Gas Sensor Electrode Corrosion Protection via Conductive Oxide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuit gas sensors face challenges in corrosion protection of electrodes, which affects resistance measurements and manufacturing processes, and existing solutions do not adequately prevent short-circuiting of gas sensitive materials.
Innovation Solution
The integration of electrically conductive corrosion protection material around each sensor electrode, forming a stack with sidewall spacers to prevent corrosion and allow impedance-based measurements without short-circuiting, using materials like TiN and processes that align with established BEOL techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer comprising an electrically insulating oxide is used to prevent corrosion of electrodes, then corrosion protection is improved, but resistance measurements cannot be performed because the insulating layer blocks electrical current
Solution Approach 1:
The patent applies different material properties to different regions: the bottom and top surfaces of the electrode use electrically insulating oxide for corrosion protection, while the sidewalls use electrically conductive oxide to enable resistance measurements. This local differentiation resolves the contradiction by providing both corrosion protection and measurement capability in different locations.
Solution Approach 2:
The electrode structure uses a composite approach with multiple oxide layers having different electrical properties. The insulating oxide layer provides corrosion protection, while the conductive oxide sidewall layer enables electrical measurements. This composite material strategy allows simultaneous achievement of both protection and measurement functions.
2Adaptability or versatility
If capacitor electrodes are provided outside the passivation stack to enable gas sensing, then sensor functionality is improved, but electrodes become susceptible to corrosion
Solution Approach 1:
The patent provides corrosion protection specifically where needed by coating the electrode surfaces with oxide layers. The bottom surface has insulating oxide protection, the sidewalls have conductive oxide protection enabling both mechanical stability and electrical functionality, while the top surface has insulating oxide protection. This localized protection strategy maintains gas sensing capability while preventing corrosion.
Solution Approach 2:
The oxide layers are deposited beforehand to protect the electrode surfaces from corrosion before the electrodes are exposed to the operating environment. This preventive approach ensures long-term reliability of the gas sensor by protecting the electrodes from corrosive gases while maintaining their sensing functionality.
3Ease of manufacture
If a single layer of corrosion protection material is used, then manufacturing simplicity is improved, but adequate protection against both corrosion and short-circuiting cannot be achieved
Solution Approach 1:
The patent uses a single deposition process that creates different oxide materials in different locations through spatial control. The insulating oxide forms on horizontal surfaces (bottom and top) while conductive oxide forms on vertical sidewalls. This approach maintains manufacturing simplicity while achieving differentiated protection and functionality.
Solution Approach 2:
The patent controls the deposition parameters (such as deposition angle, temperature, or chemistry) to produce oxide layers with different electrical properties in different locations. By changing physical or chemical parameters during deposition, the process generates both insulating and conductive oxide regions from a single processing step, maintaining ease of manufacture while achieving reliable protection.
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 approach enhances the accuracy and sensitivity of gas sensors by protecting electrodes from corrosion and enabling resistance measurements, while maintaining compatibility with existing manufacturing processes.
Implementation Method 1
The gas sensitive layer 12 has a dielectric constant that is sensitive to a gas to be sensed. In operation, the dielectric constant of the gas sensitive layer 12 varies in accordance with the levels of the target gas that are present in the vicinity of the sensor.
Implementation Method 2
Each sensor electrode is enclosed in an electrically conductive corrosion protection material
Implementation Method 3
The impedance of the gas sensitive material is sensitive to a gas to be sensed
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An integrated circuit and a method of making the same. The integrated circuit includes a semiconductor substrate. The integrated circuit also includes an electrical impedance based gas sensor located on the substrate. The sensor includes first and second electrically conductive sensor electrodes. Each sensor electrode is enclosed in an electrically conductive corrosion protection material. The sensor also includes a gas sensitive material located between the sensor electrodes. The impedance of the gas sensitive material is sensitive to a gas to be sensed.