Temperature-Compensated MR Sensor Using Diffused Metal Layers
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Solution Overview
Problem
Magnetoresistance elements used in sensors are affected by temperature changes, which can lead to inaccurate magnetic field measurements due to their temperature-dependent electrical resistance.
Innovation Solution
A temperature-compensated magneto-resistive sensor is fabricated using a Wheatstone bridge circuit with both active and less active magnetoresistive elements, where the less active elements have metal layers diffused into other layers to minimize their response to magnetic fields, allowing the sensor to maintain stability across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistance elements are used to sense magnetic fields, then magnetic field detection capability is improved, but temperature stability deteriorates due to temperature-dependent electrical resistance
Solution Approach 1:
The sensor is divided into multiple magnetoresistance elements arranged in a Wheatstone bridge circuit. By segmenting the sensing function across multiple elements with different magnetic field responses, the system can differentiate between temperature effects and actual magnetic field signals, thereby maintaining measurement precision while improving temperature stability.
Solution Approach 2:
The patent applies heat treatment to deliberately alter the magnetic properties of certain magnetoresistance elements, reducing their magnetic field response. This parameter change creates elements with differentiated characteristics that respond differently to temperature versus magnetic field changes, enabling temperature compensation while preserving accurate magnetic field detection in other elements.
2Reliability
If heat is applied to diffuse metal layers in magnetoresistance elements, then temperature compensation is improved, but manufacturing complexity increases
Solution Approach 1:
The heat treatment is performed during the manufacturing process to pre-establish the desired magnetic properties of the compensation elements before final assembly. This preliminary action ensures that the temperature compensation characteristics are built into the device structure, avoiding the need for complex post-manufacturing adjustments or additional compensation circuitry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively cancels out temperature-induced voltage differences, ensuring that the output voltage is responsive only to magnetic fields and not temperature changes, thereby enhancing the accuracy and reliability of magnetic field sensors.
Implementation Method 1
applying heat to a semiconductor structure that includes a first magnetoresistive (MR) element to diffuse at least one metal layer of the first MR element into other layers of the first MR element
Implementation Method 2
Magnetoresistance elements are known to be manufactured in a variety of configurations, including, but not limited to giant magnetoresistance (GMR) elements and anisotropic magnetoresistance (AMR) elements
Data Source
AI summary
In one aspect, an integrated circuit (IC) includes a sensor that includes a first magnetoresistive (MR) element and a second MR element less active to a presence of a magnetic field than the first MR element. The second MR element includes a metal layer diffused into other layers of the second MR element.