Cointegration of High-Performance Tied-Gate Three-Terminal FinFETs and Variable Threshold-Voltage Independent-Gate Four-Terminal FinFETs With Asymmetric Gate-Oxide Thicknesses

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Cointegration of titanium nitride (TiN)-gate high-performance tied-gate three-terminal FinFETs with symmetric gate-oxide thicknesses <formula formulatype="inline"><tex>$(t_{{\rm ox}1} = t_{{\rm ox}2} = \hbox{1.7}\ \hbox{nm})$ </tex></formula> and variable threshold-voltage <formula formulatype="inline"><tex>$V_{\rm th}$</tex></formula> independent-gate four-terminal (4T) FinFETs with asymmetric gate-oxide thicknesses (<formula formulatype="inline"> <tex>$t_{{\rm ox}1} = \hbox{1.7}\ \hbox{nm}$</tex></formula> for the driving-gate-oxide, and <formula formulatype="inline"><tex>$t_{{\rm ox}2} = \hbox{3.4}\ \hbox{or}\ \hbox{7.0}\ \hbox{nm}$</tex></formula> for the control-gate-oxide) has been successfully developed using conventional reactive sputtering, two-step Si-fin and gate-oxide formation, and resist etch-back processes. A significantly improved subthreshold slope and an extremely low <emphasis emphasistype="smcaps">OFF</emphasis>-state current <formula formulatype="inline"><tex>$I_{ \rm off}$</tex></formula> are experimentally confirmed in the asymmetric gate-oxide thickness 4T FinFETs by increasing the control-gate-oxide thickness to twice or more the driving-gate-oxide thickness. The developed techniques are attractive for high-performance and low-power FinFET very large-scale integration circuits. </para>