Post-CMP Cleaners for Tungsten at Advanced Nodes

Abstract:

We discuss several mechanistic approaches and experimental data for improving post-CMP cleaning of W plugs with TiN as barrier liner, and dielectric substrates SiO₂ and Si₃N₄ for use at the 10 nm technology node (metal pitch of 40 nm). Particle charge in the low pH, W CMP slurries are usually positive, and the W surface is always negatively charged at pH >3. Therefore, a strong electrostatic attraction is expected to occur between the W surface and the residual particles during post-CMP cleaning. Two main approaches were chosen to break down the strong particles-W surface post-CMP electrostatic interactions, as well as particles dispersion and prevention of redeposition: (1) using cleaning additives able to adsorb at the W surface and reverse the W surface charge; (2) using organic additives to reverse the particle charge. The latter approach results in two strongly negative charged surfaces, which are able to repulse each other, and leads to the best cleaning.

• Periodical: Solid State Phenomena (Volume 255)
• Pages: 186-194
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.255.186
• Online since: September 2016
• Authors: Ruben R. Lieten*, Daniela White, Thomas Parson, Shi Ning Jenq, Don Frye, Michael White, Lieve Teugels, Herbert Struyf
• Keywords: FTIR, Galvanic Corrosion, Organic Residue, Particle-Count Defectivity, Post-CMP Formulations, Silicon Nitride, SiO₂, Tafel, Tungsten 10 nm Node, W/TiN Barrier Liners, XPS

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