Nanoindentation Measurements of the Mechanical Properties of Ni Thin Films: Effects of Film Microstructure and Substrate Modulus

Abstract

This paper presents the results of nanoindentation measurements of the hardness and moduli of normally and obliquely deposited nanocrystalline Ni films on substrates of SiO₂, Si, and bulk Ni. Following an initial characterization of film microstructure and surface topography with atomic force microscopy (AFM), the paper examines the effects of film microstructure, film thickness, and substrate modulus on the measured film mechanical properties. Obliquely deposited films are shown to have lower hardness values than normally deposited films. The measured hardness values and material pile-up are also shown to depend significantly on the mismatch between the film modulus and substrate modulus. A framework is presented for quantifying the effects of substrate modulus mismatch on basic film mechanical properties.

Keywords:

• Hardness
• Microstructure
• Modulus
• Ni
• Oblique
• Substrate effects
• Thin films

ACKNOWLEDGMENTS

The research was supported by the Division of Materials Research of the National Science Foundation (Grant No: DMR 0213706 and Grant No: DMR 0231418). The authors would like to thank the NSF Program Managers (Dr. Carmen Huber and Dr. Ulrich Strom) for their encouragement and support. One of the authors (TO) is grateful to Makerere University for granting him study leave to undertake this research.