Characterization of Copper-Hydrogen Peroxide Film Growth Kinetics

摘要

As copper CMP modeling efforts become increasingly more sophisticated, it is important to understand the individual steps that have been found to play integral roles in the removal process such as oxidation, film dissolution, abrasion, and dissolution of byproducts. This study focuses on copper oxidation using H{sub}2O{sub}2, which is the most common oxidant added to slurries in the industry today. Ellipsometry, field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize copper film growth characteristics. Ellipsometric results concluded that copper film growth occurs in hydrogen peroxide solutions of varying concentrations at pH 5. The film growth profile for 1 weight percent hydrogen peroxide reaches a saturation point at approximately 500 Angstroms after about 12 hours. SEM images reveal that 50-100 nm crystals are observed for t < 60 hour and 200-300 nm crystals are formed at 22 hours, indicating that reaction by-products diffusing away from the film-metal interface contribute to film growth. XPS spectra indicate the presence of Cu (II) and possibly Cu (I) oxides and hydroxides for all t > 0.