Effect of Microstructure on Microhardness of AlN Thin Films
- PDF / 331,019 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 90 Downloads / 291 Views
Effect of Microstructure on Microhardness of AlN Thin Films Shuichi Miyabe, Masami Aono, Nobuaki Kitazawa, and Yoshihisa Watanabe Department of Materials Science and Engineering, National Defense Academy, Yokosuka, Kanagawa 239-8686, Japan ABSTRACT Aluminum nitride (AlN) thin films with columnar and granular structures were prepared by ion-beam assisted deposition method by changing nitrogen ion beam energy, and the effects of the film microstructure and film thickness on their microhardness were studied by using a nano-indentation system with the maximum force of 3 mN. For the columnar structure film of 600 nm in thickness, the microhardness is found to be approximately 24 GPa when the normalized penetration depth to the film thickness is about 0.1. For the granular structure film of 700 nm in thickness, the microhardness is found to be approximately 14 GPa. These results reveal that the microhardness of the AlN films strongly depends on the film microstructure, which can be controlled by regulating the nitrogen ion beam energy. INTRODUCTION Ion beam assisted deposition (IBAD) is a film deposition method combining evaporation of metals and simultaneous irradiation with an ion beam. The IBAD method has the advantages of low temperature synthesis due to using an energetic ion beam and also well-defined and independent control of ion bombardment parameters, such as ion beam current, ion beam energy, ion species, and incident angle to substrates [1]. Taking the advantages mentioned above, the present authors' group has prepared aluminum nitride (AlN) films and investigated their microstructure, surface morphology and optical properties [2-6]. AlN films have attracted attention due to their desirable electrical, mechanical, optical and acoustical properties [7-9]. In addition, very recently, visible light emission has been reported from amorphous AlN films incorporated with Cu, Mn or Cr [10]. In pervious works, we have found that the microstructure of AlN films prepared by the IBAD changes from columnar to granular structure with increasing the nitrogen ion beam energy and their optical properties and durability against water depend on the film microstructure [5, 11]. Mechanical properties of thin films have been studied intensively after development of nano-indentation technique [12]. Although many researchers have investigated mechanical properties of different kinds of thin films on various substrates [13-15], it is not completely understood how substrate materials affect on film mechanical properties. As mentioned above, the optical properties of IBAD-AlN films depend on their microstructure and this suggests that the mechanical properties are also in dependence on the film microstructure. Therefore, it is interesting to study the relation between film microstructure and mechanical properties and also the effects of substrate materials on film mechanical properties are attractive to be examined. In this paper, AlN films with different microstructures are prepared by the IBAD method and studied the relation between t
Data Loading...
