Behavior of Ta thin film as a diffusion barrier in the Cu/barrier/SiO2 system

Ji Sheng Pan; Andrew Thye Shen Wee; C. H. Alfred Huan; Jian Wei Chai

doi:10.1117/12.405381

24 October 2000 Behavior of Ta thin film as a diffusion barrier in the Cu/barrier/SiO₂ system

Ji Sheng Pan, Andrew Thye Shen Wee, C. H. Alfred Huan, Jian Wei Chai

Proceedings Volume 4227, Advanced Microelectronic Processing Techniques; (2000) https://doi.org/10.1117/12.405381
Event: International Symposium on Microelectronics and Assembly, 2000, Singapore, Singapore

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.

Citation Download Citation

Ji Sheng Pan, Andrew Thye Shen Wee, C. H. Alfred Huan, and Jian Wei Chai "Behavior of Ta thin film as a diffusion barrier in the Cu/barrier/SiO₂ system", Proc. SPIE 4227, Advanced Microelectronic Processing Techniques, (24 October 2000); https://doi.org/10.1117/12.405381

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