Atomic layer deposition (ALD) and plasma enhanced chemical vapour deposition (PECVD) are gaseous deposition techniques used to create conformal coatings. 

Thermal ALD uses alternating gaseous precursors to realise monolayer growth to allow the reproducible formation of films only a few nanometres thick with excellent step coverage. ALD can be used for many applications including realising thin gate dielectrics and for surface encapsulation and passivation. PECVD is a technique that allows a variety of silicon-based materials to be deposited by creating a mixture of reactive ions and radicals from gasoues precursors, which then react on the substrate surface to form a thin film. PECVD films are typically much thicker than those grown by ALD (50nm up to several microns). PECVD is a widely used technique within the CNC to form insulation and encapsulation layers; to create hard masks for applications such as dry etching, and to realise anti-reflection coatings for optical devices.