Consequently, the maximum amount of material deposited on the surface after a single exposure to all of the precursors (a so-called ALD cycle) is determined by the nature of the precursor-surface interaction.
ALD is considered one deposition method with great potential for producing very thin, conformal films with control of the thickness and composition of the films possible at the atomic level.
In panel A, precursor 1 (blue) is added to the reaction chamber containing the material surface to be coated by ALD.
After precursor 1 has adsorbed on the surface, any excess is removed from the reaction chamber.
The sister technique of atomic layer deposition, molecular layer deposition (MLD), is employed when organic precursors are wished to be used.
By combining the ALD/MLD techniques, it is possible to make highly conformal and pure hybrid films for many applications.
TFEL display manufacturing remained until the 1990s the only industrial application of ALE.
In 1987, Suntola started the development of the ALE technology for new applications like photovoltaic devices and heterogeneous catalysts in Microchemistry Ltd., established for that purpose by the Finnish national oil company Neste Oy.
The remaining reactant molecules are flushed away and only then reactant B is inserted into the reactor.Microchemistry Ltd/ASM Microchemistry Ltd was the only manufacturer of commercial ALD-reactors in the 1990s.In the early 2000s, the expertise on ALD reactors in Finland triggered two new manufacturers, Beneq Oy and Picosun Oy, the latter started by Sven Lindfors, Suntola's close coworker since 1975.Also, rather than using the concept of growth rate, ALD processes are described in terms of their growth per cycle.
In ALD, enough time must be allowed in each reaction step so that a full adsorption density can be achieved.
In the 1990s, ALE development in Microchemistry was directed to semiconductor applications and ALE reactors suitable for silicon wafer processing. and the ALD technology were sold to the Dutch ASM International, a major supplier of semiconductor manufacturing equipment and Microchemistry Ltd.