U.S. patent application number 16/656882 was filed with the patent office on 2021-04-22 for semiconductor device with biofet and biometric sensors.
This patent application is currently assigned to Taiwan Semiconductor Manufacturing Co., Ltd.. The applicant listed for this patent is Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Chun-Ren CHENG, Fu-Chun HUANG, Shih-Fen HUANG, Ching-Hui LIN.
Application Number | 20210117636 16/656882 |
Document ID | / |
Family ID | 1000005505185 |
Filed Date | 2021-04-22 |
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United States Patent
Application |
20210117636 |
Kind Code |
A1 |
LIN; Ching-Hui ; et
al. |
April 22, 2021 |
SEMICONDUCTOR DEVICE WITH BIOFET AND BIOMETRIC SENSORS
Abstract
The structure of a semiconductor device with an array of bioFET
sensors, a biometric fingerprint sensor, and a temperature sensor
and a method of fabricating the semiconductor device are disclosed.
A method for fabricating the semiconductor device includes forming
a gate electrode on a first side of a semiconductor substrate,
forming a channel region between source and drain regions within
the semiconductor substrate, and forming a piezoelectric sensor
region on a second side of the semiconductor substrate. The second
side is substantially parallel and opposite to the first side. The
method further includes forming a temperature sensing electrode on
the second side during the forming of the piezoelectric sensor
region, forming a sensing well on the channel region, and binding
capture reagents on the sensing well.
Inventors: |
LIN; Ching-Hui; (Taichung
City, TW) ; CHENG; Chun-Ren; (Hsin-Chu City, TW)
; HUANG; Shih-Fen; (Jhubei, TW) ; HUANG;
Fu-Chun; (Zhibei City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Semiconductor Manufacturing Co., Ltd. |
Hsinchu |
|
TW |
|
|
Assignee: |
Taiwan Semiconductor Manufacturing
Co., Ltd.
Hsinchu
TW
|
Family ID: |
1000005505185 |
Appl. No.: |
16/656882 |
Filed: |
October 18, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 27/4145 20130101;
G06K 9/0002 20130101; H01L 41/1132 20130101 |
International
Class: |
G06K 9/00 20060101
G06K009/00; G01N 27/414 20060101 G01N027/414; H01L 41/113 20060101
H01L041/113 |
Claims
1. A method for fabricating a semiconductor device, comprising:
forming a gate electrode on a first side of a semiconductor
substrate; forming a channel region between source and drain
regions within the semiconductor substrate; forming a piezoelectric
sensor region with a piezoelectric material on a second side of the
semiconductor substrate, wherein the second side is substantially
parallel and opposite to the first side; forming a temperature
sensing electrode on the second side during the forming of the
piezoelectric sensor region; forming a sensing well on the channel
region; and binding capture reagents on the sensing well.
2. The method of claim 1, wherein the forming the piezoelectric
sensor region comprises: depositing an isolation layer on the
second side; depositing a first electrode on the isolation layer;
depositing the piezoelectric material on the first electrode; and
depositing a second electrode on the piezoelectric material.
3. The method of claim 1, wherein the forming the piezoelectric
sensor region comprises forming an array of piezoelectric sensor
regions with the piezoelectric material.
4. The method of claim 1, wherein the forming the piezoelectric
sensor region comprises: depositing a first electrode on the second
side; forming an array of piezoelectric regions with the
piezoelectric material on the first electrode; and depositing an
insulating layer between adjacent piezoelectric regions of the
array of piezoelectric regions.
5. The method of claim 1, wherein the forming the piezoelectric
sensor region comprises: depositing a layer of conductive material
on the second side; and etching the layer of conductive material to
simultaneously form a bottom electrode of the piezoelectric sensor
region on a first region of the second side and the temperature
sensing electrode on a second region of the second side.
