Relationships between grain structure and stress in thin Volmer-Weber metallic films

In Volmer-Weber growth, islands that nucleate on the substrate surface impinge and coalesce into grains of a continuous film. During deposition of these polycrystalline films, the intrinsic stress for materials of sufficiently high mobility often evolves through three distinct stages, switching from compressive to tensile and back to compressive. Many studies of stress evolution during this process have indicated that a tensile stress develops as the islands coalescence, with the peak stress occurring when the film become continuous. The magnitude of this tensile stress is strongly dependent on the grain structure. The grain structure is in turn strongly dependent on atomic processes at the substrate surface at the onset of film growth. In this study, Kinetic Monte Carlo simulations were used to investigate the relationship between characteristics of the amorphous surface, nucleation and growth of islands, and the tensile stresses observed as films form. It is demonstrated that island nucleation on amorphous substrates can be dominated by the spatial characteristics of the amorphous surface. The simulation parameters providing the best fit to experimental data from gold deposited on silicon nitride included a trapping energy of ET = 0.69 eV. The compressive stresses that develop have also been shown to reversibly change during interruptions of growth. One proposed model for this reversibility is that the compressive stress is related to adatom trapping and de-trapping at grain boundaries, while others attribute the stress to surface changes. In the current study, intrinsic stresses monitored in-situ using a capacitive curvature measurement system are studied with respect to the film grain structure, deposition rate, and substrate temperature.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Leib, Jeffrey Scott

Advisor dc:contributor.advisor

• Carl V. Thompson.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/46682

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/46682