| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Monday Sessions |
| Session TF1-MoM |
| Session: | Precursors and Surface Reactions |
| Presenter: | Brent Sperling, National Institute of Sandards and Technology (NIST) |
| Authors: | B.A. Sperling, National Institute of Sandards and Technology (NIST) B. Kalanyan, National Institute of Sandards and Technology (NIST) J.E. Maslar, National Institute of Sandards and Technology (NIST) |
| Correspondent: | Click to Email |
Despite being arguably the most well-studied and widely-used precursor pairing used for atomic layer deposition, trimethylaluminum (TMA) and H2O continue to provide surprises. One of the most recent is the discovery that "residual" surface methyl groups persist at low temperatures even after large doses of H2O, as observed using broadband sum-frequency generation (BB-SFG).[1] Our measurements using in situ reflection-absorption infrared spectroscopy (RAIRS) in a laminar-flow reactor have found evidence supporting the BB-SFG findings under typical ALD conditions. Post-deposition XPS measurements indicate that, in agreement with numerous other studies, very low concentrations of carbon are present in the resulting films even at low temperatures when residual methyls are present. With RAIRS, we observe a significant (approximately 10 cm-1) reduction in the frequency of the deformation mode at ~1210 cm-1 after H2O dosing. Small additions of H2O allow the dynamics to be captured; as the intensity decreases and peak position changes, the peak shape remains constant. Explanations for the behavior are discussed along with suggestions on how this observation might be used to elucidate some the finer details of TMA/H2O surface chemistry.
[1] V. Vandalon and W.M.M. Kessels, Appl. Phys. Lett.108, 011607 (2016).