6. The method of claim 1, wherein the forming the sensing well
comprises: depositing an isolation layer on the second side;
etching a portion of the isolation layer overlying the channel
region to form an opening on the channel region; blanket depositing
an insulating layer on the isolation layer, the channel region, and
sidewalls of the opening; and etching the insulating layer to
simultaneously form the sensing well on a first region of the
second side and a sensing layer on a second region of the second
side.
7. The method of claim 1, further comprising depositing a coupling
layer on the piezoelectric sensor region.
8. The method of claim 1, further comprising forming a contact
opening between the piezoelectric sensor region and the sensing
well after the forming of the piezoelectric sensor region and the
sensing well.
9. The method of claim 1, further comprising: forming an
interconnect structure prior to the forming of the piezoelectric
sensor region and the sensing well; and forming a contact opening
on the interconnect structure and between the piezoelectric sensor
region and the sensing well after the forming of the piezoelectric
sensor region and the sensing well.
10. The method of claim 1, further comprising forming an
interconnect structure prior to the forming of the piezoelectric
sensor region and the sensing well; and forming a heater during the
forming of the interconnect structure.
11. A method for fabricating a semiconductor device, comprising:
forming a bioFET sensor on a carrier substrate comprising: forming
a gate electrode on a first side of a semiconductor substrate
disposed on the carrier substrate, and forming a channel region
between source and drain regions within the semiconductor
substrate; and forming a biometric sensor on the carrier substrate
comprising: forming a piezoelectric sensor region with a
piezoelectric material on a second side of the semiconductor
substrate, wherein the second side is substantially parallel and
opposite to the first side; and depositing a sensing layer on the
piezoelectric sensor region.
12. The method of claim 11, further comprising simultaneously
forming a temperature sensor electrode on a first region of the
second side and a bottom electrode of the piezoelectric sensor
region on a second region of the second side.
13. The method of claim 11, further comprising simultaneously
forming the sensing layer on a first region of the second side and
a sensing well of the bioFET sensor on a second region of the
second side.
14. The method of claim 11, wherein the forming the piezoelectric
sensor region comprises forming an array of piezoelectric sensor
regions with the piezoelectric material.
15. The method of claim 11, wherein the forming the piezoelectric
sensor region comprises: depositing a first electrode on the second
side; depositing an array of piezoelectric regions with the
piezoelectric material on the first electrode; and depositing an
array of second electrodes on the array of piezoelectric
regions.
16. The method of claim 15, wherein the forming the biometric
sensor comprises: coupling the first electrode to a ground voltage;
and coupling the array of second electrodes to an array of voltage
sources.
17-20. (canceled)
21. A method, comprising: forming a gate electrode on a first side
of a semiconductor substrate; forming source and drain regions
within the semiconductor substrate with a channel region disposed
between the source and drain regions; forming a piezoelectric
sensor region with a piezoelectric material on a second side of the
semiconductor substrate, wherein the second side is substantially
parallel and opposite to the first side; and depositing a sensing
layer on the piezoelectric sensor region.
22. The method of claim 21, further comprising forming a contact
region within the semiconductor substrate between the piezoelectric
sensor region and the gate electrode.
23. The method of claim 21, further comprising forming an array of
cavities under the piezoelectric sensor region.
24. The method of claim 21, wherein the forming the piezoelectric
sensor region comprises forming an array of fingerprint sensing
regions.
Description
BACKGROUND
[0001] Biosensor systems can be used for sensing and detecting
biomolecules and can operate on the basis of electronic,
electrochemical, optical, and/or mechanical detection principles.
Biosensor systems with field effect transistors (FETs) can
electrically sense charges, photons, and/or mechanical properties
of bio-entities or biomolecules. The detection can be performed by
detecting the bio-entities or biomolecules themselves, or through
interaction and reaction between specified reactants and
bio-entities/biomolecules. Such biosensor systems can be
manufactured using semiconductor processes, can quickly convert
electric signals, and can be easily applied to integrated circuits
(ICs) and microelectromechanical systems (MEMS).
