Impact of Fin Doping and Gate Stack on FinFET (110) and (100) Electron and Hole Mobilities

• Published in: IEEE electron device letters 2012-03, Vol.33 (3), p.351-353
• Main Authors: Akarvardar, K., Young, C. D., Baykan, M. O., Injo Ok, Tat Ngai, Kah-Wee Ang, Rodgers, M. P., Gausepohl, S., Majhi, P., Hobbs, C., Kirsch, P. D., Jammy, R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Charge carrier processes; Doping; Electronics; Exact sciences and technology; FinFET; FinFETs; Hafnium compounds; high- K; Logic gates; metal gate; mobility; Scattering; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Tin; Transistors
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2011.2182603

Double-gate FinFET (110) (110) and (100) (100} electron mobility (μ e ) and hole mobility (μ h ) are experimentally investigated for the following: 1) a wide range of boron and phosphorus fin doping concentrations and 2) a wide variety of gate stacks combining HfO 2 , SiO 2 , or SiON insulators with TiN or poly-Si electrodes. It is found out that, irrespective of fin doping and gate stack, (110) (110) μ e is competitive with the (100)(100) μ e , while (110)(110) μ h is ≥ 2× higher than (100) (100) μ h . Inversion μ e and μ h are independent of doping as long as the effective field/doping combination enables the screening of the depletion charge. Mobility degradation with doping is significantly lower in accumulation mode (AM) than in inversion mode (IM) such that, for heavily B-doped fins, AM hole mobility exceeds the IM electron mobility even in (100) FinFETs. In undoped fins, ALD TiN gate stress is observed to improve μ e for both orientations without degrading μ h .