Study of Thermal Oxidation of SiGe for Advanced CMOS FD-SOI Technologies

Abstract : The tremendous spread of electronic devices and networks into our day-to-day life has been enabled by the constant downscaling of transistors since the 60’s. However, downsizing transistors has become increasingly difficult in the past few years and going to the nanometer scale brings new detrimental effects that have put power consumption and performances on quasi-plateaux for a few years. To overcome these limitations, high mobility channels based on new materials and new transistor architectures are being introduced. Ultrathin compressivelystrained SiGe-On-Insulator (SGOI) films benefit from the advantages of both the higher hole mobility of compressively strained SiGe as well as of the better electrostatic control of On-Insulator structures. The condensation techniqueis a CMOS-compatible technique that allows fabrication of such films with possibly high Ge content and high strain levels. The technique is based on Si-selective thermal oxidation of SiGe and concurrent SiGe diffusion between the thermal oxide and the buried oxide layer that acts as a diffusion barrier.Two main challenges still need to be taken up for an efficient and optimized use of the condensation technique in an industrial environment: oxidation mechanisms and kinetics must be well controlled, and strain and crystal quality of the SGOI film must be as high as possible.Firstly, this work bridges the gap between previous studies by covering various oxidation processes relevant to today’s technological needs with a new and quantitative analysis methodology of oxidation kinetics. A correlation is established between the diffusivity of the oxidizing species that governs oxidation kinetics, the Ge concentration at the oxidation interface, and the oxide density measured by X-Ray Reflectivity on a synchrotron beamline.Secondly, SGOI films with Ge concentrations up to 80% were fabricated by the condensation technique. The evolution of strain of SGOI films is discussed as a function of process parameters and strain energy levels. How the condensation technique alters the crystal quality, both at interfaces with oxides and in the bulk of the SiGe crystal, is evaluated by the Medium Energy Ion Scattering (MEIS) technique by using the channeling effect.
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Submitted on : Wednesday, June 6, 2018 - 12:54:26 PM
Last modification on : Wednesday, February 20, 2019 - 12:40:06 PM


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  • HAL Id : tel-01809031, version 1



Fabien Rozé. Study of Thermal Oxidation of SiGe for Advanced CMOS FD-SOI Technologies. Electric power. Université Grenoble Alpes, 2018. English. ⟨NNT : 2018GREAI018⟩. ⟨tel-01809031⟩



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