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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Abstract

A critical challenge for the microelectronics industry is the need for higher permittivity dielectrics to replace silicon dioxide. A number of different high-<sub>κ</sub> materials have been proposed and analyzed as SiO<sub>2</sub> replacements in the next generation of MOSFETs. High-<sub>κ</sub> 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 SiO<sub>2</sub>. 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 SiO<sub>2</sub> interfacial layer between the channel and the HfO<sub>2</sub> 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-<sub>κ</sub> gate stacks is hafnium silicate (Si<sub>x</sub>Hf<sub>1</sub>−<sub>x</sub>O<sub>2</sub>), being thermally stable and offering a good compromise between small EOT and large electron mobility.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Asenov, Professor Asen and Watling, Dr Jeremy and Roy, Professor Scott
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:0022-3093
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