Dual damascene fully aligned via in interconnects

Abstract

Dual damascene interconnect structures with fully aligned via integration schemes are formed using different dielectric materials having different physical properties. A low-k dielectric material having good fill capabilities fills nanoscopic trenches in such structures. Another dielectric material forms the remainder of the dielectric portion of the interconnect layer and has good reliability properties, though not necessarily good trench filling capability. The nanoscopic trenches may be filled with a flowable polymer using flowable chemical vapor deposition. A further dielectric layer having good reliability properties is deposited over the metal lines and dual damascene patterned to form interconnect line and via patterns. The patterned dielectric layer is filled with interconnect metal, thereby forming interconnect lines and fully aligned via conductors. The via conductors are electrically connected to previously formed metal lines below.