Thèse soutenue

Caractérisation physico-chimique front-end : canal-diélectrique-métal
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Auteur / Autrice : Clément Gaumer
Direction : Bernard Drévillon
Type : Thèse de doctorat
Discipline(s) : Micro et nanoélectronique
Date : Soutenance en 2010
Etablissement(s) : Grenoble INPG

Résumé

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For the sub-32 nm technological nodes, a high dielectric constant oxide (high-k) and a metal gate electrode have to be implemented in MOSFET devices. Hf-based oxides are identified as the best option for the high-k. Titanium and tantalum nitrides are the mûst prûmising metals. This work focuses on the characterization of oxygen and nitrogen interdiffusions in gate stacks elaborated in the Gate First approach, containing TiN or TaN metal gates on HfOz. We show that metal gate deposition using ALD or A VD induces nitrogen diffusion to hafnia and the pedestal silicon oxide. Due to their high thermal budget, the poly-Si deposition and the spike anneal at 1050°C for dopant activation both give rise to oxygen diffusion and increase the amount of nitrogen in the pedestal 8iOz. The amount of atoms that diffuse at each step increase with the metal thickness, which expIrons the EOT and mobility degradations observed for devices with thicker metal electrodes. Finally, studying agate stack where Hf Oz has been plasma nitrided enables to demonstrate that defects initiaUy present in the high-k layer behave like traps for species diffusing during the gate electrode elaboration.