24 October 2000 Behavior of Ta thin film as a diffusion barrier in the Cu/barrier/SiO2 system
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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.
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Ji Sheng Pan, Andrew Thye Shen Wee, C. H. Alfred Huan, 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); doi: 10.1117/12.405381; https://doi.org/10.1117/12.405381
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