Stress-assisted thermal diffusion barrier breakdown in ion beam deposited Cu/W nano-multilayers on Si substrate observed by in situ GISAXS and transmission EDX

DOI: 10.1021/acsami.0c19173

Authors: Leon Romano Brandt (University of Oxford) , Enrico Salvati (University of Oxford; University of Udine) , Didier Wermeille (European Synchrotron Radiation Facility (ESRF)) , Chrysanthi Papadaki (University of Oxford) , Eric Le Bourhis (Institut P’, UPR 3346, CNRS, Université de Poitiers) , Alexander Korsunsky (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Applied Materials & Interfaces

State: Published (Approved)
Published: January 2021
Diamond Proposal Number(s): 19192

Abstract: The thermal stability of Cu/W nano-multilayers deposited on a Si substrate using ion beam deposition was analyzed in situ by GISAXS and transmission EDX—a combination of methods permitting the observation of diffusion processes within buried layers. Further supporting techniques such as XRR, TEM, WAXS, and AFM were employed to develop an extensive microstructural understanding of the multilayer before and during heating. It was found that the pronounced in-plane compressive residual stress and defect population induced by ion beam deposition result in low thermal stability driven by thermally activated self-interstitial and vacancy diffusion, ultimately leading to complete degradation of the layered structure at moderate temperatures. The formation of Cu protrusions was observed, and a model was formulated for stress-assisted Cu diffusion driven by Coble creep along W grain boundaries, along with the interaction with Si substrate, which showed excellent agreement with the observed experimental data. The model provided the explanation for the experimentally observed strong correlation between thin film deposition conditions, microstructural properties, and low thermal stability that can be applied to other multilayer systems.

Journal Keywords: nano-multilayer; residual stress; thermal diffusion; GISAXS; copper/tungsten

Subject Areas: Materials, Chemistry


Instruments: B16-Test Beamline

Other Facilities: ESRF

Discipline Tags:

Physical Chemistry Material Sciences Physics Surfaces interfaces and thin films Chemistry

Technical Tags:

Scattering Wide Angle X-ray Scattering (WAXS)