Effect of Pd precursor status on sonochemical surface activation in Cu electroless deposition

- Sonochemistry makes the Pd activation with Pd size of 1-3 nm possible on Ta barrier substrate.
- NH4OH improves uniformity and the adhesion of Pd nano-particles on substrate.
- N2 purging changes the solvent atmosphere for Pd nano-particle formation.
- Cu film quality was improved by aging activation solution and purging activation solution with N2.