Semiconductor device and fabrication method thereof

A semiconductor device fabrication method comprising:

• providing a starting wafer, the starting wafer including a substrate, a sacrificial layer formed over the substrate, and a conductor layer formed over the sacrificial layer;
• patterning the conductor layer to form a trench in the conductor layer, the trench isolating a region of the conductor layer surrounded by the trench from other portions of the conductor layer;
• and
• filling an insulation material in the trench to form an isolator.

A memory system comprising:

• a memory device including:
• a memory cell wafer including:
• a dielectric layer;
• a conductor layer over the dielectric layer;
• one or more through contacts penetrating through the dielectric layer and the conductor layer, each of the one or more through contacts including:
• a column part in the dielectric layer;
• and
• a pad part in the conductor layer;
• and
• an isolator in the conductor layer, the isolator surrounding a region of the conductor layer and at least one of the one or more through contacts in a horizontal direction and extending vertically through the conductor layer to be connected to the dielectric layer, and the region of the conductor layer surrounded by the isolator being isolated from other portions of the conductor layer;
• and
• a memory controller configured to control operation of the memory device.