1. Context

ALD was first developed in Finland in the early 1970s to meet a need in the electroluminescent panel industry (TFELs). To develop these products, it was necessary to deposit high-quality dielectric and luminescent thin films on large surfaces. The conventional deposition processes used at the time, such as evaporation or sputtering, did not meet these requirements.

T. Suntola and his team came up with the idea of depositing a material with the desired properties, ZnS, brick by brick, starting with elementary precursors (zinc and sulfur). In this way, precise thickness control could be achieved even over a large surface area. The ALE (Atomic Layer Epitaxy) technique was born.

From the 2000s onwards, ALE became ALD (Atomic Layer Deposition), as most deposition was by self-limiting surface reaction rather than epitaxy. For reasons of process...