Improved operation characteristics for charge-trapping flash memory devices with SiGe buried channel and stacked charge-trapping layers

Two approaches are proposed in this work to improve the operation characteristics of charge-trapping (CT) flash devices, namely, SiGe buried channel and stacked charge-trapping layer. SiGe buried channel with different Ge contents and various thicknesses of Si-cap layer on operation characteristics of CT flash devices were studied. The programming and erasing speeds of CT flash devices are significantly improved by employing SiGe buried channel. The retention properties of CT flash devices are satisfactory with suitable Ge content in SiGe buried channel and proper thickness of Si-cap layer. Moreover, the programming and erasing speeds of CT flash devices are significantly improved by applying Si₃N₄/Hf_xAl_1-xO charge trapping layers due to the enhanced carrier capture efficiency with extra interface (Si₃N₄/Hf_xAl_1-xO). The retention property is clearly improved as well.