Evaluation of integrity and barrier performance of atomic layer deposited WNxCy films on plasma enhanced chemical vapor deposited SiO2 for Cu metallization

Abstract

The nucleation and growth of WNxCy films deposited by atomic layer deposition (ALD) on plasma enhanced chemical vapor deposited (PECVD) SiO2 is characterized as a function of the number of ALD cycles using transmission electron microscopy analysis. The island growth of isolated WNxCy nanocrystals is directly observed at the early stages of film growth. The nucleation of the WNxCy film can be significantly enhanced by NH3 plasma treatment before the deposition of WNxCy. The capacitance-voltage measurements conducted after bias-temperature stressing reveals that an ALD-WNxCy film deposited with a thickness of approximately 5.2nm on the NH3 plasma-treated PECVD SiO2 shows good diffusion barrier performance against Cu migration.

Structure and mechanical properties of reactive sputtered WCN films

“…9 On this basis, WCN has been proposed and studied for use as diffusion barriers or protective films in recent years. 10-12 As reported, WCN films exhibit thermal stability after annealing up to 700°C, 13 low electrical resistivity and good adhesion to many different substrates. 11 Most studies reported in the past years, with specific regard to the production of WCN films, have used CVD techniques 14,15 since Gesheva et al .…”

Reversible Tuning of the Surface Chemical Reactivity of Titanium Nitride and Nitride−Carbide Diffusion Barrier Thin Films

“…This work has shown that the surface reactivity of diffusion barrier films can be tuned through the control of the carbon content in the top layers. With metal nitride−carbides gaining more attention, ,, it is important to realize that, although those materials often feature a lower reactivity (toward Lewis bases) than that of carbon-free metal nitride films, nitridation of the top layers of nitride−carbide films would constitute a simple but effective way to enhance their surface reactivity. On the other hand, the reactivity of a carbon-free metal nitride film can be lowered through the partial carbidization of its surface sites.…”

“…Since carbon increases the resistivity of barrier films, , several strategies were developed to reduce the +carbon content in nitride films, including the use of easily controllable film deposition techniques (such as atomic layer deposition, ALD) ,,− ,− and the implementation of postdeposition (e.g., plasma ,− and thermal − ) treatments. However, interest in nitride−carbide films has been boosted recently because the crystallinity of pure nitrides is disrupted by the presence of carbon, avoiding potential diffusion through grain boundaries. ,, Tungsten nitride−carbide (WNC) is currently receiving considerable attention as a copper diffusion barrier, − and nitride−carbides of titanium (TiNC) and tantalum (TaNC) have been investigated for this purpose as well. ,− Oxygen incorporation, which also increases the resistivity of these films and occurs readily upon exposure to ambient atmospheric conditions following vacuum deposition, is a more persistent problem that has also received substantial attention. ,,,,,− …”