Source structure of three-dimensional memory device and method for forming the same

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

• forming an alternating conductor/dielectric stack on a first substrate;
• forming a plurality of memory strings extending vertically through the alternating conductor/dielectric stack, so that a first end of each of the plurality of memory strings is in contact with a first surface of the first substrate;
• removing the first substrate;
• and
• forming a source conductor layer, so that the first end of each of the plurality of memory strings is in physical contact with a first surface of the source conductor layer.

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

• forming an alternating conductor/dielectric stack on a first substrate;
• forming, on a first side of the first substrate, a plurality of memory strings extending vertically through the alternating conductor/dielectric stack;
• thinning the first substrate from a second side of the first substrate;
• forming, on the second side of the thinned first substrate, a metal layer;
• and
• causing a reaction between at least part of the metal layer and the thinned first substrate to form a source conductor layer in the thinned first substrate.