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Hybrid Barrier Structure for Damascene Cu Interconnect

IP.com Disclosure Number: IPCOM000238189D
Publication Date: 2014-Aug-07
Document File: 2 page(s) / 39K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a hybrid barrier scheme in which a self-forming barrier layer coats the feature sidewalls, while a tantalum nitride/tantalum (TaN/Ta) layer at the feature bottom provides a Cu diffusion blocking barrier at the via bottom. This enables TaN/Ta barrier scaling to the narrow dimensions required for the 10nm node and beyond.

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Hybrid Barrier Structure for Damascene Cu Interconnect

Conventional tantalum nitride/tantalum (TaN/Ta) barriers provide good protection against Copper (Cu) diffusion, but are proving difficult to scale to the narrow dimensions required for the 10nm node and beyond. Moreover, since a minimum TaN/Ta thickness is required to serve as a barrier, an increasing fraction of the interconnect area is occupied by the barrier material, resulting in an increased interconnect line resistance as feature sizes shrink. Self-forming barriers (SFB) that react at the barrier/dielectric interface can be uniformly deposited in thinner layers and are one possible solution to the barrier scaling. However, the SFB approach does not result in the Cu diffusion blocking barrier at the via bottom necessary for the Blech effect and associated electromigration (EM) benefit.

The novel contribution is a hybrid barrier scheme in which a self-forming barrier layer coats the feature sidewalls, while a TaN/Ta layer at the feature bottom provides a Cu diffusion blocking barrier at the via bottom. The advantages of this approach include: a wider gap opening for plated Cu fill, a Cu diffusion blocking barrier at the via bottom for good EM performance, a higher Cu cross sectional area for lower line resistance, and a Chemical Mechanical Planarization (CMP) stop layer for the Cu slurry, resulting from the Ta(N) layer deposited in the field areas.

A hybrid barrier consisting of an SFB on the interconnec...