Perpendicular current giant magnetoresistance in 0.4 mu m diameter Co-Cu multilayer sensors

We have fabricated a novel giant magnetoresistive (GMR) multilayer (ML) flux sensor that is designed to operate in the current perpendicular to the plane (CPP) mode. The CPP-GMR sensor is a 0.4 mu m diameter, 0.09 mu m tall Co-Cu ML pedestal. The sensors are patterned using electron beam lithography. The Al2O3-TiC substrate is coated with a sputter deposited Al2O3 film that is polished to <0.2 nm root mean square (RMS) roughness. Contact to the bottom of the CPP-GMR sensor is made by depositing the Co-Cu multilayers onto a smooth 0.45 mu m thick Mo-Si ML stack. The top contact is self-aligned to the CPP-GMR sensor. This is accomplished, in part, by chemical mechanical polishing (CMP). The top and bottom contacts are electrically isolated by a plasma enhanced chemical vapor deposited (PECVD) Si3N4 film. The configuration of the contacts allows four point probe resistance measurements. The CPP-GMR coefficient for these 0.4 mu m diameter sensors is 13%.