(515b) The Pressure Dependence of Atomic Layer Deposition Processes On Particles in a Fluidized Bed Reactor
Standard atomic layer deposition (ALD) processes are operated under vacuum conditions to allow for the effective chemisorption of precursors while minimizing the physisorption of unwanted contaminants. Particle ALD processes can be performed in a variety of reactor configurations, but the most common is the fluidized bed reactor. There is a desire to increase the operating pressure in order to significantly decrease the processing time to functionalize particle surfaces at the pilot and industrial scales without sacrificing film quality. It is well known that the steric hindrance of adsorbed precursors can be overcome at elevated pressures, causing tighter packing and increased film growth per cycle. Reaction progress was measured using an in situ mass spectrometer downstream from the fluidized bed reactor. A comprehensive evaluation of the pressure-dependent attributes of ALD films was performed. Implications on process time and scale-up are discussed for lab-scale and pilot-scale fluidized beds, and these results are compared to ALD processes performed in alternate reactor configurations.