High resistivity iron-based, thermally stable magnetic material for on-chip integrated inductors
An on-chip magnetic structure includes a palladium activated seed layer and a substantially amorphous magnetic material disposed onto the palladium activated seed layer. The substantially amorphous magnetic material includes nickel in a range from about 50 to about 80 atomic % (at. %) based on the total number of atoms of the magnetic material, iron in a range from about 10 to about 50 at. % based on the total number of atoms of the magnetic material, and phosphorous in a range from about 0.1 to about 30 at. % based on the total number of atoms of the magnetic material. The magnetic material can include boron in a range from about 0.1 to about 5 at. % based on the total number of atoms of the magnetic material.
1. A method for forming an on-chip magnetic structure, the method comprising:
activating a magnetic seed layer with palladium, the magnetic seed layer being positioned over a substrate; and
electrolessly plating a soft magnetic alloy onto the palladium in the presence of a magnetic field bias;
wherein the soft magnetic alloy comprises nickel in a range from about 50 to about 80 at % based on the total number of atoms of the soft metallic alloy, iron in a range from about 10 to about 50 at. % based on the total number of atoms of the soft metallic alloy, phosphorous in a range from about 0.1 to about 30 at. % based on the total number of atoms in the soft metallic alloy, and boron in a range from about 0.1 to about 5 at. % based on the total number of atoms of the soft magnetic alloy.
2. The method of claim 1 , wherein activating the magnetic seed layer comprises exposing the magnetic seed layer to a solution comprising palladium.
3. The method of claim 2 , wherein the solution further comprises an acid.
4. The method of claim 3 , wherein the palladium is present in an amount in a range from about 45 to about 65 ppm.
5. The method of claim 3 , wherein the acid is sulfuric acid, hydrochloric acid, nitric acid, or any combination thereof.
6. The method of claim of claim 1 , wherein the soft metallic alloy's resistivity is at least 110 μΩ·cm.
7. The method of claim 1 , wherein the magnetic field bias is in a range from about 0.1 to about 1.5 Tesla.
8. The method of claim 1 , wherein the soft magnetic alloy's coercivity is about or less than about 1 oersted (Oe).
9. The method of claim 1 , wherein the magnetic seed layer comprises nickel.
10. The method of claim 9 , wherein the magnetic seed layer further comprises an iron layer.
11. The method of claim 1 , wherein the on-chip magnetic structure is an inductor.
12. The method of claim 1 , wherein the magnetic seed layer comprises nickel in an amount in a range from about 0.1 to about 80 at. %.
13. The method of claim 1 , wherein the magnetic seed layer comprises iron in an amount in a range from about 0.1 to about 50 at. %.
14. The method of claim 1 , wherein the magnetic seed layer comprises about 80 wt. % nickel and about 20 wt. % iron.
15. The method of claim 1 , wherein the magnetic seed layer has a thickness in a range from about 50 to about 70 nm.
16. The method of claim 1 , wherein the magnetic seed layer further comprises a protective layer, and the protective layer is removed before electrolessly plating.
17. The method of claim 16 , wherein the protective layer is a metal or a non-metal.
18. The method of claim 17 , wherein the protective layer is the metal, and the metal is titanium.
19. The method of claim 1 , wherein activating the magnetic seed layer comprises immersing the substrate in a palladium sulfate solution.
20. The method of claim 1 , wherein activating the magnetic seed layer comprises immersing the substrate in a palladium salt solution.