High-mobility Ge pMOSFET With 1-nm EOT Al 2O 3GeO xGe gate stack fabricated by plasma post oxidation

摘要

An ultrathin equivalent oxide thickness (EOT) Al 2O 3GeO xGe gate stack with a superior GeO xGe metal-oxide-semiconductor (MOS) interface and p-channel metal-oxide- semiconductor field-effect transistors (pMOSFETs) using this gate stack have been fabricated by a plasma post oxidation method. The properties of the GeO xGe MOS interfaces are systemically investigated, and it is revealed that there is a universal relationship between the interface state density (D it) at the GeO xGe interface and the GeO x interfacial layer thickness. Ge pMOSFETs on a (100) Ge substrate using the Al 2O 3GeO xGe gate stack have been demonstrated with an EOT down to 0.98 nm. It is found that the Ge pMOSFETs exhibit the peak hole mobility values of 515, 466, and 401 cm 2V ? s at an EOT of 1.18, 1.06, and 0.98 nm, respectively, which has much weaker EOT dependence than the trend of the hole mobility values reported so far, because of low D it of the present gate stack in the ultrathin EOT region of ～ nm.

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