Reactions of surface hydrogen on amorphous carbon films with hydrogen plasma

Abstract

Reactions of surface hydrocarbon components exposed to hydrogen plasma at a substrate temperature of 200 °C were investigated by in-situ infrared spectroscopy, and changes in film thickness were measured. Both the concentration of hydrocarbon components and film thickness decreased because of the hydrogen plasma exposure. The decrease in the former was larger than that in the latter. These results indicate that the abstraction effect of surface hydrogen, as well as the etching effect, was enhanced at 200 °C.

Adsorption of hydrocarbon components generated in deuterated benzene plasma studied by in situ real-time infrared absorption spectroscopy

“…The PECVD stainless-steel chamber used in this study was equipped with a plasma source and an MIR-IRAS monitoring system. 11,[25][26][27][28] The chamber was evacuated using a highvacuum pump to maintain a base pressure of less than 5 © 10 ¹6 Torr. Benzene was placed in a glass cylinder to which a valve (ANELVA Variable Leak Valve) was attached.…”

“…We conducted infrared absorption spectroscopy (IRAS) in the multiple internal reflection (MIR) geometry (MIR-IRAS) to monitor the film deposition during benzene-PECVD. This method can be applied to in situ and real-time monitoring of plasma processes, [11][12][13][22][23][24][25][26][27][28] as it is applicable to a wide variety of environmental situations. We monitored the evolution of various hydride components to elucidate the deposition on the atomic scale.…”

“…For instance, the presence of water molecules in the source and vacuum chamber will disrupt the monitoring, as O-H peaks can overlap with the C-H peaks, but the C-D peaks are located at wavelengths different from those of the O-H peaks; the O-H stretching vibration region is at 3000-3600 cm ¹1 and the C-H stretching region is at 2800-3200 cm ¹1 , whereas the C-D stretching region is at 2000-2400 cm ¹1 . [26][27][28][30][31][32][33][34][35] Furthermore, the penetration depth increases proportion all to the wavelength of IR light; for an incident IR light of ³3000 cm ¹1 , i.e., in the C-H vibration region, the penetration depth is approximately 280 nm [22][23][24] (assuming refractive indices of 1.6 and 3.4 for amorphous carbon and Si, respectively 36,37) ). For incident IR light of ³2500 cm ¹1 , near the C-D region, the penetration depth is ³340 nm.…”

Effect of H atoms and UV wideband radiation on cured low-k OSG films

“…As shown in various works, for example [19,20], the ratio of C-H 2 and C-H 3 peaks in the region of C-H x bonds of 2800-3000 cm −1 exhibits the highest sensitivity to the organic content. In figures 1(a) and (b), this area is highlighted in grey.…”

“…to the organics etching (see below). At the same time the main volatile product of the reactions of H atoms with amorphous carbon (which is the basis of the porogen residue) is mostly the methyl radical -CH 3 [19,20,[27][28][29]. The reactions of a-C etching by atomic hydrogen are temperature dependent which may explain the temperature dependence of the evolution of surface -CH 3 groups.…”