Sensor Moat Electrode Path for Passivation Failure Detection
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Solution Overview
Problem
Existing biosensors face challenges in detecting passivation failure in piezoelectric resonators, which can lead to bottom electrode attack and subsequent metal structure degradation, especially in liquid media applications, where visual inspection is not practical or feasible.
Innovation Solution
A sensor test structure with a moat configuration surrounding the resonating structure, featuring an electrode path that crosses the moat multiple times, allowing for detection of resistance changes indicative of passivation failure, enabling electrical testing to determine the integrity of the passivation layer without visual inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual inspection is used to detect passivation failure, then detection capability is limited to visible defects, but it is not practical or feasible for liquid media applications
Solution Approach 1:
The patent replaces visual inspection (optical/mechanical system) with electrical resistance measurement (electrical system). The electrode path integrated into the moat structure allows electrical detection of passivation failure through resistance changes, which can be performed in liquid media without requiring optical access or dry conditions.
Solution Approach 2:
The patent introduces an intermediary electrode path within the moat structure that mediates between the passivation layer and the detection system. This electrode path serves as a sensor that converts the physical state of the passivation layer into measurable electrical resistance changes, enabling indirect detection that works in liquid environments.
2Reliability
If the electrode path crosses the moat multiple times, then detection reliability improves through multiple measurement opportunities, but device complexity increases
Solution Approach 1:
The moat structure serves multiple functions: it provides mechanical support, defines the sensing region, and contains the electrode path that performs detection. By making the electrode path cross the moat multiple times, the same structural element serves as both the boundary definition and the repeated measurement points, avoiding the need for separate sensing structures.
Solution Approach 2:
The patent merges the moat structure with the electrode path by integrating the electrode into the moat region. This combination allows the electrode to follow the moat's geometry and cross it multiple times, providing redundant measurement paths without requiring additional separate components or structures.
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 proposed solution effectively detects passivation failure by measuring resistance changes across the electrode path, providing multiple opportunities to identify metal attack and ensuring the integrity of the passivation layer, thus preventing bottom electrode degradation.
Implementation Method 1
Each moat crossing is configured to cause a change in resistance based on passivation failure of the moat structure
Implementation Method 2
A piezoelectric resonator is typically constructed as a thin, planar layer of crystalline or polycrystalline piezoelectric material sandwiched between two electrode layers
Implementation Method 3
The changed mass results in changes to the resonance phase, frequency, etc., of the resonator
Data Source
AI summary
Embodiments described herein involve a sensor test structure, comprising a substrate. A moat structure is configured to at least partially surround a resonating structure comprising at least one piezoelectric layer. An electrode comprises an electrode path. The electrode path crosses the moat region at least one time. Each moat crossing is configured to cause a change in resistance based on passivation failure of the moat structure.