Optimization of SiGe interface properties with ozone oxidation and a stacked HfO2/Al2O3 dielectric for a SiGe channel FinFET transistor

Abstract

In this paper, the optimization of SiGe interface properties for the SiGe channel fin field effect transistor (FinFET) transistor is explored in detail. First, optimal low-temperature ozone oxidation at 300 °C for 30 min was confirmed based on Al2O3/Si0.7Ge0.3 metal-oxide-semiconductor (MOS) capacitors. This is because a higher oxidation temperature and a longer oxidation time can suppress the formation of GeO X in the interface layer (IL) and significantly improve the interface state density (D it). Moreover, compared with the Al2O3 sample, the HfO2 sample can obtain a thinner capacitance equivalent oxide thickness (CET), but it is more vulnerable to deterioration of Si0.7Ge0.3 interface properties because the GeO X in the IL is more likely to diffuse into the HfO2 layer. To further optimize the D it and CET of the Si0.7Ge0.3 MOS capacitor simultaneously, a stacked HfO2/Al2O3 dielectric is proposed. Compared with the HfO2 sample, its frequency dispersion characteristics and D it have been improved significantly, as the thin Al2O3 layer prevents the diffusion of GeO X to the HfO2 layer and controls the growth of GeO X . Therefore, a high-quality Si0.7Ge0.3 interface property optimization technology is realized via the development of a low-temperature ozone oxidation (300 °C, 30 min) method combined with a stacked HfO2/Al2O3 dielectric. In addition, a Si0.7Ge0.3 FinFET utilizing this newly developed interface property optimization scheme is successfully prepared. Its excellent subthreshold swing performance indicates that good interface quality of the Si0.7Ge0.3 is obtained. The above results prove that this newly developed interface property optimization scheme is a practical technology for high-mobility SiGe FinFET.