Semiconductor devices

A semiconductor device, comprising:

• a first stacked layer;
• an insulating layer disposed over the first stacked layer;
• a second stacked layer disposed over the insulating layer;
• and
• a channel structure extending through the second stacked layer, the insulating layer and the first stacked layer;
• and
• a filling structure extending through the insulating layer, wherein a portion of the channel structure is in contact with a topmost surface of the filling structure,
• wherein a size of a portion of the channel structure located in the insulating layer in a first direction is larger than a size of a portion of the channel structure located in the first stacked layer in the first direction;
• and
• the first direction is perpendicular to a stacking direction of the first stacked layer.

A semiconductor device, comprising:

• a first stacked layer;
• an insulating layer disposed over the first stacked layer;
• a second stacked layer disposed over the insulating layer;
• a channel structure extending through the second stacked layer, the insulating layer and the first stacked layer, wherein a size of a portion of the channel structure located in the insulating layer in a first direction is larger than a size of a portion of the channel structure located in the first stacked layer in the first direction, the first direction is perpendicular to a stacking direction of the first stacked layer, the channel structure is continuous;
• and
• a first filling structure in contact with an inner surface of the portion of the channel structure located in the first stacked layer;
• and
• a second filling structure in contact with the first filling structure and an inner surface of a portion of the channel structure located in the second stacked layer.