Three-dimensional flash memory and method of forming the same

A method of forming a three-dimensional (3D) flash memory, comprising:

• forming a stop layer and a stack structure on a substrate, wherein the stack structure comprises a plurality of dielectric layers and a plurality of sacrificial layers stacked alternately;
• forming a plurality of first openings in the stack structure and the stop layer;
• respectively forming a plurality of vertical channel structures in the plurality of first openings;
• forming a plurality of second openings exposing the stop layer in the stack structure, wherein the plurality of second openings at least comprise two adjacent slit trenches having an average width 30w and a plurality of slit holes having have an average width W, the plurality of vertical channel structures are formed between the two slit trenches, and the plurality of slit holes are discretely formed between the plurality of vertical channel structures, wherein the average width W of the plurality of slit holes is greater than or equal to the average width 30w of the two adjacent slit trenches;
• and
• performing a gate replacement process through the plurality of second openings, so that the plurality of sacrificial layers are replaced by a plurality of conductive layers.