Three-dimensional memory devices and methods for forming the same

A memory system, comprising:

• a three-dimensional (3D) memory device, comprising:
• a first semiconductor structure comprising alternating first dielectric layers and first conductive layers;
• an array common source (ACS) film over the first semiconductor structure;
• a second semiconductor structure over the ACS film, wherein the second semiconductor structure comprises alternating second dielectric layers and second conductive layers;
• and
• a channel structure extending in the first semiconductor structure, the ACS film, and the second semiconductor structure in a first direction, wherein the channel structure is electrically connected to the ACS film;
• and
• a memory controller coupled to the 3D memory device and configured to control operations of the 3D memory device.

A method of forming a three-dimensional (3D) memory device, comprising:

• providing a first substrate, a first semiconductor structure over the first substrate, a sacrificial array common source (ACS) film over the first semiconductor structure, a second semiconductor structure over the sacrificial ACS film, wherein the first semiconductor structure comprises alternating first dielectric layers and first sacrificial layers, and the second semiconductor structure comprises alternating second dielectric layers and second sacrificial layers;
• forming a through channel hole extending through the first semiconductor structure, the sacrificial ACS film, and the second semiconductor structure, and forming a channel structure in the through channel hole;
• and
• forming a gate line slit hole extending through the first semiconductor structure, the sacrificial ACS film, and the second semiconductor structure, replacing the first sacrificial layers with first conductive layers, replacing the second sacrificial layers with second conductive layers, and replacing the sacrificial ACS film with an ACS film.