Semiconductor devices and data storage systems including the same

Abstract

A semiconductor device includes a substrate; gate electrodes spaced apart from each other and stacked in a direction, perpendicular to an upper surface of the substrate; first and second horizontal conductive layers sequentially stacked between the substrate and the gate electrodes; and a channel structure passing through the gate electrodes and extending perpendicularly, and including a channel layer contacting the first horizontal conductive layer, wherein the channel layer has a region having a reduced diameter below a first level in which a lower surface of a lowermost gate electrode is located, among the gate electrodes, and the channel structure further includes a metal silicide region located below the first level and in the channel structure to contact the channel layer.