By Melbourne Centre for Nanofabrication
The process Atomic Layer Deposition (ALD) involves the deposition of materials one atomic monolayer at a time. It forms extremely uniform, conformal, pin-hole-free coatings on high aspect ratio structures. This is achieved by pulsing a chemical precursor onto a hydroxylated substrate surface. The precursor reacts with this surface but not with itself resulting in a monolayer of material. The precursor is purged from the chamber and then the surface is again hydroxylated with water vapour or oxygen, followed by another purge. These two steps are then repeated until the desired thickness of material is achieved. The uses ALD has a vast array of applications from semiconductors, MEMS, nanostructures and optics through to wear-resistant coatings. The instruments MCN has two ALD instruments – the Fiji F200 and the Savannah S100, both from Cambridge Nanotech. The Savannah system is thermal only and is integrated into a glovebox system so that samples can be kept in an inert environment. The Fiji F200 is capable of both thermal and Plasma Assisted ALD (PA-ALD). PA-ALD expands the window for materials by decreasing activation energy and allows for deposition at lower temperatures to reduce precursor decomposition, deposition times and film contaminations. Both systems are equipped to enable Cambridge Nanotech’s unique Exposure Mode™ for thin film deposition on ultra high aspect ratio substrates.
