Three-dimensional memory devices and methods for forming the same

1 . A three-dimensional (3D) memory device, comprising:

channel structures in a first region;

word line pick-up structures in a first portion of a second region, the first region and the second region being arranged in a first direction;

word lines each extending in the first region and a second portion of the second region, the first portion and the second portion of the second region being arranged in a second direction perpendicular to the first direction, and the first portion comprising a dielectric stack structure that comprises interleaved first dielectric layers and second dielectric layers; and

dummy channel structures in the second portion of the second region,

wherein:

adjacent channel structures are spaced apart from each other by a first distance; and

adjacent dummy channel structures are spaced apart from each other by a second distance that is smaller than the first distance.

2 . The 3D memory device of claim 1 , wherein the first distance is a shortest distance between the adjacent channel structures.

3 . The 3D memory device of claim 1 , wherein the first distance is measured between edges of adjacent channel structures.

4 . The 3D memory device of claim 1 , wherein the second distance is a longest distance between the adjacent dummy channel structures.

5 . The 3D memory device of claim 1 , wherein the second distance is measured between edges of adjacent dummy channel structures.

6 . The 3D memory device of claim 1 , wherein a cross-section of at least one of the dummy channel structures is of a circular shape.

7 . The 3D memory device of claim 1 , wherein a cross-section of at least one of the dummy channel structures is of an oval shape.

8 . The 3D memory device of claim 7 , wherein the dummy channel structures are staggered along the second direction.

9 . The 3D memory device of claim 7 , wherein a major axis of the cross-section of the at least one of the dummy channel structures is parallel to the first direction.

10 . The 3D memory device of claim 7 , wherein a major axis of the cross-section of the at least one of the dummy channel structures is transversal to the first direction.

11 . The 3D memory device of claim 10 , wherein a major axis of the cross-section of the at least one of the dummy channel structures is perpendicular to the first direction.

12 . A three-dimensional (3D) memory device, comprising:

a first stack structure comprising interleaved conductive layers and first dielectric layers;

a second stack structure comprising interleaved second dielectric layers and the first dielectric layers;

word line pick-up structures extending into the second stack structure at different depths and each comprising a vertical contact, and an interconnect line in contact with the vertical contact and a respective one of the conductive layers in the first stack structure; and

dummy channel structures extending through the first stack structure,

wherein:

adjacent channel structures are spaced apart from each other by a first distance; and

adjacent dummy channel structures are spaced apart from each other by a second distance that is smaller than the first distance.

13 . The 3D memory device of claim 12 , wherein the first distance is a shortest distance between the adjacent channel structures.

14 . The 3D memory device of claim 12 , wherein the first distance is measured between edges of adjacent channel structures.

15 . The 3D memory device of claim 12 , wherein the second distance is a longest distance between the adjacent dummy channel structures.

16 . The 3D memory device of claim 12 , wherein the second distance is measured between edges of adjacent dummy channel structures.

17 . The 3D memory device of claim 1 , wherein in the first portion, one of the word lines extends within the dielectric stack structure that comprises the interleaved first dielectric layers and second dielectric layers.

18 . The 3D memory device of claim 1 , wherein portions of the dielectric stack structure, comprising the interleaved first dielectric layers and second dielectric layers, are arranged below respective ones of the word line pick-up structures.

19 . The 3D memory device of claim 1 , wherein a word line pick-up structure of the word line pick-up structures extends through a portion of a dielectric stack structure comprising interleaved first dielectric layers and second dielectric layers without extending through another portion of the dielectric stack structure below the word line pick-up structure.

20 . The 3D memory device of claim 1 , wherein an interconnect line is arranged within the dielectric stack structure and configured to contact one of the word lines to a corresponding word line pick-up structure.