Sequential atomic layer deposition of electrodes and resistive switching components
View Patent ↗Provided are methods of forming nonvolatile memory elements using atomic layer deposition techniques, in which at least two different layers of a memory element are deposited sequentially and without breaking vacuum in a deposition chamber. This approach may be used to prevent oxidation of various materials used for electrodes without a need for separate oxygen barrier layers. A combination of signal lines and resistive switching layers may be used to cap the electrodes and to minimize their oxidation. As such, fewer layers are needed in a memory element. Furthermore, atomic layer deposition allows more precise control of electrode thicknesses. In some embodiments, a thickness of an electrode may be less than 50 Angstroms. Overall, atomic layer deposition of electrodes and resistive switching layers lead to smaller thicknesses of entire memory elements making them more suitable for low aspect ratio features of advanced nodes.
1. A method for forming a nonvolatile memory element, the method comprising:
forming a first layer using atomic layer deposition,
the first layer being operable as a first electrode,
the first layer comprising an oxygen sensitive material; and
forming a second layer using atomic layer deposition,
the second layer being operable as a resistive switching layer,
wherein the second layer is formed directly over the first layer without breaking vacuum in a processing chamber between forming the first layer and forming the second layer,
wherein the first layer and the second layer form a continuous interface; and
forming a third layer over the second layer, the third layer being operable as a second electrode,
wherein a composition of the third layer is same as a composition of the first layer.
2. The method of claim 1 , wherein a composition of the first layer differs throughout a thickness of the first layer.
3. The method of claim 1 , wherein the first layer is a nanolaminate.
4. The method of claim 1 , wherein the oxygen sensitive material is a nitride.
5. The method of claim 1 , wherein the oxygen sensitive material is a tertiary nitride.
6. The method of claim 1 , wherein forming the second layer comprises:
introducing a first precursor into the processing chamber;
purging a portion of the first precursor from the processing chamber;
wherein the first precursor is purged before full saturation of the first precursor on the deposition surface; and
introducing a reactant into the processing chamber.
7. The method of claim 1 , wherein forming the first layer comprises:
introducing a metal containing precursor into the processing chamber;
purging a portion of the metal containing precursor from the processing chamber; and
introducing a nitrogen containing reactant into the processing chamber.
8. The method of claim 7 , wherein the nitrogen containing reactant is introduced into the processing chamber together with carbon monoxide.
9. The method of claim 7 , wherein the metal containing precursor is one of a titanium containing precursor, a tantalum containing precursor, or a tungsten containing precursor.
10. The method of claim 1 , wherein a combined thickness of the first layer, the second layer, and the third layer is less than about 300 Angstroms.
11. The method of claim 1 , further comprising forming a fourth layer over the third layer, wherein the third layer comprises an additional oxygen sensitive material, and wherein the fourth layer is formed directly over the third layer without breaking vacuum in the processing chamber between forming the third layer and forming the fourth layer.
12. The method of claim 11 , wherein the fourth layer comprises copper.
13. The method of claim 11 , wherein the fourth layer is a capping layer.
14. The method of claim 11 , wherein the fourth layer is a signal line.
15. The method of claim 1 , wherein the first layer has a thickness of less than 50 Angstroms.
16. The method of claim 1 , wherein the first layer is formed over a signal line, and wherein the signal line and the second layer protect the first layer from oxidation.