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Linearity and mobility degradation in strained Si MOSFETs with thin gate dielectrics

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Alatise, Olayiwola M., Olsen, Sarah H. and O'Neill, Anthony G.. (2010) Linearity and mobility degradation in strained Si MOSFETs with thin gate dielectrics. Solid-State Electronics, Vol.54 (No.6). pp. 628-634. ISSN 00381101

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Abstract

As gate dielectrics are scaled to a few atomic layers and the channel doping is increased to mitigate short channel effects, high vertical electric fields cause considerable mobility degradation through surface-roughness scattering in silicon MOSFETs. This high-field mobility degradation is known to influence the harmonic distortion through higher order derivatives of the drain current. Failure to take these higher order derivatives into account can cause significant error in the predictive evaluation of linearity (VIP3) in MOSFETs. Electrical measurements are used to extract the 2nd order mobility degradation factor (θ2) from strained silicon MOSFETs fabricated on silicon germanium strain relaxed buffers with 15%, 20% and 25% germanium. Linearity and high-field mobility degradation are shown to be independent of strain in spite of atomic force microscopy measurements showing that the amplitude of the root-mean-square surface roughness increases with the germanium content. It is also shown that θ2 is required for accurate modelling of linearity. The impact of oxide thickness on linearity is also investigated through θ2. In this paper, an analytical relationship between θ2 and the effective oxide thickness is developed and validated by electrical measurements on MOSFETs with different oxide thicknesses and θ2 values from the literature. Using the extracted θ2 values as inputs to analytical MOSFET models, a correlation between the oxide thickness and linearity is analyzed.

Item Type: Journal Article
Subjects: Q Science > QC Physics
T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Faculty of Science > Engineering
Library of Congress Subject Headings (LCSH): Electron mobility, Silicon, Silicon alloys, Metal oxide semiconductors, Complementary, Metal oxide semiconductor field-effect transistors
Journal or Publication Title: Solid-State Electronics
Publisher: Pergamon
ISSN: 00381101
Official Date: 2010
Volume: Vol.54
Number: No.6
Page Range: pp. 628-634
Identification Number: 10.1016/j.sse.2009.12.036
Status: Peer Reviewed
Publication Status: Published
Access rights to Published version: Restricted or Subscription Access
Funder: Engineering and Physical Sciences Research Council (EPSRC), Seventh Framework Programme (European Commission) (FP7)
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URI: http://wrap.warwick.ac.uk/id/eprint/37110

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