Three dimensional NAND flash with self-aligned select gate
An integrated circuit may include a pillar of semiconductor material, a field effect transistor having a channel that is formed in the pillar of semiconductor material, and two or more memory cells, stacked vertically on top of the field effect transistor, and having channels that are formed in the pillar semiconductor of material.
1. A memory structure, comprising:
a conductive source layer of doped material in a substrate;
an insulating layer over the conductive source layer;
a select gate over the insulating layer;
a stack of cells over the select gate; and
a conductive channel to provide an electrical contact from the conductive source layer to the stack of cells, the channel including a first portion to extend through the stack of cells, and a second portion to extend through the select gate and the insulating layer to the conductive source layer, the second portion aligned with the first portion, the channel also include a polysilicon layer on a wall of the channel extending from the stack of cells to the conductive source layer, the polysilicon deposited separately from a material to fill the channel.
2. The memory structure of claim 1 , wherein the insulating layer over the conductive source layer comprises a layer of oxide material.
3. The memory structure of claim 1 , wherein the insulating layer comprises a first insulating layer, and further comprising:
a second insulating layer between the select gate and the stack of cells.
4. The memory structure of claim 1 , wherein the select gate over the insulating layer comprises a select gate source layer.
5. The memory structure of claim 4 , wherein the select gate source layer comprises a conductor, and further comprising:
a gate dielectric between the channel and the conductor of the select gate source layer.
6. The memory structure of claim 1 , wherein the stack of cells comprises one of multiple stacks of memory cells.
7. The memory structure of claim 6 , wherein the stack of cells comprises alternating layers of oxide and charge storage material.
8. The memory structure of claim 6 , wherein the stack of cells comprises charge trap flash (CTF) memory cells.
9. The memory structure of claim 6 , wherein the stack of cells comprises floating gate memory cells.
10. The memory structure of claim 6 , wherein the stack of cells comprises vertical NAND strings.
11. The memory structure of claim 1 , wherein the 3D memory structure comprises a three-dimensional memory structure that is part of a solid state drive (SSD).
12. The memory structure of claim 1 , wherein the 3D memory structure comprises a three-dimensional memory structure that is part of a thumb drive.
13. The memory structure of claim 1 , further comprising:
a bitline coupled to the channel above the stack of cells.
14. The memory structure of claim 1 , wherein the select gate comprises a control gate between a select gate conductor and the channel, wherein the stack of cells comprises control gates between the cells and the channel, and wherein the control gate of the select gate is aligned with the control gates of the stack of cells.
15. A system comprising:
a processor; and
a memory device coupled to the processor, the memory device having a memory structure including:
a conductive source layer of doped material in a substrate;
an insulating layer over the conductive source layer;
a select gate over the insulating layer;
a stack of cells over the select gate, the stack of cells including NAND memory cells; and
a conductive channel to provide an electrical contact from the conductive source layer to the stack of cells, the channel including a first portion to extend through the stack of cells, and a second portion to extend through the select gate and the insulating layer to the conductive source layer, the second portion aligned with the first portion, the conductive channel also include a polysilicon layer on a wall of the channel extending from the stack of cells to the conductive source layer, the polysilicon deposited separately from a material to fill the channel.
16. The system of claim 15 , wherein the insulating layer over the conductive source layer comprises a layer of oxide material.
17. The system of claim 15 , wherein the insulating layer comprises a first insulating layer, and further comprising:
a second insulating layer between the select gate and the stack of cells.
18. The system of claim 15 , wherein the select gate over the insulating layer comprises a select gate source layer.
19. The system of claim 18 , wherein the select gate source layer comprises a conductor, and further comprising:
a gate dielectric between the channel and the conductor of the select gate source layer.
20. The system of claim 15 , wherein the stack of cells comprises alternating layers of oxide and charge storage material.
21. The system of claim 15 , wherein the stack of cells comprises charge trap flash (CTF) memory cells.
22. The system of claim 15 , wherein the stack of cells comprises floating gate memory cells.
23. The system of claim 15 , wherein the memory structure comprises part of a solid state drive (SSD).
24. The system of claim 15 , wherein the memory structure comprises part of a thumb drive.
25. The system of claim 15 , wherein the memory structure further comprises:
a bitline coupled to the channel above the stack of cells.
26. The system of claim 15 , wherein the select gate comprises a control gate between a select gate conductor and the channel, wherein the stack of cells comprises control gates between the cells and the channel, and wherein the control gate of the select gate is aligned with the control gates of the stack of cells.
27. The system of claim 15 , further comprising:
a video graphics controller to drive a display based on operations executed by the processor.