Local defect-free elastic strain relaxation of Si1-xGex embedded into SiO2

Assaf, Elie; Berbézier, Isabelle; Bouabdellaoui, Mohammed; Abbarchi, Marco; Ronda, A.; Valenducq, Damien; Deprat, Fabien; Gourhant, Olivier; Campos, Andreas; Favre, Luc

doi:10.1016/j.apsusc.2022.153015

Cited by 3 publications

(1 citation statement)

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“…In addition, at this temperature (i.e., below the glass transition temperature), SiO 2 has a low viscosity that could allow a slow layer-by-layer redistribution of Si 1−x Ge x slightly pushing SiO 2 in a planar way which would provide elastic strain relaxation without buckling. 58 The annealing is also very efficient to flatten the Si 1−x Ge x /BOX interface. The temperature of annealing is here very crucial since at lower temperature, strain is not relaxed (SiO 2 is too rigid), whereas at higher temperature, there is nucleation of dislocations.…”

Section: Methodsmentioning

confidence: 99%

New Strategies for Engineering Tensile Strained Si Layers for Novel n-Type MOSFET

David¹,

Berbézier

Aqua³

et al. 2020

ACS Appl. Mater. Interfaces

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We report a novel approach for engineering tensely strained Si layers on a relaxed Silicon Germanium On Insulator (SGOI) film using a combination of condensation, annealing and epitaxy in selected conditions well chosen based on elastic simulations. The study evidences the remarkable role of SiO2 buried oxide layer (BOX) on the elastic behavior of the system. We show that tensely strained Si can be engineered by using alternatively rigidity (at low temperature) and viscoelasticity (at high temperature) of the SiO2 substrate. In these conditions, we get a Si strained layer perfectly flat and free of defects on top of relaxed Si1−xGex. We found very specific annealing conditions to relax SGOI while keeping an homogeneous Ge concentration and an excellent thickness uniformity resulting from the viscoelasticity of SiO2 at this temperature, which would allow layer by layer matter redistribution.Remarkably, Si layer epitaxially grown on relaxed SGOI remains fully strained with -0.85 % tensile strain. The absence of strain sharing (between Si1−xGex and Si) is explained by the rigidity of the Si1−xGex/BOX interface at low temperature. Elastic simulations of the real system show that, due to the very specific elastic characteristics of SiO2, there are unique experimental conditions that both relax Si1−xGex and keep Si strained. Various epitaxial processes could be revisited in the light of these new results. The generic and simple process implemented here meets all the requirements of the microelectronics industry and should be rapidly integrated in the fabrication lines of large multifinger 2.5 V n-type MOSFET on SOI used for RF-switches applications and for many other applications.

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Section: Methodsmentioning

confidence: 99%