Magneto-Resistive Sensor Module Stress Buffer Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magneto-resistive sensors integrated with ICs face temperature-dependent stress issues due to differing coefficients of thermal expansion, leading to asymmetrical stress distribution and increased temperature-dependent offset voltage, which impairs their precision and reliability in automotive applications.
Innovation Solution
Incorporating a stress buffer layer with a coefficient of thermal expansion between that of the dielectric layer and the magneto-resistive sensor elements, positioned between the integrated circuit and the magneto-resistive sensor elements, to absorb temperature-dependent stress and reduce offset voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If magneto-resistive sensor elements are monolithically integrated on the integrated circuit, then device size is reduced and manufacturing cost is reduced, but temperature-dependent stress is induced due to differing coefficients of thermal expansion
Solution Approach 1:
A stress buffer layer is introduced as an intermediary component between the integrated circuit and the magneto-resistive sensor elements. This buffer layer has a coefficient of thermal expansion intermediate between that of the IC and the sensor elements, acting as a mediator that absorbs and distributes thermal stress, preventing direct stress transmission to the sensor elements while maintaining the benefits of monolithic integration.
Solution Approach 2:
The coefficient of thermal expansion of the stress buffer layer is specifically selected to be between that of the integrated circuit and the magneto-resistive sensor elements. By changing this material parameter, the buffer layer creates a gradient that gradually accommodates the thermal expansion mismatch, reducing the abrupt stress that would otherwise be induced in the sensor elements during temperature variations.
2Measurement precision
If a stress buffer layer is added to mitigate thermal stress, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The stress buffer layer is applied selectively only in regions where magneto-resistive sensor elements are present, rather than covering the entire integrated circuit surface. This localized application approach maintains measurement precision where needed while minimizing the overall added complexity and material usage, as the buffer layer is concentrated in the critical sensor regions.
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 stress buffer layer effectively mitigates thermally induced stresses, enhancing the precision and reliability of magneto-resistive sensor modules by minimizing temperature-dependent offset voltage, thereby improving measurement accuracy over a wide temperature range.
Implementation Method 1
The stress buffer layer has a coefficient of thermal expansion between that of the dielectric layer and that of the magneto-resistive sensor element and the stress buffer layer is arranged to absorb temperature dependent stress induced in the magneto-resistive sensor element
Data Source
AI summary
According to embodiments there is provided a magneto-resistive sensor module. The sensor module may comprise: an integrated circuit; magneto-resistive sensor elements arranged as a bridge circuit monolithically integrated on the integrated circuit; and a stress buffer layer arranged between the integrated circuit and the magneto-resistive sensor element. There is also a provided a method of manufacturing the magneto-resistive sensor module.