Abstract
Low throughput is a major limitation for industrial level atomic layer deposition (ALD)
applications. Spatial ALD is regarded as a promising solution to this issue. With numerical
simulations, this paper studies an in-line spatial ALD reactor by investigating the effects of
gap size, temperature, and pumping pressure on the flow and surface chemical deposition
processes in Al2O3 ALD. The precursor intermixing is a critical issue in spatial ALD system
design, and it is highly dependent on the flow and material distributions. By numerical studies,
it’s found that bigger gap, e.g., 2 mm, results in less precursor intermixing, but generates
slightly lower saturated deposition rate. Wafer temperature is shown as a significant factor in
both flow and surface deposition processes. Higher temperature accelerates the diffusive mass
transport, which largely contributes to the precursor intermixing. On the other hand, higher
temperature increases film deposition rate. Well-maintained pumping pressure is beneficial to
decrease the precursor intermixing level, but its effect on the chemical process is shown very
weak. It is revealed that the time scale of in-line spatial ALD cycle is only in tens of
milliseconds, i.e., ~15 ms. Considering that the in-line spatial ALD is a continuous process
without purging step, the ALD cycle time is greatly shortened, and hence the overall
throughput is shown as high as ~8 nm/s, compared to several nm/min in traditional ALD.