Nuclear reaction analyses of boron nitride films deposited by ion beam based techniques

Abstract

Abstract Nuclear reaction analysis (NRA) and Rutherford backscattering spectrometry (RBS) measurements were carried out to study the growth mechanisms of boron nitride films deposited at room temperature by reactive ion beam sputter deposition (RIBSD), ion beam assisted deposition (IBAD) and ion beam deposition (IBD) from borazine (B3N3H6). The nuclear reactions 14 N(d , α) 12 C , 10 B(d , α) 8 Be , 11 B(d , α) 9 Be, and H ( 15 N , αγ) 12 C were respectively used to measure the areal concentrations of nitrogen, boron and hydrogen in films deposited on silicon. The calibration of the spectra was made by comparison with standard samples. BNx films analyzed by RBS were deposited on carbon substrates coated in situ with a silicon or an iron layer in order to avoid overlapping of the 11B peak and the carbon plateau. By using complementarily in situ Auger electron spectrometry and ex situ nuclear analyses to determine the respective surface and bulk N-concentrations in the IBAD films, we were able to identify the different phases of the mechanism leading to the nitridation of evaporated boron by nitrogen ions. The composition of RIBSD films is found to depend only on the primary ion energy. In the case of IBD, the H-content decreases with the ion energy, from 19% at 0.5 keV down to 5% at 1.5 keV. In addition, we observed a chemical sputtering process which reduces drastically the deposition yield (i.e. the ratio of deposited atoms to the incident atomic fluence) when the ion energy is increased.