The effects of silicon surface nitridation on metal–oxide–semiconductor capacitors with zirconium oxide (ZrO2)(ZrO2) gate dielectrics were investigated. Surface nitridation was introduced via ammonia (NH3)(NH3) annealing prior to ZrO2ZrO2 sputter-deposition, and tantalum nitride (TaN) was used for the gate electrode. It was found that capacitors with the nitridation had thinner equivalent oxide thickness (∼8.7 Å), comparable leakage current, and slightly increased capacitance–voltage hysteresis as compared to samples without nitridation. Additionally, transmission electron microscopy pictures revealed that nitrided samples had a thicker interfacial layer (IL), which had a higher dielectric constant than that of the non-nitrided IL.
R. Nieh, Choi, R., Dr. Sundararaman Gopalan, Onishi, K., Kang, C. Seok, Cho, H. - J., Krishnan, S., and Lee, J. C., “Evaluation of silicon surface nitridation effects on ultra-thin ZrO2 gate dielectrics”, Applied physics letters, vol. 81, pp. 1663–1665, 2002.