Oxygen-free plasma etching for contact etching of resistive random access memory
A resistive random access memory (RERAM) apparatus and method for forming the apparatus are provided. Oxygen content control in the RERAM is provided. To provide oxygen content control, a via to an electrode of the RERAM is formed utilizing an oxygen-free plasma etch step. In one embodiment, the dielectric within which the via is formed is silicon nitride (SiN). In exemplary embodiments, the plasma chemistry is a hydrofluorocarbon (C x H y F z )-based plasma chemistry or a fluorocarbon (C x F y )-based plasma chemistry. In one embodiment, the resistive layer of the RERAM is a metal oxide. In another embodiment, the oxygen concentrations in the electrode of the RERAM under the via and outside the via are the same after formation of the via.
1. A method of forming a resistive random access memory (RERAM), comprising:
providing a first RERAM electrode layer;
providing a RERAM resistive dielectric layer;
providing a second RERAM electrode layer, wherein the RERAM resistive dielectric layer is between the first RERAM electrode layer and the second RERAM electrode layer;
providing a first dielectric layer overlying the second RERAM electrode layer;
utilizing an oxygen-free plasma etch to etch at least a portion of the first dielectric layer so as to expose a portion of the second RERAM electrode as part of a process to form a via in the first dielectric layer so as to provide a region for making electrical contact to the second RERAM electrode; and
filling the via with a via conductor that extends from the second RERAM electrode layer to a top of the via, the via conductor having (i) a bottom surface that is in direct contact with the second RERAM electrode and (ii) a top surface that is in direct contact with a metal layer at the top of the via,
wherein utilizing the oxygen-free plasma etch controls oxygen vacancies in the RERAM.
2. The method of claim 1 , wherein the RERAM resistive dielectric layer comprises a metal oxide selected from a group of hafnium oxide (HfO), tantalum oxide (TaOx), aluminum oxide (AlOx), zirconium oxide (ZrOx) or titanium oxide (TiOx) and their mixtures.
3. The method of claim 1 , the first dielectric layer comprising silicon nitride.
4. The method of claim 3 , the RERAM resistive dielectric layer comprising hafnium oxide (HfO), tantalum oxide (TaOx), aluminum oxide (AlOx), zirconium oxide (ZrOx) or titanium oxide (TiOx) and their mixtures.
5. The method of claim 4 , the oxygen-free plasma etch being a hydrofluorocarbon or fluorocarbon-based plasma etch.
6. The method of claim 5 , the oxygen-free plasma etch being a hydrofluorocarbon-based plasma etch.
7. The method of claim 6 , the hydrofluorocarbon comprising C 4 H 9 F.
8. The method of claim 1 , the oxygen-free plasma etch being a hydrofluorocarbon or fluorocarbon-based plasma etch.
9. The method of claim 8 , the oxygen-free plasma etch being a hydrofluorocarbon-based plasma etch.
10. The method of claim 9 , the hydrofluorocarbon comprising C 4 H 9 F.
11. A method of forming a resistive random access memory (RERAM), comprising:
providing a first RERAM electrode layer;
providing a RERAM resistive dielectric layer;
providing a second RERAM electrode layer, wherein the RERAM resistive dielectric layer is between the first RERAM electrode layer and the second RERAM electrode layer;
encapsulating at least a portion of the first RERAM electrode layer, the second RERAM electrode layer and the RERAM resistive dielectric layer with a first dielectric;
etching a via through the first dielectric so as to expose a first portion of the second RERAM electrode layer, the etching performed in a manner so that the first portion of the second RERAM electrode layer is subjected to an oxygen-free plasma etch, the oxygen-free plasma etch being a hydrofluorocarbon or fluorocarbon-based plasma etch, and
filling the via with a via conductor that extends from the second RERAM electrode layer to a top of the via, the via conductor having (i) a bottom surface that is in direct contact with the second RERAM electrode and (ii) a top surface that is in direct contact with a metal layer at the top of the via.
12. The method of claim 11 , the first dielectric comprising a silicon nitride.
13. The method of claim 12 , the oxygen-free plasma etch being a hydrofluorocarbon-based plasma etch.
14. The method of claim 13 , the hydrofluorocarbon comprising C 4 H 9 F.
15. A method of forming a resistive random access memory (RERAM), comprising:
providing a first RERAM electrode layer;
providing a RERAM resistive dielectric layer;
providing a second RERAM electrode layer, wherein the RERAM resistive dielectric layer is between the first RERAM electrode layer and the second RERAM electrode layer;
encapsulating at least a portion of the first RERAM electrode layer, the second RERAM electrode layer and the RERAM resistive dielectric layer with a first dielectric; and
etching a via through the first dielectric so as to expose a first portion of the second RERAM electrode layer, the etching performed in a manner so that the first portion of the second RERAM electrode layer is subjected to an oxygen-free plasma etch, the oxygen-free plasma etch being a hydrofluorocarbon or fluorocarbon-based plasma etch,
wherein a first oxygen concentration in the first portion of the second RERAM electrode layer is the same as a second oxygen concentration in second portions of the second RERAM electrode layer, the second portions of the second RERAM electrode layer not being exposed to the oxygen-free plasma etch.
16. The method of claim 15 , wherein the RERAM resistive dielectric layer comprises hafnium oxide (HfO).
17. The method of claim 1 , wherein the first RERAM electrode layer and the second RERAM electrode layer are formed of a same material.
18. The method of claim 1 , wherein the second RERAM electrode layer is in direct contact with the RERAM resistive dielectric layer.
19. The method of claim 11 , wherein the first RERAM electrode layer and the second RERAM electrode layer are formed of a same material.
20. The method of claim 11 , wherein the second RERAM electrode layer is in direct contact with the RERAM resistive dielectric layer.