Samsung Stacks Two 450-Layer NAND Chips Into a 900-Layer V-NAND

Samsung is steadily working towards its goal of creating 1000-layer NAND Flash storage modules. However, as manufacturing complexities increase, the company cannot achieve this with a single chip. Instead, it is turning to advanced packaging solutions to stack two 450-layer V-NAND modules into a single 900-layer V-NAND chip. According to ET News, which first reported this manufacturing achievement, Samsung is using Cell Multi-Bonding (CMB) technology, a variant of wafer stacking achieved through hybrid bonding. This process forms a permanent bond between two silicon chips using embedded metal bumps that are fused together to create a single chip. Multiple dies, or in Samsung's case, multiple whole silicon wafers, can be connected by stacking two chip back ends together. Samsung's proprietary process, called CMB, paves the way for 1000-layer V-NAND chips by 2030.

Early last year, Samsung unveiled its 10th-generation V-NAND technology, enabling over 400 layers on a single module. The company also introduced hybrid bonding for the first time, indicating that the technology has since been refined. Interestingly, wafer bonding on already thick 450-layer designs is challenging due to wafer warping. Thankfully, Samsung developed microscopic chucks to address this, along with new bonding techniques to correct overlay issues and misalignment errors when wafers are bonded together. Within the NAND itself, Samsung created new bitline and wordline structures to help manage power consumption and maintain reasonable individual chip sizes.