Beyond SiO2 technology: simulation of the impact of high-κ dielectrics on mobility

Ferrari, G., Watling, J.R., Roy, S., Barker, J.R. and Asenov, A. (2007) Beyond SiO2 technology: simulation of the impact of high-κ dielectrics on mobility. Journal of Non-Crystalline Solids, 353(5-7), pp. 630-634. (doi:10.1016/j.jnoncrysol.2006.10.044)

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A critical challenge for the microelectronics industry is the need for higher permittivity dielectrics to replace silicon dioxide. A number of different high-κ materials have been proposed and analyzed as SiO2 replacements in the next generation of MOSFETs. High-κ materials allow the use of a thicker gate dielectric, maintaining the gate capacitance with reduced gate leakage. However they all lead to mobility degradation due to, among other factors, the coupling of carriers to surface soft-optical (SO) phonons. A severe mobility degradation in the presence of high-κ becomes evident when comparing the vertical field dependence of mobility for a wide range of high-κ materials against SiO2. As oxides containing Hf presently appears to be the leading high-κ contenders, we have performed a detailed analysis of Hf-based gate stacks, exploiting alternative structures and compositions. The introduction of a SiO2 interfacial layer between the channel and the HfO2 reduces the detrimental mobility degradation resulting from the mobility SO phonon scattering, but increases the equivalent oxide thickness (EOT) of the gate dielectric. A possible material of choice for the first commercial introduction of high-κ gate stacks is hafnium silicate (SixHf1xO2), being thermally stable and offering a good compromise between small EOT and large electron mobility.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Watling, Dr Jeremy and Roy, Professor Scott and Asenov, Professor Asen
Authors: Ferrari, G., Watling, J.R., Roy, S., Barker, J.R., and Asenov, A.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Journal of Non-Crystalline Solids
ISSN (Online):1873-4812
Published Online:14 February 2007

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
370511The impact of Interface Roughness & Self-Heating on the performance of Nano-Scale MOSFETsJeremy WatlingEngineering & Physical Sciences Research Council (EPSRC)GR/S97194/01Electronic and Nanoscale Engineering