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] Aspects of this disclosure are best understood from the
following detailed description when read with the accompanying
figures. It is noted that, in accordance with the common practice
in the industry, various features are not drawn to scale. In fact,
the dimensions of the various features may be arbitrarily increased
or reduced for clarity of discussion.
[0003] FIG. 1 illustrates components of a sensor system, in
accordance with some embodiments.
[0004] FIG. 2 illustrates a cross-sectional view of a dual-gate
back-side sensing bioFET sensor, in accordance with some
embodiments.
[0005] FIG. 3 illustrates a circuit diagram of a plurality of
bioFET sensors configured in an addressable array, in accordance
with some embodiments.
[0006] FIG. 4 illustrates a circuit diagram of an addressable array
of dual gate back-side sensing FET sensors and heaters, in
accordance with some embodiments.
[0007] FIGS. 5A-5B illustrate cross-sectional views of a
semiconductor device with a bioFET sensor, a biometric fingerprint
sensor, and a temperature sensor, in accordance with some
embodiments.
[0008] FIG. 6 illustrates a circuit diagram of a biometric
fingerprint sensor, in accordance with some embodiments.
[0009] FIG. 7 is a flow diagram of a method for fabricating a
semiconductor device with a bioFET sensor, a biometric fingerprint
sensor, and a temperature sensor, in accordance with some
embodiments.
[0010] FIGS. 8-18 illustrate cross-sectional views of a
semiconductor device with a bioFET sensor, a biometric fingerprint
sensor, and a temperature sensor at various stages of its
fabrication process, in accordance with some embodiments.
[0011] Illustrative embodiments will now be described with
reference to the accompanying drawings. In the drawings, like
reference numerals generally indicate identical, functionally
similar, and/or structurally similar elements.
DETAILED DESCRIPTION
[0012] The following disclosure provides many different
embodiments, or examples, for implementing different features of
the provided subject matter. Specific examples of components and
arrangements are described below to simplify the present
disclosure. These are, of course, merely examples and are not
intended to be limiting. For example, the process for forming a
first feature over a second feature in the description that follows
can include embodiments in which the first and second features are
formed in direct contact, and can also include embodiments in which
additional features can be formed between the first and second
features, such that the first and second features may not be in
direct contact. As used herein, the formation of a first feature on
a second feature means the first feature is formed in direct
contact with the second feature. In addition, the present
disclosure can repeat reference numerals and/or letters in the
various examples. This repetition does not in itself dictate a
relationship between the various embodiments and/or configurations
discussed.
[0013] Spatially relative terms, such as "beneath," "below,"
"lower," "above," "upper," and the like can be used herein for ease
of description to describe one element or feature's relationship to
another element(s) or feature(s) as illustrated in the figures. The
spatially relative terms are intended to encompass different
orientations of the device in use or operation in addition to the
orientation depicted in the figures. The apparatus can be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein can likewise be
interpreted accordingly.
[0014] It is noted that references in the specification to "one
embodiment," "an embodiment," "an example embodiment," "exemplary,"
etc., indicate that the embodiment described can include a
particular feature, structure, or characteristic, but every
embodiment may not necessarily include the particular feature,
structure, or characteristic. Moreover, such phrases do not
necessarily refer to the same embodiment. Further, when a
particular feature, structure or characteristic is described in
connection with an embodiment, it would be within the knowledge of
one skilled in the art to effect such feature, structure or
characteristic in connection with other embodiments whether or not
explicitly described.
Terminology
[0015] Unless defined otherwise, all technical and scientific terms
used herein have the same meanings as commonly understood by one of
ordinary skill in the art to which this disclosure belongs.
Although any methods and materials similar or equivalent to those
described herein can be used in the practice or testing of
embodiments in accordance with the disclosure; the methods,
devices, and materials are now described. All patents and
publications mentioned herein are incorporated herein by reference
for the purpose of describing and disclosing the materials and
methodologies that are reported in the publications can be used in
connection with the present disclosure.
