What is the relation between cycle time and film non-uniformity in ALD processes?
An ALD growth cycle consists of precursor pulses followed by inert gas purges. A two component ALD process proceeds as follows: precursor A pulse -> purge -> precursor B pulse -> purge. This growth cycle is repeated as long as desired film thickness is reached. In case the purge steps are too short, the precursor pulses overlap and film uniformity will typically degrade. However, in a well designed ALD process tool, uniform high quality films can be achieved even with short cycle times. A good example of SUNALE™ ALD process tool quality is that our customers have obtained < 1 % ( standard deviation / average) aluminum oxide film non-uniformity on 6’’ wafer with 2.2 seconds cycle time. Growth of 100 nm aluminum oxide film requires about 1000 growth cycles. Therefore a highly uniform 100 nm aluminum oxide film can be deposited in 37 minutes in our ALD process tools. Some ALD systems on the market require longer than 30 seconds cycle times, which means that it takes over 8 h 20 min to gro
