A method of fabricating a semiconductor device includes forming trenches in active areas respectively, the trenches having sidewalls and upper openings respectively, forming first conductive regions in the trenches so that the first conductive regions serve as electrodes of the trench capacitors, respectively, each first conductive region including first impurity of a predetermined conductive type, forming sidewall insulating films on the sidewalls located over the first conductive regions respectively, forming second conductive regions inside the sidewall insulating films respectively, removing the sidewall insulating film located above the second conductive regions respectively, doping regions of the substrate located under the gate electrodes with second impurity of a reverse conduction type relative to the first impurity in the second direction from the upper openings through portions of the trenches from which the sidewall insulating films have been removed respectively, and forming third conductive regions in the portions of the trenches.