Capacitive Biosensor Stacked Electrode Acid Resistance
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Solution Overview
Problem
Existing capacitive biosensors face high manufacturing costs and reduced sensitivity due to high resistance in sensing electrodes and potential damage from acid components in bio-samples, which complicates the detection process.
Innovation Solution
A capacitive biosensor design that utilizes a stacked interconnect structure with conductive coatings as sensing electrodes, integrated with a passivation layer and sidewall spacers to protect the electrodes and enhance bio-sample attachment, compatible with existing MOS processes, reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional sensing electrode structures are used, then manufacturing process is simpler, but manufacturing cost increases and sensitivity decreases due to high resistance
Solution Approach 1:
The sensing electrode is divided into multiple stacked conductive layers (first conductive layer, second conductive layer, third conductive layer) with different materials. Each layer serves specific functions: the first layer provides low resistance, the second layer provides chemical stability against acid components, and the third layer enhances sensitivity. This segmentation allows optimization of each layer's properties independently, resolving the contradiction between manufacturing simplicity and detection sensitivity.
Solution Approach 2:
The sensing electrode uses a composite structure combining multiple conductive materials in stacked layers. This composite approach enables the electrode to simultaneously achieve low resistance (improving sensitivity), chemical stability (protecting from acid damage), and manufacturability through integration with existing interconnect structures.
2Ease of operation
If sensing electrodes are exposed to bio-samples, then detection function is achieved, but electrodes are damaged by acid components
Solution Approach 1:
A passivation layer is introduced as an intermediary between the sensing electrode and the bio-sample environment. This passivation layer acts as a protective barrier that prevents acid components in the bio-sample from directly contacting and damaging the conductive layers, while still allowing the sensing function to operate through the structure.
Solution Approach 2:
The second conductive layer is specifically designed with acid-resistant properties and is positioned between the first and third conductive layers. This local quality enhancement at the critical interface provides targeted protection against acid components while maintaining the overall sensing functionality of the electrode structure.
3Reliability
If multi-layer interconnect structure is used, then sensitivity and stability improve, but device complexity increases
Solution Approach 1:
The sensing electrode structure is merged with the interconnect structure by using the third metal structure as the sensing region. The first, second, and third conductive layers are integrated into the interconnect architecture, combining the functions of electrical interconnection and sensing. This merging reduces device complexity by eliminating separate sensing electrode structures while maintaining enhanced sensing performance.
Solution Approach 2:
The multi-layer interconnect structure serves multiple functions: it provides electrical connectivity, acts as the sensing electrode, and offers chemical protection through the passivation layer. This multi-functionality reduces the need for additional dedicated sensing components, thereby reducing overall device complexity while improving sensing reliability.
Data Source
AI summary
A capacitive biosensor is provided. The capacitive biosensor includes: a transistor, an interconnect structure on the transistor, and a passivation layer on the interconnect structure. The interconnect structure includes a first metal structure on the transistor, a second metal structure on the first metal structure, and a third metal structure on the second metal structure. The third metal structure includes a first conductive layer, a second conductive layer, and a third conductive layer that are sequentially stacked. The passivation has an opening exposing a portion of the third metal structure. The capacitive biosensor further includes a sensing region on the interconnect structure. The sensing region includes a first sensing electrode and a second sensing electrode. The first sensing electrode is formed of the third conductive layer, and the second sensing electrode is disposed on the passivation layer.