Thin Data Reader Cap

Abstract

A data reader may have a magnetoresistive stack with a magnetically free layer decoupled from a first shield by a cap. The cap can have one or more sub-layers respectively configured with a thickness of 4 nm or less as measured parallel to a longitudinal axis of the magnetoresistive stack on an air bearing surface.

1 . An apparatus comprising a magnetoresistive stack having a less than 4 nm reader width offset and comprising a magnetically free layer contacting a bi-layer cap comprising a cap layer and a first mask layer, the cap layer deposited with having a width equal to or greater than that of the first mask layer as measured perpendicular to a longitudinal axis of the magnetoresistive stack and with a thickness of 4 nm or less as measured parallel to the longitudinal axis of the magnetoresistive stack on an air bearing surface (ABS), the cap layer having a thickness of 2 nm or more, decoupling the magnetically free layer from a first shield, and contacting the magnetically free layer and the first shield after the first mask layer is removed. 
     
     
         2 . The apparatus of  claim 1 , wherein the first mask layer has a vertical sidewall oriented parallel to the longitudinal axis of the magnetoresistive stack. 
     
     
         3 . The apparatus of  claim 1 , wherein the cap and first mask layers are different materials. 
     
     
         4 . The apparatus of  claim 3 , wherein the cap layer comprises a first polish stop material and the first mask layer comprises a second material which can be removed by reactive etch. 
     
     
         5 . The apparatus of  claim 1 , wherein the magnetoresistive stack comprises a fixed magnetization structure having a greater width than the free layer. 
     
     
         6 . The apparatus of  claim 1 , wherein the magnetoresistive stack contacts first and second shields along the longitudinal axis, the magnetoresistive stack disposed between and separated from first and second side shields along a transverse axis oriented perpendicular to the longitudinal axis. 
     
     
         7 . The apparatus of  claim 1 , wherein a second mask layer contacts the first mask layer prior to removal of the first mask layer, the second mask layer selected to be removed by a technique that will not remove the first mask layer. 
     
     
         8 . The apparatus of  claim 1 , wherein the first mask layer comprises a metal, oxide, nitride material, or amorphous Carbon. 
     
     
         9 . An apparatus comprising a magnetoresistive stack having a less than 4 nm reader width offset and comprising a magnetically free layer decoupled from a shield by a cap having a thickness of 2 nm or less as measured parallel to a longitudinal axis of the magnetoresistive stack on an air bearing surface (ABS) after a first mask layer is removed, the cap comprising a material that decomposes into metal, the cap disposed between and contacting the magnetically free layer and the shield. 
     
     
         10 . The apparatus of  claim 9 , wherein the cap comprises CuN. 
     
     
         11 . The apparatus of  claim 9 , wherein the cap decomposes from an oxide or nitride to a metal. 
     
     
         12 . The apparatus of  claim 9 , wherein the shield comprises a fixed magnetization structure. 
     
     
         13 . A method comprising:
 depositing a magnetoresistive stack having a magnetically free layer;   forming a cap layer atop the magnetically free layer, the cap having a thickness of 4 nm or less as measured parallel to a longitudinal axis of the magnetoresistive stack on an air bearing surface (ABS);   depositing a first mask layer on the cap layer;   forming a second mask layer on the first mask layer, the first and second layers being independently definable;   patterning the first and second mask layers to a common reduced width;   patterning the magnetoresistive stack to have a less than 4 nm reader width offset;   depositing an isolation structure and side shield structure;   removing the second mask layer;   removing the first mask layer to provide a cap thickness of 2 nm or more; and   depositing a shield in contact with the cap layer, the cap layer decoupling the magnetically free layer from the shield.   
     
     
         14 . The method of  claim 13 , wherein the first mask layer is removed with a different material removal process than the second mask layer. 
     
     
         15 . The method of  claim 14 , wherein the second mask layer is removed with a reactive etch material removal process, the first mask layer being inert to the reactive etch material removal process. 
     
     
         16 . The method of  claim 15 , wherein the first mask layer is patterned with a process that does not add to the reader width offset. 
     
     
         17 . The method of  claim 13 , wherein the first mask layer protects the cap and magnetically free layer during at least one subsequent process prior to deposition of the shield. 
     
     
         18 . The method of  claim 17 , wherein the first mask layer is removed immediately prior to shield deposition. 
     
     
         19 . The method of  claim 15 , wherein the reactive etch material removal process comprises an inductively coupled plasma. 
     
     
         20 . The method of  claim 13 , wherein the first mask layer masks the cap layer from a material removal process that removes the second mask layer.