Three-dimensional semiconductor memory devices

Abstract

3D semiconductor memory devices may include a horizontal structure that may be on an upper surface of a substrate and may include first and second horizontal patterns sequentially stacked on the upper surface of the substrate, a stack structure including electrodes stacked on the horizontal structure, a vertical pattern extending through the electrodes and connected to the first horizontal pattern, and a separation structure intersecting the stack structure and the horizontal structure and protruding into the upper surface of the substrate. A lowermost electrode may have first inner sidewalls facing each other with the separation structure interposed therebetween. The second horizontal pattern may have second inner sidewalls facing each other with the separation structure interposed therebetween. A maximum distance between the first inner sidewalls in the first direction may be less than a maximum distance between the second inner sidewalls in the first direction.