Tiered 3D NAND Source Region Layout for Taller Word Line Stacks

The channel structure is segmented into multiple independent vertical channels, each with its own source region and drain region. This segmentation allows each channel to maintain a manageable vertical height while collectively providing high storage capacity through parallel architecture. The channel height is controlled by the distance between source and drain regions, preventing excessive resistance in any single channel.

The patent transitions from a single vertical channel architecture to a three-dimensional array of stacked tiers with alternating conductive and insulating layers. By adding horizontal dimensions (multiple pillars per tier, multiple tiers stacked), the design achieves high storage capacity without increasing the vertical channel height, thus maintaining low electrical resistance while scaling capacity.

Multiple pillars are merged into a single tier structure, with each pillar representing an independent memory string. This merging allows the device to achieve high storage capacity through parallel processing of multiple channels simultaneously, rather than requiring a single tall channel. The source region serves as a common connection point for multiple pillars, enabling scalable capacity without increasing individual channel resistance.

The source region and drain region serve universal functions across multiple pillars and tiers. A single source region can serve as the starting point for multiple independent memory strings, and control gates can control multiple memory cells across different tiers. This multi-functionality allows the same structural elements to support increased capacity without proportionally increasing channel height or resistance.

The patent employs periodic alternating layers of conductive material and insulating material to form the tiered stack structure. This periodic arrangement creates a regular, repeating pattern that simplifies fabrication processes and structural design. Control gates are systematically positioned at regular intervals through the stack, allowing for predictable electrical characteristics and simplified control logic, thereby increasing memory density without proportionally increasing complexity.

The invention changes the physical parameters of the channel structures by controlling the vertical distance between source and drain regions and the dimensions of pillars. By optimizing these geometric parameters, the patent achieves high memory density within constrained vertical dimensions, balancing capacity improvement with manageable structural complexity through precise dimensional control rather than arbitrary structural additions.