Protecting hard bias magnets during a CMP process using a sacrificial layer
View Patent ↗Read elements and associated methods of fabrication are disclosed. During fabrication of the read element, and more particularly, the fabrication of the hard bias magnets, a non-magnetic sacrificial layer is deposited on top of the hard bias material. When a CMP process is subsequently performed, the sacrificial layer is polished instead of the hard bias material. The thicknesses of the hard bias magnets are not affected by the CMP process, but are rather defined by the deposition process of the hard bias material. As a result, the variations in the CMP process will not negatively affect the magnetic properties of the hard bias magnets so that they are able to provide substantially uniform effective magnetic fields to bias the free layer of the magnetoresistance (MR) sensor of the read element.
1. A read element of a magnetic recording head, the read element comprising:
a first shield;
a magnetoresistance (MR) sensor formed on and in contact with the first shield, wherein the MR sensor has a top surface;
an insulation layer formed on and in contact with the first shield within side regions of the MR sensor;
hard bias magnets formed on and in contact with the insulation layer within the side regions of the MR sensor to a height that is completely below the top surface of the MR sensor;
a sacrificial layer formed on and in contact with the hard bias magnets within the side regions of the MR sensor to a height that is completely above the top surface of the MR sensor; and
a second shield formed on and in contact with the MR sensor and the sacrificial layer, wherein the sacrificial layer is sandwiched between and in contact with the hard bias magnets and the second shield within the side regions of the MR sensor.
2. The read element of claim 1 wherein the sacrificial layer is formed from CrMo.
3. The read element of claim 1 wherein the insulating layer has a thickness less than about 80 Å.
4. The read element of claim 1 wherein the MR sensor comprises Giant MR (GMR) sensor.
5. The read element of claim 1 wherein the MR sensor comprises a Tunneling MR (TMR) sensor.
6. A magnetic disk drive system, comprising:
a magnetic disk; and
a recording head that includes a read element for reading data from the magnetic disk, the read element comprising:
a first shield;
a magnetoresistance (MR) sensor formed on and in contact with the first shield, wherein the MR sensor has a top surface;
an insulation layer formed on and in contact with the first shield within side regions of the MR sensor;
hard bias magnets formed on and in contact with the insulation layer within the side regions of the MR sensor to a height that is completely below the top surface of the MR sensor;
a sacrificial layer formed on and in contact with the hard bias magnets within the side regions of the MR sensor to a height that is completely above the top surface of the MR sensor; and
a second shield formed on and in contact with the MR sensor and the sacrificial layer, wherein the sacrificial layer is sandwiched between and in contact with the hard bias magnets and the second shield within the side regions of the MR sensor.
7. The magnetic disk drive system of claim 6 wherein the sacrificial layer is formed from CrMo.
8. The magnetic disk drive system of claim 6 wherein the insulating layer has a thickness less than about 80 Å.
9. The magnetic disk drive system of claim 6 wherein the MR sensor comprises Giant MR (GMR) sensor.
10. The magnetic disk drive system of claim 6 wherein the MR sensor comprises a Tunneling MR (TMR) sensor.