Recently, diamond-like carbon (DLC) has been extensively used in industrial products and spreading to medical materials.  The properties of DLCs have a wide variety depending on fabrication processes. Generally, CVD-DLCs are soft and have a small friction coefficient. On the other hand, tetragonal amorphous carbon (ta-C) without hydrogen produced by PVD method has quite large hardness. Element doping such as silicon or fluorine is considered one of the promising methods to functionalize DLCs.  

Density and composition are the most important properties which determine the mechanical and chemical properties of DLCs.  However, for example, widely used density measurement using a weight of film and EDX composition measurement have inevitable error. In this study, we measured density and composition of various DLCs at a time using RBS-ERDA.

 DLCs (a-C:H, ta-C, a-C:F and a-C:Si) were fabricated by filtered arc deposition method (PVD) or plasma based ion implantation and deposition method (CVD) on silicon wafer.  The thickness of the films was measured by a stylus method. The RBS-ERDA measurement for the composition determination was performed at a time using 2.28MeV He⁺ with two detectors. The density was calculated with an energy loss of He atoms backscattered by a silicon substrate using SRIM code. For example, the calculated density of ta-C was 2.9-3.0 g/cm³ which corresponded to the value measured by X-ray reflectivity (XRR) method.  In the paper, we will discuss the relationship among density, composition and mechanical properties of DLCs.

Tomohiro Kobayashi*, RIKEN, Japan
Haruyuki Yasui, Industrial Research Institute of Ishikawa, Japan

*presenting author