A vertical type integrated circuit device includes a substrate and a pillar vertically protruding from the substrate. The pillar includes a lower impurity region and an upper impurity region therein and a vertical channel region therebetween. A portion of the pillar including the lower impurity region therein includes a mesa laterally extending therefrom. The device further includes a first conductive line extending on a first sidewall of the pillar and electrically contacting the lower impurity region, and a second conductive line extending on a second sidewall of the pillar adjacent the vertical channel region. The second conductive line extends in a direction perpendicular to the first conductive line and is spaced apart from the mesa. Related devices and methods of fabrication are also discussed.