Semiconductor memory devices with high gate coupling ratio and methods of manufacturing the same

Abstract

A semiconductor memory device includes a substrate of a first impurity type, a first well region of a second impurity type in the substrate, the second impurity type being different from the first impurity type, a second well region of the first impurity type in the substrate, a patterned first dielectric layer on the substrate extending over the first and second well regions, a patterned first gate structure on the patterned first dielectric layer, a patterned second dielectric layer on the patterned first gate structure, and a patterned second gate structure on the patterned second dielectric layer. The patterned first gate structure may include a first section extending in a first direction and a second section extending in a second direction orthogonal to the first section, wherein the first section and the second section intersects each other in a cross pattern. The patterned second gate structure may include at least one of a first section extending in the first direction over the first section of the patterned first gate structure or a second section extending in the second direction over the second section of the patterned first gate structure.