According to example embodiments of inventive concepts, method of forming a semiconductor memory devices includes sequentially forming a first mold layer, a first support layer, a second mold layer, and a second support layer on a substrate, forming lower electrodes penetrating the second support layer, the second mold layer, the first support layer, and the first mold layer on the substrate, patterning the second support layer to form a second support pattern including an opening, removing the second mold layer to expose portions of sidewalls of the lower electrodes, and etching the exposed sidewalls of the lower electrodes.