Surface reactions of aminosilane precursors during N 2 plasma‐assisted atomic layer deposition of SiN x

The surface reactions during atomic layer deposition (ALD) of SiNx were studied using in situ attenuated total reflection Fourier transform infrared spectroscopy. Specifically, di(sec-butylamino)silane (DSBAS) and bis(diethylamino)silane (BDEAS) were used as the silicon precursors with N-2 plasma as the nitrogen source for SiNx ALD over a temperature range of 225-375 degrees C. The infrared spectra recorded during each ALD half-cycle provide unambiguous experimental evidence that surface secondary amines (>NH) are the primary reactive sites for chemisorption of DSBAS and BDEAS on a SiNx surface that was exposed to an N-2 plasma. Based on these observations, we predict that most aminosilane precursors will primarily react with surface >NH groups: This observation is contrary to most atomistic-level simulations for this reaction that predict a high activation energy barrier.