Tantalum nitride interface layer influence on dielectric properties of hafnium doped tantalum oxide high dielectric constant thin films
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Drastic improvement of the dielectric properties of the hafnium-doped tantalum oxide high dielectric constant thin film with the insertion of a 5 Å tantalum nitride interface layer was observed. The film's breakdown strength, leakage current, and apparent dielectric constant were improved with the addition of the interface layer. However, the interface layer introduced additional fixed charges to the film, which can only be partially removed with the 700°C annealing step. This thin interface layer did not change the phenomenon that the lightly doped film has an anomalous high k value compared with other doped or undoped films. The deposited TaNx interface film contained Ta-N, Ta-O and Si-O bonds after the 700°C anneal, which is a high k film. It also prevented the formation of an interface film with inferior qualities. This interface modification method is viable for future high k gate dielectric applications.
author list (cited authors)
Kuo, Y., Lu, J., & Tewg, J. Y.