Transient CFD-Guided Fast-Cycle ALD: Effects of Reactor Configuration and Process Window

Abstract Atomic layer deposition (ALD) is a powerful vapor-phase thin-film technique that relies on sequential, self-limiting surface reactions to achieve atomic-scale thickness control and excellent conformality on three-dimensional substrates. In practical reactors, however, throughput is frequently constrained by transient transport, mixing, and purge/clearance dynamics rather than by surface chemistry alone, making the intrinsically low deposition rate a key limitation. A transient CFD framework is established to quantify near-substrate precursor exposure and purge efficiency, with emphasis on (i), upstream pulse shaping and mixing; (ii), carrier-gas flow-rate effects under short dosing; and (iii), chamber-height-dependent clearance time. Under the optimized configuration, 1.0 s/cycle Al2O3 ALD is realized at 120 °C using TMA/H2O as precursors. The fast-cycle ALD operation yields about 138 Å Al2O3 film after 100 cycles with a thickness nonuniformity of ±2.3% (137–143 Å). The combined CFD-experiment methodology provides actionable design rules for rapid-cycling ALD reactors and high-throughput thin-film deposition.