Abstract
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.
Funder
the Science and Technology Program of Beijing Municipal Science and Technology Commission
Beijing Municipal Natural Science Foundation
National Natural Science Foundation of China
Subject
General Materials Science,General Chemical Engineering
Cited by
8 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献