Optical investigations of the microstructure of carbon nitride films deposited by magnetron sputtering

Analysis of carbon nitride films (CNx) deposited by RF magnetron sputtering on (100) silicon wafers, under different target self-bias, is reported. The properties of as-deposited films were determined using X-ray photoelectron spectroscopy (XPS), IR absorption, Raman spectra, transmission spectroscopy and photothermal deflexion spectroscopy (PDS). The presence of various types of CN bond, as well as of hydrogen and oxygen, was revealed. Good correlation was observed between the variation of nitrogen content (N/C ratio), the optical gap and the Raman features as a function of the target bias. The optical gap decrease is discussed in terms of N/C ratio evolution and the sp2 content.