MAGNETIC READ SENSOR HAVING FLAT SHIELD PROFILE
A magnetic read sensor having a flat shield for improved gap thickness definition and control. The magnetic read head includes a sensor stack and hard bias layer formed at either side of the sensor stack. A SiNx hard bias capping layer is formed over the hard bias layers between the hard bias structure and the upper magnetic shield. The hard bias capping layer has an upper surface that has been planarized by chemical mechanical polishing that is co-planar with an upper surface of the sensor stack. The read sensor is constructed by a method wherein the hard bias capping layer is constructed of a material (e.g. SiNx) that is also used as a CMP stop layer and that can be planarized by chemical mechanical polishing while having some resistance to removal by chemical mechanical polishing.
1 . A magnetic read head, comprising:
a sensor stack having first and second laterally opposed sides;
a magnetic hard bias structure formed adjacent to each of the first and second sides of the sensor stack;
a hard bias capping layer comprising SiNx formed over each of the first and second hard bias layers; and
a magnetic shield formed over the sensor stack and over the hard bias capping layers.
2 . The magnetic read head as in claim 1 wherein each of the hard bias capping layers has a smooth, flat surface that is coplanar with a surface of the sensor stack.
3 . The magnetic read head as in claim 1 wherein the magnetic shield is flat.
4 . The magnetic read head as in claim 1 having an interface between the magnetic shield and the sensor stack and hard bias capping layers, the interface being smooth and flat.
5 . A magnetic data recording system, comprising:
a housing;
a magnetic media held within the housing;
an actuator;
a slider connected with the actuator for movement adjacent to a surface of the magnetic media; and
a magnetic read head formed on the slider, the magnetic read head further comprising:
a sensor stack having first and second laterally opposed sides;
a magnetic hard bias structure formed adjacent to each of the first and second sides of the sensor stack;
a hard bias capping layer comprising SiNx formed over each of the first and second hard bias layers; and
a magnetic shield formed over the sensor stack and over the hard bias capping layers.
6 . The magnetic data recording system as in claim 5 wherein each of the hard bias capping layers has a smooth, flat surface that is coplanar with a surface of the sensor stack.
7 . The magnetic data recording system as in claim 5 wherein the magnetic shield is flat.
8 . The magnetic data recording system as in claim 5 having an interface between the magnetic shield and the sensor stack and hard bias capping layers, the interface being smooth and flat.
9 . A method for manufacturing a magnetic read head, comprising:
depositing a sensor layer;
depositing a first CMP stop layer over the sensor stack;
forming a mask structure over the first CMP stop layer;
performing a first ion milling to transfer the image of the mask structure onto the under-lying first CMP stop layer and sensor material;
depositing a hard magnetic bias material;
depositing a second CMP stop layer;
performing a chemical mechanical polishing process to remove the mask structure; and
performing a second ion milling to remove the first CMP stop layer, leaving a portion of the second CMP stop layer remaining over the hard magnetic bias material.
10 . The method as in claim 9 , wherein the second CMP stop layer comprises SiNx.
11 . The method as in claim 9 wherein the first and second CMP stop layers each comprise SiNx.
12 . The method as in claim 9 wherein the chemical mechanical polishing forms a smooth flat surface on the second CMP stop layer.
13 . The method as in claim 9 wherein the second CMP stop layer is deposited thicker than the first CMP stop layer so that the second ion milling can remove all of the first CMP stop layer while leaving a portion of the second CMP stop layer remaining over the hard magnetic bias layers.
14 . The method as in claim 9 wherein the chemical mechanical polishing and second ion milling are performed in such a manner to leave the second CMP stop layer with an upper surface that is co-planar with an upper surface of the sensor stack.
15 . The method as in claim 9 wherein the magnetic hard bias material is deposited to such a thickness that it has an upper surface that is below an upper surface of the sensor stack.
16 . The method as in claim 9 further comprising after performing the first ion milling and before depositing the hard magnetic bias material, depositing a thin, non-magnetic, electrically insulating material.
17 . The method as in claim 9 further comprising, after performing the second ion milling, forming an upper magnetic shield over the sensor stack and the second CMP stop material.
18 . The method as in claim 9 wherein the hard magnetic bias material comprises CoPt or CoPtCr.
19 . The method as in claim 9 wherein the sensor material further comprises a pinned magnetic layer, a free magnetic layer, a non-magnetic layer sandwiched between the pinned magnetic layer and the free magnetic layer and a non-magnetic capping layer formed over the free magnetic layer.