[0016] The acronym "FET," as used herein, refers to a field effect
transistor. A type of FET is referred to as a "metal oxide
semiconductor field effect transistor" (MOSFET). MOSFETs can be
planar structures built in and on the planar surface of a substrate
such as a semiconductor wafer. MOSFETs can also have a
three-dimensional, fin-based structures.
[0017] The term "bioFET" (also referred to as "bioFET sensor")
refers to a FET that includes a layer of capture reagents that act
as surface receptors to detect the presence of a target analyte of
biological origin. A bioFET is a field-effect sensor with a
semiconductor transducer, according to some embodiments. One
advantage of bioFETs is the prospect of label-free operation.
Specifically, bioFETs enable the avoidance of costly and
time-consuming labeling operations such as the labeling of an
analyte with, for instance, fluorescent or radioactive probes. One
specific type of bioFET described herein is a "dual-gate back-side
sensing bioFET." The analytes for detection by a bioFET can be of
biological origin, such as proteins, carbohydrates, lipids, tissue
fragments, or portions thereof. A bioFET can be part of a broader
genus of FET sensors that can also detect a chemical compound; this
type of bioFET is known as a "ChemFET") or any other element. A
bioFET can also detect ions such as protons or metallic ions; this
type of bioFET is known as an "ISFET." The present disclosure
applies to all types of FET-based sensors ("FET Sensors"). One
specific type of FET Sensor described herein is a "Dual-Gate Back
Side Sensing FET Sensor" (DG BSS FET Sensor).
[0018] The term "source/drain" refers to the source/drain junctions
that form two of the four terminals of a FET.
[0019] The term "high-k" refers to a high dielectric constant. In
the field of semiconductor device structures and manufacturing
processes, high-k refers to a dielectric constant that is greater
than the dielectric constant of SiO2 (i.e., greater than 3.9).
[0020] The term "vertical," as used herein, means nominally
perpendicular to the surface of a substrate.
[0021] The term "etch selectivity" refers to the ratio of the etch
rates of two different materials under the same etching
conditions.
[0022] The term "p-type" defines a structure, layer, and/or region
as being doped with p-type dopants, such as boron.
[0023] The term "n-type" defines a structure, layer, and/or region
as being doped with n-type dopants, such as phosphorus.
[0024] In some embodiments, the terms "about" and "substantially"
can indicate a value of a given quantity that varies within 5% of
the value (e.g., .+-.1%, .+-.2%, .+-.3%, .+-.4%, .+-.5% of the
value).
[0025] In some embodiments, the term "analysis" refers to a process
or step involving physical, chemical, biochemical, or biological
analysis that includes, but is not limited to, characterization,
testing, measurement, optimization, separation, synthesis,
addition, filtration, dissolution, or mixing.
[0026] In some embodiments, the term "assay" refers to a process or
step involving the analysis of a chemical or a target analyte and
includes, but is not limited to, cell-based assays, biochemical
assays, high-throughput assays and screening, diagnostic assays, pH
determination, nucleic acid hybridization assays, polymerase
activity assays, nucleic acid and protein sequencing, immunoassays
(e.g., antibody-antigen binding assays, ELISAs, and iqPCR),
bisulfate methylation assays for detecting methylation pattern of
genes, protein assays, protein binding assays (e.g.,
protein-protein, protein-nucleic acid, and protein-ligand binding
assays), enzymatic assays, coupled enzymatic assays, kinetic
measurements (e.g., kinetics of protein folding and enzymatic
reaction kinetics), enzyme inhibitor and activator screening,
chemiluminescence and electrochemiluminescence assays, fluorescent
assays, fluorescence polarization and anisotropy assays, absorbance
and colorimetric assays (e.g., Bradford assay, Lowry assay,
Hartree-Lowry assay, Biuret assay, and BCA assay), chemical assays
(e.g., for the detection of environmental pollutants and
contaminants, nanoparticles, or polymers), and drug discovery
assays, whole genome analysis, genome typing analysis, genomic,
exome analysis, micro-biome analysis, and clinical analysis
including, but not limited to, cancer analysis, non-invasive
prenatal testing (NIPT) analysis, and/or UCS analysis. The
apparatus, systems, and methods described herein can use or adopt
one or more of these assays to be used with any of the FET Sensor
described designs.
