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.

Performance of WCN diffusion barrier for Cu multilevel interconnects

“…1,[7][8][9][10] Thus far, many metal nitrides, silicides, and metal oxides have been investigated as diffusion barriers. [11][12][13][14][15][16][17][18] With increasing aspect ratios of scaled vias, a carbon nanotube (CNT) is suggested as a new diffusion barrier to suppress electron migration owing to its lower resistivity. [19][20][21] From the fact that C reduces electrical resistivity, in this work, we have prepared WCN by atomic layer deposition (ALD) and introduced very thin, low-resistivity diffusion barrier films with conformal step coverage and strong adhesion between the copper seed layer and the underlying insulator.…”