Integrated hall effect sensors with voltage controllable sensitivity

A method of forming a device comprising:

• providing a crystalline-on-insulator (COI) substrate having
• a bulk crystalline substrate,
• a surface crystalline substrate, and
• a buried oxide layer disposed between the bulk and surface crystalline substrates;
• preparing a sensor region, the sensor region having
• a surface sensor region disposed on the surface crystalline substrate, and
• a bulk sensor region disposed on the bulk crystalline substrate;
• and
• forming a Hall effect sensor in the sensor region, wherein forming the Hall effect sensor comprises
• forming a Hall plate in the surface sensor region, the Hall plate is part of the surface crystalline substrate, the Hall plate comprises
• first and second current terminals, the Hall plate is configured to flow current through the Hall plate between the first and second current terminals in a length direction of the Hall plate, and
• first and second sensing terminals, the first and second sensing terminals are configured to sense a Hall voltage Vu along a width direction of the Hall plate,
• wherein the length and width directions are perpendicular directions, and
• wherein a predetermined thickness of the Hall plate is determined by a thickness of the surface crystalline substrate,
• forming a sensor well in the bulk sensor region in the bulk crystalline substrate, and
• forming a sensor well tap in the sensor well, the sensor well tap is coupled to a sensor well bias voltage for biasing the sensor well for varying a thickness of the Hall plate from the predetermined thickness of the Hall plate to tune the sensitivity of the Hall effect sensor.

A device comprising:

• a crystalline-on-insulator (COI) substrate having
• a bulk crystalline substrate,
• a surface crystalline substrate, and
• a buried oxide layer disposed between the bulk and surface crystalline substrates;
• a sensor region, the sensor region having
• a surface sensor region disposed on the surface crystalline substrate, and
• a bulk sensor region disposed on the bulk crystalline substrate;
• a Hall effect sensor disposed in the sensor region, the Hall effect sensor comprises
• a Hall plate in the surface sensor region, the Hall plate is part of the surface crystalline substrate, the Hall plate comprises
• first and second current terminals, the Hall plate is configured to flow current through the Hall plate between the first and second current terminals in a length direction of the Hall plate,
• first and second sensing terminals, the first and second sensing terminals are configured to sense a Hall voltage Vu along a width direction of the Hall plate,
• wherein the length and width directions are perpendicular directions, and
• wherein a predetermined thickness of the Hall plate is determined by a thickness of the surface crystalline substrate,
• a sensor well disposed in the bulk sensor region in the bulk crystalline substrate, and
• a sensor well tap in the sensor well, the sensor well tap is coupled to a sensor well bias voltage for biasing the sensor well for varying a thickness of the Hall plate from the predetermined thickness of Hall plate to tune the sensitivity of the Hall effect sensor;
• and
• a gate disposed on the Hall effect sensor, wherein the gate is coupled to a gate bias voltage for varying the thickness of the Hall plate from the predetermined thickness from a top of the Hall plate to tune the sensitivity of the Hall effect sensor.