[0027] In some embodiments, the term "liquid biopsy" refers to a
biopsy sample obtained from a subject's bodily fluid as compared to
a subject's tissue sample. The ability to perform assays using a
body fluid sample is oftentimes more desirable than using a tissue
sample. The less invasive approach using a body fluid sample has
wide ranging implications in terms of patient welfare, the ability
to conduct longitudinal disease monitoring, and the ability to
obtain expression profiles even when tissue cells are not easily
accessible, for example, in the prostate gland. Assays used to
detect target analytes in liquid biopsy samples include, but are
not limited to, those described above. As a non-limiting example, a
circulating tumor cell (CTC) assay can be conducted on a liquid
biopsy sample.
[0028] For example, a capture reagent (e.g., an antibody)
immobilized on a FET Sensor can be used for detection of a target
analyte (e.g., a tumor cell marker) in a liquid biopsy sample using
a CTC assay. CTCs are cells that have shed into the vasculature
from a tumor and circulate, for example, in the bloodstream.
Generally CTCs are present in circulation in low concentrations. To
assay the CTCs, CTCs are enriched from patient blood or plasma by
various techniques known in the art. CTCs can be stained for
specific markers using methods known in the art including, but not
limited to, cytometry (e.g., flow cytometry)-based methods and
IHC-based methods. For the apparatus, systems, and methods
described herein, CTCs can be captured or detected using a capture
reagent or the nucleic acids, proteins, or other cellular milieu
from the CTCs can be targeted as target analytes for binding to or
detection by a capture reagent.
[0029] When a target analyte is detected on or from a CTC, for
example, an increase in target analyte expressing or containing
CTCs can help identify the subject as having a cancer that is
likely to respond to a specific therapy (e.g., one associated with
a target analyte) or allow for optimization of a therapeutic
regimen with, for example, an antibody to the target analyte. CTC
measurement and quantitation can provide information on, for
example, the stage of tumor, response to therapy, disease
progression, or a combination thereof. The information obtained
from detecting the target analyte on the CTC can be used, for
example, as a prognostic, predictive, or pharmacodynamic biomarker.
In addition, CTCs assays for a liquid biopsy sample can be used
either alone or in combination with additional tumor marker
analysis of solid biopsy samples.
[0030] In some embodiments, the term "identification" refers to the
process of determining the identity of a target analyte based on
its binding to a capture reagent whose identity is known.
[0031] In some embodiments, the term "measurement" refers to the
process of determining the amount, quantity, quality, or property
of a target analyte based on its binding to a capture reagent.
[0032] In some embodiments, the term "quantitation" refers to the
process of determining the quantity or concentration of a target
analyte based on its binding to a capture reagent.
[0033] In some embodiments, the term "detection" refers to the
process of determining the presence or absence of a target analyte
based on its binding to a capture reagent. Detection includes but
is not limited to identification, measurement, and
quantitation.
[0034] In some embodiments, the term "chemical" refers to a
substance, compound, mixture, solution, emulsion, dispersion,
molecule, ion, dimer, macromolecule such as a polymer or protein,
biomolecule, precipitate, crystal, chemical moiety or group,
particle, nanoparticle, reagent, reaction product, solvent, or
fluid any one of which can exist in the solid, liquid, or gaseous
state, and which can be the subject of an analysis.
[0035] In some embodiments, the term "reaction" refers to a
physical, chemical, biochemical, or biological transformation that
involves at least one chemical and that generally involves (in the
case of chemical, biochemical, and biological transformations) the
breaking or formation of one or more bonds such as covalent,
noncovalent, van der Waals, hydrogen, or ionic bonds. The term
includes chemical reactions, such as synthesis reactions,
neutralization reactions, decomposition reactions, displacement
reactions, reduction-oxidation reactions, precipitation,
crystallization, combustion reactions, and polymerization
reactions, as well as covalent and noncovalent binding, phase
change, color change, phase formation, crystallization,
dissolution, light emission, changes of light absorption or
emissive properties, temperature change or heat absorption or
emission, conformational change, and folding or unfolding of a
macromolecule such as a protein.
