A NEW 4-LEVEL METAL INTERCONNECT SYSTEM TAILORED TO AN ADVANCED 0.5-MU-M BICMOS TECHNOLOGY

A four-level metal interconnect strategy designed specifically for an advanced 0.5-mu m BiCMOS technology is described. Unique features of t he new technology include a) the use of a non-etchback spin on polymer , hydrogen silsesquioxane (HSQ), for planarization and for lower capac itance of the interlayer dielectric, b) low-temperature polycrystallin e silicon planarization by HSQ, c) a thick fourth layer of metal for h igh quality spiral inductors, d) a low cost chemical vapor tungsten de position followed by sputtered hot aluminum for greater process simpli city and reliability by eliminating the tungsten etchback step, and e) a preventive high refractive index, ''silicon-rich'' glass for device protection from the interconnect processes.