3D Extended Metal Gate ISFET for CMOS-Compatible pH Sensing
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Solution Overview
Problem
Existing Ion-Sensitive Field-Effect Transistors (ISFETs) face challenges in achieving high sensitivity, linearity, and stability when using oxynitrides as sensing gate insulators, particularly in commercial CMOS processes, which are difficult to modify for miniaturized Point-of-Care and wearable applications.
Innovation Solution
A 3D-Extended Metal Gate Field-Effect Transistor device (3D-EMG-ISFET) is developed by vertically co-integrating the transducing transistor and sensing gate electrode on a post-processed 0.18 μm commercial CMOS chip, utilizing an Al with Al2O3 native oxide, achieving a sensitivity of 56.8 mV/pH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ISFETs are fabricated using commercial CMOS processes with oxynitrides as sensing gate insulator, then manufacturing compatibility is improved, but sensitivity, linearity and stability deteriorate
Solution Approach 1:
The patent changes the material parameter of the sensing gate insulator from oxynitride to aluminum oxide (Al2O3), which maintains compatibility with commercial CMOS processes while significantly improving sensitivity, linearity and stability measurements
Solution Approach 2:
The patent employs a composite structure combining aluminum gate electrode with aluminum oxide insulator layer, creating a material combination that achieves both manufacturing compatibility and superior sensing performance
2Ease of manufacture
If ISFETs are fabricated using oxynitrides as sensing gate insulator, then manufacturing compatibility is improved, but linearity deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter of the gate insulator from oxynitride to pure aluminum oxide, which preserves CMOS manufacturing compatibility while achieving superior linearity characteristics in the sensing response
3Ease of manufacture
If ISFETs are fabricated using oxynitrides as sensing gate insulator, then manufacturing compatibility is improved, but stability deteriorates
Solution Approach 1:
The patent modifies the material parameter of the sensing gate insulator to aluminum oxide, maintaining ease of manufacture through standard CMOS processes while achieving enhanced stability and reliability in sensing measurements
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 device demonstrates improved sensitivity and stability as a full-scale pH sensor, fabricated in a non-modified commercial CMOS process, suitable for miniaturized and wearable applications.
Implementation Method 1
Ion-Sensitive Field-Effect Transistors (ISFETs) have been fabricated using a variety of technologies based on the idea of an ion-sensitive gate
Data Source
AI summary
The present disclosure concerns a Field-Effect Transistor device or sensor comprising at least one drain region, at least one source region, at least a channel region, at least a first gate connected to the channel region, at least one stack comprising at least one metal layer or metal extension and at least one via layer or via extension; or a plurality of alternating (i) metal layers or metal extensions and (ii) via layers or via extensions, at least one second gate or second layer connected to the at least one first gate by the at least one stack, the at least one second gate or second layer permitting sensing of ions, and/or molecules and/or biomarkers, and at least one microfluidic channel or structure connected to or provided on the at least one second gate or second layer.