[0036] In some embodiments, the term "capture reagent" refers to a
molecule or compound capable of binding the target analyte, which
can be directly or indirectly attached to a substantially solid
material. The capture reagent can be a chemical, and specifically
any substance for which there exists a naturally occurring target
analyte (e.g., an antibody, polypeptide, DNA, RNA, cell, virus,
etc.) or for which a target analyte can be prepared, and the
capture reagent can bind to one or more target analytes in an
assay. The capture reagent can be non-naturally occurring or
naturally-occurring, and if naturally-occurring can be synthesized
in vivo or in vitro.
[0037] In some embodiments, the term "target analyte" refers to the
substance to be detected in the test sample using embodiments of
the present disclosure. The target analyte can be a chemical, and
specifically any substance for which there exists a naturally
occurring capture reagent (e.g., an antibody, polypeptide, DNA,
RNA, cell, virus, etc.) or for which a capture reagent can be
prepared, and the target analyte can bind to one or more capture
reagents in an assay. "Target analyte" also includes any antigenic
substances, antibodies, and combinations thereof. The target
analyte can include a protein, a peptide, an amino acid, a
carbohydrate, a hormone, a steroid, a vitamin, a drug including
those administered for therapeutic purposes as well as those
administered for illicit purposes, a bacterium, a virus, and
metabolites of or antibodies to any of the above substances.
[0038] In some embodiments, the term "test sample" refers to the
composition, solution, substance, gas, or liquid containing the
target analyte to be detected and assayed using embodiments of the
present disclosure. The test sample can contain other components
besides the target analyte, can have the physical attributes of a
liquid, or a gas, and can be of any size or volume, including for
example, a moving stream of liquid or gas. The test sample can
contain any substances other than the target analyte as long as the
other substances do not interfere with the binding of the target
analyte with the capture reagent or the specific binding of the
first binding member to the second binding member. Examples of test
samples include, but are not limited to, naturally-occurring and
non-naturally occurring samples or combinations thereof.
Naturally-occurring test samples can be synthetic or synthesized.
Naturally-occurring test samples include body or bodily fluids
isolated from anywhere in or on the body of a subject including,
but not limited to, blood, plasma, serum, urine, saliva or sputum,
spinal fluid, cerebrospinal fluid, pleural fluid, nipple aspirates,
lymph fluid, fluid of the respiratory, intestinal, and
genitourinary tracts, tear fluid, saliva, breast milk, fluid from
the lymphatic system, semen, cerebrospinal fluid, intra-organ
system fluid, ascitic fluid, tumor cyst fluid, amniotic fluid and
combinations thereof, and environmental samples such as ground
water or waste water, soil extracts, air, and pesticide residues or
food-related samples.
[0039] Detected substances can include, for example, nucleic acids
(including DNA and RNA), hormones, different pathogens (including a
biological agent that causes disease or illness to its host, such
as a virus (e.g., H7N9 or HIV), a protozoan (e.g.,
Plasmodium-causing malaria), or a bacteria (e.g., E. coli or
Mycobacterium tuberculosis), proteins, antibodies, various drugs or
therapeutics or other chemical or biological substances, including
hydrogen or other ions, non-ionic molecules or compounds,
polysaccharides, small chemical compounds such as chemical
combinatorial library members, and the like. Detected or determined
parameters can include but are not limited to, for example, pH
changes, lactose changes, changing concentration, particles per
unit time where a fluid flows over the device for a period of time
to detect particles, for example, particles that are sparse, and
other parameters.
[0040] In some embodiments, the term "immobilized" when used with
respect to, for example, a capture reagent, includes substantially
attaching the capture reagent at a molecular level to a surface.
