Current-perpendicular-to-plane (cpp) read sensor with multiple reference layers

Abstract

A current-to-perpendicular-to-plane (CPP) read sensor with multiple reference layers and associated fabrication methods are disclosed. According to one embodiment of the invention, the multiple reference layers of a CPP tunneling magnetoresistance (TMR) read sensor includes a first reference layer formed by a ferromagnetic polycrystalline Co—Fe film, a second reference layer formed by a ferromagnetic substitute-type amorphous Co—Fe—X film where X is Hf, Zr or Y, and a third reference layer formed by a ferromagnetic interstitial-type amorphous Co—Fe—B film. The first reference layer facilitates the CPP TMR read sensor to exhibit high exchange and antiparallel-coupling fields. The second reference layer provides a thermally stable flat surface, thus facilitating the CPP TMR read sensor to exhibit a low ferromagnetic-coupling field. The multiple reference layers may induce spin-dependent scattering, thus facilitating the CPP TMR sensor to exhibit a high TMR coefficient.

I claim: 
     
         1 . A method of fabricating a flux-closure structure for a current-perpendicular-to-plane (CPP) read sensor, the method comprising:
 depositing a keeper layer;   depositing an antiparallel coupling layer on the keeper layer;   depositing a first reference layer of a ferromagnetic polycrystalline film on the antiparallel coupling layer;   depositing a second reference layer of a ferromagnetic substitute-type amorphous film on the first reference layer; and   depositing a third reference layer of a ferromagnetic interstitial-type amorphous film on the second reference layer.   
     
     
         2 . The method of  claim 1  wherein the first reference layer is formed by a Co—Fe film including Co with a content ranging from 50 to 90 at % and Fe with a content ranging from 10 to 50 at %, and having a thickness ranging from 0.2 to 1 nanometers. 
     
     
         3 . The method of  claim 1  wherein the second reference layer is formed by a Co—Fe—X film including Co with a content ranging from 60 to 80 at %, Fe with a content ranging from 0 to 40 at %, and X with a content ranging from 6 to 30 at %, where X is Hf, Zr or Y, and having a thickness ranging from 0.6 to 2 nanometers. 
     
     
         4 . The method of  claim 1  wherein the third reference layer is formed by a Co—Fe—B film including Co with a content ranging from 60 to 80 at %, Fe with a content ranging from 0 to 40 at %, and B with a content ranging from 6 to 30 at %, and having a thickness ranging from 1 to 2 nanometers.