Investigation of Paramagnetic Defects in SiCN and SiCO-based Wafer Bonding

We present fundamental exploration of inorganic dielectric wafer-to-wafer (W2W) bonding by electron spin resonance (ESR) to assess the function of dangling bond-type interface defects. As compared to a standard PECVD SiO2 which contains negligible dangling bonds (DBs), it is found that a substantial amount of silicon and carbon types of DBs, as high as 1014 cm-2, are present in the pre-bonding layer of SiCN and SiCO, mainly as a result of surface modification by means of low energy plasma activation prior to bonding. It is inferred that the evolution of DBs has a positive influence on improving the wafer bonding energy during post-bond anneal, in that the results suggest that a decrease of DBs translates into the formation of chemical bonds at the bonding interface.