Current perpendicular-to-plane read sensor with back shield

1. A read head for reading data from a magnetic media, comprising:

a bottom magnetic shield layer;

a top magnetic shield layer;

a read sensor disposed between the bottom and top magnetic shield layers configured for sensing changes in a magnetic field of the magnetic media positioned under the read sensor, the read sensor having a front end adjacent to an air bearing surface (ABS) and a back end opposite the front end; and

a back magnetic shield layer positioned between the bottom and top magnetic shield layers and behind the back end of the read sensor distal to the ABS,

wherein a ratio of a thickness of the back magnetic shield layer to a spacing between the bottom and top magnetic shield layers is greater than 0.25 with the spacing being based on a height of the read sensor.

2. The read head of claim 1 , wherein the back magnetic shield layer is coupled to the top magnetic shield layer.

3. The read head of claim 2 , further comprising an insulating layer that separates the back end of the read sensor and the bottom shield from the back shield.

4. The read head of claim 1 , wherein the back magnetic shield layer is positioned behind the back end of the read sensor to increase a magnitude of the magnetic field sensed from the magnetic media.

5. The read head of claim 1 , wherein the back magnetic shield layer is positioned behind the back end of the read sensor to improve uniformity of a magnetic field sensed from the magnetic media.

6. The read head of claim 1 , wherein the read head is a current perpendicular-to-plane read head.

7. The read head of claim 1 , wherein the back magnetic shield layer is a soft magnetic alloy.

8. A method of fabricating a thin film read head, comprising:

providing a substrate;

depositing a bottom magnetic shield layer over the substrate;

forming a reader stack on the bottom magnetic shield layer;

depositing an insulating layer over the bottom magnetic shield layer and the reader stack;

depositing a back magnetic shield layer over the insulating layer; and

removing a portion of the back magnetic shield layer and a portion of the insulating layer until reaching the reader stack.

9. The method of claim 8 , further comprises depositing a top magnetic shield layer over the back magnetic shield layer, insulating layer, and reader stack.

10. The method of claim 8 , wherein a ratio of a thickness of the back magnetic shield layer to a spacing between the bottom and top magnetic shield layers is greater than 0.25 with the spacing being based on a height of the reader stack.

11. The method of claim 8 , wherein forming the reader stack further comprises:

forming a photoresist patterned layer on top of the reader stack;

removing a first side portion and a second side portion of the reader stack;

depositing another insulating layer and hard bias materials over the bottom shield, reader stack, and photoresist patterned layer;

forming another photoresist patterned layer on top of the hard bias materials; and

removing third and fourth side portions of the reader stack.

12. The method of claim 8 , wherein removing the portion of the back magnetic shield layer and the portion of the insulating layer until reaching the reader stack comprises a chemical mechanical polishing operation that planarizes the layers above the reader stack prior to the deposition of the top magnetic shield layer.

13. The method of claim 8 , wherein removing the portion of the back magnetic shield layer and the portion of the insulating layer until reaching the reader stack comprises an etching operation that planarizes the back magnetic shield layer with respect to the reader stack while the insulating layer is non-planar with respect to the reader stack prior to the deposition of the top magnetic shield layer.

14. The method of claim 8 , wherein the reader stack comprises a front end adjacent to an air bearing surface (ABS) and a back end opposite the front end with the insulating layer being conformally deposited on the back end and forming an angle between 45 degrees and substantially 90 degrees with respect to the substrate.

15. The method of claim 8 , wherein the insulating layer has a thickness of less than approximately 50 nanometers with a thinner insulating layer increasing a magnetic field being sensed by the reader stack.

16. A system for storing and retrieving data to and from a magnetic recording media, comprising:

a head assembly, positionable adjacent the magnetic recording media, the head assembly having a write head and a read head, the read head comprising:

a bottom magnetic shield layer;

a top magnetic shield layer;

a read sensor disposed between the bottom and top magnetic shield layers configured for sensing changes in magnetic properties of a track on the magnetic media positioned under the read sensor, the read sensor having a front end adjacent to an air bearing surface (ABS) and a back end opposite the front end;

a back magnetic shield layer positioned between the bottom and top magnetic shield layers and behind the back end of the read sensor; and

a drive device for coupling to the media so as to move the media with respect to the head assembly,

wherein a ratio of a thickness of the back magnetic shield layer to a spacing between the bottom and top magnetic shield layers is greater than 0.25 and less than or equal to 2.0 with the spacing being based on a height of the read sensor.

17. The system of claim 16 , wherein the back magnetic shield layer is coupled to the top magnetic shield layer.

18. The system of claim 16 , further comprising an insulating layer that separates the back end of the read sensor and the bottom shield from the back shield.