Adhesion of particles (molecules) of a phase on the surface of a solid. Particles are held by the mechanisms of physisorption and chemisorption, with chemisorption causing significantly stronger bonding energies. Adsorption on a surface is only possible if the phases can come into direct contact; as a precondition, in particular the separating intermediate layers must be removed. A perfect way to reach this goal is ultra-fine cleaning with plasma. Plasma etching and plasma activation can increase the adsorption, and plasma coating with the appropriate coats can prevent it. Adsorption is not to be confused with absorption. In absorption, particles of one phase are taken up in the volume of another phase.