ALD throughput comparison by tool architecture

For thin films, most of the processing time per wafer in every architecture is overhead such as transfer and heat-up. For high-k films and liners a few nm thick, single-wafer tools with short overhead and spatial tools that process several wafers on a susceptor at once come out ahead. As films get thicker, cycle time dominates, and spatial tools with no purge waits and batch tools that spread time over many wafers gain ground.

Throughput is not the only factor, though. Single-wafer tools make it easy to adjust conditions per wafer and to fine-tune film quality and uniformity; batch tools take long to heat and cool and lose many wafers in a single failure; spatial tools are limited in usable chemistries by gas separation and rotation speed. The pulse time needed for deep holes can be checked with the ALD step coverage and exposure calculator.