Manufacturing methods of three-dimensional vertical memory
A manufacturing method of a three-dimensional vertical memory (3D-M V ) includes the steps of: (A) forming a stack of interleaved lightly-doped layers and insulating layers; and, (B) a first photolithography step and an ion-implant step to form first and second regions in each lightly-doped layer. The first region, disposed around and shared by a plurality of memory holes, has a higher resistivity than the second region.
1. A manufacturing method of a three-dimensional vertical memory (3D-M V ), including the steps of:
1) forming a substrate circuit on a semiconductor substrate;
2) forming a stack of interleaved lightly-doped layers and insulating layers;
3) performing a first photolithography step and an ion-implant step to form first and second regions in each of said lightly-doped layers, wherein said first region has a higher resistivity than said second region;
4) performing a second photolithography step and an etch step to form horizontal address lines;
5) performing a third photolithography step and another etch step to form memory holes penetrating through said stack;
6) forming programmable layers covering the sidewalls of said memory holes;
7) forming vertical address lines in contact with said programmable layers in said memory holes.
2. The method according to claim 1 , wherein said first region receives no dopant during said ion-implant step; and, said second region receives dopants during said ion-implant step.
3. The method according to claim 1 , wherein said first region is in contact with and surrounding at least one of said memory holes.
4. The method according to claim 1 , wherein said first region is in contact with and surrounding at least three adjacent ones of said memory holes.
5. The method according to claim 4 , wherein the intersections of said three adjacent ones of said memory holes and said each of said horizontal address lines are neither disposed on a single straight line nor separated by said second region.
6. The method according to claim 1 , wherein the total area of said first region is larger than said second region.
7. The method according to claim 1 , wherein a plurality of memory cells formed at the intersections of said horizontal address lines and said vertical address lines, with the areal density of said memory cells in said first region larger than said second region.
8. The method according to claim 1 , wherein:
said second region comprises at least a heavily-doped semiconductor material; and,
said vertical address lines comprise at least a metallic material or another heavily-doped semiconductor material with polarity opposite to said heavily-doped semiconductor material.
9. The method according to claim 1 , wherein:
said second region comprises at least a metallic material; and,
said vertical address lines comprise at least a heavily-doped semiconductor material.
10. The method according to claim 1 , wherein said programmable layer is one-time programmable, multiple-time programmable, or re-programmable.
11. The method according to claim 1 , wherein first selected ones of said memory holes penetrate through said first region; and, second selected ones of said memory holes penetrate through said second region.
12. The method according to claim 11 , wherein a plurality of low-leakage memory cells are formed at the intersections between said first selected ones of said memory holes and said first region; and, another plurality of high-leakage memory cells are formed at the intersections between said second selected ones of said memory holes and said second region.
13. The method according to claim 11 , wherein the intersections of said first selected ones of said memory holes and said each of said horizontal address lines constitute at least two rows and at least two columns.
14. The method according to claim 11 , wherein the shape of said first region is rectangular or hexagonal.
15. The method according to claim 11 , wherein third selected ones of said memory holes are in contact with both of said first and second regions.
16. The method according to claim 1 , wherein said memory holes penetrate through said first region; and, none of said memory holes penetrate through said second region.
17. The method according to claim 16 , wherein the intersections of said memory holes and said each of said horizontal address lines constitute at least two rows and at least two columns.
18. The method according to claim 16 , wherein the shape of said first region is rectangular or hexagonal.
19. The method according to claim 16 , wherein the total area of said first region is larger than said second region.
20. The method according to claim 16 , wherein a plurality of memory cells formed at the intersections of said horizontal address lines and said vertical address lines, with the areal density of said memory cells in said first region larger than said second region.