Methods for forming three-dimensional memory device having bent backside word lines

A method for forming a three-dimensional (3D) memory device, comprising:

• forming a notch on at least one edge of a substrate;
• forming a semiconductor layer above the substrate and extending laterally beyond the at least one edge of the substrate to cover the notch;
• alternatingly depositing a plurality of sacrificial layers and dielectric layers along a front side and the at least one edge of the semiconductor layer and along a top surface, a side surface, and a bottom surface of the notch;
• removing a portion of the substrate to expose the interleaved sacrificial layers and dielectric layers below the semiconductor layer;
• and
• replacing the sacrificial layers with a plurality of conductive layers.

A method for forming a three-dimensional (3D) memory device, comprising:

• forming a notch on at least one edge of a substrate;
• forming a semiconductor layer above the substrate and extending laterally beyond the at least one edge of the substrate to cover the notch;
• alternatingly depositing a plurality of conductive layers and dielectric layers along a front side and the at least one edge of the semiconductor layer and along a top surface, a side surface, and a bottom surface of the notch;
• and
• removing a portion of the substrate to expose the interleaved conductive layers and dielectric layers below the semiconductor layer.