A Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor, transverse to an electric current in the conductor, and a magnetic field perpendicular to the current. When a current-carrying semiconductor is kept in a magnetic field, the charge carriers of the semiconductor experience a force in a direction perpendicular to both the magnetic field and the current. At equilibrium, a voltage appears at the semiconductor edges. The formula for the Hall coefficient becomes more complex in semiconductors where the carriers are generally both electrons and holes which may be present in different concentrations and have different mobilities.
Hall effect sensors are used as proximity sensors, slide-by switch sensors, wheel speed sensors, and brushless DC motor sensors in a variety of industries. Hall sensors are used in the household appliances, gaming systems, construction equipment, utility meters and in the automotive industry as magnetic sensors for position measurements. Traditional mechanical based switches tend to wear out over many “close”/“open” operations, having long-term reliability issues. Hall effect sensors offer excellent long-term reliability since they can operate without the need to have any contacting mechanical parts and are beneficial for automotive applications which have stringent reliability requirements.
One-dimensional (1D) Hall effect sensors sense a magnetic field perpendicular to a semiconductor chip. Three-dimensional (3D) sensors are advantageous over 1D sensors, since fewer 3D sensors can be used, thereby saving space, time and cost. 3D Hall effect sensors are an improvement over 1D sensors, since they sense a magnetic field both perpendicular and in-plane to the chip. 3-Axis Hall sensors are integrated 1D and two dimensional (2D) elements and assembled from six building blocks, thereby making the assembly process too complicated, and the resulting sensor undesirably large. Further, with 3-Axis sensors, the magnetic field may not be sensed in one common region. For a multiple contact Hall sensor, each sensing terminal is a result or under the influence of at least two magnetic fields, which leads to cross interference. Moreover, with existing 3D Hall sensors, the employment of one n-type element makes it more difficult to design planar and vertical Hall elements for sensitivity optimization.
A need therefore exists for devices and methodologies for enabling vertical and planar elements to be integrated within a 3D Hall effect sensor to improve sensing accuracy and to reduce cost and cross-interference within the resulting devices.