Planarity and control of the configuration of the cross-sectional area are important parameters to be considered for high density VLSI devices. The anodization process seems best to fulfill such conditions, but anisotropy (i.e., difference in vertical and lateral anodization rates), must be increased to obtain a competitive technique. In this work factors affecting the anisotropy of the aluminum anodization process were investigated. By varying the electrochemical process parameters, a degree of anisotropy of about 0.6 was obtained. The dimensions of the aluminum porous oxide were determined by scanning electron microscopy. At high forming voltages, the electric field across the barrier layer of the porous oxide cells were calculated and plotted.