(432c) Linear Vibration and Mixing in Continuous Spatial Particle ALD

Continuous spatial Particle ALD reactors enable powders to be continuously coated with sub nanometer films by sending the powder through alternating regions of precursor gas using a process called linear vibration. Linear vibration systems use a self-reversing actuator to vibrate the bed, producing steady and uniform powder flow. Some materials do not flow as easily using linear vibration, particularly as the powder diameter decreases. Fine powders are frequently used in Particle ALD, so understanding and predicting their flow behavior is essential for process control. Another important aspect of process control is guaranteeing equal exposure time of each particle to the precursor gas. For thick powder beds, effective powder flow and top-bottom mixing must occur simultaneously to guarantee equal exposure time with high powder throughput. In this work, the relationship between linear vibration and mixing in a continuous spatial Particle ALD reactor is investigated. An MFIX-DEM model was developed and the results were compared to in-situ images of dyed glass microsphere mixing during continuous bed vibration.