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Open AccessArticle

Investigate on the Mechanism of HfO2/Si0.7Ge0.3 Interface Passivation Based on Low-Temperature Ozone Oxidation and Si-Cap Methods

1
School of Information Science and Technology, North China University of Technology, Beijing 100144, China
2
Integrated Circuit Advanced Process Center, Institute of Microelectronics, Chinese Academy of Science, Beijing 100029, China
*
Authors to whom correspondence should be addressed.
Academic Editor: Alexander Kromka
Nanomaterials 2021, 11(4), 955; https://doi.org/10.3390/nano11040955
Received: 23 February 2021 / Revised: 2 April 2021 / Accepted: 7 April 2021 / Published: 9 April 2021
(This article belongs to the Special Issue Silicon Nanodevices)
The interface passivation of the HfO2/Si0.7Ge0.3 stack is systematically investigated based on low-temperature ozone oxidation and Si-cap methods. Compared with the Al2O3/Si0.7Ge0.3 stack, the dispersive feature and interface state density (Dit) of the HfO2/Si0.7Ge0.3 stack MOS (Metal-Oxide-Semiconductor) capacitor under ozone direct oxidation (pre-O sample) increases obviously. This is because the tiny amounts of GeOx in the formed interlayer (IL) oxide layer are more likely to diffuse into HfO2 and cause the HfO2/Si0.7Ge0.3 interface to deteriorate. Moreover, a post-HfO2-deposition (post-O) ozone indirect oxidation is proposed for the HfO2/Si0.7Ge0.3 stack; it is found that compared with pre-O sample, the Dit of the post-O sample decreases by about 50% due to less GeOx available in the IL layer. This is because the amount of oxygen atoms reaching the interface of HfO2/Si0.7Ge0.3 decreases and the thickness of IL in the post-O sample also decreases. To further reduce the Dit of the HfO2/Si0.7Ge0.3 interface, a Si-cap passivation with the optimal thickness of 1 nm is developed and an excellent HfO2/Si0.7Ge0.3 interface with Dit of 1.53 × 1011 eV−1cm−2 @ E−Ev = 0.36 eV is attained. After detailed analysis of the chemical structure of the HfO2/IL/Si-cap/Si0.7Ge0.3 using X-ray photoelectron spectroscopy (XPS), it is confirmed that the excellent HfO2/Si0.7Ge0.3 interface is realized by preventing the formation of Hf-silicate/Hf-germanate and Si oxide originating from the reaction between HfO2 and Si0.7Ge0.3 substrate. View Full-Text
Keywords: HfO2/Si0.7Ge0.3 gate stack; ozone oxidation; Si-cap; interface state density; passivation HfO2/Si0.7Ge0.3 gate stack; ozone oxidation; Si-cap; interface state density; passivation
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MDPI and ACS Style

Yao, Q.; Ma, X.; Wang, H.; Wang, Y.; Wang, G.; Zhang, J.; Liu, W.; Wang, X.; Yan, J.; Li, Y.; Wang, W. Investigate on the Mechanism of HfO2/Si0.7Ge0.3 Interface Passivation Based on Low-Temperature Ozone Oxidation and Si-Cap Methods. Nanomaterials 2021, 11, 955. https://doi.org/10.3390/nano11040955

AMA Style

Yao Q, Ma X, Wang H, Wang Y, Wang G, Zhang J, Liu W, Wang X, Yan J, Li Y, Wang W. Investigate on the Mechanism of HfO2/Si0.7Ge0.3 Interface Passivation Based on Low-Temperature Ozone Oxidation and Si-Cap Methods. Nanomaterials. 2021; 11(4):955. https://doi.org/10.3390/nano11040955

Chicago/Turabian Style

Yao, Qide; Ma, Xueli; Wang, Hanxiang; Wang, Yanrong; Wang, Guilei; Zhang, Jing; Liu, Wenkai; Wang, Xiaolei; Yan, Jiang; Li, Yongliang; Wang, Wenwu. 2021. "Investigate on the Mechanism of HfO2/Si0.7Ge0.3 Interface Passivation Based on Low-Temperature Ozone Oxidation and Si-Cap Methods" Nanomaterials 11, no. 4: 955. https://doi.org/10.3390/nano11040955

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