Electro-deposition of high saturation magnetization Fe-Ni-Co films

Abstract

High density magnetic recording requires the write head materials to have high saturation magnetic flux density. Preparation of such materials has been achieved by providing an aqueous solution of nickel, iron, and cobalt salts, each present within a specified concentration range, together with selected additives. When used, under the specified operating conditions, as the electrolyte during electro-deposition, said solution provides a ferromagnetic layer having improved magnetic properties, particularly high saturation magnetic flux density. One embodiment of the process teaches formation of pole tips for use in a magnetic write head.

What is claimed is:  
     
         1 . A process for depositing a ferromagnetic film, comprising: 
 forming an aqueous solution that further comprises: 
 NiSO 4 .6H 2 O at a concentration of between 0 and 80 g/L,  
 NiCl 2 .6H 2 O at a concentration of between 0 and 50 g/L,  
 CoSO 4 .7H 2 O at a concentration of between 0 and 50 g/L,  
 FeSO 4 .7H 2 O at a concentration of between 10 and 70 g/L,  
 H 3 BO 3  at a concentration of between 26 and 27 g/L,  
 NH 4 Cl at a concentration of between 0 and 20 g/L,  
 (NH 4 ) 2 SO 4  at a concentration of between 0 and 20 g/L,  
 Sodium Saccharin at a concentration of between 0 and 2.0 g/L, and  
 Sodium Lauryl Sulfate at a concentration of between 0.01 and 0.15 g/L.  
   through electro-deposition from said solution, depositing said ferromagnetic film.    
     
     
         2 . The process described in  claim 1  wherein said aqueous solution is adjusted to and maintained at a pH between about 2 and 4.  
     
     
         3 . The process described in  claim 1  wherein, during electro-deposition, said solution is maintained at a temperature between about 10 and 40° C.  
     
     
         4 . The process described in  claim 1  wherein a cobalt anode is used for CoFe plating.  
     
     
         5 . The process described in  claim 1  wherein a nickel anode is used for NiFe or FeCoNi plating.  
     
     
         6 . The process described in  claim 1  wherein said ferromagnetic film contains between about 50 and 85 weight % iron, between about 0 and 30 weight % nickel, and between about 0 and 50 weight % cobalt.  
     
     
         7 . The process described in  claim 1  wherein, during electro-deposition, a current density of between about 3 and 30 mA/cm 2  is maintained.  
     
     
         8 . A process for manufacturing a pole tip for a magnetic recording head, comprising: 
 on a wafer, forming a conductive seed layer    forming a removable photoresist pattern on said conductive seed layer;    providing an aqueous solution that further comprises: 
 NiSO 4 .6H 2 O at a concentration of between 0 and 80 g/L,  
 NiCl 2 .6H 2 O at a concentration of between 0 and 50 g/L,  
 CoSO 4 .7H 2 O at a concentration of between 0 and 50 g/L,  
 FeSO 4 .7H 2 O at a concentration of between 10 and 70 g/L,  
 H 3 BO 3  at a concentration of between 26 and 27 g/L,  
 NH 4 Cl at a concentration of between 0 and 20 g/L,  
 (NH 4 ) 2 SO 4  at a concentration of between 0 and 20 g/L,  
 Sodium Saccharin at a concentration of between 0 and 2.0 g/L, and  
 Sodium Lauryl Sulfate at a concentration of between 0.01 and 0.15 g/L.  
   adjusting said aqueous solution to have a pH between about 2 and 4;    immersing said photoresist pattern in said solution and, using said seed layer as a cathode, electro-depositing material from said solution to a desired thickness inside the pattern;    removing said photoresist and said seed layer, thereby forming said pole tip; and    then subjecting said pole tip to a heat treatment.    
     
     
         9 . The process described in  claim 8  wherein said pole piece is electro-deposited to a thickness between about 1 and 5 microns.  
     
     
         10 . The process described in  claim 8  wherein said pole tip is formed by electroplating through a photoresist pattern made using a photolithography process.  
     
     
         11 . The process described in  claim 8  wherein a cobalt anode is used for CoFe plating.  
     
     
         12 . The process described in  claim 8  wherein a nickel anode is used for NiFe or FeCoNi plating.  
     
     
         13 . The process described in  claim 8  wherein said pole piece contains between about 50 and 85 weight % iron, between about 0 and 30 weight % nickel, and between about 0 and 50 weight % cobalt.  
     
     
         14 . The process described in  claim 8  wherein said heat treatment further comprises heating NiFe or FeCoNi films at a temperature between about 100 and 300° C. for between about 60 and 120 minutes in nitrogen.  
     
     
         15 . An apparatus for electro-depositing a ferromagnetic film, comprising: 
 an aqueous solution that further comprises: 
 NiSO 4 .6H 2 O at a concentration of between 0 and 80 g/L,  
 NiCl 2 .6H 2 O at a concentration of between 0 and 50 g/L,  
 CoSO 4 .7H 2 O at a concentration of between 0 and 50 g/L,  
 FeSO 4 .7H 2 O at a concentration of between 10 and 70 g/L,  
 H 3 BO 3  at a concentration of between 26 and 27 g/L,  
 NH 4 Cl at a concentration of between 0 and 20 g/L,  
 (NH 4 ) 2 SO 4  at a concentration of between 0 and 20 g/L,  
 Sodium Saccharin at a concentration of between 0 and 2.0 g/L, and  
 Sodium Lauryl Sulfate at a concentration of between 0.01 and 0.15 g/L.  
   said aqueous having a pH between 2 and 4;    immersed in said solution, a seed layer on which to grow said ferromagnetic film; and    means for passing a direct current between the seed layer and an anode.    
     
     
         16 . The apparatus described in  claim 15  further comprising means for maintaining said solution at a temperature between about 10 and 40° C. during electro-deposition.  
     
     
         17 . The apparatus described in  claim 15  wherein said anode is cobalt during CoFe plating.  
     
     
         18 . The apparatus described in  claim 15  wherein said anode is nickel during FeCoNi plating.  
     
     
         19 . The apparatus described in  claim 15  wherein said current has a density of between about 3 and 30 mA/cm 2 .