Environmentally clean slurry using nano-TiO2-abrasive mixed with oxidizer H2O2 for ruthenium-film chemical mechanical planarization

• Published in: Applied surface science Vol. 282; pp. 844 - 850
• Main Authors: Cui, Hao, Park, Jin-Hyung, Park, Jea-Gun
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2013; Elsevier
• Subjects: Chemical mechanical polishing; Cleaning; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Contamination; Corrosion; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; H2O2; Nanostructure; Oxidizers; Physics; Planarization; Polishing; Ruthenium; Silicon dioxide; Slurries; TiO2; Ruthenium; H2O2; Chemical mechanical polishing; TiO2; Planarization; Mechanical polishing; Inorganic compounds; Transition elements; Transition element compounds; Chemical polishing; H; TiO; Titanium oxide; O
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.06.068

•Nano-crystalline TiO2 was used as the abrasive instead of the amorphous silica.•TiO2 slurry has high polishing rate of Ru film with H2O2.•TiO2 slurry was environmentally clean for Ru CMP.•Spin-torque transfer magnetic random access memory requires clean Ru CMP slurry.•TiO2 slurry provides a solution to environmentally clean Ru CMP. A colloidal silica-abrasive-based slurry mixed with periodate salts has been used for chemical mechanical planarization (CMP) of ruthenium (Ru) film in semiconductor-chip fabrication. This slurry has serious environmental problems such as generation of toxic RuO4 gas, corrosion, and ionic contamination. We developed an environmentally clean slurry using nano-TiO2 abrasive mixed with hydrogen peroxide (H2O2) for the purpose of Ru-film CMP. Moreover, this slurry is free of corrosion and ionic contamination. The polishing rates of Ru and SiO2 films with this slurry strongly depended on the H2O2 concentration; the Ru-film polishing rate rapidly increased with H2O2 concentration up to 1wt% and then slightly decreased or saturated, whereas the SiO2-film polishing rate abruptly dropped to ∼50Å/min. In particular, the adsorbed amount of H2O2 on nano-TiO2 abrasive directly determined the Ru-film polishing rate, indicating a new CMP mechanism of Ru film in the slurry.