Magnetic head having high conductivity lead structures seeded by epitaxially matched seed layer
View Patent ↗The present invention is directed towards increasing the conductivity of the electrical lead material in the read head portion of a magnetic head, such that thinner electrical leads can be fabricated while the current carrying capacity of the leads is maintained. This increase in electrical lead conductivity is accomplished by fabricating the electrical lead upon an epitaxially matched seed layer, such that the crystalline microstructure of the electrical lead material has fewer grain boundaries, whereby the electrical conductivity of the lead material is increased. In a preferred embodiment, the electrical lead material is comprised of Rh, which has an FCC crystal structure, and the seed layer is comprised of a metal, or metal alloy having a BCC crystal structure with unit cell lattice constant dimensions that satisfy the relationship that a bcc is approximately equal to 0.816a fcc . In various embodiments, the seed layer is comprised of VMo or VW.
1. A magnetic head comprising:
a read head structure including a magnetoresistive sensor and an electrical lead structure that includes a seed layer and an electrical lead layer;
said electrical lead layer being composed of a material selected from the group consisting of Cu, Ag, Mo, Ir, Rh and Ru; and
said seed layer being comprised of a material that is epitaxially matched between atomic sites along a first closest packed direction of a first closest packed plane in said seed layer across an interface of said seed layer with said lead layer, to a second closest packed direction of a second closest packed plane in said electrical lead layer material, wherein said first closest packed plane in said seed layer is essentially parallel to said second closest packed plane in said electrical lead layer.
2. A magnetic head as described in claim 1 , wherein said seed layer is comprised of material selected from the group consisting of V, Mo, W and alloys of two or more constituents selected from the group consisting of V, Mo, W, Nb, Ta, Ti and Cr.
3. A magnetic head as described in claim 2 wherein said seed layer has a thickness of from 5 Å to 100 Å.
4. A magnetic head as described in claim 2 wherein said seed layer has a thickness of approximately 35 Å.
5. A magnetic head as described in claim 1 wherein said lead layer is Rh and said seed layer is comprised of VMo, wherein the amount of V is from approximately 29 at. % to 39 at. %.
6. A magnetic head as described in claim 1 wherein said lead layer is Rh and said seed layer is comprised of VMo, wherein the amount of V is approximately equal to 34 at. %.
7. A magnetic head as described in claim 1 wherein said lead layer is Rh and said seed layer is comprised of VW, wherein the amount of V is from approximately 38 at. % to 48 at. %.
8. A magnetic head as described in claim 1 wherein said lead layer is Rh and said seed layer is comprised of VW, wherein the amount of V is approximately equal to 43 at. %.
9. A magnetic head comprising:
a read head structure including a magnetoresistive sensor and an electrical lead structure that includes a seed layer and an electrical lead layer;
said electrical lead layer being comprised of a material having an FCC crystal structure and being selected from the group consisting of Cu, Ag, Ir and Rh, and said seed layer being comprised of a material having a BCC crystal structure, and wherein said FCC crystal structure and said BCC crystal structure have the relationship that a bcc is approximately equal to 0.816a fcc .
10. A magnetic head as described in claim 9 , wherein said electrical lead layer is comprised of Rh, and said seed layer is comprised of a material selected from the group consisting of V, Mo, W and alloys of two or more constituents selected from the group consisting of V, Mo, W, Nb, Ta, Ti and Cr.
11. A magnetic head as described in claim 10 wherein said seed layer has a thickness of from 5 Å to 100 Å.
12. A magnetic head as described in claim 10 wherein said seed layer has a thickness of approximately 35 Å.
13. A magnetic head as described in claim 9 wherein said lead layer is Rh and said seed layer is comprised of VMo, wherein the amount of V is from approximately 29 at. % to 39 at. %.
14. A magnetic head as described in claim 9 wherein said lead layer is Rh and said seed layer is comprised of VMo, wherein the amount of V is approximately equal to 34 at. %.
15. A magnetic head as described in claim 9 wherein said lead layer is Rh and said seed layer is comprised of VW, wherein the amount of V is from approximately 38 at. % to 48 at. %.
16. A magnetic head as described in claim 9 wherein said lead layer is Rh and said seed layer is comprised of VW, wherein the amount of V is approximately equal to 43 at. %.
17. A hard disk drive comprising:
a motor for rotating a spindle;
a thin film magnetic disk mounted on the spindle; and
an actuator assembly having a magnetic head mounted thereon wherein said magnetic head includes:
a read head structure including a magnetoresistive sensor and an electrical lead structure including a seed layer and an electrical lead layer
said electrical lead layer being comprised of a material having an FCC crystal structure and being selected from the group consisting of Cu, Ag, Ir and Rh, and said seed layer being comprised of a material having a BCC crystal structure, and wherein said FCC crystal structure and said BCC crystal structure have the relationship that a bcc is approximately equal to 0.816a fcc .
18. A hard disk drive as described in claim 17 , wherein said electrical lead layer is comprised of Rh, and said seed layer is comprised of a material selected from the group consisting of V, Mo, W and alloys of two or more constituents selected from the group consisting of V, Mo, W, Nb, Ta, Ti and Cr.
19. A hard disk drive as described in claim 18 wherein said seed layer has a thickness of from 5 Å to 100 Å.
20. A hard disk drive as described in claim 18 wherein said seed layer has a thickness of approximately 35 Å.
21. A magnetic head as described in claim 17 wherein said lead layer is Rh and said seed layer is comprised of VMo, wherein the amount of V is from approximately 29 at % to 39 at. %.
22. A magnetic head as described in claim 17 wherein said lead layer is Rh and said seed layer is comprised of VMo, wherein the amount of V is approximately equal to 34 at. %.
23. A magnetic head as described in claim 17 wherein said lead layer is Rh and said seed layer is comprised of VW, wherein the amount of V is from approximately 38 at. % to 48 at. %.
24. A magnetic head as described in claim 17 wherein said lead layer is Rh and said seed layer is comprised of VW, wherein the amount of V is approximately equal to 43 at. %.