Electrode for a metal-insulator-metal structure, capacitor of metal-insulator-metal type, and method for fabricating one such electrode and one such capacitor
The electrode for a structure of Metal-Insulator-Metal type is formed by a stack successively comprising a gold layer, a barrier layer made from electrically conducting oxide and a platinum layer. The electrically conducting oxide is advantageously a noble metal oxide, and preferentially ruthenium oxide. The electrode is arranged on a substrate. The gold layer of the electrode is separated from the substrate by an adhesion layer made from titanium dioxide. The electrode is used to fabricate a capacitor of Metal-Insulator-Metal type.
1. Electrode for a structure of Metal-Insulator-Metal type formed on a substrate by a stack successively comprising, from the substrate, an adhesion layer comprising a layer made from TiO 2 , a gold layer in direct contact with the adhesion layer, a barrier layer made from electrically conducting oxide in direct contact with the gold layer, and a platinum layer in direct contact with the barrier layer.
2. Electrode according to claim 1 , wherein the barrier layer is made from RuO 2 .
3. Electrode according to claim 2 , wherein the barrier layer has a thickness greater than or equal to 15 nm.
4. Electrode according to claim 3 , wherein the barrier layer has a thickness greater than or equal to 80 nm.
5. Electrode according to claim 1 , wherein the adhesion layer is a TiO 2 /metal bilayer, the metal being chosen from titanium, chromium, or tantalum, and the gold layer is in direct contact with the layer made from TiO 2 .
6. Electrode according to claim 1 , wherein the platinum layer has a thickness of about 100 nm and the gold layer has a thickness ranging from 1 μm to 2 μm.
7. Method for fabricating the electrode according to claim 1 , comprising successively:
providing a substrate covered by an adhesion layer made from titanium dioxide,
forming an electrode on the adhesion layer, the electrode being formed by successive depositions of a gold layer, a barrier layer made from electrically conducting oxide and a platinum layer, the electrically conducting oxide being a noble metal oxide.
8. Method for fabricating a capacitor comprising successively:
fabricating an electrode according to claim 1 as a first electrode,
forming a layer of perovskite type dielectric material on the platinum layer of the first electrode,
performing heat treatment at a temperature greater than or equal to 700° C. under oxygen so as to crystallize the dielectric material,
forming a second electrode on the crystallized dielectric material layer.
9. Method according to claim 8 , wherein the heat treatment temperature is greater than or equal to 850° C.
10. Electrode according to claim 5 , wherein the adhesion layer is a TiO 2 /titanium bilayer.
11. Electrode according to claim 1 , wherein the gold layer has a thickness ranging from 1 μm to 2 μm.
12. Method according to claim 7 , wherein the layer made of TiO 2 is formed by oxidation of the layer made of Ti metal.
13. Electrode according to claim 1 , wherein the adhesion layer completely separates the gold layer and the substrate.
14. Electrode according to claim 1 , wherein the layer made of TiO 2 completely separates the Ti metal layer and the gold layer.
15. Capacitor of Metal-Insulator-Metal type comprising:
a first electrode formed by a stack successively comprising a gold layer in direct contact with the adhesion layer, a barrier layer made from electrically conducting oxide in direct contact with the gold layer, and a platinum layer in direct contact with the barrier layer, the electrically conducting oxide being a noble metal oxide,
a second electrode,
a layer of perovskite type dielectric material arranged between the first electrode and the second electrode.
16. Capacitor according to claim 15 , wherein the barrier layer is made from RuO 2 with a thickness greater than or equal to 15 nm.
17. Capacitor according to claim 15 , comprising a substrate and wherein the gold layer is separated from the substrate by an adhesive layer made from titanium dioxide.
18. Capacitor according to claim 15 , wherein the perovskite type dielectric material is selected from a group consisting of Pb[Zr x Ti 1-x ]O 3 , SrTiO 3 , BaTiO 3 , and Ba[Sr x Ti 1-x ]O 3 .
19. Electrode for a structure of Metal-Insulator-Metal type formed on a substrate by a stack successively comprising, from the substrate, a gold layer, a barrier layer made from RuO 2 in direct contact with the gold layer and a platinum layer in direct contact with the barrier layer and wherein the barrier layer has a thickness greater than or equal to 15 nm so as to block diffusion of gold and platinum.