Influences of annealing in reducing and oxidizing ambients on flatband voltage properties of HfO2 gate stack structures

K. Ohmori, P. Ahmet, M. Yoshitake, T. Chikyow, K. Shiraishi, K. Yamabe, H. Watanabe, Y. Akasaka, Y. Nara, K. S. Chang, M. L. Green, K. Yamada

研究成果: Article同行評審

20 引文 斯高帕斯(Scopus)

摘要

We have applied a combinatorial technique to fabricate work function (WF) tuned Pt-W alloy films and used the films as metal electrodes for HfO2 SiO2 Si capacitors. As the ratio, RPt, of Pt to W changes from 0 to 1, the WF value varies continuously from 4.7 to 5.5 eV. This tunability enables us to systematically investigate the effect of WF variation on electrical properties. After a forming gas annealing process, the values of flatband voltage (Vfb) from capacitance-voltage properties are almost constant, regardless of the WF variation, because of oxygen vacancy formation that results in Fermi level pinning. On additional oxidizing gas annealing (OGA), the effect of WF value on Vfb becomes dominant. However, the difference in Vfb between W and Pt is 0.34 V, which is much smaller than the observed WF difference of 0.8 eV. We attribute this phenomenon to the lowering of the effective WF due to an electric dipole, induced by oxygen vacancy formation at the metal/ HfO2 interface. Moreover, a decrease in Vfb in W-rich regions was observed following the OGA, suggesting the formation of a W-O bond at the interface. These results clearly indicate that the control of bonding states at the metal/ HfO2 interfaces on an atomic scale is essential for the realization of a combination of metal and high- k dielectric films in future complementary metal-oxide-semiconductor devices.

原文English
文章編號084118
期刊Journal of Applied Physics
101
發行號8
DOIs
出版狀態Published - 2007

All Science Journal Classification (ASJC) codes

  • 物理與天文學 (全部)

指紋

深入研究「Influences of annealing in reducing and oxidizing ambients on flatband voltage properties of HfO<sub>2</sub> gate stack structures」主題。共同形成了獨特的指紋。

引用此