Memory device and method for forming the same

A method for forming a memory device, comprising:

• forming a bottom-select-gate (BSG) structure on a substrate;
• forming cut slits vertically through the BSG structure on the substrate;
• forming a cell-layers structure on the BSG structure;
• and
• forming gate-line slits that are vertically through the cell-layers structure and the BSG structure, into the substrate and arranged along a first lateral direction to distinguish a plurality of finger regions, wherein:
• the gate-line slits include a first gate-line slit between first and second finger regions of the plurality of finger regions, the first gate-line slit including gate-line sub-slits, and
• the first finger region is divided into a first string region and a second string region by a first cut-slit of the cut slits, wherein:
• the first cut-slit is formed in the first finger region along a second lateral direction and further extended into at least the second finger region along the first lateral direction, and
• at least one BSG defined by the first cut-slit is located in at least the second finger region to connect to cell strings in the first string region through an inter-portion between adjacent gate-line sub-slits of the first gate-line slit.