Method for making a current-perpendicular-to-the-plane (CPP) magnetoresistive sensor containing a ferromagnetic alloy requiring post-deposition annealing

A method for making a current-perpendicular-to-the-plane (CPP) magnetoresistive sensor having a pinned layer comprising:

• providing a substrate in a vacuum chamber;
• depositing on the substrate a pinning layer of a Mn alloy capable of becoming antiferromagnetic;
• and
• forming on the pinning layer a multilayer pinned layer comprising the steps of:
• depositing on the Mn alloy layer a non-Heusler alloy ferromagnetic layer;
• depositing on the non-Heusler alloy ferromagnetic layer a layer of a ferromagnetic alloy comprising B and one or more of Ta, Ti, Zr, Nb, Si and W;
• after depositing said ferromagnetic alloy comprising B and one or more of Ta, Ti, Zr, Nb, Si and W, performing a first annealing in the vacuum chamber by subjecting the deposited layers to a temperature between 250-400° C for between 1-60 minutes;
• after said first annealing, depositing at least one layer of material selected from a Heusler alloy material and a non-Heusler alloy material of the form (CoyFe(100-y))(100-z)Xz(where X is one or more of Ge, Al, Si or Ga, y is between about 45 and 55 atomic percent, and z is between about 20 and 40 atomic percent);
• and
• performing a second annealing in the vacuum chamber by subjecting the deposited layers to a temperature between 300-550° C for between 1-60 minutes to thereby form said multilayer pinned layer;
• after said second annealing step, depositing a nonmagnetic spacer layer on said layer of material selected from a Heusler alloy material and a non-Heusler alloy material of the form CoyFe(100-y))(100-z)Xz (where X is one or more of Ge, Al, Si or Ga, y is between about 45 and 55 atomic percent, and z is between about 20 and 40 atomic percent), and a non-Heusler alloy ferromagnetic free layer on the nonmagnetic spacer layer.