Use of Ta-capped metal line to improve formation of memory element films
View Patent ↗Disclosed are methods for deposition of improved memory element films for semiconductor devices. The methods involve providing a hard mask over an upper surface of a metal line of a semiconductor substrate where vias are to be placed, recess etching the mask substantially in all upper surfaces except where vias are to be placed, depositing a Ta-containing capping layer over substantially all the metal line surfaces except the surface where vias are to be placed, polishing the Ta-containing capping layer to produce a damascened Ta-containing cap while exposing the metal line at the via forming surface, depositing a dielectric layer, patterning the dielectric layer to form a via to expose a portion of the metal line, and depositing memory element films. The improved Ta—Cu interface of the subject invention mitigates and/or eliminates lateral growth of memory element films and copper voiding under the dielectric layer at the top surface of the metal line, and thereby enhances reliability and performance of semiconductor devices.
1. A method for improving deposition of memory element films in a semiconductor device comprising:
providing a hard mask on an upper surface of a metal line upon which vias are to be placed;
etching substantially all upper surfaces of the metal line except the upper surface of the metal line covered by the hard mask;
depositing a Ta-containing capping layer material over substantially all upper surfaces of the metal line including the upper surface of the metal line covered by the hard mask;
polishing the Ta-containing capping layer and the hard mask to produce a damascene Ta-containing cap while exposing a first portion of the metal line;
depositing a dielectric material over the exposed first portion of the metal line and the damascened cap;
patterning the dielectric layer to form a via to expose the first portion of the metal line; and
depositing the memory element films in the via.
2. The method of claim 1 , wherein the metal line comprises copper.
3. The method of claim 1 , wherein the etching comprises a copper recess etch.
4. The method of claim 1 , wherein the Ta-containing capping layer comprises tantalum.
5. The method of claim 1 , wherein the Ta-containing capping layer comprises at least one selected from the group consisting of alpha tantalum, beta tantalum, alpha-beta tantalum, compounds of tantalum, and alloys of tantalum.
6. The method of claim 1 , wherein the Ta-containing capping layer has a thickness from about 5 Å to about 500 Å.
7. The method of claim 1 , wherein the Ta-containing cap has a thickness from about 1 Å to about 200 Å.
8. The method claim 1 , wherein the polishing comprises chemical mechanical polishing.
9. The method of claim 1 , further comprising forming a top electrode over the memory element films and patterning the top electrode to form the semiconductor device.
10. The method of claim 1 , wherein the memory element films comprise a passive layer and an active layer.
11. The method of claim 10 , wherein the passive layer comprises copper sulfide.
12. The method of claim 10 , wherein the active layer comprises at least one of an organic semiconducting material and an inorganic semiconducting material.
13. The method of claim 12 , wherein the organic semiconducting material comprises a semiconducting polymer.
14. The method of claim 10 , further comprising forming a thin conductive metal barrier layer over the memory element films.
15. The method of claim 1 , wherein the Ta-containing capping layer comprises tantalum sulfide.
16. The method of claim 1 , wherein the Ta-containing capping layer comprises tantalum nitride.
17. The method of claim 1 , wherein the Ta-containing capping layer comprises tantalum and tungsten.
18. The method of claim 1 , wherein the Ta-containing capping layer comprises tantalum and titanium.
19. The method of claim 10 , wherein the active layer comprises a conjugated organic polymer.
20. The method of claim 1 O, wherein the active layer comprises at least one of polyacetylene and polydiphenylacetylene.
21. The method of claim 10 , wherein the active layer comprises at least one of polyaniline and poly thiophene.
22. The method of claim 10 , wherein the active layer comprises at least one of polypyrrole and polypyridine.