Semiconductor devices having contact structures

Abstract

A semiconductor device includes: a substrate; an active region in the substrate; a device isolation layer defining the active region; a gate structure in the substrate and extending across the active region in a first horizontal direction; bit line structures on the substrate, extending in a second horizontal direction intersecting the first horizontal direction, and crossing the gate structure; and a contact structure between the bit line structures, wherein the contact structure includes: a first contact plug in contact with the active region; a second contact plug on the first contact plug; and a third contact plug on the second contact plug, and wherein a first vertical central axis of the active region, a second vertical central axis of the first contact plug, and a third vertical central axis of the third contact plug are offset from each other in a cross-sectional view.

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