Enhanced adhesive bonding based on surface modification with silicon nanowire arrays

Adhesive bonding is one of the methods extensively used for 3D packaging, which has many advantageous features except for relatively poor bonding strength. In this paper, we present a novel method to strengthen adhesive bonding via modifying the wafer surface with silicon nanowire (SiNW) arrays. The SiNW was synthesized using a micro-electrochemical wet etching method. The nanostructure was characterized and its formation process was revealed in detail. Contact angle measurement and the observation of wetting frontier indicates good wetting behavior of epoxy adhesives on SiNW arrays. Adhesion strength increased 42% after the surface modification, accompanying with more failure occurring within the adhesive. A micromechanical composite structure model was proposed to demonstrate the interlock effect in the bonding interface. Bonding strengthening mechanism was investigated based on surface science theories.