Lithographic implications for Cu/low-k integration

Low dielectric constant materials in the back-end-of-line process are needed to reduce resistive-capacitive delays due to continually shrinking interconnect dimensions. Several organic dielectrics which have etch rates similar to photoresists, such as benzocyclobutene and diamond-like carbon, have been explored for compatibility with lithographic processes. In this paper we discuss integration issues from a lithographic perspective, including low-k materials selection and properties, integration sequences, use of hard masks and the effects on reflectivity, resist process compatibility and focus effects using an advanced DUV scanning system.