Extendibility of Cu damascene to 0.1 μm wide interconnections

Abstract

We demonstrate the extendibility of the Cu damascene process to 0.1 μm wide lines. Cu interconnects, 0.1 - 1 μm wide, were fabricated by a damascene process that produced planarized lines and vias, imbedded in insulators. This process was defined by 1) trench and via formation in blanket dielectrics using e-beam lithography and reactive ion etching, 2) trench fill using a series of metal depositions, and 3) chemical mechanical polishing to remove the field metals. Physical vapor and ionized physical vapor deposition techniques were used to deposit the adhesion/diffusion barrier liner and the Cu seed layer, respectively. The main Cu conductor was deposited by an electroplating method. The width of lines and vias were varied from 0.1 μm to 1 μm while the thicknesses were held constant at 0.45 μm. A near bamboo-like structure was observed in the sub-μm wide lines. The effective resistivity of the Cu lines was found to be about 2.3 μΩ-cm and was independent of width after annealing at 400°C.