Micro- and nanoscaled systems can be classified by the number of constituting components (homogeneous, binary or ternary systems), by their regularity (statistical or regular systems), by the mechanism of formation (actively or passively ordered) and by their aspect ratio A (A = depth divided by width). Examples given here are porous silicon, galvanized microstructures, phosphate layers and heterostructures deposited within porous aluminum oxide layers or porous silicon. Engineering aspects refer to : formation of the structured substrate, deposition of the heterostructure, a post treatment and finally an application. The formation of vertical systems with large aspect ratios is well known for systems ordered passively in the pm-range. Self organized nanostructuring is discussed which is only possible in systems with a major anisotropy. This anisotropy can be given by electronic factors (silicon) or by a field dependent corrosion (porous Al oxide). As an example polymerization of bithiophene within porous silicon (PS) is described. Electrochemical and ESCA measurements proved that Si oxidation takes place simultaneously. Thus a ternary nanostructured system Si/Si-oxide/polybithiophene (semiconductor/insulator/conductor) with an aspect ratio of A > 100 is obtained. This nanostructured system can be electrochemically switched between a conducting (SIG) and a semiconducting state (SIS) referred to the polymer deposited within the pores of PS. Different process steps can be distinguished in potentiostatic or galvanostatic transients : initial oxidation of porous silicon, polymerization within the pores, polymerization on the outer surface of PS. The deposition process within the pores can be controlled due to these process stages. It is proved by electrochemical and surface analytical methods that the polymerization starts at the bottom of the pores. The growth of polybithiophene within the pores takes place at a lower overpotential compared to the deposition on gold due to a higher degree of order of the polymer. Therefore the electrochemical properties remain unchanged. Complete oxidation of the porous silicon is not observed during the anodic polymerization. Polymer deposition even partially prohibits Si oxidation.