A non-floating vertical transistor includes a substrate and a protuberant structure extending from the substrate. A segregating pillar is inside the protuberant structure. A pair of segregated bit-lines which are segregated by the segregating pillar is disposed in the substrate and in the protuberant structure and adjacent to the bottom of the segregating pillar. A gate oxide layer is attached to the sidewall of the protuberant structure. A word-line is adjacent to the gate oxide layer so that the gate oxide layer is sandwiched between the word-line and a doped deposition layer.