Keynote: Accelerating the Evolution of NAND Flash Memory with Bonding Technologies
NAND flash memory was invented in 1987 by KIOXIA (formerly known as TOSHIBA Memory) and has been evolving for about four decades. Continuous improvement in bit density has been achieved through 2D and subsequent 3D scaling, overcoming trade-offs in performance. While 3D scaling will continue to drive higher bit density, the transition from a monolithic die to a multi-die approach contributes to improved performance with fewer constraints. CBA (CMOS directly Bonded to Array) technology, introduced in the 8th generation of BiCS FLASH, enhances the flexibility of process optimization and improves the lead time for new products by separating a monolithic die into the CMOS die and the array die, and bonding them through wafer-to-wafer copper direct bonding. Expanding the range of bonding technologies being introduced will help us meet increasing requirements such as higher bandwidth, more functions in memory, and lower power consumption as well as higher bit capacity. Multi die stacking of CMOS dies provides greater flexibility for computing functions in memory. Multi die stacking of array dies accelerates the increase in bit density per unit area. Die-to-wafer(die-to-die) bonding eliminates restrictions on chip sizes that can be bonded, and it allows for the bonding KGD (Known Good Die) after testing. In this talk, we will review process options for bonding technology and discuss potential advantages of multi die bonding in various applications.
Key Technologies Covered
- Advantages of wafer-to-wafer bonding for NAND flash memory
- Advantages of die-to-wafer bonding for NAND flash memory
- Bonding process options for NAND flash memory