Resistive Element With Lateral And Vertical Piezo-Resistive Coefficients
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Solution Overview
Problem
Current Hall plates are affected by mechanical stress, which impacts their magnetic sensitivity, and there is a lack of resistors with the required piezo-resistive coefficient to compensate for this stress effectively.
Innovation Solution
A resistive element with specific piezo-resistive coefficients for lateral and vertical current flows is designed, comprising a semiconductor substrate with isolated resistive regions and contact structures that generate a current flow distribution to achieve a targeted piezo-resistive coefficient, allowing for mechanical stress-dependent signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resistors are used to compensate for mechanical stress in Hall plates, then the magnetic sensitivity measurement can be performed, but the compensation is ineffective due to mismatched piezo-resistive coefficients
Solution Approach 1:
The patent changes the piezo-resistive coefficient parameter by designing a resistive element with specific lateral and vertical current flow paths in silicon, achieving a piezo-resistive coefficient that matches the Hall plate's piezo-Hall coefficient. This parameter matching enables effective stress compensation and improves measurement accuracy.
2Device complexity
If the current generator is placed close to the Hall plate to reduce device complexity, then the overall device size is reduced, but the current generator is also affected by the same mechanical stress, compromising compensation accuracy
Solution Approach 1:
The patent applies local quality by creating a resistive element with non-uniform current flow distribution, where lateral and vertical current paths experience different mechanical stress conditions. This local differentiation in stress exposure allows the resistive element to generate a compensation signal that accurately reflects the Hall plate's stress state while maintaining compact integration.
3Measurement precision
If a resistive element with directional current flow paths is designed to achieve specific piezo-resistive coefficient, then the compensation accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent introduces a vertical dimension to the current flow paths in addition to lateral paths, creating a three-dimensional current distribution within the resistive element. This dimensional approach enables the generation of a specific piezo-resistive coefficient that matches the Hall plate's characteristics while maintaining a compact planar structure suitable for integrated circuit fabrication.
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 resistive element effectively compensates for mechanical stress-induced sensitivity variations in Hall plates by generating a signal with a specific piezo-resistive coefficient, improving the stability and accuracy of magnetic sensitivity measurements.
Implementation Method 1
The resistive region extends in a lateral direction parallel to the main surface area and in a vertical direction perpendicular to the main surface area, is isolated from the semiconductor substrate in the lateral direction and comprises for a (specific) stress component a first piezo-resistive coefficient for a current flow in the lateral direction and a second piezo-resistive coefficient, different from the first piezo-resistive coefficient, for a current flow in the vertical direction
Data Source
AI summary
A resistive element includes a resistive region in a semiconductor substrate, a first contact structure and a second contact structure. The semiconductor substrate includes a first main surface area. The resistive region extends in a lateral direction parallel to the main surface area and in a vertical direction perpendicular to the main surface area, and includes a first piezo-resistive coefficient for a current flow in the lateral direction and a second piezo-resistive coefficient for a current flow in the vertical direction. The first contact structure contacts a portion of a first face of the resistive region and the second contact structure contacts a portion of a second face of the resistive region. The resistive element generates a current flow distribution within the resistive region having a lateral component and a vertical component that results in a piezo-resistive coefficient of the resistive element.