US Patent:
20080309331, Dec 18, 2008
Inventors:
Zhenghong Qian - Westborough MA, US
Gunther Baubock - Southborough MA, US
Barry T. O'Connell - Worcester MA, US
International Classification:
G01R 33/09
H01L 43/08
H01L 43/12
US Classification:
324252, 338 32 R, 438 3, 257E43004, 257E43006
Abstract:
A giant magnetoresistive sensor apparatus is described that provides improved multilayer quality, hysteresis, linearity and sensitivity. The multilayer structure includes NiFeCr as buffer and cap layers. The sensing resistor is designed in the form of a serpentine structure. To minimize the hysteresis and improve the linearity, the resistor end is tapered and elongated. In forming the sensor in a Wheatstone bridge configuration, two resistors are shielded by thick NiFe layers, while the two sensing resistors are not shielded and open to external signal fields. The shields can not only shield the influence of the external field on the shielded resistors but also serve as magnetic flux concentrators to magnify the external field on the unshielded resistors. The bridge output reflects the resistance change of the two unshielded sensing resistors.
