Films minces d'oxydes à grande permittivité pour la nanoélectronique : organisation structurale et chimique et propriétés diélectriques

Pierre Eugene Coulon 1
1 CEMES-MEM - Matériaux et dispositifs pour l'Electronique et le Magnétisme
CEMES - Centre d'élaboration de matériaux et d'études structurales
Abstract : Despite the considerable research work devoted since ten years to the study of new high permittivity (κ) thin films for replacing silica in microelectronics, the relationships that exist between the structural/chemical and electrical properties of the films are not widely studied today. Thin Zr- and La-based oxide films, prepared by atomic layer deposition on silicon and/or germanium, are considered in this work. Quantitative parameters in relation with the organization at the nanometre level in the films and at the interfaces, determined by high resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS) operated on a modern electron microscope, are directly connected to electrical parameters such as κ and Dit (interface state density). After annealing under vacuum, the La2O3 sesquioxide can be obtained with its high permittivity hexagonal phase (κ ∼ 27) but is not stable. It is hygroscopic and forms with the silicon substrate an extended amorphous interfacial layer silicate in composition. The LaxZr1-xO2-δ (x ≤ 0.2) ternary oxide is not hygroscopic. On a silicon substrate and with x ∼ 0.2, it is stabilized in the cubic structure (κ ∼ 30) with annealing and forms a silica-rich interfacial layer with a spatial extension limited to 1-2 nanometres. On a germanium substrate and with x ∼ 0.05, the ternary is stabilized with the high permittivity tetragonal structure (κ ∼ 40) due to germanium diffusion within the film and develops in direct contact with the substrate. Lanthanum is essentially present near the interface and forms a germanate that lowers the Dit. This work has been developed in line with the European program REALISE.
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Pierre Eugene Coulon. Films minces d'oxydes à grande permittivité pour la nanoélectronique : organisation structurale et chimique et propriétés diélectriques. Science des matériaux [cond-mat.mtrl-sci]. Université Toulouse III - Paul Sabatier, 2009. Français. ⟨NNT : 2009TOU30025⟩. ⟨tel-02080581⟩



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