Wafer level bonding process is a key fabrication step in several integration systems including microelectromechanical (MEMs) and nanoelectromechanical (NEMs). Often, harsh bonding conditions used result in large thermomechanical stresses built-up which leads to undesired degradation in device performance. Our recent study revealed the capability of nanostructured organic coatings (NSOCs) in reducing the bonding temperature needed to bond copper surfaces from 300°C to 60°C. In this study, room temperature copper bonding is demonstrated successfully with the help of the organic layers. Further investigation is made to evaluate the influence of thickness of NSOCs to alleviate bonding temperature. We found that all NSOCs (1, 2, 3) showed superior bond strength (>25MPa) as compared to that of the uncoated copper (<23MPa) at bonding temperatures from 25°C to 80°C. Since it is imperative that surface oxide has to be removed for bonding to take place, the enhancement exhibited is attributed to an effective surface passivation by the organic layer. It is postulated that this ultrathin layer, which behaves as a milder layer as compared to the bulk oxide layer, can be easily displaced for bond formation.

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