The fabrication process of a multilevel structure with a central electrode isolated from the outer gates is presented. Polymethylmethacrylate is used as the dielectric material that provides the electrical isolation. Dot gates with a diameter as small as 30 nm aligned in the middle of 0.10 mum split gates have been fabricated. The operation of the dot gates has been tested by conductance measurements through the constriction formed by the split gates.