TEOS and thermal oxide low temperature direct wafer bonding dynamics

Dielectric wafer fusion bonding is essential in 3D integration. The dynamic aspect of the process is often overlooked despite its strong impact on overlay and distortion performance. In this work we will review the experimental parameters that influence this dynamic. The influence of relative humidity, bonding atmosphere and surface preparation will be evaluated. We highlight the importance of capillary bridges for bonding wave propagation as well as surface roughness. The impact on post annealing bond strength will be also studied. To demonstrate that these learning can be applied to tune the dynamics of bonding process in 3D applications, a focus is made on bonding of tetraethyl orthosilicate surfaces. Finally, we demonstrate that bonding wave speed can be changed independently of bonding strength. Controlling bonding atmosphere humidity allows us to tune the bonding wave velocity while maintaining high post annealing bond strength using plasma activation or chemical booster.