In this approach, the different reactivity of two substrates with regard to the precursor is used to achieve selectivity. It has also been called "substrate-specific ALD" . This can be achieved using chemically different surfaces (e.g., Cu and SiO2 ), different surface terminations of the same material (e.g., H-Si and HO-Si ) or different facets (e.g., Pt (100) and Pt(111) ). It has long been known in the ALD community that growth depends on surface type and termination. The Parsons group then first used this concept specifically to achieve selective ALD growth between two substrates. Among others, the Chen group extended the concept considerably until today. The key advantage of intrinsically selective AS-ALD is that no new chemical species is introduced. This is beneficial for complex application environments where contamination and simplicity of production plays a key role. The disadvantage is the limitation in terms of suitable material combinations. Furthermore, it is important to control the surface termination for selective reactivity. Often, this approach is combined with selectivity-enhancing post-treatment (section 1.3.4). A variation of this idea uses different diffusion coefficients on GS and NGS to achieve selectivity (section 4.8). The difference in surface properties like electric resistivity has also been exploited. The main computational challenges for intrinsically selective AS-ALD are: