Abstract: The present invention relates to an apparatus and method of forming one or more FETs having a vertical trench-formed double-gate, with a plurality of nitride layers having oxide marker etch-stop layers provided periodically there-through, thereby adapting the FETs to have a plurality of selectable gate lengths. The present invention provides for control and formation of gate lengths scaled down to about 5 nm to about 100 nm, preferably from about 5 nm to about 50 nm. The plurality of pad nitride layers with the oxide etch-stop layers provide for the present FET to be connected to a plurality of contacts having a variety of connection depths corresponding to the gate lengths used, by etching a plurality of via in the pad nitride layers whereby such vias stop at selected ones of the etch-stop layers to provide vias adapted to connect with the selected ones of such contacts.