In situ mass spectrometry study on surface reactions in atomic layer deposition of TiN and Ti(Al)N thin films

Surface reactions in the atomic layer deposition (ALD) of TiN and Ti(Al)N films from titanium tetrachloride (TiCl4), trimethylaluminum (Al(CH3)(3), and deuterated ammonia (ND3) were studied by using a mass spectrometer to determine the amounts of reaction products formed during each deposition step. Since the Al(CH3)(3) dose has been noticed to have a considerable effect on the properties of the deposited Ti(Al)N films, the deposition was studied with low and high Al(CH3)(3)doses. Deuterium chloride, DCl, was the most noticeable reaction byproduct during each deposition step, and the other byproducts increased to significant amounts merely with the high Al(CH3)(3) dose. With the low Al(CH3)(3) dose, most of the chlorine was eliminated during the ammonia pulse similarly to the TiN process. On the other hand, with the high Al(CH3)(3) dose, most of the chlorine was removed during the TiCl4 pulse. The detection of ethane during the Ti(AI)N deposition with the high Al(CH3)(3) dose implied that Al(CH3)(3) acts as an additional reducing agent releasing methyl radicals. During the deposition of AlN films, no ethane evolvement could be detected.