Material-Mechanistic Interplay in SiCN Wafer Bonding for 3D Integration

Wafer bonding is a step in processing of state-of-the-art integration architectures in CMOS devices. Sufficiently high bonding strength and low distortion with high alignment accuracy are essential to realize these device structures. A challenge in realizing advanced architectures is reducing the thermal history associated with the bonding process. Although much research has been conducted on wafer bonding methods compatible with the latest semiconductor manufacturing processes, discussions on the interface mechanisms during low temperature annealing have been insufficient. In this study, plasma-activated bonding was carried out using SiCN, which is a major bonding dielectric material. The bonding strength and water remaining at the interface were subsequently evaluated. We found that a SiCN film achieved greater bonding strength after post bond annealing at a low temperature of 250 °C and completely consumed the interfacial water. Analyses of the surface and interface revealed the carbon bonding leads to great bonding interface by low-temperature annealing.