In this study low temperature copper-gold bonding in ambient is demonstrated successfully with the help of organic monolayers. Further investigation is made to evaluate the influence of chain length of these monolayers to alleviate bonding temperature. We found that a single coat of organic monolayer on copper showed superior bond strength as compared to a double-coating on both copper and gold surfaces respectively. Despite effective surface passivation against oxide formation (Cu) and organic contaminant from ambient (Au) by long chain organic monolayers, when both surfaces are coated with the longest monolayer, weaker bond strength was observed. The results suggest that the ease of removal of organic monolayers from Cu and Au surface respectively prior to bonding plays a dominant role in enabling low temperature Cu-Au bonding.

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