No 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.

The required thickness for closure of WNxCy layers deposited with the Atomic Layer Deposition (ALD) technique on Plasma Enhanced CVD SiOx and Aurora® low-k dielectric was investigated using Low Energy Ion Scattering Spectroscopy (LEIS). This analysis technique has proven to be very surface sensitive and uniquely suited to determine closure of deposited layers with atomic precision. It was shown that the WNxCy layer closes around 40 ALD deposition cycles, setting the upper thickness limit for closure at 3.2 nm. This thickness is in line with the requirements for copper diffusion barriers for the metallization of Si-devices for 45 nm node and beyond.

No abstract