Methods of fabricating vertical semiconductor device utilizing phase changes in semiconductor materials

A method of fabricating a vertical non-volatile semiconductor device, comprising:

• forming a stack structure on a substrate, the stack structure including openings exposing a top surface of the substrate;
• forming a first preliminary semiconductor layer to partially fill the openings;
• phase-changing the first preliminary semiconductor layer to form a first single crystalline semiconductor layer in the openings;
• forming a second preliminary semiconductor layer on the first single crystalline semiconductor layer in the openings;
• phase-changing the second preliminary semiconductor layer to form a second single crystalline semiconductor layer that combines with the first single crystalline semiconductor layers to form a single crystalline semiconductor layer in the openings;
• and
• forming transistors on sidewalls of the single crystalline semiconductor layer.

A method of fabricating a vertical NAND semiconductor device, comprising:

• changing a phase of a first preliminary semiconductor layer in an opening from solid to liquid to form a first single crystalline semiconductor layer in the opening;
• and then
• forming a second preliminary semiconductor layer on the first single crystalline semiconductor layer;
• and
• changing a phase of the second preliminary semiconductor layer from solid to liquid to form a second single crystalline semiconductor layer that combines with the first single crystalline semiconductor layers to form a single crystalline semiconductor layer in the opening.