Patent ID: 8456781

Claim:
A method of forming a magnetoresistive element in a TMR sensor, comprising: (a) forming a seed layer on a substrate; (b) depositing a first ferromagnetic layer (FL2) on the seed layer, said (FL2) layer has an inner surface contacting the seed layer, an outer surface facing away from the seed layer, and is comprised of one or more of Co W Fe (100-W) where w is from 0 to about 100 atomic %, Ni Z Fe (100-Z) where z is from about 70% to 100%, and an alloy wherein CoFe or NiFe are combined with one or more elements selected from Ni, Ta, Mn, Ti, W, Zr, Hf, Tb, Nb, and B; (c) performing a weak plasma etch treatment (PT) on the outer surface of said first ferromagnetic layer (FL2) thereby forming a modified (FL2) layer that has one or both of a modified surface structure and increased surface energy with respect to other portions of the (FL2) layer; (d) sequentially depositing an insertion layer (INS) and a second ferromagnetic layer (FL1) on the modified surface of the first ferromagnetic layer (FL2) to give a composite free layer with a (FL2)(PT)/(INS)/(FL1) configuration, said insertion layer has at least one magnetic element selected from Fe, Co, and Ni and at least one non-magnetic element selected from Ta, Ti, W, Zr, Hf, Nb, Mo, V, Mg, and Cr, and said second ferromagnetic layer is comprised of one or more of Co W Fe (100-W) , [Co W Fe (100-W) ] (100-Y) B Y where w is from 0 to about 100% and y is from 10 atomic % to about 40 atomic %, and an alloy of Co W Fe (100-W) , or [Co W Fe (100-W) ] (100-Y) B Y that is comprised of one or more additional elements including Ni, Ta, Mn, Ti, W, Zr, Hf, Tb, and Nb; (e) sequentially forming a non-magnetic spacer, pinned layer, and antiferromagnetic (AFM) layer on the (FL1) layer; and (f) forming a capping layer on the AFM layer.