As we outlined in Sec. 3, there are two basic approaches to patterning for the purpose of creating multilevel interconnect structures. To put it in the simplest terms: The traditional, subtractive approach consists of patterning the metal by dry etching, filling the gaps in the metal pattern with ILD, and planarizing the ILD. The new damascene approach consists of patterning the ILD by dry etching, filling the features in the ILD with metal, and planarizing the metal by chemical-mechanical polishing (CMP). In this section, we will describe both approaches as they apply to Cu interconnect technology. The damascene approach is in the process of being adopted for mainstream applications with SiO2 as the ILD, but new developments continue to be made with the subtractive approach.
Online access to SPIE eBooks is limited to subscribing institutions.