In this work, a thick silicon carbide films were synthesized on the c-Si surface by simultaneous mag­netron sputtering of a silicon target and a graphite target in the high-frequency mode of 13.56 MHz. The mag­netron sputtering parameters were as follows: magnetron power - 150 W, argon gas flow rate 2.4 l/h, chamber pressure 0.4 Pa, silicon substrate temperature - 100 °C, deposition time 3 hours. The domination of shortened Si-C-bonds in an amorphous silicon carbide film immediately after deposition was shown for the first time, which led to a shift in the maximum of the IR spectrum to a region above 800 cm-1 - up to 870 cm-1. The results are interpreted by intensive nucleation during the deposition process. It was shown that after film deposition, almost half (49.2%) of Si-C bonds are contained in very small nuclei of nanocrystals with sizes less than 3 nm. Rapid annealing for 5 minutes was carried out at a temperature of970°C, which was reached within 10 s. A shift of the maximum of the SiC peak of the IR spectrum from the short-wavelength region (870 cm-1) to the long-wavelength region (820 cm-1) of the IR spectrum was observed after rapid annealing of the film. It was revealed that the crystallization of a thick film of silicon carbide does not occur due to crystallization of the amorphous phase, but due to an increase in the size and ordering of the structure of small SiC nuclei and theirtransformation into SiC nanocrystals.