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 a palladium solution to form a palladium-activated magnetic seed layer, the magnetic seed layer being positioned over a semiconductor substrate; and
electrolessly plating a magnetic alloy onto the palladium-activated seed layer to form an amorphous soft magnetic layer;
wherein the amorphous soft magnetic layer comprises nickel in a range from about 50 to about 80 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.
2. The method of claim 1 , wherein the on-chip magnetic structure is an inductor.
3. The method of claim 1 , wherein the palladium solution comprises from about 40 to about 70 parts per million (ppm) of a palladium salt and an acid.
4. The method of claim 1 , wherein the amorphous soft magnetic layer has a resistivity of at least 100 μΩ·cm.
5. The method of claim 1 , wherein the amorphous soft magnetic layer is magnetically stable at a temperature of 250° C. for at least 1 hour.
6. The method of claim 1 , wherein the amorphous soft magnetic layer further comprises boron in an amount in a range from about 0.1 to about 1.0 at. %.