Atomistic simulation investigation of various plasma surface activations in SiCN dielectric bonding

In hybrid bonding, dielectric material should work as a metal diffusion barrier and be able to obtain a sufficient bonding strength to support the metal bonding during annealing process. Thus, tight bonding of dielectric has been issued. Here, we obtained insights of surface structures on dielectric and built the possible bonding mechanism during the surface activation and hydration processes by using a variety of modeling techniques in different scales and combining with the experimental results. We calculated the bonding strength of surface activated SiCN/SiCN bonding by the Maszara-Method after the annealing process. As a result, 3.1 (J/m
²
) for O
2
treatment and 2.5 (J/m
²
) for N
2
treatment on SiCN/SiCN bonding were obtained as the maximum bonding strength under the same conditions. Using the atomic-scale simulation techniques, we found that O
2
surface activation helped to enhance a bonding energy to boost Si-O-H functional group on SiCN surface by removing C and N components and to generate possible additional Si-C-Si bonding. In the case of N
2
surface activation, the bonding energy was degraded by dominant Si3N4-Si3N4 bonding characteristics. Our simulation and experimental results also gave us a hint for the importance of existing oxygen amount on deposited SiCN that can be controlled by power and deposition method. We extended our simulation work to find another surface activation case to evaluate the improvement of a bonding. With additional H
2
pre-treatment, the presence of H in the film made the C and N removal with O
2
treatment, that we anticipated the good bonding energy with the similar bonding mechanism into no pre-treatment case. However, N
2
activation was independent on H
2
pre-treatment. It indicated that H
2
pretreatment guaranteed to help but not the significant enhancement of bonding strength. We believe this study would be beneficial to develop the process to obtain a high bonding strength on hybrid bonding process.