Improvement of Adhesion Performances of CVD-W Films Deposited on B2H6-Based ALD-W Nucleation Layer

Abstract

The resistivity of chemical-vapor-deposited (CVD)-W film was reported to be significantly reduced using a B2H6-based atomic layer deposited (ALD)-W nucleation layer for continuously shrinking memory devices. But, we found that the adhesion performances of CVD-W films growing on the B2H6-based ALD-W nucleation layer were poor compared to those on the SiH4-based W nucleation layer. Scanning electron microscopy and secondary ion mass spectrometry analysis clearly suggest that the boron penetration into the interface between underlying TiN and SiO2 during the deposition of W nucleation layer is a possible reason to degrade the adhesion performances of CVD-W films with B2H6-based W nucleation layers. By rigorous selection of both the deposition conditions for W nucleation layer and diffusion barrier materials, we can demonstrate the successful deposition of CVD-W film with a very low resistivity of similar to 12 mu Omega cm (50 nm in thickness) without an adhesion failure. Noticeably, the application of 5 nm thick sputter-deposited WNx film as a glue layer was found to present an excellent adhesion performance, which was due to its excellent diffusion barrier performance with amorphous structure. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3056376] All rights reserved.