Preparation and properties of amorphous carbon oxynitrides a-CN x O y films made by a nitrogen radical sputter method an
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Preparation and properties of amorphous carbon oxynitrides a-CNxOy films made by a nitrogen radical sputter method and by the layer-by-layer method Yohko Naruse, Shoji Nitta and Hitoe Habuchi* Department of Electrical Engineering, Gifu University, 1-1 Yanaido, Gifu, 501-1193, Japan *Department of Electrical and Computer Engineering, Gifu National College of Technology, Sinsei-cho, Motosu-gun, Gifu, 501-0495, Japan ABSTRACT We have tried to prepare amorphous carbon oxynitrides (a-CNxOy) films by the oxygen radical treatment (ORT) of amorphous carbon nitrides (a-CNx) and also by the layer-by-layer method. Properties of a-CNxOy films were studied with X-ray photoelectron spectroscopy (XPS), photothermal deflection spectroscopy (PDS), ultraviolet-visible (UV-VIS) optical transmittance spectra, Raman spectra and electron spin resonance (ESR). Oxygen radical affects to a-CNx by etching, termination of defects and oxidation. A-CNxOy films are interesting for the application to luminescent materials and also to low dielectric constant materials.
INTRODUCTION The amorphous phase of carbon nitride (a-CNx) made by a nitrogen radical sputter method shows high photosensitivity and high resistively [1-3]. A-CNx has attractive properties as a low dielectric constant material for ultra large-scale integration ULSI [4-6]. The hydrogen plasma treatment on a-CNx is a very effective method to refine electronic properties. The hydrogenplasma, i.e. atomic hydrogen, etches a-CNx, decreasing dangling bonds density but hydrogen is not included into a-CNx not like the hydrogen termination in a-Si:H [2]. A cycle process of the deposition of thin a-CNx film and the hydrogen-plasma treatment, which is called the layer-bylayer (LL) process, has been used to make LLa-CNx films to refine a-CNx. It has been reported that LLa-CNx has higher photosensitivity and smaller dielectric constant than a-CNx and shows photoluminescence, including ultraviolet light to 3.5 eV [6~7]. In this paper, we are interested to study the effect of oxygen radicals to a-CNx, especially to prepare amorphous carbon oxynitrides (a-CNxOy) films. Properties of a-CNxOy films are studied using X-ray photoelectron spectroscopy (XPS), photothermal deflection spectroscopy (PDS), ultraviolet-visible (UV-VIS) transmittance spectra and Raman spectra. Preliminary study on preparation of the layer-by-layer a-CNxOy, i.e. LLa-CNxOy is also presented.
EXPERIMENTALS The radio frequency (rf) magnetron sputtering apparatus is used for a nitrogen radical sputtering of a graphite target with a sputter gas of nitrogen molecules to prepare a-CNx films. At first, we have tried to prepare a-CNxOy films by using nitrogen and oxygen gases together as a sputter gas, but no film growth has been observed, because the etching properties of plasma
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made by a mixed O2-N2 gas is stronger than the growth rate. Therefore, we have tried to prepare a-CNxOy by the oxygen radical treatment (ORT) using oxygen plasma on surface of a-CNx, which is deposited by a nitrogen radical sputter of carbon target.
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