25-nm Gate Length nMOSFET With Steep Channel Profiles Utilizing Carbon-Doped Silicon Layers (A P-Type Dopant Confinement Layer)

• Published in: IEEE transactions on electron devices Vol. 58; no. 5; pp. 1302 - 1310
• Main Authors: Hokazono, A, Itokawa, H, Kusunoki, N, Mizushima, I, Inaba, S, Kawanaka, S, Toyoshima, Y
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-05-2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Carbon; Carbon-doped Si (Si:C); Channels; Design. Technologies. Operation analysis. Testing; Doping; Electronics; Epitaxial growth; epitaxial layers (epi-layer); Exact sciences and technology; Gates; Indium; Integrated circuits; Logic gates; Metal oxide semiconductors; mobility; MOS devices; MOSFETs; random dopant fluctuation; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon; steep channel profile; Transistors; Voltage threshold; High performance; MOSFET; mobility; Impurity; steep channel profile; Channel structure; Doped materials; epitaxial layers (epi-layer); Indium; Boron; p channel; Carbon addition; p type semiconductor; Complementary MOS technology; Carbon-doped Si (Si:C); Silicon; NMOS technology; random dopant fluctuation
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2011.2112770

Steep channel profiles of scaled transistors are a promising approach for advancing transistor generation in bulk complementary metal-oxide-semiconductor (MOS). In this paper, a carbon-doped Si (Si:C) layer under an undoped Si layer is proposed to form steep p-type channel profiles in n-channel MOS field-effect transistors (nMOSFETs) due to extremely low diffusivity of boron and indium in Si:C layers. This structure with low channel impurity improves mobility and suppresses threshold voltage ( V TH ) variation. Both items are essential for aggressively scaled MOSFETs with a gate length less than 25 nm. We demonstrated well-controlled, high-performance, and low V TH variability nMOSFETs with a Si:C-Si epitaxial channel structure.