Methods and apparatus for forming memory lines and vias in three dimensional memory arrays using dual damascene process and imprint lithography
View Patent ↗The present invention provides systems, apparatus, and methods for forming three dimensional memory arrays using a multi-depth imprint lithography mask and a damascene process. An imprint lithography mask for manufacturing a memory layer in a three dimensional memory is described. The mask includes a translucent material formed with features for making an imprint in a transfer material to be used in a damascene process, the mask having a plurality of imprint depths. At least one imprint depth corresponds to trenches for forming memory lines and at least one depth corresponds to holes for forming vias. Numerous other aspects are disclosed.
1. A method of forming a memory layer in a three-dimensional memory array, the method comprising:
forming a template having a plurality of depths, wherein at least one depth corresponds to a first memory line and wherein at least one depth corresponds to a via;
imprinting the template into a transfer material layer formed on a hard mask material layer which is formed on a dielectric layer which is formed on a wire layer;
curing the imprinted transfer material; and
simultaneously etching the cured and imprinted transfer material and the dielectric layer to form a memory layer using the imprinted and cured transfer material,
wherein imprinting the template into the transfer material layer includes imprinting the template into the transfer material layer such that at least one imprint depth reaches the hardmask layer.
2. The method of claim 1 wherein forming the template includes forming the template from at least one of quartz and fused silica.
3. The method of claim 1 wherein forming the template includes forming a template including a plurality of rails corresponding to trenches for a plurality of memory lines.
4. The method of claim 1 wherein forming the template includes forming a template including a plurality of pillars corresponding to holes for a plurality of vias.
5. The method of claim 1 wherein forming the template includes forming a template including a plurality of pillars corresponding to holes for a plurality of vias and a plurality of rails corresponding to trenches for a plurality of memory lines.
6. The method of claim 5 wherein forming the template includes forming the pillars on the rails.
7. The method of claim 6 wherein forming the pillars on the rails includes forming a pillar on an alternate opposite end of each adjacent rail.
8. The method of claim 7 wherein forming the pillars on the rails includes forming pillars on rails having a combined height greater than a height of the rails alone.
9. The method of claim 1 wherein forming the template includes forming a template including a plurality of landings corresponding to contact pads.
10. The method of claim 1 wherein forming the template includes forming a template including a plurality of pillars corresponding to holes for vias, a plurality of rails corresponding to trenches for memory lines, and a plurality of landings corresponding to contact pads.
11. The method of claim 10 wherein forming the template includes forming a landing at an alternate opposite end of each adjacent rail.
12. The method of claim 11 wherein forming the template includes forming the pillars on the landings.
13. The method of claim 1 wherein forming the template includes forming a template including a plurality of pillars wherein at least some of the pillars include at least one shoulder.
14. The method of claim 13 wherein forming a template including a plurality of pillars includes forming pillars with shoulders disposed at a depth to contact a second memory line.
15. The method of claim 1 wherein imprinting the template into a transfer material includes imprinting the template into a transfer material that includes resist.
16. The method of claim 1 wherein imprinting the template into a transfer material includes imprinting the template to form a pattern of trenches and holes in the transfer material.
17. The method of claim 1 , wherein forming a memory layer using the imprinted and cured transfer material includes etching the area of hardmask layer reached by the template.
18. The method of claim 17 wherein forming a memory layer using the imprinted and cured transfer material includes etching the dielectric area below the etched area of the hardmask layer to form at least one via hole.
19. The method of claim 1 wherein forming a memory layer using the imprinted and cured transfer material includes etching the transfer material down to the hardmask layer.
20. The method of claim 19 wherein forming a memory layer using the imprinted and cured transfer material includes etching away the hardmask layer previously exposed by etching the transfer material down to the hardmask layer.
21. The method of claim 20 wherein forming a memory layer using the imprinted and cured transfer material includes partially etching the dielectric layer previously exposed by etching away the hardmask layer which was previously exposed by etching the transfer material down to the hardmask layer, wherein the partial etch of the dielectric layer forms at least one trench for a memory line in the dielectric layer.