Analysis of excimer laser annealing of amorphous SiGe on La2O3//Si structures

L. Fornarini, J.C. Conde, S. S.Chiussi, P. Gonzalez, B. Leon, S. Martelli

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Abstract

The reduction of complementary metal oxide semiconductor dimensions through transistor scaling is in part limited by the SiO2dielectric layer thickness. Among the materials evaluated as alternative gate dielectrics one of the leading candidate is La2O3due to its high permittivity and thermodynamic stability. However, during device processing, thermal annealing can promote deleterious interactions between the silicon substrate and the high-k dielectric degrading the desired oxide insulating properties. The possibility to grow poly-SiGe on top of La2O3//Si by laser assisted techniques therefore seems to be very attractive. Low thermal budget techniques such as pulsed laser deposition and crystallization can be a good choice to reduce possible interface modifications due to their localized and limited thermal effect. In this work the laser annealing by ArF excimer laser irradiation of amorphous SiGe grown on La2O3//Si has been analysed theoretically by a numerical model based on the heat conduction differential equation with the aim to control possible modifications at the La2O3//Si interface. Simulations have been carried out using different laser energy densities (0.26-0.58 J/cm2), different La2O3film thickness (5-20 nm) and a 50 nm, 30 nm thick amorphous SiGe layer. The temperature distributions have been studied in both the two films and substrate, the melting depth and interfaces temperature have been evaluated. The fluences ranges for which the interfaces start to melt have been calculated for the different configurations. Thermal profiles and interfaces melting point have shown to be sensitive to the thickness of the La2O3film, the thicker the film the lower the temperature at Si interface. Good agreement between theoretical and preliminary experimental data has been found. According to our results the oxide degradation is not expected during the laser crystallization of amorphous Si0.7Ge0.3for the examined ranges of film thickness and fluences. © 2007 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)7957 - 7963
Number of pages7
JournalApplied Surface Science
Volume253
Issue number19
DOIs
Publication statusPublished - 31 Jul 2007
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Condensed Matter Physics

Cite this

Fornarini, L., Conde, J. C., S.Chiussi, S., Gonzalez, P., Leon, B., & Martelli, S. (2007). Analysis of excimer laser annealing of amorphous SiGe on La2O3//Si structures. Applied Surface Science, 253(19), 7957 - 7963. https://doi.org/10.1016/j.apsusc.2007.02.063