Semiconductor memory devices and methods of manufacturing thereof

A semiconductor die, comprising:

• an array of semiconductor devices, each row of the array of semiconductor devices extending in a first direction, each semiconductor device comprising:
• a source,
• a drain spaced apart from the source in the first direction,
• a channel layer disposed radially outwards of at least one radially outer surface of the source and the drain in a second direction perpendicular to the first direction, the channel layer extending in the first direction,
• a memory layer disposed on a radially outer surface of the channel layer in the second direction and extending in the first direction,
• at least one gate layer disposed on a radially outer surface of the memory layer in the second direction and extending in the first direction,
• a gate extension structure disposed between the drain and the channel layer such that at least a portion of a gate length of each semiconductor device is defined by each of the gate extension structures, and
• a contact structure wrapped around the drain such that a first portion of the contact structure is interposed between the channel layer and the drain, and a second portion of the contact structure is interposed between the gate extension structure and the drain, the contact structure having a lower resistance than the channel layer.

A method of making a semiconductor device, comprising:

• providing a stack comprising a plurality of insulating layers and a plurality of sacrificial layers alternatively stacked on top of each other, the stack extending in a first direction;
• forming a plurality of gate layers by replacing the plurality of sacrificial layers;
• forming a memory layer extending along the first direction radially inwards of and coupled to the plurality of gate layers in a second direction perpendicular to the first direction;
• forming a channel layer extending along the first direction and coupled to a radially inner surface of the memory layer in the second direction;
• forming a contact structure having a lower resistance than the channel layer;
• and
• forming a source and a drain spaced apart from the source in the first direction, such that the contact structure is interposed between the channel layer and at least a portion of the source and/or the drain.