Capacitive Pressure Sensor Electrodes With Integrated Gas Gettering
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Solution Overview
Problem
Pressure sensors face measurement inaccuracies due to gas molecules outgassing or entering the device, which can be addressed by integrating a getter material into the electrodes to trap and absorb these gases, thereby maintaining measurement quality without requiring additional space or increasing the sensor's size.
Innovation Solution
Incorporating a getter material into the electrodes of a pressure sensor, which serves multiple functions: sensing membrane deflection, chemically binding or absorbing gas molecules, and protecting underlying electrode materials from corrosion, while being manufactured using conventional processes like CMOS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate getter arrangement is added to the pressure sensor, then gas molecules can be trapped and measurement accuracy improves, but the sensor size increases
Solution Approach 1:
The patent combines the getter material with the electrode structure, creating a multi-functional component that serves both as an electrical electrode for capacitance measurement and as a getter for trapping gas molecules. This integration eliminates the need for a separate getter arrangement, maintaining measurement accuracy while avoiding increased sensor size.
Solution Approach 2:
The electrode is designed to perform multiple functions simultaneously: it acts as an electrical conductor for the capacitive sensing mechanism and as a getter material for adsorbing and trapping gas molecules. This multi-functionality resolves the contradiction by achieving gas trapping without adding separate components that would increase sensor volume.
2Measurement precision
If getter material is integrated into the electrode, then gas molecules are trapped and measurement quality is maintained, but the electrode material may be exposed to corrosive gases
Solution Approach 1:
The patent applies getter material specifically on the side of the electrode facing the cavity where gas molecules are present, while the bulk electrode material maintains its electrical properties. This localized application allows the electrode to trap gases effectively while the underlying electrode structure remains protected from corrosive exposure.
Solution Approach 2:
The electrode is constructed as a composite structure combining conductive electrode material with getter material properties. This composite design enables the electrode to simultaneously provide electrical functionality for capacitance measurement and chemical functionality for gas trapping, while the layered structure protects the base electrode material from degradation.
3Object-affected harmful factors
If additional getter components are added to the pressure sensor, then gas interference is eliminated, but manufacturing complexity increases
Solution Approach 1:
The getter functionality is merged into the existing electrode structure rather than being added as a separate component. This integration allows the electrode to be manufactured using conventional semiconductor fabrication processes, eliminating the need for additional getter deposition or assembly steps, thus maintaining manufacturing simplicity while eliminating gas interference.
Solution Approach 2:
The electrode material is selected or treated to possess both electrical conductivity and getter properties, allowing a single component to fulfill multiple functions. This approach simplifies manufacturing by avoiding additional getter components and their associated fabrication steps, while still effectively trapping gas molecules that would interfere with measurements.
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 solution effectively maintains measurement accuracy by eliminating gas interference, reduces the risk of electrode degradation, and integrates getter functionality without increasing the sensor's size or requiring additional space, making it suitable for integration on semiconductor substrates.
Implementation Method 1
The first electrode comprises a getter material for collecting gas molecules. The getter material is exposed to the cavity.
Implementation Method 2
the getter material acts as a getterer, such that it reacts with and traps unwanted gases
Data Source
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AI summary
A pressure sensor, comprising a deformable membrane (42) deflecting in response to pressure applied, a first stationary electrode (43) and a second electrode (44) coupled to the deformable membrane (42), for determining a change in a capacitance between the first and the second electrode (43, 44) in response to the pressure applied, wherein at least one of the first and the second electrode (43, 44) comprises a getter material for collecting gas molecules.