Microscopic investigations of chemo-mechanical polishing of tungsten

• Published in: Thin solid films 2004-06, Vol.457 (2), p.346-353
• Main Authors: Lim, Min Soo, van der Heide, Paul A.W., Perry, Scott S., Galloway, Heather C., Koeck, Deborah C.
• Format: Article
• Language: English
• Subjects: Adsorbed layers and thin films; Atomic force Microscopy (AFM); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Materials science; Oxidation; Photoemission and photoelectron spectra; Physics; Planarization; Polishing; Surface treatments; Tungsten; X-Ray photoelectron spectroscopy (XPS)
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2003.11.301

The influence of aqueous solutions of KNO 3, KClO 3, and KIO 3 on tungsten surfaces has been investigated in terms of the degree of surface oxidation, metal dissolution and interfacial friction. The surface properties of tungsten films have been measured ex-situ with X-ray photoelectron spectroscopy and in situ with atomic force microscopy. Measurements of the surface composition reveal a greater degree of oxidation for surfaces treated in solutions of KIO 3 in comparison to the other solutions. This increase in surface oxidation is correlated to a greater rate of localized film dissolution that occurs under the action of the scanning probe tip. In turn, the process of material removal is the predominant origin of the higher interfacial friction measured at tungsten surfaces immersed in KIO 3 solutions, as compared to KClO 3 and KNO 3 solutions. Collectively, these measurements portray a fundamental pathway of material removal at tungsten surfaces in the presence of oxidizing species and highlight complementary roles of chemical and mechanical action.