We investigated the electrical properties of TaN/HfO2/Si gate stack structure. It was found that the effective work function (陸eff) strongly depends on the interfacial layer formed near the TaN/HfO2 interface. The analysis by X-ray photoelectron spectroscopy (XPS) indicated that Ta oxide is formed near the TaN/HfO2 interface. The results suggested that the modification of 陸eff is attributed to the change in the composition of the interfacial layer. The modified陸eff is discussed on the basis of the XPS results.
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