Abstract—Our work reports on the influence of etching modes and their combination on the design, microstructural and optical properties of compliant substrates based on porous silicon. It is shown on the basis of the data of a set of microstructural and spectroscopic methods of analysis that at constant lattice parameters, the magnitude of residual stresses, the size of crystallites, the volume of the crystalline fraction, as well as the reflectivity and energy of direct transitions in the porous silicon layer depend on the combination of etching modes, but do not always correlate with the value of the layer porosity calculated from the analysis of SEM images.