Time-Resolved Surface Infrared Spectroscopy during Atomic Layer Deposition

Abstract

This work presents a novel method for obtaining surface infrared spectra with sub-second time resolution during atomic layer deposition (ALD). Using a rapid-scan Fourier transform infrared (FT-IR) spectrometer, we obtain a series of synchronized interferograms (120 ms) during multiple ALD cycles to observe the dynamics of an average ALD cycle. We use a buried metal layer (BML) substrate to enhance absorption by the surface species. The surface selection rules of the BML allow us to determine the contribution from the substrate surface as opposed to that from gas-phase molecules and species adsorbed at the windows. In addition, we use simulation to examine the origins of increased reflectivity associated with phonon absorption by the oxide layers. The simulations are also used to determine the decay in enhancement by the buried metal layer substrate as the oxide layer grows during the experiment. These calculations are used to estimate the optimal number of ALD cycles for our experimental method.

A Secondary Reaction Pathway for the Alumina Atomic Layer Deposition Process with Trimethylaluminum and Water, Revealed by Full-Range, Time-Resolved In Situ Mass Spectrometry

“…Where Sperling et al relied on hardware triggers to synchronize and average out their IR measurements, we solely rely on post-processing the data to construct the time-resolved spectrum. 24,25…”

“…Calculations on how this can be optimized can be found in the Supporting Information. Where Sperling et al relied on hardware triggers to synchronize and average out their IR measurements, we solely rely on postprocessing the data to construct the time-resolved spectrum. , …”

“…Where Sperling et al relied on hardware triggers to synchronize and average out their IR measurements, we solely rely on postprocessing the data to construct the time-resolved spectrum. 24,25 Practical Issues. When naively applying the scheme depicted in Figure 2 it became apparent that it is critical to determine the exact value of τ ALD because the slightest error on the length of the ALD cycle will increase the misalignment of subsequent cycles in the postprocessing.…”

Initial Growth Study of Atomic-Layer Deposition of Al2O3 by Vibrational Sum-Frequency Generation

“…This phase of the ALD process is referred to as the steady-growth regime or in the ALD literature occasionally as “steady-state growth”. The primary focus of mechanistic ALD studies so far has been on characterizing the steady-growth regime. ,− However, at the start of deposition, the growth is influenced by the starting surface and the process parameters can vary from cycle-to-cycle. This initial growth regime is commonly referred to as the “nucleation” phase in the ALD literature.…”

Design and Operation of an Optically-Accessible Modular Reactor for Diagnostics of Thermal Thin Film Deposition Processes

“…In past works we presented the design and characterization of a diagnostics-accessible ALD reactor [ 7 ], which provided good optical access [ 8 , 9 ] and was capable of depositing device quality oxides [ 10 ]. The complexity and size of that reactor limited the ease in which it could be integrated into an optical train, making it impractical for use with a wide range of optical measurements.…”