Deposition of Mechanically Hard Amorphous Carbon Nitride Films with High [N]/([N]+[C]) Ratio

Abstract

Mechanically hard amorphous carbon nitride films were prepared by a combination of radio frequency (RF) bias voltage applied to a substrate and chemical vapor deposition using a decomposition reaction of BrCN with a microwave discharge flow of Ar. A pulsed operation of the negative RF bias voltage (-V RF) was applied to avoid excess sputtering of the film. The [N]/([N]+[C]) ratios of the films were ≈0.5 irrespective of the application of -V RF. The maximum hardness was 36±10 GPa for the film obtained under the conditions of -V RF=100 V, a pulse period of 1000 s, and a pulse-on time of 800 s. According to the IR spectra, the intensity of the stretching vibration of the C–N bond was increased by the application of -V RF. The Raman spectra showed increases in the relative intensity and width of the D-band. From these observations, the mechanism of film hardening when -V RF is applied was discussed.

Dissociative Excitation Process of BrCN in the ECR Plasmas of Rare Gases

“…These films have the following characteristics. [17]. These high ratios have been rationalized in the case of MW discharge flow of Ar as the precursors of film formation are predominantly the ground (X 2 Σ + ) state of CN radicals [18,19].…”

“…These high ratios have been rationalized in the case of MW discharge flow of Ar as the precursors of film formation are predominantly the ground (X 2 Σ + ) state of CN radicals [18,19]. (b) When H 2 O molecules are removed from the reaction system and the RF-bias voltage is applied to the substrate, the hardness of the films reaches as high as 36±10 GPa [13,16,17]. (c) High efficiency of electricfield emission have been shown for a-CN x :H films when they are deposited onto the Al-doped single crystal whiskers of ZnO [14,15,22].…”

“…We have applied these reactions to the synthesis of a-CN x and a-CN x :H thin films, where the microwave (MW) discharge flow of Ar [11][12][13][14][15][16][17][18][19] and the ECR discharge flows of Ar [20,21] and He [22] have been used. These films have the following characteristics.…”

Fabrication of a-CN_<i>x</i> films by RF-plasma decomposition of BrCN

“…Films so far been synthesized using the plasma-enhanced chemical vapor deposition (PECVD) based on the electric discharge of the gas mixture of N 2 and hydrocarbons such as CH 4 Ito and co-workers have developed an alternative method to synthesize a-CN x using the dissociation reaction of BrCN with the microwave (MW) discharge flow of Ar. In this reaction, films exhibited high [N]/([N]+[C]) ratios (0.5) [8][9][10]. Precursor of the film formation is almost specifically CN radicals [11][12][13] formed via the energy transfer reaction of BrCN with the metastable ( 3 P 0,2 ) atoms of Ar [13], Ar( 3 P 0,2 )+BrCNAr+Br+CN.…”

“…[8][9][10][11][12][13] has been the remote type where the MW discharge is generated 0.2 m upstream from the inlet of BrCN, high-energy electrons generated by the MW discharge may be sufficiently quenched. Under such circumstances, Ar( 3 P 0,2 ) atoms may be the major species that excites BrCN molecules to dissociate.…”