Plasma assisted bonding of copper and silver substrates

In this research, copper and silver substrates have been bonded by plasma activated bonding method at 190°C. Furthermore, additional formic acid process after plasma process for both surfaces had effect to be bonded more tightly. The surface conditions were analyzed by SEM, AFM and XPS. As results, silver surfaces were etched and smoothed by plasma, and the surface oxidation adsorbent was removed, according to XPS O1s spectra. Moreover, oxidation layer of silver surface was reduced by formic acid process. On the other hand, copper surface was less changed by plasma, but copper surface was also reduced, and copper precipitation was observed on the surface by formic acid process.