Three-dimensional semiconductor devices

A three-dimensional (3D) semiconductor device, comprising:

• an electrode structure on a substrate that includes a first region and a second region, the electrode structure including a plurality of electrodes which are stacked in a direction perpendicular to a top surface of the substrate,
• wherein the plurality of the electrodes respectively include pads which define a stepped structure in the second region of the substrate;
• dummy pillars penetrating the pads and a portion of the electrode structure under the pads;
• and
• contact plugs electrically connected to the pads, respectively,
• wherein adjacent pads of the pads share at least one of the dummy pillars.

A three-dimensional (3D) semiconductor device, comprising:

• an electrode structure on a substrate that includes a first region and a second region, the electrode structure including a plurality of electrodes which are stacked in a direction perpendicular to a top surface of the substrate,
• wherein the plurality of the electrodes respectively include pads which define a stepped structure in the second region of the substrate;
• a plurality of vertical patterns penetrating the electrode structure in the first region;
• a plurality of dummy pillars through the pads and the electrode structure under the pads;
• and
• a contact plug electrically connected to a corresponding pad of the pads,
• wherein the vertical patterns include a first vertical pattern and second vertical patterns surrounding the first vertical pattern, and the second vertical patterns are respectively at vertexes of a first imaginary polygon in a plan view,
• wherein the dummy pillars are respectively disposed at vertexes of a second imaginary polygon in a plan view, and
• wherein a number of the vertexes of the first imaginary polygon is different from a number of the vertexes of the second imaginary polygon.