Programmable resistive memory cell with filament placement structure
View Patent ↗Programmable metallization memory cells having a first metal contact and a second metal contact with an ion conductor solid electrolyte material between the metal contacts. The first metal contact has a filament placement structure thereon extending into the ion conductor material. In some embodiments, the second metal contact also has a filament placement structure thereon extending into the ion conductor material toward the first filament placement structure. The filament placement structure may have a height of at least about 2 nm.
1. A method of forming a programmable metallization memory cell, comprising steps of:
forming a filament placement structure on a first metal contact, wherein forming the filament placement structure comprises removing a portion of a layer;
disposing an ion conductor solid electrolyte material over the first metal contact and filament placement structure; and
disposing a second metal contact over the ion conductor material.
2. The method of claim 1 , wherein forming a filament placement structure on a first metal contact comprises:
depositing a metallic layer;
milling to remove a portion of the metallic layer while retaining a portion of the metallic layer, thus forming the filament placement structure.
3. The method of claim 2 , wherein the milling is done at an angle with respect to the metallic layer.
4. The method of claim 2 further comprising depositing a hardmask layer and a photoresist layer before the metallic layer is deposited.
5. The method of claim 4 , wherein the hardmask layer covers the entire surface of the first metal contact.
6. The method of claim 5 , wherein the photoresist layer is disposed on the hardmask layer and is disposed over only a portion of the first metal contact.
7. The method of claim 6 further comprising removing a portion of the hardmask layer not covered by the photoresist layer.
8. The method of claim 7 , wherein the hardmask layer is used as a shade to retain a portion of the metallic layer and form the filament placement structure.
9. The method of claim 8 further comprising removing the hardmask layer.
10. The method of claim 9 wherein milling comprises static milling.
11. The method of claim 10 , wherein filament placement structure has substantially the same height as the thickness of the hardmask layer.
12. The method of claim 9 wherein milling comprises rotational milling.
13. The method of claim 12 , wherein the filament placement structure has a concave surface.
14. The method of claim 12 , wherein the height of the filament placement structure is less than the thickness of the hardmask layer.
15. A method of forming a programmable metallization memory cell, comprising steps of:
forming a first metal contact supported by an insulator;
depositing a hardmask layer on the surface of the first metal contact;
depositing a photoresist layer on the hardmask layer, wherein the photoresist layer is disposed over only a portion of the first metal contact;
removing a portion of the hardmask layer not covered by the photoresist layer;
depositing a metallic layer on the remaining hardmask layer;
milling at an angle with respect to the hardmask layer to remove a portion of the metallic layer while retaining a portion of the metallic layer, thus forming the filament placement structure;
disposing an ion conductor solid electrolyte material over the first metal contact and filament placement structure; and
disposing a second metal contact over the ion conductor material.
16. A method of forming a plurality programmable metallization memory cells, comprising the steps of:
forming a structure comprising an insulator and a plurality of elongate electrodes embedded in the insulator;
depositing hardmask material over portions of the insulator and elongate electrodes, wherein apertures remain where portions of insulator and electrodes are exposed;
depositing a metallic material layer over the hardmask material and apertures;
removing at least a portion of the metallic material layer, leaving filament placement structures in each corner of the apertures;
removing the remaining hardmask layer;
disposing an ion conductor solid electrolyte material over the first metal contact and filament placement structure; and
forming a plurality of second electrodes over the ion conductor solid electrolyte material.
17. The method of claim 16 , wherein removing at least a portion of the metallic material layer comprises utilizing rotational milling.
18. The method of claim 16 , wherein removing at least a portion of the metallic material layer comprises utilizing isotropic plasma etching.
19. The method of claim 16 , wherein removing the remaining hardmask layer comprises chemical etching or plasma etching.