The main blocking mechanism for SAMs is steric blocking (Fig. .c,d). Thus, a continuous and dense monolayer formation is crucial. In experiment, this ideal monolayer is not straightforward to achieve. Surprisingly, very few AS-ALD related studies investigated this building up of the SAM inhibitor layer. In the most extensive and elaborate computational study by Clerix et al., alkanethiolate SAMs with differing chain lengths (C1-12) were investigated on copper. The authors conclude that the type and structure of the surface, the SAM chain length and the resulting coverage determine the phase of the SAM layer and thus the blocking properties. They could show that for longer chain lengths (C6, C12), lying-down and standing-up phases are found, and the saturation coverage is determined through steric hindrance. Interestingly, they show that the SAM behavior on Cu is different from the well-studied behavior on Au where intermolecular interactions in the SAM layer are decisive. The Cu-SAM interaction still dominates at saturation coverage which is in line with the higher reactivity of the Cu surfaces in other surface chemistry studies. The authors also show that short chain-length monomers (C1, C2) show no coherent phase on the surface and their ordering is determined by steric hindrance. Indeed, these short chain "SAMs" should better be termed SMIs which show exactly this behavior as discussed in the next paragraphs. Another study by Wojtecki et al. examined the SAM packing density as function of the head group combined with experimental results. Nevertheless, it is a bit surprising at first that there are so few computational investigations although SAMs have been an intensively researched topic in experimental AS-ALD for a long time. The reason is threefold: (i) SAM layer formation is the crucial step for blocking and this has been investigated in other communities for a long time already, (ii) the investigation of inhibitor layer formation requires extensive computational efforts and know-how, and (iii) the decomposition of the layer is essentially always precursor interaction with the alkane chain of the tail group which has been already modelled in cluster studies.