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

Abstract

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 /spl mu/m diameter, 0.09 /spl mu/m tall Co-Cu ML pedestal. The sensors are patterned using electron beam lithography. The Al/sub 2/O/sub 3/-TiC substrate is coated with a sputter deposited Al/sub 2/O/sub 3/ 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 and Co-Cu multilayers onto a smooth 0.45 /spl 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) Si/sub 3/N/sub 4/ film. The configuration of the contacts allows four point probe resistance measurements. The CPP-GMR coefficient for these 0.4 /spl mu/m diameter sensors is 13%.