The effect of TAD based cleaning solution on post Cu CMP process

• TAD showed the best cleaning performance among various complexing agents.
• The cleaning performance improved as the number of functional group increased.
• In alkali condition, the amine functional group was superior to other groups.
• Abrasive re-adsorption was inhibited by the repulsive force of same zeta potential.

A cleaning solution has been introduced to remove the residue from Cu substrate after the Cu chemical mechanical polishing (CMP) process. In this study, the effects of complexing agents on the performance of cleaning solutions were studied depending on different functional groups and concentration based on a lift-off mechanism. The cleaning performance of the cleaning solution was assessed based on zeta potential, residual particle density, and etch rates. To prove that the cleaning is based on the lift-off mechanism, the Cu oxide layer composition and thickness were investigated by X-ray photoelectron spectroscopy. The thickness of Cu oxide increased up to 3.48 nm after the Cu CMP process; however, it dramatically decreased to 0.80 nm after the cleaning process. As the number of functional group for complexing agent and its concentration increased, the cleaning performance improved. In alkali condition, the amine functional group was found to be superior to other functional groups.

Schematic diagram of (a) Cu substrate after contamination, (b) residual removal occurring during cleaning process, and (c) the repulsion between residue and Cu substrate based on zeta potential after cleaning process.Figure optionsDownload as PowerPoint slide