Direct Bonding Using Low Temperature SiCN Dielectrics

For several 3D integration schemes, such as CoD2W and solder based D2W bonding, the thermal budget needs to be well below 250 °C due to the presence of temporary bonding materials. In this paper we present a new PECVD SiCN layer deposited at 175 °C and optimized for W2W bonding applications. The layer provides void-free W2W bonding interface characterized by high bond strength even at a relatively low (200 °C) post bond annealing temperature, enabling extreme thinning of the bonded stack. Moreover, it has been verified that the layer can withstand post bond annealing processes up to 350 °C without inducing the appearance of bonding voids.