Magnetic random access memory cells having improved size and shape characteristics
View Patent ↗A manufacturing method to form a memory device includes: (1) forming a dielectric layer adjacent to a magnetic stack; (2) forming an opening in the dielectric layer; (3) applying a hard mask material adjacent to the dielectric layer to form a pillar disposed in the opening of the dielectric layer; and (4) using the pillar as a hard mask, patterning the magnetic stack to form a MRAM cell.
1. A manufacturing method to form a memory device, comprising:
forming a dielectric layer adjacent to a magnetic stack;
forming an opening in the dielectric layer;
forming a first layer adjacent to a sidewall of the opening to reduce a lateral extent of the opening;
applying a hard mask material adjacent to the first layer to form a pillar disposed in the opening of the dielectric layer, wherein the hard mask material is electrically conductive, and the pillar having a lateral boundary that circumscribes the pillar;
removing the first layer to expose the lateral boundary of the pillar; and
using the pillar as a hard mask, and subsequent to removing the first layer, patterning the magnetic stack to form a magnetic random access memory (MRAM) cell such that the lateral boundary of the pillar is substantially aligned with a full extent of a lateral boundary of the MRAM cell that circumscribes the MRAM cell.
2. The manufacturing method of claim 1 , wherein forming the opening in the dielectric layer is carried out such that the opening extends through the dielectric layer.
3. The manufacturing method of claim 1 , wherein:
the first layer includes a spacer; and
forming the spacer is carried out such that the spacer partially fills the opening to reduce the lateral extent of the opening.
4. The manufacturing method of claim 1 , wherein the first layer includes a spacer, and wherein forming the spacer includes:
forming a liner layer adjacent to the dielectric layer and extending into the opening; and
removing a portion of the liner layer, with the spacer remaining and disposed adjacent to the sidewall of the opening.
5. The manufacturing method of claim 1 , wherein the hard mask material is electrically conductive.
6. The manufacturing method of claim 1 , wherein the hard mask material is selected from hard metals and alloys of hard metals.
7. The manufacturing method of claim 6 , wherein the hard mask material includes at least one of tungsten, molybdenum, and titanium.
8. The manufacturing method of claim 1 , wherein applying the hard mask material is carried out such that the pillar substantially fills the opening.
9. The manufacturing method of claim 1 , wherein applying the hard mask material includes:
forming a layer of the hard mask material adjacent to the dielectric layer and extending into the opening; and
removing a portion of the layer of the hard mask material, with the pillar remaining and disposed in the opening.
10. The manufacturing method of claim 9 , wherein removing the portion of the layer of the hard mask material is carried out by chemical mechanical polishing.
11. The manufacturing method of claim 1 , wherein patterning the magnetic stack is carried out by at least one of ion beam etching and reactive ion etching.
12. The manufacturing method of claim 1 , further comprising removing the dielectric layer, with the pillar remaining and disposed adjacent to the magnetic stack, and wherein patterning the magnetic stack is carried out subsequent to removing the dielectric layer.
13. The manufacturing method of claim 12 , wherein the dielectric layer is a first dielectric layer, and further comprising:
subsequent to patterning the magnetic stack, forming a second dielectric layer covering the pillar and the MRAM cell; and
removing a portion of the second dielectric layer.
14. The manufacturing method of claim 13 , wherein removing the portion of the second dielectric layer is carried out by a leveling technique, using the pillar as a stop layer.
15. The manufacturing method of claim 1 , wherein a first lateral dimension defined by the lateral boundary of the pillar is substantially the same as a second lateral dimension defined by the lateral boundary of the MRAM cell.