Three-dimensional memory devices and methods for forming the same

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;
• and
• 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,
• wherein one of the word line pick-up structures further comprises:
• a spacer circumscribing the vertical contact;
• and
• a filler circumscribed by the vertical contact.

A system, comprising:

• a three-dimensional (3D) memory device configured to store data, the 3D memory device comprising:
• channel structures in a first region, the first region comprising a first stack structure;
• word line pick-up structures in a first portion of a second region, a second portion of the second region comprising a second stack structure, and the first region and the second region being arranged in a first direction;
• and
• word lines each extending in the first region and reaching 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,
• wherein the word lines are discontinuous in the first portion of the second region and are electrically connected to the word line pick-up structures, respectively, and heights of the first stack structure and the second stack structure are uniform;
• and
• a memory controller electrically connected to the 3D memory device and configured to operate the channel structures through the word lines.