Word line structure of three-dimensional memory device

A memory device, comprising:

• a substrate;
• a stack over the substrate;
• at least one gate line slit extending along a first direction and dividing the stack into at least two portions;
• a source region in the substrate;
• and
• a source contact via in the at least one gate line slit and connected to the source region,
• wherein the at least two portions of the stack are insulated from the source contact via, the stack comprises at least one connection portion that connects the two portions of the stack, the connection portion comprises at least two sub-connection portions along a second direction perpendicular to the first direction, the gate line slit comprises at least two portions along the first direction, and each sub-connection portion is between adjacent two portions of the gate line slit.

A method for forming a memory device, comprising:

• providing a substrate;
• forming a stack structure on the substrate;
• forming at least one gate line slit extending along a first direction and dividing the stack structure into at least two portions, wherein the gate line slit comprises at least two portions along the first direction;
• and
• forming at least one connection portion comprising at least two sub-connection portions along a second direction perpendicular to the first direction, wherein each sub-connection portion is between adjacent two portions of the gate line slit.