Identification of infrared absorption peaks of amorphous silicon-carbon alloy by thermal annealing

Abstract

Amorphous silicon-carbon hydrogen alloy was prepared by radio frequency glow discharge decomposition of a silane-methane mixture. The infrared absorption spectra were measured at various stages of thermal annealing. By observing the change of relative intensities between these peaks the hydrogen bonding responsible for the absorption peaks could be assigned more accurately, for example, the stretching mode of monohydride Si–H is determined by its local environment, which supports H. Wagner’s and W. Beyer’s results [Solid State Commun. 48, 585 (1983)] but is inconsistent with the commonly believed view. It is also found that a significant fraction of carbon atoms are introduced into the film in –CH3 configuration which forms a local void and enhances the formation of polysilane chain and dangling bond defects. Only after high-temperature annealing are the hydrogen atoms driven out, and Si and C start to form a better silicon carbide network.

Fourier transform infrared spectroscopy investigation of chemical bonding in low-k a-SiC:H thin films

“…For SiC:H3-6, a third lower wavenumber peak centered at 2069 cm − 1 also appears. These positions of maximum intensity for the SiH x band are consistent with values previously reported by others for similar a-SiC:H films [71][72][73][74][75]. Similar shifts in the position of the Si\H stretch have also been reported by others for PECVD a-SiC x :H films of varying stoichiometry.…”

Plasma‐enhanced chemical vapor deposited silicon carbide as an implantable dielectric coating

“…Amorphous SiC films produced by PECVD at low temperatures (200 -400°C), however, are stable and tolerate wet processing in aggressive acidic and alkaline etchants. 21,23 During leakage current measurements, the steadystate DC current at each bias voltage is maintained by reduction and oxidation (redox) reactions at the electrode under test and at the Pt counterelectrode. The interface at which the reactions occur on a dielectriccoated test electrode depends on the electronic conductivity of the dielectric and its H 2 O and ion transport properties.…”

“…With a SiH 4 /CH 4 gas ratio of 0.25, the a-SiC exhibited absorption bands at 740 -760 cm Ϫ1 from SiOC stretching and at 2071 cm Ϫ1 from SiOH stretching. 21,22 The shoulder at Ϸ1000 cm Ϫ1 is indicative of ϪCH 2 groups attached to Si. Several weak absorption bands were also observed between 1240 -1445 cm Ϫ1 and are assigned to SiOCH 3 and COH related vibrations.…”

Vibrational local modes of a-Si1−xCx:H alloys and variation of local modes in different local environments

“…From the IR measurement, we can have the vibrational local modes of the films. The assignment [5][6][7] of SiH n , Si-C, and CH n groups greatly facilitate our understanding of the microstructures in the films. The concentration of each local mode is closely related to the deposition and postdeposition processes of the film.…”

“…We discussed the experiment performed by Lin and co-workers. 6 They annealed as-deposited a-Si 1Ϫx C x :H films at different temperature and found the structural change through the measurement of IR absorption spectroscopy. They described the phenomenon as due to the effusion of two H atoms from SiCH 3 and creation of a -C-H group, as well as the formation of SiC network connecting dangling bonds of Si and C. The shift to lower frequency of the Si-C vibrational mode is caused by the C-dangling bond in the previous study.…”