Strategy Utilizing Electrochemical ALD of Cu-Zn for Enabling Metallization of Sub-10 nm Semiconductor Device Nodes

Strategy Utilizing Electrochemical ALD of Cu-Zn for Enabling Metallization of Sub-10 nm Semiconductor Device Nodes

Aniruddha Joi, Kailash Venkatraman, Kuang-Chih Tso, Dries Dictus, Yezdi Dordi, Pu-Wei Wu, Chih-Wen Pao and Rohan Akolkar

doi: 10.1149/2.0181909 jss ECS J. Solid State Sci. Technol. 2019 volume 8, issue 9, P516-P521 

A novel interface engineering approach, utilizing electrochemical atomic layer deposition (e-ALD) of Cu(Zn) on a Ru liner, is presented for enabling the metallization of sub-10 nm interconnects in future semiconductor devices. Upon thermal treatment, Zn present in the e-ALD Cu layer at ∼0.8 at.% is shown to diffuse through the Ru liner and react with the SiO₂ to form a Zn-silicate layer at the Ru-SiO₂ interface. This ‘self-forming’ interfacial layer provides adhesion enhancement to the Ru-SiO₂ interface and serves as a diffusion barrier retarding Cu diffusion into the SiO₂ layer while enabling void-free gap-filling of high aspect ratio trench structures. Absorption Near-Edge Spectroscopy and Extended X-ray Absorption Fine Structure analyses confirm that the self-formed barrier layer is composed primarily of Zn₂SiO₄. The interface engineering approach utilizing Cu(Zn) presented herein offers several potential advantages over traditional Mn-based self-forming barrier approaches, i.e., scalability to narrower dimensions and minimal impact to interconnect resistance.

Process flow for adhesion testing by scratch and peel method for (a) Cu/Cu-Zn/Ru/SiO2 and (b) Cu/Ru/SiO2 stack without the Zn-containing interlayer.