Patent ID: 7636223
Filing Date: 2009-12-22
Classification: B82Y,G01R,G11B,H01L

Abstract:
1. A three terminal magnetic sensor (TTM) comprising: a sensor stack structure comprising a base region, a collector region, and an emitter region; a first barrier layer located between the emitter region and the base region; a second barrier layer located between the collector region and the base region; a plurality of terminals of the TTM comprising a base lead coupled to the base region, a collector lead coupled to the collector region, and an emitter lead coupled to the emitter region; the collector region comprising a layer of semiconductor material; the base region comprising a free layer structure made of ferromagnetic materials; an in-stack longitudinal biasing layer structure formed in stack with the sensor stack structure and having a magnetic moment that is parallel to a sensing plane of the TTM for longitudinally biasing the free layer structure; the in-stack longitudinal biasing layer comprising a first self-pinned layer structure which is separated from the base region by one of the first and the second barrier layers, which also serves as a spacer layer for the in-stack longitudinal biasing layer structure; a second self-pinned layer structure which is separated from the base region by the other one of the first and the second barrier layers; an insulator layer which is offset from the sensing plane and in between the base region and the collector region; and a layer of metal which is offset from the sensing plane and in contact with the ferromagnetic materials of the base region, the layer of metal having an electrical resistivity of less than 10 μΩ-centimeters so that a combined electrical resistivity of the base region is between about 2-18 μΩ-centimeters.