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

Abstract

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 (NH3) plasma treatment, ammonia (NH3) pulsed plasma treatment, and diborane (B2H6) pulsed gas injection treatment. In an experimental result of a method with B2H6 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 B2H6 pulsed gas injection is a useful method for obtaining high-quality WN films for use as a DBL on a Cu contact via a 15 nm node. (C) 2013 The Japan Society of Applied Physics