Fabrication and Characterization of Suspended Uniaxial Tensile Strained-SiNanowires for Gate-All-Around n-MOSFETs

摘要

Suspended strained-Si nano-wires (NWs) were fabricated from arnhighly biaxially strained-Si substrate (with an initial stress of 2.16rnGpa). Using e-beam lithography, ～25nm thick NWs with thernwidths in the range of 20 to 80 nm were fabricated and the stressrnwas investigated by UV micro-Raman spectroscopy. SuspendedrnNWs are strained to an average uniaxial tensile stress level of ～2.1rnGpa which is almost independent of NW width, in the rangernstudied in this work. Ultra-dense (25 NWs per micron) sub-20 nmrnsuspended strained-Si NWs were fabricated using resolutionenhancedrnlithography to improve the Raman signal-to-noise ratio.rnA tensile in-plane stress level of 1.7GPa was measured for 18 nmwidernNWs at 40 nm pitch. Gate-all-around n-MOSFETs werernfabricated based on these strained-Si NWs. Electricalrnmeasurements on these MOSFETs demonstrate near idealrnsubthreshold behavior, very high on-to-off ratio and current drivernand transconductance enhancement of ～2X over unstrained NWs.