Reliability Improvement for Stacked Dielectric with Low-k SiOCH Dielectric and SiCN Barrier by UV-Assisted Thermal Curing

In this study, the effect of ultraviolet (UV)-assisted thermal curing on the electrical properties and reliability of a SiCN/SiCOH stacked dielectric was investigated. UV-assisted thermal curing on the SiCN/ porogen-contained SiOCH stacked dielectric did not impose any improvement due to the remained carbon residues at the interface. With the SiCN capping layer, carbon residues resulted from porogen precursor in the SiOCH film were limited, thereby hardly diffusing out to air. On the other hand, for the SiCN/porous SiOCH (p-siOCH) stacked dielectric, post UV-assisted thermal curing indeed improved the hardness, adhesion, electrical characteristics, and reliability. Additionally, its barrier capacity against Cu migration under an annealing at 450 °C was not degraded for UV-assisted thermal cured SiCN/p-SiOCH stacked dielectrics. Consequently, post UV-assisted thermal curing on an integrated dielectric stack with a porous low-k SiOCH dielectric and a SiCN capping barrier is a promising processing for reliability enhancement.