REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

EFFECT OF SUBSTRATE TYPE ON MICROHARDNESS OF MULTILAYER THIN FILM COMPOSITE SYSTEM

JELENA LAMOVEC

IChTM-Department of Microelectronic Technologies and Single Crystals, University of Belgrade, jejal@nanosys.ihtm.bg.ac.rs

VESNA JOVIĆ

IChTM-Department of Microelectronic Technologies and Single Crystals, University of Belgrade vjovic@nanosys.ihtm.bg.ac.rs

IVANA MLADENOVIĆ

IChTM-Department of Microelectronic Technologies and Single Crystals, University of Belgrade, ivana@nanosys.ihtm.bg.ac.rs

BOGDAN POPOVIĆ

IChTM-Department of Microelectronic Technologies and Single Crystals, University of Belgrade, bpopovic@nanosys.ihtm.bg.ac.rs

VESNA RADOJEVIĆ

Faculty of Technology and Metallurgy, University of Belgrade, vesnar@tmf.bg.ac.rs

Abstract: Thin metallic multilayer films consisting of nanometer layer thickness deposited on different substrates have shown promising mechanical, electrical and magnetical properties, especially for applications in fabrication of microelectromechanical (MEMS) structures and wear-resistant applications.

Electrodeposition of Ni/Cu multilayer films on substrates of (111)-oriented single crystal Si and 100µm-thick electrodeposited Ni film was carried out using dual-bath technique (DBT). The current density values was maintained at 10 mA×cm^-2 and projected thickness of deposit was 5µm. Vickers microhardness of Ni/Cu thin multilayer films was investigated. The substrate starts to contribute the measured hardness at penetration depths of the order of 0.07 - 0.20 times the film thickness. The measured “composite hardness” is a complex value that depends on the microstructure and the hardness of the film and the substrate and their relative differences.

Ni/Cu films on (111)-oriented Si wafer and 100µm-thick electrodeposited Ni film as the substrates can be thought as “soft film on hard substrate” composite systems. Chicot-Lesage model based on the model for reinforced composites can be applied to experimental data for all specimen and the film hardness was calculated for each indentation diagonal. The values obtained for the film hardness H_F are not constant for all types of these composite systems, but influenced by the applied load.

Keywords: Composite metallic multilayer films, Vickers microhardness, Composite hardness models.