Memory device and forming method thereof

A memory device, comprising:

• a substrate having a plurality of recess in a surface of the substrate;
• an epitaxially-grown material formed in the plurality of recesses;
• a first layer stack disposed on the substrate, the first layer stack comprising alternating conductor layers and dielectric layers;
• a silicon carbide layer disposed on a top surface of the first layer stack;
• a second layer stack disposed over the silicon carbide layer, the second layer stack comprising alternating conductor layers and dielectric layers;
• one or more first structures extending orthogonally with respect to the surface of the substrate through the first layer stack and over the epitaxially-grown material disposed in the plurality of recesses;
• and
• one or more second structures extending orthogonally with respect to the surface of the substrate through the second layer stack, the one or more second structures being substantially aligned over corresponding ones of the one or more first structures.