Direct Bonding Using Low Temperature SiCN Dielectrics

Abstract

For several 3D integration schemes, such as CoD2W and solder based D2W bonding, the thermal budget needs to be well below 250 degrees C due to the presence of temporary bonding materials. In this paper we present a new PECVD SiCN layer deposited at 175 degrees 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 degrees 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 degrees C without inducing the appearance of bonding voids.