ISFET Sensor with Insulating Window for Ion Detection

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Solution Overview

Problem

Current sensors based on ion-sensitive field effect transistors (ISFETs) face challenges in effectively detecting and measuring ion concentrations in samples due to limitations in integrating light excitation spectroscopy for ion detection and identification within semiconductor structures.

Innovation Solution

A semiconductor structure is developed with a cavity in the substrate, an ISFET positioned over it, and an insulating material window allowing light from a tunable source to enter the cavity, enabling excitation spectroscopy for ion detection and identification by measuring source-to-drain current variations based on light frequency and energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ISFET is used for ion detection, then ion concentration measurement capability is provided, but sensitivity and accuracy for ion identification are insufficient

Engineering Contradiction:

Improveion detection sensitivityVSAvoidion identification capability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent combines ISFET technology with light excitation spectroscopy into a single integrated sensor structure. The ISFET measures source-to-drain current while light at predetermined frequencies excites ions in the sample, enabling both concentration measurement and identification simultaneously. This merging resolves the contradiction by providing both measurement precision and adaptability within one device.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sensor structure performs multiple functions: the ISFET component measures ion concentration through current variation, while the light excitation component identifies ion types through spectral analysis. This multi-functionality allows the single device to address both the sensitivity requirement and the identification capability requirement, resolving the technical contradiction.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If light excitation spectroscopy is integrated into semiconductor structure, then ion identification capability is enhanced, but device complexity increases

Engineering Contradiction:

Improveion identification capabilityVSAvoidsemiconductor structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the sensor into distinct functional regions: the ISFET portion for current measurement and the cavity portion with insulating material window for light excitation. This segmentation allows each component to perform its specific function efficiently while maintaining overall integration, reducing the complexity that would arise from a fully homogenized structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The insulating material window acts as an intermediary element that allows light to enter the cavity while maintaining the semiconductor structure's integrity. This intermediary component enables light excitation spectroscopy integration without requiring complex modifications to the bulk semiconductor material, thus enhancing ion identification capability while limiting complexity increase.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If insulating material window is added to direct light into cavity, then light excitation capability is provided, but manufacturing steps increase

Engineering Contradiction:

Improvelight excitation capabilityVSAvoidmanufacturing process simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The insulating material window is formed as part of the preliminary sensor fabrication process, integrated into the cavity structure before final assembly. By incorporating this light-directing feature during initial manufacturing steps rather than as a post-processing addition, the patent enables light excitation capability while minimizing the increase in manufacturing complexity.

Inventive Principle:

Principle #10Preliminary action

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 sensitivity and accuracy of ion detection and identification by utilizing the insulating material window to direct light into the cavity, allowing for precise measurement of ion concentrations and types within the sample.

Implementation Method 1

directing light at a predetermined frequency through an insulating material window into a cavity

Methodology Applied

Scientific EffectLight: Light

Implementation Method 2

sensing a source to drain current of an ion-sensitive field effect transistor (ISFET) positioned over the cavity

Methodology Applied

Scientific EffectIon-sensitive field effect transistor (ISFET):

Data Source

PatentEP4357770A1Ion-sensitive field effect transistor above microfluidic cavity for ion detection and identification

Publication Date: 2024.04.24 GLOBALFOUNDRIES US INC

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AI summary

A structure (100) includes a cavity (140) in a semiconductor substrate (108); a field effect transistor (112) positioned over the cavity (140); an opening (130) in the semiconductor substrate (108) extending to the cavity (140); and a layer of insulating material (132) filling the opening (130) and forming an insulating material window (132) to the cavity (140).