Fabrication of Electroless CoWP/NiB Diffusion Barrier Layer on SiO2 for ULSI Devices

Abstract

We investigated the electroless CoWP/NiB diffusion barrier layer for ultralarge-scale integration (ULSI) interconnection by forming the immobilizing Pd catalyst on an organosilane layer. When the electroless CoWP film was formed directly on a Pd-activated organosilane layer, it became islandlike and did not form a continuous layer. When it was formed on an electroless NiB deposited on a Pd-activated organosilane layer, the electroless CoWP film was uniform and formed a continuous layer 10 nm thick. The transmission electron microscopy images of the interfaces of showed that, at an annealing temperature up to for 30 min, the interfaces remained unchanged and clear, showing no trace of Cu diffusion into the substrate. In-plane X-ray diffraction patterns indicated that the CoWP/NiB film had an amorphous structure and was stable against heat-treatment up to for 30 min. An evaluation of sheet resistance measurements suggested that the CoWP/NiB film shows appropriate barrier properties for Cu diffusion up to . The CoWP/NiB film was used as a seed for electroless Cu plating. Trenches 100 nm wide were coated with a 10 nm CoWP/NiB barrier followed by successful trench filling by electroless Cu plating.