<p>ABSTRACT: Atomic layer deposition (ALD) raises global interest
through its unparalleled conformality. This work describes new microscopic
lateral high-aspect-ratio (LHAR) test structures for conformality analysis of
ALD. The LHAR structures are made of silicon and consist of rectangular
channels supported by pillars. Extreme aspect ratios even beyond 10 000:1
enable investigations where the adsorption front does not penetrate to the end of
the channel, thus exposing the saturation profile for detailed analysis. We use
the archetypical trimethylaluminum (TMA)-water ALD process to grow alumina as a
test vehicle to demonstrate the applicability, repeatability and
reproducibility of the saturation profile measurement and to provide a
benchmark for future saturation profile studies. Through varying the TMA
reaction and purge times, we obtained new information on the surface chemistry
characteristics and the chemisorption kinetics of this widely studied ALD process.
We propose new saturation profile related classifications and terminology. </p>
Aluminium oxide and titanium oxide films were deposited using the Atomic Layer Deposition method on n-type 4H SiC and p-type Si {001} substrates, with doping 6×1015cm-3 and 2×1016cm-3, respectively, and on 1.2 kV PiN 4H SiC diodes for passivation studies. The Al2O3 and SiC interface was characterised for the existence of an effective negative charge with a density of 1×1012-2×1012 cm-2. The dielectric constant of Al2O3 as determined from capacitance-voltage data was about 8.3. The maximum electric field supported by the Al2O3 film was up to 7.5 MV/cm and 8.4 MV/cm on SiC and Si, respectively.
Saturation Profile Based Conformality Analysis for Atomic Layer Deposition: Aluminum Oxide in Lateral High-Aspect-Ratio Channels