Magnetoresistive sensor having a novel junction structure for improved track width definition and pinned layer stability

Abstract

A magnetoresistive sensor having improved pinned layer stability at small track widths. The sensor has substantially vertical side walls that define the track width of the sensor. The free layer terminates at the substantially vertical side walls, but the pinned layer structure or a portion thereof extends beyond the track width region into the field. The extended pinned layer structure provides improved resistance to amplitude flipping, while allowing the track width to remain small.

1 . A magnetoresistive sensor, comprising: 
 a free layer;    a spacer layer, terminating at first and second substantially vertical side walls that define a track width; and    a pinned layer that extends beyond the track width.    
     
     
         2 . A sensor as in  claim 1 , wherein the free layer has a surface that defines a plane, and the substantially vertical side walls each define an angle of no more than 20 degrees with respect to a normal to the plane of the free layer surface.  
     
     
         3 . A sensor as in  claim 1 , wherein the pinned layer has first and second laterally extending portions that extend beyond the track width by a distance at least equal to the trackwidth.  
     
     
         4 . A sensor as in  claim 3 , wherein each of the laterally extending portions has an upper surface that defines a plane that is substantially parallel with a plane defined by a surface of the free layer.  
     
     
         5 . A sensor as in  claim 3 , wherein each of the laterally extending portions has an upper surface that defines a plane that is parallel within 20 degrees with a plane defined by a surface of the free layer.  
     
     
         6 . A sensor as in  claim 3 , wherein each of the laterally extending portions of the pinned layer structure is generally non-tapered.  
     
     
         7 . A sensor as in  claim 1 , wherein the pinned layer meets each of the first and second substantially vertical side walls at a sharp junction that forms an angle of substantially 90 degrees.  
     
     
         8 . A sensor as in  claim 1 , wherein the pinned layer meets each of the first and second substantially vertical side walls at a junction that forms an angle of 70-110 degrees.  
     
     
         9 . A magnetoresistive sensor, comprising: 
 a sensor stack, a portion of the sensor stack terminating at first and second substantially vertical side walls; and    the sensor stack including first and second laterally extending portions that extend laterally beyond the substantially vertical side walls.    
     
     
         10 . A magnetoresistive sensor as in  claim 9 , wherein the sensor stack includes a free layer that terminates at the first and second substantially vertical side walls, and the laterally extending portions include a pinned layer.  
     
     
         11 . A magnetoresistive sensor as in  claim 9  wherein the sensor stack includes a free layer that terminates at the first and second substantially vertical side walls, and includes a pinned layer, a portion of which extends beyond the first and second substantially vertical side walls.  
     
     
         12 . A magnetoresistive sensor as in  claim 9  wherein the sensor stack includes a free layer, a pinned layer and an AFM layer and wherein the free layer and the pinned layer terminate at the substantially vertical side walls and wherein the laterally extending portion includes the AFM layer.  
     
     
         13 . A magnetoresistive sensor as in  claim 9  wherein the laterally extending portion is generally non-tapered.  
     
     
         14 . A magnetoresistive sensro as in  claim 9  wherein each laterally extending portion has an upper surface that defines a plane that is substantially parallel with a plane defined by the free layer.  
     
     
         15 . A magnetoresisitive sensor as in  claim 9  wherein each laterally extending portion has an upper surface that defines a plane that is parallel within 5 degrees with a plane defined by the free layer.  
     
     
         16 . A disk drive system, comprising: 
 a magnetic disk;    a slider;    a suspension connected with the slider;    an actuator connected with the suspension to move the slider adjacent to a surface of the magnetic disk; and    a mangetoresistive sensor connected with the slider, the sensor comprising: 
 a sensor stack, a portion of the sensor stack terminating at first and second substantially vertical side walls; and  
 the sensor stack including first and second laterally extending portions that extend laterally beyond the substantially vertical side wall.  
   
     
     
         17 . A method for manufacturing a magnetoresistive sensor, comprising: 
 providing a substrate;    depositing a plurality of sensor layers;    depositing a layer of material that is resistant to removal by chemical mechanical polishing (CMP stop layer);    depositing an antireflective coating layer;    forming a photoresist mask on the antireflective layer;    performing a reactive ion etch (RIE) to remove portions of the ion mill resistant mask that are not covered by the photoresist mask, the RIE being performed in a plasma chamber having a platen, the performing the RIE further comprising applying a platen power of at least 70 W;    performing an ion mill to remove a portion of the sensor layers; and    terminating the ion mill process before all of the sensor materials have been removed.    
     
     
         18 . A method as in  claim 17 , wherein the plurality of sensor layers includes a pinned layer, and wherein the ion mill is terminated prior to removal of the pinned layer.  
     
     
         19 . A method as in  claim 17 , wherein the plurality of sensor layers includes a pinned layer, and wherein the ion mill is terminated after a portion of the pinned layer has been removed, but prior to removal of all of the pinned layer.  
     
     
         20 . A method as in  claim 17 , wherein the platen power applied to the platen is between 70 W and 500 W.  
     
     
         21 . A method as in  claim 17  wherein the platen power applied to the platen is between 250 W and 350 W.  
     
     
         22 . A method as in  claim 17  wherein the platen power applied to the platen is about 300 W.  
     
     
         23 . A method as in  claim 17  wherein the RIE is performed in a plasma chamber containing an O 2  atmosphere.  
     
     
         24 . A method as in  claim 17  wherein the plurality of sensor layers includes a pinned layer and an AFM layer, and wherein the ion mill is performed sufficiently to remove the pinned layer, but is terminated before removing the AFM layer.  
     
     
         25 . A sensor as in  claim 9 , wherein each of the laterally extending portions meets one of the first and second substantially vertical side walls at a junction that forms an angle of 70-110 degrees.