U-Shaped Channel 3D Non-Volatile Memory Device Fabrication

The fabrication process is divided into two main stages: first forming select transistors in trenches, then forming memory cells in subsequent trenches. This segmentation allows each stage to be optimized independently, reducing overall process complexity while enabling high memory cell density through vertical stacking.

The invention transitions from two-dimensional planar memory cells to three-dimensional vertically stacked memory cells. By stacking multiple memory cells vertically along the same footprint area, the memory cell density is dramatically increased without proportionally increasing the fabrication process complexity, as the same trench formation and filling techniques are applied in the vertical dimension.

The invention merges the formation of select transistors and memory cells into a unified fabrication sequence where both structures are created using the same trench formation and material deposition techniques. This merging reduces the number of unique process steps required, simplifying manufacturing while maintaining the necessary device structure for reliable operation.

The fabrication process employs universal techniques for both select transistor and memory cell formation, including trench etching, gate electrode deposition, and interlayer dielectric formation. These multi-functional process steps can be applied repeatedly to create different device structures, reducing the need for specialized processes and lowering production costs.