Method of making a magnetoresistive reader structure

A method of forming a magnetoresistive (MR) read sensor, comprising:

• providing a read sensor stack on a magnetic bottom shield;
• depositing an electrically conductive cap layer on the read sensor stack, wherein the cap layer has a lower polishing rate than a hard bias layer;
• depositing a hard mask layer on the cap layer;
• developing a photoresist patterned on the hard mask layer;
• reactive ion etching the mask layer where the photoresist is patterned;
• removing the photoresist;
• ion milling the read sensor stack that is unprotected by the mask layer except where a track width is defined;
• reactive ion etching the hard mask layer remaining on the cap layer;
• depositing, on the cap layer and both sides of the read sensor stack where the ion milling left voids, an insulation layer and then the hard bias layer;
• chemical mechanical polishing the hard bias and insulation layers to remove the hard bias and insulation layers from the cap layer and produce a planar top surface;
• and
• plating a magnetic top shield above the read sensor stack and the hard bias layer that remains following the polishing.

A method of forming a magnetoresistive (MR) read sensor, comprising:

• providing a MR sensor stack with a polishing stop layer containing one of rhodium (Rh) and chromium (Cr) disposed above the MR sensor stack and a patterned mask layer containing amorphous carbon disposed above the polishing stop layer;
• ion milling the MR sensor stack where unprotected by the mask layer;
• reactive ion etching the mask layer to remove the patterned mask layer;
• then, depositing hard bias magnetic material on the polishing stop layer and at sides of the MR sensor stack within voids defined by the ion milling;
• and
• polishing to produce a planar top surface defined in part by the polishing stop layer.