Monolithic 3D NAND Flash Memories

3d ic

Technology

Monolithic 3D IC technology is applied to producing a monolithically stacked single crystal silicon double-gated NAND flash memory. Lithography steps are shared among multiple memory layers to reduce bit cost. Peripheral circuits below the monolithic memory stack provide control functions.

Reduce NAND flash bit cost without investing in expensive scaling down.

Benefits

  • 4X the density of conventional NAND flash
  • Similar number of litho steps as conventional NAND flash
  • Single crystal silicon on all layers obtained with ion-cut
  • Scalable: Multiple generations of cost-per-bit improvement for same equipment cost and process node: use the same fab for 3 generations
  • Forestalls next gen litho-tool risk
  • Uses manufacturable aspect ratios

Process Flow

Our 3D flash technology innovatively combines these well-studied technologies:
  • Monolithic 3D with litho steps shared among multiple memory layers
  • Stacked Single crystal Si with ion-cut

3d ic

For more details, please see

[1] Our blog post titled "Looking beyond lithography", April 2011.
[2] Our blog-post on cost of ion-cut, July 2011.