MEMS Pressure Sensor With Membrane-Driven Magnetic Field Sensing
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Solution Overview
Problem
Conventional pressure sensors face challenges such as high manufacturing costs and integration difficulties, particularly with piezoelectric sensors being sensitive to stress and requiring significant IC area for anodic bonding, and capacitive conversion methods needing complex glass bonding.
Innovation Solution
A MEMS pressure sensor design featuring separate electrodes and a conductive or dielectric membrane that moves relative to these electrodes, allowing capacitance measurement without direct electrical connection, and incorporating a magnetic sensor element to generate signals based on a magnetic field influenced by the membrane's movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric sensor concepts are used, then pressure sensing function is achieved, but integration difficulty increases and stress sensitivity causes reliability issues
Solution Approach 1:
The patent extracts the piezoelectric active elements from the integrated circuit structure and places them in a separate MEMS structure. This allows the IC to be manufactured using standard semiconductor processes without piezoelectric materials, while the MEMS structure handles the pressure sensing function. The separation resolves the integration difficulty and stress sensitivity issues by eliminating the need to integrate piezoelectric elements directly into the IC.
Solution Approach 2:
The sensor system is divided into two independent parts: an IC chip containing readout circuits and a separate MEMS structure containing the piezoelectric elements and pressure-sensitive membrane. These segments are connected through wire bonds or other interconnection methods. This segmentation allows each component to be optimized and manufactured independently, resolving the contradiction between integration difficulty and reliability.
2Measurement precision
If capacitive conversion with floating counter electrodes is used, then pressure measurement is enabled, but manufacturing cost increases due to complex glass bonding requirements
Solution Approach 1:
The patent replaces the complex mechanical glass bonding process with a simpler approach using standard semiconductor fabrication techniques. The capacitive electrodes are formed directly in the MEMS structure using deposited metal or conductive polymer layers, eliminating the need for anodic bonding between silicon and glass. This substitution dramatically simplifies manufacturing while maintaining measurement precision.
Solution Approach 2:
The patent changes the material parameters and fabrication process parameters to achieve capacitive sensing without glass bonding. By using deposited conductive layers and standard semiconductor processing, the system achieves the required capacitance measurement capability through parameter optimization rather than complex mechanical bonding processes.
3Reliability
If bulk micro machined pressure sensors are used, then pressure sensing is achieved, but manufacturing cost increases
Solution Approach 1:
The patent makes the MEMS structure serve multiple functions: it provides the pressure-sensitive membrane, contains the piezoelectric elements, forms the capacitive electrodes, and creates the hermetically sealed cavity. This multi-functionality eliminates the need for separate components and complex assembly processes, reducing manufacturing cost while maintaining reliable pressure sensing.
Solution Approach 2:
The patent merges the pressure sensing function, capacitive conversion function, and hermetic sealing function into a single integrated MEMS structure. The membrane, electrodes, and cavity are formed as one piece through standard semiconductor processing, eliminating the need for separate manufacturing steps and reducing overall manufacturing cost.
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
This design reduces manufacturing costs and avoids integration issues, enabling precise pressure measurement with improved sensitivity and temperature compensation, while maintaining a simple MEMS structure free from electronic components.
Implementation Method 1
an integrated circuit configured to sense a capacitance between the at least two electrodes
Implementation Method 2
a conductive or dielectric membrane configured to move, depending on the pressure, relative to the at least two electrodes
Implementation Method 3
a magnetic sensor element configured to generate a signal based on a magnetic field sensed by the magnetic sensor element
Implementation Method 4
a field influencing element configured to modify the magnetic field based on a movement of the membrane
Data Source
AI summary
A pressure sensor is provided. The pressure sensor includes a magnetic sensor element configured to generate a signal based on a magnetic field sensed by the magnetic sensor element; a microelectromechanical system (MEMS) structure including a membrane configured to move, depending on a pressure applied thereto, relative to the magnetic sensor element; and a field influencing element configured to modify the magnetic field based on a movement of the membrane, wherein the field influencing element is arranged on the membrane.