CHEMICAL VAPOR DEPOSITION OF Zr_xHf_1-xO₂ THIN FILMS USING ANHYDROUS MIXED-METAL NITRATES PRECURSORS

ABSTRACT

Hafnium-based dielectrics have been extensively investigated as a possible replacement for SiO₂. A novel volatile anhydrous Zr/Hf mixed-metal nitrate precursor Zr_xHf_1-x(NO₃)₄(ZHN) was successfully synthesized. Zr_xHf_1-xO₂ thin films were first prepared by the chemical vapor deposition (CVD) technique from the precursor of this mixed-metal nitrate. Differential scanning calorimetry (DSC) and infrared spectra (IR) measurements of ZHN indicated that ZHN may be mixture of single Hf(NO₃)₄ and a solid solution of Zr(NO₃)₄ and Hf(NO₃)₄. The Zr_xHf_1-xO₂ thin films exhibit good dielectric properties with a moderate bandgap value of 5.6 eV and a value for k of 22. Zr_xHf_1-xO₂ is, therefore, a promising candidate for gate-dielectric application, and the anhydrous mixed-metal nitrate can be a potential precursor for high-k materials derived from CVD.

Keywords:

• Anhydrous mixed-metal nitrate
• Zr_xHf_1-xO₂
• high-k materials
• chemical vapor deposition (CVD)

ACKNOWLEDGMENTS

This project was supported by the Program for New Century Excellent Talents in University (NCET-04-0451). It was also supported by the Natural Science Foundation of China and Jiangsu Province (50672036 and BK2006122) and a grant from the State Key Program for Basic Research of China.