Method for fabricating a magnetic head
View Patent ↗A GMR read head for a magnetic head, in which the hard bias layers are fabricated immediately next to the side edges of the free magnetic layer, and such that the midplane of the hard bias layer and the midplane of the free magnetic layer are approximately coplanar. The positioning of the hard bias layer is achieved by depositing a thick hard bias seed layer, followed by an ion milling step is to remove seed layer sidewall deposits. Thereafter, the hard bias layer is deposited on top of the thick seed layer. Alternatively, a first portion of the hard bias seed layer is deposited, followed by an ion milling step to remove sidewall deposits. A thin second portion of the seed layer is next deposited, and the hard bias layer is then deposited.
1. A method for fabricating a magnetic head comprising:
fabricating a plurality of thin film layers to create a read sensor, said read sensor including a first insulation (G 1 ) layer, a pinned layer, a pinning layer, a spacer layer, a free magnetic layer having a midplane thereof, and a cap layer;
milling said plurality of thin films such that a central sensor region is protected from milling and unprotected outer regions are milled down to said G 1 layer, such that said free magnetic layer is formed with a central portion and outwardly disposed side edge portions;
fabricating a hard bias structure upon said G 1 layer at said outer regions such that said hard bias structure is disposed proximate said side edge portions of said free magnetic layer, said hard bias structure including a seed layer and a hard bias layer, wherein said hard bias structure is fabricated by;
depositing said seed layer upon said G 1 layer;
removing an upper portion of said seed layer to create an upper surface of said seed layer;
depositing hard bias material upon said upper surface of said seed layer to create said hard bias layer that is disposed upon said seed layer; and
wherein said hard bias layer has a midplane that is disposed at a horizontal level within the magnetic head that is approximately coplanar with said midplane of said free magnetic layer.
2. The method for fabricating a magnetic head as described in claim 1 wherein said hard bias layer is deposited next to said side edge portions of said free magnetic layer.
3. The method for fabricating a magnetic head as described in claim 2 wherein said seed layer has a thickness of approximately 25–30 nm, and wherein said hard bias layer has a thickness of approximately 15–20 nm.
4. The method for fabricating a magnetic head as described in claim 3 wherein said removing of said upper surface of said seed layer includes ion milling said seed layer.
5. The method for fabricating a magnetic head as described in claim 1 wherein said seed layer is formed with an initial thickness of approximately 30–40 nm, said upper portion of said seed layer is approximately 6–10 nm thick, such that a final thickness of said seed layer is approximately 25–30 nm.
6. The method for fabricating a magnetic head as described in claim 1 wherein said seed layer is comprised of Cr or CrMo, and said hard bias material is CoPtCr.