The gaseous starting materials are simultaneously introduced into the heated reaction chamber. The reaction product that forms is deposited on the substrate.
Chemical vapour deposition (CVD, chemical vapour deposition) differs from atomic layer deposition in that the starting materials are introduced into the reaction chamber at the same time. This achieves significantly higher deposition rates. The combination with a plasma (PE-CVD, plasma enhanced CVD) keeps the deposition temperature low (50-300°C) and thermally sensitive substrates such as polymers can also be coated. The layer deposition is not as conformal as with ALD due to the directed plasma, the edge coverage is limited as with sputtering processes. Established processes include SiO2 and Si3N4 layers as well as polycrystalline silicon (also doped).