A vertical semiconductor device and a method of making a vertical semiconductor device include a first semiconductor pattern formed on a substrate and a first gate structure formed on a sidewall of the first semiconductor pattern. A second semiconductor pattern is formed on the first semiconductor pattern. A plurality of insulating interlayer patterns is formed on sidewalls of the second semiconductor pattern. The insulating interlayer patterns are spaced apart from each other to define grooves between the insulating interlayer patterns. The plurality of second gate structures is disposed in the grooves, respectively.