Comparison of a-C:N:H layers grown at the anode and cathode in RF-PACVD processing

Formation of amorphous hydrogenated carbon nitride layers, a-C:N:H, by radio frequency plasma - assisted chemical vapour deposition, RF-PACVD, 13.56 MHz, is studied. The repeatability of the process is examined in a series of experiments conducted at the same conditions. The layers deposited on silicon wafers placed at the cathode and the anode are compared. Thicknesses and optical parameters of the layers are measured using spectroscopic ellipsometry. Structural studies are performed with the use of scanning electron microscope SEM, atomic force microscope AFM, Fourier transform infrared FTIR and Raman spectroscopic techniques. The results confirm that high repeatability of processing has been achieved for each electrode. Significant differences are however observed between the layers deposited at different electrodes. The differences concern deposition rate, optical constants, depolarization coefficient and morphology of the layers. Differences in the morphology appear as some inclusions in a matrix of the anode layers, being confirmed by bidirectional reflectance distribution function BRDF, depolarization and Raman spectra measurements. The cathode layers are entirely amorphous.