The influence of various types of metal nitride gate electrodes, i.e., tantalum nitride, molybdenum nitride, and tungsten nitride, on electrical characteristics of metal-oxide-semiconductor capacitors with hafnium oxide as the gate dielectric material has been studied. The result shows that both the physical and electrical properties of the high- gate stack are influenced by the gate electrode materials and the post-metal-annealing temperature. Both the physical thickness and equivalent oxide thickness of the gate stack increased after the high-temperature annealing step. The leakage current density decreased with the increase of the annealing temperature from . The work functions of these metal nitride electrodes decreased with the annealing temperature due to the variance of microstructure and chemical composition, as indicated by x-ray diffraction and second-ion-mass spectroscopy data. These metal nitride electrodes are suitable for -channel metal-oxide-semiconductor device applications after annealing because their work functions are between 4.05 and . The interface state density and oxide trap density of the high- gate stack were also reduced by the high-temperature annealing step.
Physical and electrical properties of Ta–N, Mo–N, and W–N electrodes on high- gate dielectric
Jiang Lu, Yue Kuo, Somenath Chatterjee, Jun-Yen Tewg; Physical and electrical properties of Ta–N, Mo–N, and W–N electrodes on high- gate dielectric. J. Vac. Sci. Technol. B 1 January 2006; 24 (1): 349–357. https://doi.org/10.1116/1.2163883
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