Three-Dimensional Memory Device and Method

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

• forming a layer stack over a substrate, the layer stack comprising layers of a first conductive material interleaved with layers of a first dielectric material;
• forming a trench through the layer stack;
• conformally forming a memory film in the trench;
• conformally forming a channel material in the trench over the memory film, the channel material comprising an amorphous material;
• filling the trench with a second dielectric material after conformally forming the channel material;
• forming source lines (SLs) and bit lines (BLs) in the second dielectric material, the SLs and the BLs extending through the layer stack along a vertical direction perpendicular to a major upper surface of the substrate;
• and
• after forming the SLs and BLs, converting first portions of the channel material into a crystalline material by performing a thermal process.

A memory device comprising:

• a layer stack over a substrate, the layer stack comprising alternating layers of word lines and a first dielectric material;
• a second dielectric material embedded in the layer stack and extending vertically in the layer stack along a direction perpendicular to a major upper surface of the substrate;
• source lines (SLs) and bit lines (BLs) in the second dielectric material and extending vertically through the layer stack;
• a memory film between the layer stack and the second dielectric material;
• and
• a channel layer comprising a channel material, wherein first portions of the channel layer are disposed between the memory film and the SLs or between the memory film and BLs, wherein second portions of the channel layer are disposed between the memory film and the second dielectric material, wherein the first portions of the channel layer comprises a crystalline material of the channel material, and the second portions of the channel layer comprises an amorphous material of the channel material.