MEMS Membrane Sensor Layout for Tilting Mode Compensation
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Solution Overview
Problem
MEMS semiconductor devices with deformable membranes for measuring acceleration, vibration, or pressure face issues with noise due to imperfect membrane deformation and tilting modes of the mass element, which complicates signal filtering.
Innovation Solution
A semiconductor device with a deformable membrane and multiple mass elements suspended from its border, positioned to compensate tilting modes symmetrically, ensuring a translatorily oscillating mode and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single mass element is attached to the membrane, then the device structure is simple, but tilting modes occur causing noise and measurement errors
Solution Approach 1:
The single mass element is divided into multiple mass elements (at least two) that are distributed around the membrane center. Each mass element generates its own tilting mode, but the symmetric arrangement causes these tilting modes to compensate for each other, resulting in a net translational oscillation without unwanted tilting. This segmentation resolves the contradiction by improving measurement accuracy through tilting compensation while maintaining reasonable structural complexity.
Solution Approach 2:
The mass elements are positioned asymmetrically relative to the membrane center, with each mass element located at a different position around the center. This asymmetric distribution is carefully designed so that the combined center of mass remains at the membrane center, creating symmetric compensation of tilting modes. The asymmetric positioning of individual elements achieves the goal of eliminating net tilting while maintaining simple structure.
2Reliability
If electric filters are used to filter noise from the electric signal, then noise is reduced, but the filtering operation becomes too complicated
Solution Approach 1:
Instead of trying to filter out the harmful tilting modes after they occur, the invention converts the harmful effect into a beneficial one by using the symmetric arrangement of multiple mass elements to cause the tilting modes to automatically compensate for each other. The harmful tilting motion is transformed into a beneficial self-cancelling effect, producing only the desired translational oscillation. This eliminates the need for complex electric filtering operations.
3Measurement precision
If the membrane thickness is reduced to improve sensitivity, then measurement sensitivity increases, but the membrane becomes more difficult to control and more prone to imperfections
Solution Approach 1:
The multiple mass elements act as counterweights that balance each other's gravitational and inertial effects. By positioning at least two mass elements symmetrically around the membrane center, their individual tilting effects (which would be problematic in a thin membrane) are counterbalanced, allowing the use of thinner, more sensitive membranes without sacrificing control stability. The mass elements compensate for the membrane's reduced stiffness.
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 symmetric compensation of tilting modes in the mass elements stabilizes the oscillating mode, reducing noise and enhancing the accuracy of vibration, acceleration, and pressure measurements.
Implementation Method 1
Information on the membrane's deformation is provided by an electric signal, e.g. through a capacitive, piezoelectric, or resistive technique.
Implementation Method 2
Information on the membrane's deformation is provided by an electric signal, e.g. through a capacitive, piezoelectric, or resistive technique.
Implementation Method 3
Information on the membrane's deformation is provided by an electric signal, e.g. through a capacitive, piezoelectric, or resistive technique.
Data Source
AI summary
A semiconductor device for use in a sensor device has a deformable membrane for the measurement of an acceleration, a vibration, or a pressure. The semiconductor device includes a deformable membrane having a membrane border; a structure holding the deformable membrane in correspondence of the membrane border; at least one electric contact to obtain an electric signal indicative of deformation of the deformable membrane; and mass elements suspended from the membrane.