Carbon nanowalls (CNWs), i.e., two-dimensional carbon nanostructures, were fabricated using fluorocarbon capacitively coupled plasma-enhanced chemical vapor deposition assisted by H radical injection. The correlation between CNW growth and the fabrication conditions was investigated. The morphologies of CNWs were dependent on the types of carbon source gases and the amount of H radicals injected. In addition, H and CFx (x=1-3) radical densities in the plasma were measured using vacuum ultraviolet absorption spectroscopy and appearance mass spectrometry, respectively, to clarify the growth mechanism of CNWs. The density ratio of H radicals to CFx radicals was found to be an important factor responsible for the formation of CNWs from fluorocarbon/hydrogen systems and increased drastically as a result of H radical injection.