For example, a capture reagent can be immobilized to a surface of
the substrate material using adsorption techniques including
non-covalent interactions (e.g., electrostatic forces, van der
Waals, and dehydration of hydrophobic interfaces) and covalent
binding techniques where functional groups or linkers facilitate
attaching the capture reagent to the surface. Immobilizing a
capture reagent to a surface of a substrate material can be based
upon the properties of the substrate surface, the medium carrying
the capture reagent, and the properties of the capture reagent. In
some cases, a substrate surface can be first modified to have
functional groups bound to the surface. The functional groups can
then bind to biomolecules or biological or chemical substances to
immobilize them thereon.
[0041] In some embodiments, the term "nucleic acid" refers to a set
of nucleotides connected to each other via phosphodiester bond and
refers to a naturally occurring nucleic acid to which a naturally
occurring nucleotide existing in nature is connected, such as DNA
including deoxyribonucleotides having any of adenine, guanine,
cytosine, and thymine connected to each other and/or RNA including
ribonucleotides having any of adenine, guanine, cytosine, and
uracil connected to each other. Naturally-occurring nucleic acids
include, for example, DNA, RNA, and microRNA (miRNA). In addition,
non-naturally occurring nucleotides and non-naturally occurring
nucleic acids are within the scope of the nucleic acids of the
present disclosure. Examples include cDNA, peptide nucleic acids
(PNA), peptide nucleic acids with phosphate groups (PHONA), bridged
nucleic acids/locked nucleic acids (BNA/LNA), and morpholino
nucleic acids. Further examples include chemically-modified nucleic
acids and nucleic acid analogues, such as methylphosphonate
DNA/RNA, phosphorothioate DNA/RNA, phosphoramidate DNA/RNA, and
2'-O-methyl DNA/RNA. Nucleic acids include those that can be
modified. For example, a phosphoric acid group, a sugar, and/or a
base in a nucleic acid can be labeled as necessary. Any substances
for nucleic acid labeling known in the art can be used for
labeling. Examples thereof include but are not limited to
radioactive isotopes (e.g., 32P, 3H, and 14C), DIG, biotin,
fluorescent dyes (e.g., FITC, Texas, cy3, cy5, cy7, FAM, HEX, VIC,
JOE, Rox, TET, Bodipy493, NBD, and TAMRA), and luminescent
substances (e.g., acridinium ester).
[0042] Aptamer as used herein refers to oligonucleic acids or
peptide molecules that bind to a specific target molecule. The
concept of using single-stranded nucleic acids (aptamers) as
affinity molecules for protein binding was initially disclosed in
Ellington, Andrew D., and Jack W. Szostak, "Selection in vitro of
single-stranded DNA molecules that fold into specific
ligand-binding structures." Nature 355 (1992): 850-852; Tuerk,
Craig, and Larry Gold, "Systematic evolution of ligands by
exponential enrichment: RNA ligands to bacteriophage T4 DNA
polymerase." Science 249.4968 (1990): 505-510) and is based on the
ability of short sequences to fold, in the presence of a target,
into unique, three-dimensional structures that bind the target with
high affinity and specificity. Ng, Eugene W M, et al. "Pegaptanib,
a targeted anti-VEGF aptamer for ocular vascular disease." Nature
Reviews, Drug Discovery 5.2 (2006): 123, discloses that aptamers
are oligonucleotide ligands that are selected for high-affinity
binding to molecular targets.
