In this investigation, we aim to produce highly nitrogen-doped carbon, so-called carbon nitride, films without the incorporation of hydrogen. In the physical vapor deposition process, irradiation by energetic nitrogen ions increases nitrogen content without the incorporation of hydrogen. In the chemical vapor deposition process, hydrogen should be included into the film due to the use of a hydrocarbon reactant. In this study, the synthesis of carbon nitride films having high nitrogen and low hydrogen contents was attempted using a chemical-vapor-deposition apparatus. First of all, a CH 3 CN + Ar mixture was selected as a reactant including hydrogen. Dehydrogenation of the reactant was carried out by plasma decomposition. Second, as a reaction system without hydrogen, BrCN + Ar was also selected for starting materials. The dissociative excitation reaction of cyanides with argon metastable atoms produces CN radicals, Ar( 3 P 0,2 ) + BrCN → Ar + Br + CN(A 2 i , B 2 + , 4 + , 4 ). This finally proceeds to the deposition of CN radicals to form the carbon nitride film on a solid-state surface. When using the former reactant, large amounts of hydrogen remained in the amorphous carbon nitride films, although the amount of hydrogen varied with deposition conditions. The sample formed using the latter reactant was amorphous carbon nitride with very little hydrogen. The nitrogen fraction [N]/([N] + [C]) of the sample using the latter rectant is as high as ∼0.3, higher than those obtained from the samples synthesized with the former reactant.

Realizing photolithography on three-dimensional structures is useful for micromachining; however, a thin and uniform resist film is difficult to prepare on a non-planar sample. A spray coating technique has the potential to deposit a uniform and defect-free resist film on a three-dimensional structure. In this study, the characteristics of spray coating are examined focusing on spray flow speed. Faster spray flow is found to remove the pinhole defects even at the bottom of a deep cavity with a high aspect ratio. The results of patterning performance on a deep three-dimensional structure are also shown. A line-and-space pattern on a 200 µm deep groove is demonstrated to have thick and thin resist coverage at the convex and concave corners, respectively with no pinhole defects. The obtained results of the spray coated resist film are discussed based on the fluid dynamics.

High-resolution CN(B 2 + -X 2 + ) emission spectra were observed for the various processes to form amorphous-CN x (a-CN x ) films using the plasma-enhanced chemical-vapor deposition of the CN radical produced from the dissociative excitation reactions of cyanides. A strong correlation was confirmed between the electronic states of CN in the plasma and the bonding states of nitrogen atoms in the films. The 4 + and 4 states of CN were the precursors of the one-and/or two-dimensional C=N and C-N network structures of the films with high nitrogen content, [N]/([N]+[C]) ≤ 0.5. The CN(X 2 + ) state formed the C≡N terminations primarily, a part of which changed to the one-dimensional C=N network from the additive reactions. The above correlation was fully explained by the molecular orbitals and the electronic configurations for the relevant electronic states of CN.

High-resolution CN(B2Σ+–X2Σ+) and CH(A2Δ–X2Π) emission spectra were observed for the dissociative excitation reaction of CH3CN with the microwave-discharge flow of Ar for synthesizing hydrogenated amorphous carbon nitride (a-CN x :H) films. The simulation analysis of these spectra revealed that the relative number density of CH(A) to that of CN(B), N CH(A)/N CN(B), was strongly dependent on the pressure of Ar, P Ar, in the range of P Ar=0.1–0.8 Torr. The P Ar-dependence of N CH(A)/N CN(B) showed a strongly negative correlation with that of the [N]/([N]+[C]) ratio obtained in our previous structural analysis of the films [Saitoh et al.: Jpn. J. Appl. Phys. 39 (2000) 1258]. This correlation was fully explained in terms of the consumption of the CN radical by the hydrogen-abstraction reaction from the film surface, preventing the incorporation of the nitrogen atoms into the a-CN x :H films.

A sputtering method is used to form the seed layer for copper electric plating. In general, copper sputtering has weak adhesion to resin, so titanium sputter is combined to increase the adhesion strength. However, etching in the lithography process requires two types of processes, titanium and copper metal. Adhesion strength was improved by performing vacuum ultraviolet (VUV) treatment as a pretreatment for medium-vacuum sputtering. We discovered the relationship between the hydroxyl groups on the resin surface and the adhesion strength by the chemical modification XPS method. Furthermore, by XPS analysis of the peeled copper interface, the adhesion mechanism between the resin and copper due to VUV irradiation was estimated. We evaluated the absorption properties in the vacuum ultraviolet region of a thinly polished glass epoxy resin. We investigated the behavior of functional groups at the interface and considered the effect of vacuum ultraviolet light in the depth direction.