摘要 |
A NAND flash memory device includes a lower semiconductor layer and an upper semiconductor layer located over the lower semiconductor layer, a first drain region and a first source region located in the lower semiconductor layer, and a second drain region and a second source region located in the upper semiconductor layer. A first gate structure is located on the lower semiconductor layer, and a second gate structure is located on the upper semiconductor layer. A bit line is located over the upper semiconductor layer, and at least one bit line plug is connected between the bit line and the first drain region, where the at least one bit line plug extends through a drain throughhole located in the upper semiconductor layer.
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