Patent TW-201939676-A (TW)
Title: Semiconductor memory device capable of increasing the cell current
Inventor: KOYAMA YUKINORI
IPC: H01L21/8239
Filed: 2018-08-06
Abstract: An embodiment of the present invention provides a semiconductor memory device capable of increasing the cell current. The semiconductor memory device according to an embodiment includes a substrate; a first electrode having a first surface and a second surface, wherein the first surface is extended in a first direction parallel to the surface of the substrate, and expanded in the first direction and a second direction perpendicular to the substrate and intersecting the first direction. The second surface is expanded in the first direction and the second direction, has a peripheral edge connected to the first surface, and protrudes with respect to the first surface in a third direction parallel to the substrate and intersecting the first direction; a second electrode having a third surface and a fourth surface, wherein the third surface is extended in the first direction, spaced apart from the first electrode in the third direction, and is expanded in the first direction and the second direction. The fourth surface is expanded opposite to the second surface in the first direction and the second direction, has a peripheral edge connected to the third surface, and protrudes with respect to the third surface in the third direction; a signal line disposed between the second surface and the fourth surface, and extended in the second direction; a first charge holding film having first parts and a second part, wherein the first parts are disposed between the signal line and the second surface, and disposed at both ends in the first direction. The second part is located between the first parts and disposed at a position protruding with respect to the first parts in the third direction toward the second surface; and a second charge holding film having third parts and a fourth part, wherein the third parts are disposed between the signal line and the fourth surface, and disposed at both ends in the first direction. The fourth part is located between the third parts, and disposed at a position protruding with respect to the third parts in the third direction toward the fourth surface. In the third direction, the interval between the second surface and the fourth surface is larger than the interval between the first surface and the third surface. In the cross section passing through the first charge holding film and the second charge holding film and parallel to the surface of the substrate, the contour of the signal line is formed by a fifth part, a sixth part, a seventh part, and an eighth part. The fifth part is opposite to the second part. The sixth part is opposite to the fourth part. The seventh part is connected to one end of the fifth part in the first direction and one end of the sixth part in the first direction, the seventh part is provided in the first direction. The eighth part is connected to the other end of the fifth part in the first direction and the other end of the sixth part in the first direction, the eighth part is provided in a direction opposite to the first direction of the seventh part. The seventh part includes a portion having a curvature different from the curvature of a portion of the fifth part near one end of the fifth part or the curvature in a portion of the sixth part near one end of the sixth part. The eighth part includes a portion having a curvature different from the curvature of a portion of the fifth part near the other end of the fifth part or the curvature in a portion of the sixth part near the other end of the sixth part.