Chemically-sensitive field effect transistors, systems, and methods for manufacturing and using the same
Inventors
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Assignees
MemberParagrafParagrafParagraf specializes in the development and manufacture of wafer-scale, silicon-compatible graphene electronic devices and sensors. Utilizing a proprietary process for direct, contamination-free graphene synthesis, the company delivers scalable solutions for magnetic field sensing, molecular and biosensing, and advanced electronics integration. These technologies address challenges in cryogenics, quantum computing, automotive, aerospace, environmental monitoring, and healthcare. With a focus on large-scale integration of 2D materials, Paragraf advances next-generation sensors and components for demanding and extreme environments.
Paragraf specializes in the development and manufacture of wafer-scale, silicon-compatible graphene electronic devices and sensors. Utilizing a proprietary process for direct, contamination-free graphene synthesis, the company delivers scalable solutions for magnetic field sensing, molecular and biosensing, and advanced electronics integration. These technologies address challenges in cryogenics, quantum computing, automotive, aerospace, environmental monitoring, and healthcare. With a focus on large-scale integration of 2D materials, Paragraf advances next-generation sensors and components for demanding and extreme environments.
Publication Number
US-11016088-B2
Publication Date
2021-05-25
Expiration Date
Abstract
This invention concerns Chemically-sensitive Field Effect Transistors (ChemFETs) that are preferably fabricated using semiconductor fabrication methods on a semiconductor wafer, and in preferred embodiments, on top of an integrated circuit structure made using semiconductor fabrication methods. The instant ChemFETs typically comprise a conductive source, a conductive drain, and a channel composed of a one-dimensional (1D) or two-dimensional (2D) transistor nanomaterial, which channel extends from the source to the drain and is fabricated using semiconductor fabrication techniques on top of a wafer. The ChemFET also includes a gate, often the gate voltage is provided through a fluid or solution proximate the ChemFET. Such ChemFETs, preferably configured in independently addressable arrays, may be employed to detect a presence and/or concentration changes of various analyte types in chemical and/or biological samples, including nucleic acid hybridization and/or sequencing reactions.
Core Innovation
This disclosure relates to Chemically-sensitive Field Effect Transistors (ChemFETs) preferably fabricated using semiconductor fabrication methods on a semiconductor wafer and, in preferred embodiments, on top of an integrated circuit structure. The ChemFETs typically comprise a conductive source, a conductive drain, and a channel composed of a one-dimensional or two-dimensional transistor nanomaterial and include a gate often provided through a fluid or solution; such ChemFETs, preferably configured in independently addressable arrays, may be employed to detect presence and concentration changes of analytes including nucleic acid hybridization and sequencing reactions.
The background identifies limitations of conventional ISFET and MOSFET based sensors, including a lack of sensor sensitivity and poor signal-to-noise characteristics as semiconductor nodes scale down, and notes that optically-based NGS instrumentation tends to be bulky, costly, relatively slow and not portable. The disclosure therefore addresses the need for a FET device that comprises channels with high surface area to volume ratio that offers a FET sensitivity higher than is currently achievable for biological applications such as nucleic acid detection and sequencing.
The disclosure provides ChemFETs having channels formed of 1D nanomaterials (e.g., Si NWs or CNTs), 2D nanomaterials (e.g., graphene, MoS2) and/or 3D transistor material, and contemplates analyte or reaction-sensitive insulating layers, wells or chambers for solution gating, solution gates and backgates including dual gate and gate all-around (GAA) structures, and read-out circuitry or processors for generating and comparing I-V or Id-Vgs curves to detect reactions. Device geometries and interconnect arrangements are described to maximize transconductance (gm) by increasing W/L and by using interdigitated and multi-layered electrode configurations to improve sensitivity and signal-to-noise characteristics.
Methods for making and using the ChemFETs are described at a conceptual level and include growing or transferring nanomaterial channel layers, forming passivation and analyte-sensitive layers, and creating wells, interdigitated or vertically stacked electrode structures and sensor arrays on CMOS ROICs; [procedural detail omitted for safety] The devices are described for use in sensor IC chips with fluidics, microbead or particle placement using electric or magnetic fields, and associated computing components for on-chip processing such as base calling, mapping, alignment, and variant calling.
