An atomic layer deposition process for moving flexible substrates

A new design of atomic layer deposition (ALD) system for deposition on to moving flexible substrates has been demonstrated. The basic design is a cylindrical drum to which the substrate is attached which rotates inside a reaction chamber fitted with a number of different precursor and purge zones. It is intended as a vehicle for determining the parameters which are important in the design of a roll-to-roll ALD system. The system shows that deposition takes place according to the typical ALD model where there is dose saturation above a certain dose levels and that the thickness of film deposited is proportional to the number of ALD cycles carried out. The deposition rate for a reaction temperature of 100 °C is ∼1 Å/cycle. Good uniformity across the width of a 300 mm × 100 mm flexible substrate is demonstrated. The deposition process shows some deviations from classical ALD behaviour which can be understood taking into account the movement of the substrate.