Preparation of ZnO Thin Film on Diamond-Like Carbon/Si Substrate by RF Magnetron Sputtering for Surface Acoustic Wave Application

Abstract

Diamond-like carbon (DLC) films have received much attention due to their excellent hardness, chemical inertness, and low surface friction coefficient. But DLC films needed to be combined with one piezoelectric layer such like ZnO or AlN film for surface acoustic wave (SAW) applications. In this paper, we study the effect of DLC thin film fabricated by RF magnetron sputtering on the characteristics of the SAW devices (IDT/ZnO/DLC/Si). The comparison of the phase velocity of the ZnO/DLC/Si layered structure with different thickness of the DLC thin films is discussed. We use a two-step process for the deposition of ZnO film on DLC thin film to enhance the adhesion between them. The full width at half maximum intensity of ZnO(002) orientation obtained is only 0.19° from the X-ray diffraction. The phase velocity of the SAW devices will be increased when the thickness of the DLC thin film is increased. The results show that the characteristics of the SAW devices could be improved by the DLC films in raising the SAW phase velocity.

Keywords:

• Zinc oxide (ZnO)
• diamond-like carbon (DLC)
• sputtering
• surface acoustic wave (SAW)

Acknowledgments

This work was sponsored by the Tatung University, Taiwan, R.O.C. The authors deeply appreciated their financial and technical support.