Structural stability for UV irradiation and dielectric properties of a-CNx films

Two topics on amorphous carbon nitride (a-CNx) films prepared with 0.52⩽x⩽0.86 are studied and discussed. (a) Structural stability for ultraviolet (UV) light irradiation is measured by X-ray photoelectron spectroscopy (XPS). The x at the surface increases after UV light irradiation in air. The amplitude of C-1s peak related to C–N bond increased. Its binding energy shifts to larger energy after irradiation as does the N-1s peak also. The photo-induced change in a-CNx is discussed comparing with the properties of a-C:H. (b) Structural effect on the refractive indices, n, is studied by Raman spectroscopy. The n decreases with increasing x, which properties could be applied to a low dielectric constant insulators for ultra large-scale integrated (ULSI) technology. However, n is not correlated with the D and G Raman peaks. The structural effect on n and an application of a-CNx to an insulator for ULSI are discussed.