Improved performance of Cu-Co CPP GMR sensors

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 at 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. This configuration ensures a good electrical interface between the top of multilayer stack and the top contact, and a continuous, conductive current path to the sensor. The consequences of this modification are an increase in yield of operational devices to greater than or equal to 90% per wafer and a significant reduction of the device resistance to less than or equal to 560 mn and of the uniformity of the device resistance to less than or equal to 3%. Second, the as-deposited multilayer structure has been changed from [Cu 30 Angstrom/Co 20 Angstrom](18) (third peak) to [Cu 20.5 Angstrom/Co 12 Angstrom](30) (second peak) to increase 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.