Memory device and method of fabricating the same

A memory device, comprising:

• a composite stacked structure, comprising:
• a first stacked structure, comprising a plurality of insulating layers and a plurality of conductive layers stacked alternately, over a first region;
• and
• a second stacked structure, comprising the plurality of insulating layers and a plurality of intermediate layers stacked alternately, over a second region;
• a channel pillar, extending through the first stacked structure;
• a plurality of charge storage units, embedded in the first stacked structure, and between the channel pillar and the plurality of conductive layers;
• a tunneling layer, disposed between the channel pillar and the plurality of charge storage units;
• and
• at least one blocking layer disposed between the plurality of charge storage units and the plurality of conductive layers,
• wherein a thickness of one of the plurality of the charge storage units is greater than a thickness of a corresponding conductive layer.