Plasma Co-polymerization Technology with Molecular-level Structure Tightening in "In-situ" SiOCH Stacks for 32nm-node Cu Interconnects

A novel plasma co-polymerization technology, using flexibly-mixed molecular gas of chain-type vinyl-siloxane and 6-membered ring-type one, has been developed for new Seamless Low-k SiOCH Stacks (SEALS). An ultimate high-modulus silica-amorphous-carbon-composite (SACC)-SiOCH film with 24.8GPa was realized by 100%-injection of the chain-type siloxane, adapting to the hard-mask on molecular-pore-stack (MPS) SiOCH film (k=2.45, 3.0GPa) from 100%-injection of the ring-type siloxane. For the via-dielectrics was utilized a new co-polymerized (CP) SiOCH film (k=2.8, 12.6GPa) from these gas mixture to enhance the mechanical strength. The in-situ sequential deposition of three kinds of films without air-break accomplished excellent adhesion, high quality interface and low O2 ashing damage. The fully-scaled-down, 32nm-node Cu interconnects achieved 83fF/mm (single-load) in 100nm-pitched Cu lines with the new co-polymerized SEALS.