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Mise au point de procédés électrolytiques de dépôt de cuivre pour la métallisation de vias traversants (TSVs)

Abstract : Nowadays, 2D integration shows serious limitations when it comes to manufacturing devices with increased functionality and performance. In this context, 3D integration approaches using Through Silicon Vias (TSVs) have been investigated as a promising solution to fabricate tomorrow's microelectronics devices. In this architecture, the key challenge is the metallization of high aspect ratios (>5) TSVs by copper electrochemical deposition (Cu ECD). This metallization sequence includes barrier and seed layer deposition followed copper filling. This study is focused on seed layer deposition and TSV filling. Usually, the seed layer is grown by sputtering based deposition techniques (PVD). This technique suffers from limited sidewall coverage, eventually leading to electrical discontinuity in the features. In this work, an electrolytic process called Seed Layer Enhancement (SLE) has been investigated as a solution to improve copper seed continuity. For this purpose, copper nucleation on the resistive barrier material has been optimized using a specific surface treatment to remove native oxide on samples surface. As a result, the SLE process has been successfully inserted in the metallization sequence, as testified by good electrical performances. These promising results open the route to an alternative solution to PVD using an electrochemical process performed directly on the barrier diffusion layer (Direct On Barrier). On the other hand, two electrolytes (an old and a new generation) have been evaluated as solutions for TSV filling. In each case, the impact of additives on copper deposition and superfilling mechanism were analyzed by voltammetric and chronopotentiometric measurements on rotating disk electrode. This study shows two different filling behaviors, close to damascene electrolyte with the older generation electrolyte, and a bottom-up filling with the last generation. The main difference comes from the action of the inhibiting additive during the filling process. In the case of the last generation electrolyte, the inhibitor adsorbs strongly and irreversibly on the copper surface. Then, a strong inhibition of copper growth occurs on the sides and on the top of the TSVs, but the action of accelerator is still efficient at the pattern bottom.
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https://tel.archives-ouvertes.fr/tel-00825390
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Submitted on : Friday, July 19, 2013 - 10:04:16 AM
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  • HAL Id : tel-00825390, version 1

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Julien Cuzzocrea. Mise au point de procédés électrolytiques de dépôt de cuivre pour la métallisation de vias traversants (TSVs). Autre. Université de Grenoble, 2012. Français. ⟨NNT : 2012GRENI070⟩. ⟨tel-00825390⟩

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