Reduction of Electrical Defects in Atomic Layer Deposited HfO2 Films by Al Doping

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• 作者：Tae Joo Park ; Jeong Hwan Kim ; Jae Hyuck Jang ; Choong-Ki Lee ; Kwang Duk Na ; Sang Young Lee ; Hyung-Suk Jung ; Miyoung Kim ; Seungwu Han ; Cheol Seong Hwang
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：July 27, 2010
• 年：2010
• 卷：22
• 期：14
• 页码：4175-4184
• 全文大小：1276K
• 年卷期：v.22,no.14(July 27, 2010)
• ISSN：1520-5002

文摘

The gate leakage current density (J_g) of ultrathin (3 nm) Al-doped HfO₂ (Al:HfO₂) films with an Al concentration of 11% was lower than that of the control HfO₂ film by 2 orders of magnitude at an equivalent oxide thickness of 1 nm. The permittivity of the Al:HfO₂ film was similar to that of the control HfO₂ film. Al doping of HfO₂ films reduced the concentration of the oxygen vacancies and carbon in the film, which act as electrical defects (traps). It also increased the band gap of the film, resulting in a reduced J_g. Although the crystalline structure of a 12 nm-thick Al:HfO₂ film contained both tetragonal and monoclinic phases after high temperature annealing, the 3 nm thick Al:HfO₂ film showed a monoclinic structure, which is the same as the control HfO₂ film. Therefore, there was no modification of the crystalline structure of the Al:HfO₂ film in the ultrathin film case that would increase the permittivity. However, Si diffusion into the film and interfacial layer growth during annealing were suppressed significantly, which improved the thermal stability of the Al:HfO₂ films.