Plasma etching is a complicated process in the way it involves many ion and neutral species that, depending on plasma conditions, give rise to difficulties in controlling the etch mechanism both from a sputtering and a deposition perspective. To investigate and understand the dynamics of interactions at the interface between the plasma and the solid, surface characterization techniques are necessary: here we investigate the suitability of FTIR (Fourier Transform Infrared Spectroscopy) as a nondestructive, real-time, characterization method complementary to the standard characterization techniques such as XPS (X-Ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectroscopy). The work presented here therefore focuses the attention on both etched silicon dioxide substrates and ultra low dielectric substrates, with the purpose of studying and characterizing the surface modification due to reactions with the etching components and products, in particular to the presence of chemical bonds between silicon and fluorine and carbon. The possibility of non-destructive infrared detection of the sample surface condition would be of great help as it could be suitable for in-line characterization of the semiconductor devices during manufacturing.