Semiconductor device structure and methods of forming the same

A memory device, comprising:

• a layer stack over a substrate, the layer stack comprising alternating layers of a dielectric material and a word line material;
• a ferroelectric layer extending from an upper surface of the layer stack distal to the substrate to a lower surface of the layer stack facing the substrate, the ferroelectric layer being in contact with the alternating layers of the dielectric material and the word line material in the layer stack;
• a channel layer having a first conductivity type, the channel layer extending from the upper surface of the layer stack to the lower surface of the layer stack, and the channel layer being in contact with portions of the ferroelectric layer;
• a source line in contact with the channel layer;
• a bit line in contact with the channel layer;
• and
• a channel region disposed between the source line and the bit line, the channel region comprising:
• a first oxide material in contact with the channel layer;
• and
• a spacer layer disposed on opposite sidewalls of the first oxide material, the spacer layer having a second conductivity type that is opposite to the first conductivity type.

A method for forming a memory device, comprising:

• forming a layer stack over a substrate, the layer stack comprising alternating layers of a dielectric material and an electrical conductive material;
• forming first trenches in the layer stack to expose a top surface of the substrate;
• forming a ferroelectric layer on exposed surfaces of the layer stack;
• forming a channel layer on the ferroelectric layer, the channel layer having a first conductivity type;
• filling the first trenches with a first oxide material;
• forming second trenches in the first oxide material, the second trenches extending through the first oxide material to expose the top surface of the substrate;
• filling the second trenches with a spacer material, the spacer material having a second conductivity that is opposite to the first conductivity type;
• removing portions of the spacer material to form spacers on opposite sides of the first oxide material and third trenches between adjacent spacers;
• filling the third trenches with a sacrificial layer;
• removing portions of the sacrificial layer to form openings in the sacrificial layer;
• filling the openings with a second oxide material;
• and
• replacing the sacrificial layers with an electrically conductive material.