CHEMICAL-MECHANICAL POLISHING OF COPPER WITH OXIDE AND POLYMER INTERLEVEL DIELECTRICS

Chemical-mechanical polishing (CMP) of copper with oxide interlevel di electrics has been demonstrated as a viable patterning approach for co pper interconnect structures. This paper summarizes our understanding of the mechanisms involved in copper CMP and presents our results with both oxide interlevel dielectrics (ILDs) and low dielectric constant polymer ILDs. Our two-step model of copper CMP consists of mechanical abrasion of the copper surface followed by removal of the abraded mate rial from the vicinity of the surface and has been developed after ext ensive electrochemical and CMP experiments with alternative slurries. Although the softer and less process tolerant polymers result in Damas cene patterning difficulties compared with oxide ILDs, our results wit h both benzocyclobutene and parylene indicate that manufacturable proc esses for on-chip interconnect structures can be established with addi tional fundamental understanding and further development.