Memory device structure and fabrication method

A memory system, comprising:

• a 3D memory device, including a complementary metal-oxide-semiconductor (CMOS) structure having a page buffer region and a string driver region respectively corresponding to a cell region and a string region in an array structure, a plurality of page buffers in a folded structure formed in the page buffer region;
• and string driver circuits formed in the string region;
• a memory controller coupled to the 3D memory device for controlling the 3D memory device;
• and
• an external interface for communicating with a host for storing information in the 3D memory device.

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

• forming an array wafer having a cell region and a string region, including:
• providing a first substrate having the cell region and the string region;
• forming a plurality of memory cells on the first substrate in the cell region;
• and forming a string structure on the first substrate in the string region;
• forming a complementary metal-oxide-semiconductor (CMOS) wafer having a page buffer region and a string driver region respectively corresponding to the cell region and the string region, including:
• providing a second substrate having the page buffer region and the string driver region;
• forming a plurality of page buffers in a folded structure in the page buffer region;
• and forming string driver circuits in the string region;
• bonding the array wafer and the CMOS wafer at a bonding interface;
• and
• forming the 3D memory device based on the bonded array wafer and CMOS wafer.