Integration of Cu Damascene with Pore-sealed PECVD Porogen Low-k (k=2.5) Dielectrics for 65nm Generation

Owing to the k extendability of porogen LK formed with the incorporation and removal of organic porogen precursors, the porogen LK is the competitive candidate for inter-metal dielectrics (IMDs) of 65nm generation and beyond. However, its porosity raises major challenges in the Cu/LK integration. Chemical and metal penetrability of the porogen LK film revealed the necessity of a protective pore sealing layer in dual damascene. Pore sealing materials were evaluated and SiCxHy film demonstrated exceptional barrier property against metal diffusion and good step coverage over the trench profile. By introduction of this SiCxHy layer, 10% capacitance reduction was achieved despite the higher k of the material. With the well-controlled thickness, SiCxHy pore sealing also demonstrated no via-Rc shift compared to the scheme without pore sealing, therefore excellent protection on the trench structure without via performance degradation was accomplished.