Planar resistive random-access memory (RRAM) device with a shared top electrode
Embodiments of the present invention are directed to forming a planar Resistive Random Access Memory (RRAM) device with a shared top electrode. In a non-limiting embodiment of the invention, a first trench having a first width and a second trench having a second width less than the first width are formed in a dielectric layer. A bottom liner is formed on sidewalls of the first trench. The bottom liner pinches off the second trench. A top liner is formed on sidewalls of the bottom liner in the first trench. The top liner is formed such that a portion of the bottom liner at a bottommost region of the first trench remains exposed. The exposed portion of the bottom liner is removed, and a memory cell material is formed in the first trench.
1. A method for forming a semiconductor device, the method comprising:
forming a first trench having a first width and a second trench having a second width less than the first width in a dielectric layer;
forming a bottom liner on sidewalls of the first trench, the bottom liner pinching off the second trench;
forming a top liner on sidewalls of the bottom liner in the first trench, the top liner formed such that a portion of the bottom liner at a bottommost region of the first trench remains exposed;
removing the exposed portion of the bottom liner; and
forming a memory cell material in the first trench.
2. The method of claim 1 , wherein the top liner does not fill the second trench due to pinch off.
3. The method of claim 2 , wherein an air gap is formed between the top liner and the bottom liner in the second trench.
4. The method of claim 1 , wherein the first width is more than 10 nm and the second width is less than 10 nm.
5. The method of claim 1 , wherein removing the exposed portion of the bottom liner comprises etching the bottom liner selectively to the top liner.
6. The method of claim 5 , wherein the top liner comprises a conductive material having etch selectivity with respect to a wet etch chemistry used to remove the exposed portion of the bottom liner.
7. The method of claim 6 , wherein the bottom liner comprises TiN and the top liner comprises TaN or Ru.
8. The method of claim 6 , wherein the bottom liner comprises TaN and the top liner comprises TiN or Ru.
9. The method of claim 1 , wherein the memory cell material comprises one or more of CuO x , NiO x , CoO x , ZnO x , CrO x , TiO x , HfO x , ZrO, FeO x and NbO x .
10. The method of claim 1 , further comprising forming a bottom electrode contact electrically coupled to a pinched off portion of the bottom liner.
11. The method of claim 10 , further comprising forming a shared top electrode contact electrically coupled to the top liner.
12. The method of claim 1 , wherein forming the bottom liner comprises conformally depositing the bottom liner on the sidewalls of the first trench.
13. The method of claim 11 , wherein forming the top liner comprises non-conformally depositing the top liner on the bottom liner.
14. The method of claim 1 , further comprising forming one or more isolation trenches in a direction orthogonal to the first trench and the second trench to define one or more Resistive Random Access Memory (RRAM) cells.