Optimized interfacial strength for dense and porous SiCOH

Optimization of SiCOH interfacial strength to underlying SiCHN is a key requirement for establishing a reliable manufacturing process for a low k interlevel dielectric. After discovering that the interfacial failure was a near-interface cohesive failure in the SiCOH film, improved interfacial strength was accomplished by engineering a graded transition region from an initial oxide layer to the bulk SiCOH film. Film deposition conditions were tuned to provide ideal film composition profile, without any carbon spike, throughout this transition region. Deposition conditions were also optimized to avoid known problems with SiCOH, such as plasma instabilities and generation of gas phase nucleated defects. This process optimization approach has been successfully performed for 3 generation nodes (90, 65 & 45nm) involving various SiCOH versions with k = 3.0, 2.7 & 2.4. © 2008 Materials Research Society.