Materials characterization of ZrO{sub 2}--SiO{sub 2} and HfO{sub 2}--SiO{sub 2} binary oxides deposited by chemical solution deposition
The thermal stability, microstructure, and electrical properties of xZrO{sub 2}(100-x)SiO{sub 2}(ZSO) and xHfO{sub 2}(100-x)SiO{sub 2}(HSO) (x=15%, 25%, 50%, and 75%) binary oxides were evaluated to help assess their suitability as a replacement for silicon dioxide gate dielectrics in complementary metal--oxide--semiconductor transistors. The films were prepared by chemical solution deposition using a solution prepared from a mixture of zirconium, hafnium, and silicon butoxyethoxides dissolved in butoxyethanol. The films were spun onto SiO{sub x}N{sub y} coated Si wafers and furnace annealed at temperatures from 500 to 1200{sup o}C in oxygen for 30--60 min. The microstructure and electrical properties of ZSO and HSO films were examined as a function of the Zr/Si and Hf/Si ratio and annealing temperature. The films were characterized by x-ray diffraction, mid- and far-Fourier transform infrared (FTIR), Rutherford backscattering spectroscopy, and Auger electron spectroscopy. At ZrO{sub 2} or HfO{sub 2} concentrations {>=}50%, phase separation and crystallization of tetragonal ZrO{sub 2} or HfO{sub 2} were observed at 800{sup o}C. At ZrO{sub 2} or HfO{sub 2} concentrations {<=} 25%, phase separation and crystallization of tetragonal ZrO{sub 2} or HfO{sub 2} were observed at 1000{sup o}C. As the annealing temperature increased, a progressive change in microstructure was observed in the FTIR spectra. Additionally, the FTIR spectra suggest that HfO{sub 2} is far more disruptive of the silica network than ZrO{sub 2} even at HfO{sub 2} concentrations {<=}25%. The dielectric constants of the 25%, 50%, and 75% ZSO films were measured and were observed to be less than the linear combination of ZrO{sub 2} and SiO{sub 2} dielectric constants. The dielectric constant was also observed to increase with increasing ZrO{sub 2} content. The dielectric constant was also observed to be annealing temperature dependent with larger dielectric constants observed in nonphase separated films. The Clausius--Mossoti equation and a simple capacitor model for a phase separated system were observed to fit the data with the prediction that to achieve a dielectric constant larger than 10 doping concentrations of ZrO{sub 2} would have to be greater than 70%. {copyright} 2001 American Institute of Physics.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40230531
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 4 Vol. 90; ISSN 0021-8979
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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