Characterization of Surface Activation on Nanotwinned Copper and SiCN by using Ar and N₂ Plasma

Nanotwinned Copper (NT-Cu) and SiCN have arouse great interest as being ideal candidates for hybrid bonding. A common technique for SiCN direct bonding is through plasma activation. In this work, the effect of nitrogen and argon plasma on copper and SiCN surface were investigated. XPS shows that mainly Si-N and Si-C bonds were broken, and Si-O bonds were formed. Base on AFM and wetting angle results, it is evident that the activation process does not do any harm to NT-Cu surface, enabling successful bonding at 200 °C. Moreover, SiCN shows considerably high bonding strength after plasma activation process, followed by thermal compression bonding at 150°C for 30 min. TEM analysis shows an obvious oxide layer at the bonding interface of SiCN. Further research shows that by using the proposed plasma activation condition, SiCN/SiCN direct bonding can be realized at 100°C for 15 min.