Chemical Sensor Sidewall Spacer Sensing Surface
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Solution Overview
Problem
Large-scale chemical sensor arrays face noise susceptibility issues due to reduced sensing surface area, leading to decreased signal-to-noise ratio and accuracy in detecting chemical and biological processes.
Innovation Solution
The chemical sensors incorporate a floating gate conductor with a dielectric material opening and a conductive sidewall spacer, extending the sensing surface vertically to maintain a small footprint while increasing the sensing surface area, thereby reducing noise and enhancing signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large-scale chemical sensor arrays are used to detect chemical processes, then the detection capability and measurement coverage are improved, but the susceptibility to noise increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent extends the sensing surface from a two-dimensional planar area to a three-dimensional structure by adding vertical sidewall spacers. This dimensional transition allows the sensor to maintain a small footprint while increasing the effective sensing surface area, thereby improving signal-to-noise ratio without sacrificing detection capability in large-scale arrays
2Measurement precision
If the sensing surface area is increased to reduce noise, then the signal-to-noise ratio is improved, but the device footprint increases
Solution Approach 1:
The invention utilizes the vertical dimension by forming sidewall spacers that extend upward from the substrate. This allows the sensing surface area to be increased without expanding the lateral footprint of the device, effectively decoupling the relationship between sensing area and device area
Solution Approach 2:
The sidewall spacers are formed within the vertical profile of the sensor structure, nesting the extended sensing surface within the existing device boundaries. This nested configuration allows additional sensing area to be incorporated without increasing the overall device footprint
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 allows for high-density arrays with low noise chemical sensors, accurately detecting reaction characteristics by maintaining a large sensing surface area despite reduced footprint, improving signal-to-noise ratio and overall accuracy.
Implementation Method 1
The operation of the chemFET is based on the modulation of channel conductance, caused by changes in charge at the sensitive area due to a chemical reaction occurring nearby
Implementation Method 2
The presence of ions in an analyte solution alters the surface potential at the interface between the ion-sensitive layer and the analyte solution, due to the protonation or deprotonation of surface charge groups caused by the ions present in the analyte solution
Data Source
AI summary
In one implementation, a chemical sensor is described. The chemical sensor includes chemically-sensitive field effect transistor including a floating gate conductor having an upper surface. A dielectric material defines an opening extending to the upper surface of the floating gate conductor. A conductive sidewall spacer is on a sidewall of the opening and contacts the upper surface of the floating gate conductor.