Highly reliable Cu/low-k dual-damascene interconnect technology with hybrid (PAE/SiOC) dielectrics for 65 nm-node high performance eDRAM

摘要

100 nm half-pitch Cu dual-damascene (DD) interconnects with low-k hybrid (PAE(k2.65)/SiOC(k2.5)/SiC(k3.5)) dielectrics have been successfully integrated for a 65 nm-node high performance embedded DRAM. The hybrid-DD structure was fabricated by applying a hard mask process combined with Stacked Mask Process (S-MAP). Well-controlled DD profile of the hybrid structure can provide the advantage of void-less Cu fill, resulting from over-hang reduction of PVD barrier metal. Stress-induced voiding (SiV), which is becoming a more serious problem with down scaling of via-hole dimension was found to be drastically improved as compared with homogeneous-DD structures. Thermal cycle test (TCT) also shows no degradation of the wiring/via-hole properties. Moreover, the result of electromigration (EM) test shows a tight distribution of mean time to failure (MTF). The hybrid-DD structure can extend the PVD Cu filling process to 65 nm-node Cu metallization with excellent reliability.