In situ infrared spectroscopy study of the surface reactions during the atomic layer deposition of TiO2 on GaAs (100) surfaces

摘要

The surface reactions during the atomic layer deposition (ALD) of TiO2 on chemical oxide and hydrogen fluoride etched GaAs (100) surfaces at 100 and 200 degrees C have been studied by in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Tetrakis (dimethylamino) titanium (TDMAT) and H2O were used as precursors. The adsorption of TDMAT on both GaAs surfaces at 200 degrees C was self-limiting, while significant contribution from physisorption was confirmed at 100 degrees C. In addition to the basic ligand substitution mechanism, the presence of parallel/competing reaction pathways was confirmed through the detection of Ti metallacycles and methylmethyleneimine [CH3N=CH2] (MMI). Isotope exchange experiments using D2O and H-2 O-18 were used to confirm the presence of MMI. This product was produced at each H2O exposure step and partially removed during the subsequent TDMAT exposure leading to its accumulation in the growing film. (C) 2017 Elsevier B.V. All rights reserved.