Metal-insulator-metal capacitors with high breakdown voltage

1. A method for forming a capacitor structure, comprising:

forming a capacitor bottom electrode;

depositing a first dielectric layer on the capacitor bottom electrode;

converting a portion of the first dielectric layer into a first oxygen-rich layer;

depositing a second dielectric layer on the first oxygen-rich layer;

converting a portion of the second dielectric layer into a second oxygen-rich layer;

depositing a capacitor top electrode material on the second oxygen-rich layer; and

removing portions of the capacitor top electrode material, portions of the second oxygen-rich layer, and portions of the second dielectric layer.

2. The method of claim 1 , wherein the converting the portions of the first and second dielectric layers comprises performing a plasma treatment using oxygen-containing precursors on the first and second dielectric layers, respectively.

3. The method of claim 2 , wherein the oxygen-containing precursors comprise oxygen or nitrous oxide (N 2 O).

4. The method of claim 1 , wherein the removing comprises stopping an etching process before the first oxygen-rich layer is exposed.

5. The method of claim 1 , wherein the depositing the first and second dielectric layers comprise depositing silicon nitride.

6. A method, comprising:

forming a capacitor bottom electrode;

depositing a first dielectric layer on the capacitor bottom electrode;

performing a first oxygen plasma treatment on the first dielectric layer to increase an oxygen atomic concentration of a top portion of the first dielectric layer;

depositing a second dielectric layer on the top portion of the first dielectric layer;

performing a second oxygen plasma treatment on the second dielectric layer to increase an oxygen atomic concentration of a top portion of the second dielectric layer;

depositing a capacitor top electrode on the top portion of the second dielectric layer; and

forming interconnect structures, comprising:

forming a first contact in direct contact with the capacitor top electrode; and

forming a second contact in direct contact with the capacitor bottom electrode.

7. The method of claim 6 , further comprising removing portions of the capacitor top electrode and portions of the second dielectric layer without exposing the first dielectric layer.

8. The method of claim 6 , further comprising etching the second dielectric layer to form sloped sidewalls in the second dielectric layer, and wherein an angle between the sloped sidewalls and a horizontal direction is between about 70° and about 89°.

9. The method of claim 8 , wherein the second dielectric layer comprises substantially planar portions abutting the sloped sidewalls.

10. The apparatus of claim 6 , wherein depositing the first and second dielectric layers comprises depositing a silicon nitride material.

11. The method of claim 6 , wherein performing the first oxygen plasma treatment comprises non-uniformly increasing the oxygen atomic concentration of the top portion of the first dielectric layer.

12. The method of claim 11 , wherein the oxygen atomic concentration is greater at a top surface of the top portion than at a bottom surface of the top portion.

13. The method of claim 6 , wherein forming the second contact comprises forming a via extending through the second dielectric layer and the top portion of the first dielectric layer.

14. The method of claim 6 , wherein forming the capacitor bottom electrode comprises:

depositing a first tantalum nitride layer;

depositing an aluminum copper alloy layer on the first tantalum nitride layer; and

depositing a second tantalum nitride layer on the aluminum copper alloy layer.

15. The method of claim 6 , further comprising depositing an interlayer dielectric layer in direct contact with the second dielectric layer and the capacitor top electrode.

16. A method, comprising:

depositing a capacitor bottom electrode;

depositing a dielectric layer stack on the capacitor bottom electrode, comprising:

depositing a first dielectric layer on the capacitor bottom electrode, the first dielectric layer having a first thickness;

increasing an oxygen atomic concentration of a top portion of the first dielectric layer to form a first blocking layer comprising the top portion of the first dielectric layer;

depositing a second dielectric layer on the first blocking layer, the second dielectric layer having a second thickness that is less than the first thickness; and

increasing an oxygen atomic concentration a top portion of the second dielectric layer to form a second blocking layer comprising the top portion of the second dielectric layer; and

depositing a capacitor top electrode on the dielectric layer stack.

17. The method of claim 16 , further comprising depositing an interlayer dielectric layer in direct contact with the capacitor top electrode and the dielectric layer stack.

18. The method of claim 17 , further comprising:

forming a first contact in the interlayer dielectric layer and electrically coupling the first contact to the capacitor top electrode; and

forming a second contact in the interlayer dielectric layer and electrically coupling the second contact to the capacitor bottom electrode.

19. The method of claim 16 , wherein increasing the oxygen atomic concentration of the top portion of forming the first dielectric layer comprises performing a plasma treatment using oxygen-containing precursors on the first dielectric layer.

20. The method of claim 16 , further comprising:

etching portions of the capacitor top electrode, the second blocking layer, and the second dielectric layer without exposing the first blocking layer; and

depositing an interlayer dielectric layer directly on unetched portions of the second dielectric layer.