Proceedings Vol. 4227:
Advanced Microelectronic Processing Techniques
H. Barry Harrison; Andrew Thye Shen Wee; Subhash Gupta, Editor(s)

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