Fabrication process for hybrid magnetic material and fabrication of tunnel magnetoresistive read head

In order to fabricate a read head using tunnel magnetoresistive junction，optimization of the tunnel junction(layered structure，stacking sequence，optimal annealing condition，thickness of barrier layer)and micro-fabricating process have been studied。Two kinds of read head were successfully demonstrated.The main results are summarized as follows.1。The Ta30()/Ni_&lt；80&gt；Fe_&lt；20&gt；(30)/Cu(200)/IrMn(100)CoFe(40)/Al-oxide/CoFe(40)/Ni_&lt；80&gt；Fe_&lt；20&gt；(200)/Ta(50)junction annealed at 250℃for 1h exhibited that the values of resistance times cross section and tunnel magnetoresistance ratio were78Ω·µm^2 and 33%，respectively.2..Using the photolisography and Ar ion milling process，we fabricated a small junction with 3x3µm^2.On the other hand，small junction with 0.5x0.5µm^2was obtained by using electron beam lithography and no damage was confirmed for the junction by comparing the transport property measured before and after micro fabrication.3.Feasibility of tunnel magnetoresistive read head with flux-guide layers was investigated for helical-scan tape storage applications.A long-range exchange coupling bias scheme，with a Cu layer and an antiferromagnet were deposited on top of free layer in the tunnel-valve element，was employed.In order to stabilize domain structures in the free layer，the long range exchange coupling biasing was combined with conventional permanent magnet bias method。The maximum output voltage of the flux guide type reader was 1.75 mV_&lt；p-p&gt；which was corresponding to+1.5dB of a conventional anisotropic magnetoresistive reader.Furthermore，a tunnel magnetoresistive read head for HDD application was fabricated and an out put voltage corresponding to 10 Gb/inch^2was realized。

In order to fabricate a read head using tunnel magnetoresistive junction, optimization of the tunnel junction (layered structure, stacking sequence, optimal annealing condition, thickness of barrier layer) and micro-fabricating process have been studied. Two kinds of read head were successfully demonstrated. The main results are summarized as follows.1. The Ta30(Å)/Ni_<80>Fe_<20>(30Å)/Cu(200Å)/IrMn(100Å)CoFe(40Å)/Al-oxide/CoFe(40Å)/Ni_<80>Fe_<20>(200Å)/Ta(50Å) junction annealed at 250 ℃ for 1 h exhibited that the values of resistance times cross section and tunnel magnetoresistance ratio were 78 Ω・μm^2 and 33 %, respectively.2. Using the photolisography and Ar ion milling process, we fabricated a small junction with 3x3 μm^2. On the other hand, small junction with 0.5x0.5 μm^2 was obtained by using electron beam lithography and no damage was confirmed for the junction by comparing the transport property measured before and after micro fabrication.3. Feasibility of tunnel magnetoresistive read head with flux-guide layers was investigated for helical-scan tape storage applications. A long-range exchange coupling bias scheme, with a Cu layer and an antiferromagnet were deposited on top of free layer in the tunnel-valve element, was employed. In order to stabilize domain structures in the free layer, the long range exchange coupling biasing was combined with conventional permanent magnet bias method. The maximum output voltage of the flux guide type reader was 1.75 mV_<p-p> which was corresponding to +1.5 dB of a conventional anisotropic magnetoresistive reader. Furthermore, a tunnel magnetoresistive read head for HDD application was fabricated and an out put voltage corresponding to 10 Gb/inch^2 was realized.