This Small Business Innovation Research Phase I project is designed to demonstrate the feasibility of building giant-magnetoresistive (GMR) bridge sensors that exhibit tenfold and greater improvement in hysteresis over existing bridge sensors. Unique processing enables edge pinning in GMR sandwich resistor elements that leads to increased stability and significant reduction in hysteresis. Technical objectives required to develop the low hysteresis bridge sensors are: (1) determine the edge hardening mechanism; (2) develop a single-step edge hardening process protocol; (3) develop a two-step edge hardening process protocol; (4) design sensor prototypes utilizing low hysteresis; and (5) build and characterize hard-edge bridge sensors. The research will focus on first gaining an understanding and control of the hard edge treatment. This effort will produce a basic low hysteresis bridge sensor. That knowledge will then be applied to processing variable degrees of hard edge profiles within a given device. The result of this effort will be a self-biased full-output bride sensor and a fully symmetric bridge sensor. In addition to addressing the need for low hysteresis in magnetic bridge sensors, the processes developed can be applied to integrated linear and digital output sensors and signal isolation devices.
