GeOI pMOSFETs Scaled Down to 30-nm Gate Length With Record Off-State Current

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We present in this letter the most aggressive dimensions reported to date in Ge-channel transistors: pMOSFETs with 30-nm gate length on ultrathin germanium-on-insulator substrates <formula formulatype="inline"><tex Notation="TeX">$({T}_{\rm Ge} = \hbox{25}\ \hbox{nm})$</tex></formula>. By improving both the Ge-enrichment technique and the transistor fabrication process, we demonstrate devices with controlled threshold voltage <formula formulatype="inline"><tex Notation="TeX"> $({V}_{\rm th})$</tex></formula> and excellent short-channel effects. Moreover, the low defectivity and the very low thickness of the Ge film lead to a record drain <emphasis emphasistype="smcaps">off</emphasis>-state leakage for Ge-channel devices (<formula formulatype="inline"><tex Notation="TeX">$&lt;\hbox{1}\ \hbox{nA}/\mu\hbox{m}$</tex></formula> at <formula formulatype="inline"><tex Notation="TeX">${V}_{\rm DS} = -\hbox{1}\ \hbox{V}$</tex></formula>) and thus, to the best <emphasis emphasistype="smcaps">on</emphasis>-state to <emphasis emphasistype="smcaps">off</emphasis>-state current ratio <formula formulatype="inline"><tex Notation="TeX">$({I}_{\rm ON}/{I}_{\rm OFF} \sim \hbox{5} \times \hbox{10}^{5})$</tex> </formula>, even at <formula formulatype="inline"><tex Notation="TeX">${L}_{g} = \hbox{55}\ \hbox{nm}$</tex></formula>. </para>