Vertical memory devices

A semiconductor device, comprising:

• gate layers and insulating layers that are stacked alternatingly along a first direction perpendicular to a substrate of the semiconductor device in a first region upon the substrate, wherein the gate layers and the insulating layers are stacked of a stair-step form in a second region upon the substrate;
• channel holes that are disposed in the first region and extend in the first direction, wherein the channel holes are through the gate layers and the insulating layers, and the channel holes and the gate layers form a stack of transistors in a series configuration;
• a contact structure disposed in the second region to form a conductive connection with one of the gate layers;
• and
• multiple dummy channel holes that are disposed around the contact structure in a non-symmetric configuration with regard to the contact structure,
• wherein
• the dummy channel holes are patterned with a capsule shape and a bone shape that are different from a circle shape of the channel holes,
• the dummy channel holes are patterned with a capsule shape and an arc shape that are different from a circle shape of the channel holes,
• the dummy channel holes are patterned with a bone shape that is different from a circle shape of the channel holes,
• the dummy channel holes are patterned with an arc shape that is different from a circle shape of the channel holes,
• or
• the dummy channel holes are patterned with a rectangle shape that is different from a circle shape of the channel holes, and three of the dummy channel holes are arranged around a contact structure on three sides in a hexagonal pattern with regard to the contact structure, the three sides separated from one another.