Investigation of Tungsten Nitride Deposition Using Tungsten Hexafluoride Precursor for Via and Plug Metallization

摘要

We investigated a tungsten nitride (WN)-based diffusion barrier layer (DBL) on a Cu metal layer by atomic layer deposition (ALD) using three different treatments, namely, ammonia (NH_3) plasma treatment, ammonia (NH_3) pulsed plasma treatment, and diborane (B_2H_6) pulsed gas injection treatment. In an experimental result of a method with B_2H_6 pulsed gas injection, the fluorine (F) concentration was below 3% in the WN films, and optimum growth conditions, including a linear deposition rate, a few incubation cycles, good thermal stability, and an excellent step coverage of approximately 100%, were observed for the DBL application. These results suggest that the B_2H_6 pulsed gas injection is a useful method for obtaining high-quality WN films for use as a DBL on a Cu contact via a 15nm node.