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Differential Phase Contrast Imaging of BEOL CVD Co Liner

IP.com Disclosure Number: IPCOM000241725D
Publication Date: 2015-May-26
Document File: 5 page(s) / 333K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a simple method to evaluate the quality of Chemical Vapor Deposition (CVD) Cobalt (Co) liner materials. The method uses a differential phase contrast imaging technique for evaluating the CVD Co liner materials applied in the Back End of Line (BEOL) integration scheme for a 10 nm node and beyond.

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Differential Phase Contrast Imaging of BEOL CVD Co Liner

Starting from 10 nm node technology, Chemical Vapor Deposition (CVD) Cobalt (Co) liner has been integrated into the Back End of Line (BEOL) dual damascene process to enhance the Copper (Cu) gap-fill through the wetting improvement of the Physical Vapor Deposition (PVD) Cu seed layer. The film thickness and uniformity of the CVD-Co layer is critical for the following Cu plating, as well as the final line resistance. Thus, accurate metrology of the CVD Co liner is needed. However, the CVD Co liner is usually deposited on Tantalum Nitrogen (TaN)/Ta barrier layers; therefore, it is difficult to differentiate Co liner and barrier layers in standard bright field transmission electron microscopy (TEM) and dark field scanning transmission electron microscope (STEM) images due to the similar mass density of these materials.

Energy-dispersive x-ray (EDX) and electron energy loss spectroscopy (EELS) elemental mapping analysis are usually used to determine the Co distribution in the Co liner, where the spatial resolution is limited by the delocalization effects of the EELS and EDX signals due to the probe channeling and spreading. In addition, the EELS experiment set up is time consuming and requires advanced EELS knowledge and skill.

A quick and easy characterization technique is needed to evaluate the quality of CVD-Co liner materials.

The novel contribution is a simple method to evaluate the quality of CVD-Co liner...