Aside from reactions with the precursor, the inhibitor layer itself can become defective. Either via thermal decomposition or via desorption of the inhibitor from the NGS. Desorption and decomposition are known issues with SAM-based approaches for AS-ALD in experimental studies, but have not been investigated computationally up to now. Physisorbed SMIs are usually desorbed during purging cycles and thus the discussion is focused on chemisorbed species. For Hacac, the previously mentioned monodentate bonding mode is prone to desorption as a function of purging time. A substantial theoretical desorption rate was deduced from the barrier towards desorption applying the Arrhenius equation. Thermal inhibitor decomposition was also investigated as a beneficial process to block two NGS with one SMI. Diethyl sulfide (DES) decomposes readily after adsorption on the Cu surface leaving both fragments (ethyl and thiolate) to block the surface. On the second NGS, SiO2, the SMI shows a large barrier towards decomposition into endothermic products indicating a rare reaction event. Since the barrier towards desorption is lower than the first reaction barrier of decomposition, the SMI will more likely desorb. However, computations of the diffusion barrier showed that they are negligible for both SMI fragments resulting on the Cu surface. It was shown that recombinative desorption of the ethyl fragment as butane is likely while the thiolate fragment will remain to block the surface. For the blocking of SiO2 with ethyl fragments, the high barriers for decomposition are overcome at elevated temperatures, in line with the experimental findings of good blocking on Cu and moderate blocking on SiO2. Cross-linking of SAM layers via extreme ultraviolet lithography (EUV) radiation was proposed by Wojtecki et al. as beneficial decomposition mechanism to increase blocking ability.