Hole Mobility Boosters of (110)-Oriented Extremely Thin Body SiGe-on-Insulator (SGOI) pMOSFETs

• Published in: IEEE transactions on electron devices 2023-07, Vol.70 (7), p.1-7
• Main Authors: Chen, Chia-Tsong, Han, Xueyang, Sumita, Kei, Toprasertpong, Kasidit, Takenaka, Mitsuru, Takagi, Shinichi
• Format: Article
• Language: English
• Subjects: asymmetric strain; Asymmetry; Channel estimation; Channels; Degradation; effective hole mobility; extremely thin body (ETB); Germanium; Hole mobility; MOSFET; oriented substrate; pMOSFET; Silicon germanides; Silicon germanium; Strain; strain energy; Substrates; Thin bodies
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2023.3279306

The effectiveness of (110)-oriented substrates and strain modulation by using starting substrates with thin SiGe and channel width narrowing on mobility enhancement in SiGe-on-insulator (SGOI) pMOSFETs is systematically investigated down to the body thickness ( \textit{T}_{\text{body}}\text{)} of 3.2 nm. The initial strain of 1.6% is realized at a Ge fraction of 60% by using the optimized Ge condensation. We confirm the significant mobility enhancement by narrowing the channel width ( \textit{W}_{\text{ch}}\text{)} of (110) SGOI channels, attributed to strong asymmetric strain. At \textit{T}_{\text{body}} of around 5 nm, (110) SGOI pMOSFETs provide higher hole mobility of 971 cm ^{\text{2}} /Vs than the ones fabricated on (100) GOI substrates, resulting in 1.9 \times mobility enhancement. The effective hole mobility of 291 cm ^{\text{2}} /Vs is also achieved on 3.2-nm-thick (110) SGOI pMOSFETs with asymmetric strain channels at \textit{W}_{\text{ch}} of 120 nm, leading to mobility enhancement of 1.5 \times against the mobility of quasi-uniaxial (100) GOI ones at the same \textit{T}_{\text{body}} despite the lower Ge fraction.