A method to achieve a very low effective
dielectric constant in high performance back end of the line
chip interconnect wiring and the resulting multilayer structure are disclosed. The process involves fabricating the multilayer interconnect wiring structure by methods and materials currently known in the state of the art of
semiconductor processing; removing the intralevel
dielectric between the adjacent
metal features by a suitable
etching process; applying a thin
passivation coating over the exposed etched structure; annealing the etched structure to remove
plasma damage; laminating an insulating cover layer to the top surface of the passivated
metal features; optionally depositing an insulating environmental
barrier layer on top of the cover layer;
etching vias in the environmental
barrier layer, cover layer and the thin
passivation layer for terminal pad contacts; and completing the device by fabricating terminal input / output pads. The method obviates issues such as processability and
thermal stability associated with low
dielectric constant materials by avoiding their use. Since air, which has the lowest dielectric constant, is used as the intralevel dielectric the structure created by this method would possess a very low
capacitance and hence fast propagation speeds. Such structure is ideally suitable for
high density interconnects required in high performance microelectronic device chips.