Title

Evolution of nanoscale roughness in Cu/SiO2 and Cu/Ta interfaces

Authors

Authors

A. P. Warren; T. Sun; B. Yao; K. Barmak; M. F. Toney;K. R. Coffey

Comments

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Abbreviated Journal Title

Appl. Phys. Lett.

Keywords

SURFACE SELF-DIFFUSION; X-RAY-SCATTERING; THIN-FILMS; MULTILAYERS; ENERGY; Physics, Applied

Abstract

Synchrotron x-ray scattering was used to study the evolution of interface roughness with annealing for a series of Cu thin films. The films were encapsulated in SiO2 or Ta/SiO2 and prepared by sputter deposition. Specular x-ray reflectivity was used to determine the root mean square roughness for both the upper and the lower Cu/SiO2 (or Cu/Ta) interfaces. The lateral roughness was studied by diffuse x-ray reflectivity. Annealing the films at 600 degrees C resulted in a smoothing of only the upper interface for the Cu/SiO2 samples, while the lower Cu/SiO2 interfaces and both interfaces for the Ta encapsulated films did not evolve significantly. This difference in kinetics is consistent with the lower diffusivity expected of Cu in a Cu/Ta interface (compared to a Cu/SiO2 interface) and the mechanical rigidity of the lower Cu/SiO2 interface. As a function of roughness wavelength, the upper Cu/SiO2 interfaces exhibited a roughness decay with annealing that was only 12.5% of that expected for classical capillarity driven smoothening of a free surface. (C) 2012 American Institute of Physics. [doi:10.1063/1.3675611]

Journal Title

Applied Physics Letters

Volume

100

Issue/Number

2

Publication Date

1-1-2012

Document Type

Article

Language

English

First Page

4

WOS Identifier

WOS:000299126800101

ISSN

0003-6951

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