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We have fabricated and tested GMR magnetic sensors that operate in the CPP mode. This work is a continuation of the ultra-high density magnetic sensor research introduced a t INTERMAG 96. We have made two significant modifications to the process sequence. First, contact to the sensor is made through a metal conduit deposited in situ with the multilayers. This deposition replaces electroplating. T h i s configuration ensures a good electrical interface between the top of multilayer stack and the t o p contact, and a continuous, conductive current path to the sensor. The consequences of t h i s modification are an increase in yield of operational devices to 290% per wafer and a significant reduction of the device resistance to 4560 mil and of the uniformity of the device resistance to 1 3 % . Second, the as-deposited multilayer structure h a s been changed from [Cu 30 A/Co 20 A118 (third peak) to [Cu 20.5 &CO 12 63130 (second peak) t oincrease the GMR response. The best second peak CPP GMR response from a single device is 39%. The sensitivity of that device is 0.13 %/Oe.

Abstract-A large giant magnetoresistance (GMR) value of 7.5% has been measured in simple NiFeCo(l)lCu/NiFeCo(2) sandwich films grown on a 30 A Cr seed layer. This spin-valve GMR effect is consistent with the differential switching of the two NiFeCo layers due to an enhanced coercivity of the NiFeCo(1) layer grown on the Cr seed layer. A change in growth texture of the NiFeCo(1) layer from fee (111) to bee (110) crystallographic orientation leads to an increase in magnetic anisotropy and and an enhancement in coercivity.The GMR value increases to 8.7% when a thin CoFe interfacial enhancing layer is incorporated. Further enhancement in GMR values up to 14% is seen in the sandwich films by nanooxide layer formation. The specular reflection at oxide/magnetic layer interface further extends the mean free path of spinpolarized electrons.

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