Atomic layer deposition (ALD): from precursors to thin film structures

The principles of the atomic layer deposition (ALD) method are presented emphasizing the importance of precursor and surface chemistry. With a proper adjustment of the experimental conditions, i.e. temperatures and pulsing times, the growth proceeds via saturative steps. Selected recent ALD processes developed for films used in microelectronics are described as examples. These include deposition of oxide films for dielectrics, and nitride and metal films for metallizations. The use of a plasma source to form radicals is expanding the selection of ALD films to metals. Plasma-enhanced ALD also facilitates the deposition of nitride films at low temperatures.