Claims Coverage
This patent contains 2 independent claims from which 6 main inventive features were extracted.
Graphene layer positioned between insulating layers contacting source and drain
A graphene layer positioned between the first and second insulating layers and contacting at least a portion of the one or more surfaces of each of the source and drain electrodes, the graphene layer extending a length from a first portion of the source electrode to a first portion of the drain electrode thereby forming a channel between the source and drain electrodes.
Source and drain at least partially disposed within first insulating layer
A source electrode and a drain electrode each having one or more surfaces, the one or more surfaces defining a boundary between an interior portion and an exterior portion of each electrode, at least a portion of the one or more surfaces of the source and drain electrodes being disposed at least partially within the first insulating layer, the source electrode being separated from the drain electrode by a distance.
Surface structures forming a gate overlapping source and drain
One or more surface structures forming a gate that overlaps at least a portion of the source and the drain electrodes.
Alternating electrode layers with graphene channel spanning inner side portions
A first and second insulating layer positioned above the extended body of the substrate layer; a second source electrode and a second drain electrode each having a top surface and a bottom surface, the second source electrode being separated from the second drain electrode by a second distance; a graphene layer extending a length from at least the inner side portion of the second source electrode to the inner side portion of the second drain electrode thereby forming a channel between the source and drain electrodes, the graphene layer not extending beyond either outer side portion of the source and drain electrodes.
First gate overlapping second source and drain electrodes
One or more first structures forming a first gate that overlaps at least a portion of the second source and the second drain electrodes.
Stacked multi-layer electrode configuration including first source/drain and second source/drain
A first drain electrode and a first source electrode each having a top surface and a bottom surface, the top surface separated from the bottom surface by opposing outer and inner side portions, each pair of opposed side portions and each of the bottom surfaces of the first drain and first source electrodes being disposed proximate the substrate layer, the first drain electrode being separated from the first source electrode by a first distance; and a second set of source and drain electrodes disposed at least partially within the first or second insulating layer, the second source electrode being separated from the second drain electrode by a second distance.
The independent claims cover multi-layered ChemFET structures with graphene channel layers contacted by source/drain electrodes embedded within insulating layers, gate surface structures overlapping electrodes, and multi-level electrode stacks with graphene channels spanning inner electrode side portions; these features form the basis for claimed solution-gated, dual-gated and gate-all-around sensor configurations.
Stated Advantages
Increased sensor sensitivity and accuracy relative to conventional semiconductor FET ISFET devices for chemical and biological analyses, including nucleic acid hybridization and sequencing.
Improved signal-to-noise characteristics and lower noise performance enabling better discrimination of detection signals.
Enables smaller sensor configurations and dense arrays compatible with semiconductor IC fabrication to facilitate large-scale, high-density sensor arrays.
Facilitates real-time, lower-cost, portable electronic detection compared to optically-based NGS platforms.
Higher transconductance via increased channel W/L ratio and high-mobility 1D/2D channels, improving sensitivity (gm∝μCov W/L Vsd is cited).
Dual-gate and gate all-around (GAA) structures provide improved channel control and can improve sensor sensitivity, in some embodiments beyond the Nernst limit.
Documented Applications
Nucleic acid detection and sequencing, including sequencing by synthesis and Next Generation Sequencing (NGS) applications.
Nucleic acid hybridization detection and related assays, including probe-based detection of specific genetic sequences.
Genetic diagnostics, genome identification, whole genome analysis, genome typing analysis, exome analysis, and genotyping, including SNP genotyping.
Microarray, panel, microbial/microbiome, and other biomolecule analyses.
Clinical analyses including cancer analysis, NIPT analysis, cfDNA analysis, and blood/plasma/serum analysis.
Analyte detection and identification and general chemical or biological analyte sensing, including ion (pH) sensing.
Biosensing use cases such as antibody/antigen detection and cell monitoring for biologic activity.
Integration into sensor arrays on CMOS ROICs for high-throughput sensing with associated fluidics, microbead-based assays, and on-chip computing for base calling, mapping, alignment, and variant calling.
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