Microelectronic 3D bipolar magnetotransistor magnetometer

A pyramid shaped etch is made in an n or p type silicon substrate, or any symmetric etch with slanted edges, with p or n type implants in the slanted edges of the etch to form a PN junction. On this structure, an emitter and two collectors are formed by further implanting n+ regions in the PN junction region. To complete the device, ohmic contacts are formed to establish a base region. In operation, an appropriate bias is applied to the emitter through to the base and collectors. By so biasing the device, the device operates as a standard bipolar transistor. The currents of both the minority and majority carriers in the base region will respond to the component of the magnetic field perpendicular to the face of the slanted etch. As a result, there will be a difference in the currents in the collectors. These currents can then be simply calibrated to measure the magnetic field component. By forming similar sensors on 3 or 4 of the faces of the etched structure all three components of the magnetic field can be computed.