Reliability and electrical properties of new low dielectric constant interlevel dielectrics for high performance ULSI interconnect

We have investigated the impact of using several new promising low dielectric constant materials as inter-level dielectrics for high performance VLSI/ULSI interconnect applications. The new low dielectric constant materials under study are spin-on deposited materials which include silsesquioxane, fluorinated polyimide, fluorinated poly(arylethers), and perfluorocyclobutane with dielectric constants ranging from 2.3 to 2.8. In comparison to other spin-on deposited materials, they have relatively high thermal stability and better process compatibility. Inter-line capacitance, dielectric leakage current, metal layer resistivity, and interconnect metal linewidth were monitored as the wafers went through different thermal stress conditions. The thermal dissipation capability of the new inter-level dielectrics and their influence on metal line reliability were studied as well. The electrical and reliability properties were compared between interconnect structures using new low dielectric constant materials and structures using conventional SiO/sub 2/ deposited by plasma enhanced chemical vapor deposition. The results are important for determining how to use these new low dielectric constant materials in high performance ULSI interconnect processing. They also provide useful input for further material improvement to satisfy the ULSI processing and reliability requirement.