Paper TF-ThP1
Surface Roughness of Amorphous Carbon Nitride Films Prepared by rf-Reactive Sputtering

Thursday, October 23, 2008, 6:00 pm, Room Hall D

Amorphous carbon nitride (a-CNx) thin films were deposited on silicon single crystal substrates by rf-reactive sputtering method using a graphite target, and after deposition the films were exposed to oxygen plasma so as to be modified on their surface. The effect of the substrate temperatures, deposition time and oxygen plasma treatment on the surface roughness has been studied. The substrate temperature was varied from room temperature to 853 K and the deposition time was changed from 10 to 180 min. Oxygen gas of about 20 Pa was discharged by rf-power and oxygen plasma was generated. Plasma treatment time was changed from 10 to 60 sec. Film composition and the chemical bonding states were analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). Film surface was observed by atomic force microscopy (AFM). AFM observations has revealed that the as-deposited film surface is uniformly covered with particle-like features in the early stage of deposition and the surface changes to be covered with broccoli-like features with increasing the deposition time and correspondingly the root-mean square roughness (RMS) increases from about 0.5 to 7 nm after 180-min deposition, while the RMS slightly decreases with the substrate temperature under the constant deposition time of 10 min. After exposure to oxygen plasma, the film surface was etched selectively and the RMS increases with the plasma treatment time. It should be mentioned that the etching behavior depends on the film deposition temperatures. XPS studies have shown that the bonding states between carbon and nitrogen change with the deposition temperature. This change may be related to the different etching behavior against oxygen plasma.