[0043] In some embodiments, the term "protein" refers to a set of
amino acids linked together usually in a specific sequence. A
protein can be either naturally-occurring or non-naturally
occurring. As used herein, the term "protein" includes amino acid
sequences, as well as amino acid sequences that have been modified
to contain moieties or groups such as sugars, polymers,
metal-organic groups, fluorescent or light-emitting groups,
moieties or groups that enhance or participate in a process such as
intramolecular or intermolecular electron transfer, moieties or
groups that facilitate or induce a protein into assuming a
particular conformation or series of conformations, moieties or
groups that hinder or inhibit a protein from assuming a particular
conformation or series of conformations, moieties or groups that
induce, enhance, or inhibit protein folding, or other moieties or
groups that are incorporated into the amino acid sequence and that
are intended to modify the sequence's chemical, biochemical, or
biological properties. As used herein, proteins include, but are
not limited to, enzymes, structural elements, antibodies,
antigen-binding antibody fragments, hormones, receptors,
transcription factors, electron carriers, and other macromolecules
that are involved in processes such as cellular processes or
activities. Proteins can have up to four structural levels that
include primary, secondary, tertiary, and quaternary
structures.
[0044] In some embodiments, the term "antibody" refers to a
polypeptide of the immunoglobulin family that is capable of binding
a corresponding antigen non-covalently, reversibly, and in a
specific manner. For example, a naturally occurring IgG antibody is
a tetramer including at least two heavy (H) chains and two light
(L) chains inter-connected by disulfide bonds. Each heavy chain
includes a heavy chain variable region (abbreviated herein as VH)
and a heavy chain constant region. The heavy chain constant region
includes three domains, CH1, CH2 and CH3. Each light chain includes
a light chain variable region (abbreviated herein as VL) and a
light chain constant region. The light chain constant region
includes one domain, CL. The VH and VL regions can be further
subdivided into regions of hypervariability, termed complementarity
determining regions (CDR), interspersed with regions that are more
conserved, termed framework regions (FR). Each VH and VL is
composed of three CDRs and four FRs arranged from amino-terminus to
carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3,
CDR3, and FR4. The three CDRs constitute about 15-20% of the
variable domains. The variable regions of the heavy and light
chains contain a binding domain that interacts with an antigen. The
constant regions of the antibodies can mediate the binding of the
immunoglobulin to host tissues or factors, including various cells
of the immune system (e.g., effector cells) and the first component
(C1q) of the classical complement system. (Kuby, Immunology, 4th
ed., Chapter 4. W.H. Freeman & Co., New York, 2000).
[0045] In some embodiments, the term "antibody" includes, but is
not limited to, monoclonal antibodies, human antibodies, humanized
antibodies, chimeric antibodies, and anti-idiotypic (anti-Id)
antibodies (including, for example, anti-Id antibodies to
antibodies of the present disclosure). The antibodies can be of any
isotype/class (e.g., IgG, IgE, IgM, IgD, IgA, and IgY), or subclass
(e.g., IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2).
[0046] In some embodiments, the term "antigen binding fragment"
refers to one or more portions of an antibody that retain the
ability to specifically interact with (e.g., by binding, steric
hindrance, stabilizing/destabilizing, and spatial distribution) an
epitope of an antigen. Examples of binding fragments include, but
are not limited to, single-chain Fvs (scFv), camelid antibodies,
disulfide-linked Fvs (sdFv), Fab fragments, F(ab') fragments, a
monovalent fragment consisting of the VL, VH, CL, and CH1 domains;
a F(ab)2 fragment, a bivalent fragment including two Fab fragments
linked by a disulfide bridge at the hinge region; a Fd fragment
consisting of the VH and CH1 domains; a Fv fragment consisting of
the VL and VH domains of a single arm of an antibody; a dAb
fragment (Ward, E. Sally, et al., "Binding activities of a
repertoire of single immunoglobulin variable domains secreted from
Escherichia coli." Nature 341.6242 (1989): 544-546), which consists
of a VH domain; and an isolated complementarity determining region
(CDR), or other epitope-binding fragments of an antibody.
[0047] Furthermore, although the two domains of the Fv fragment (VL
and VH) are coded for by separate genes, they can be joined (using
recombinant methods) by a synthetic linker that enables them to be
made as a single protein chain, in which the VL and VH regions pair
to form monovalent molecules (known as single chain Fv ("scFv");
see, e.g., Bird, Robert E., et al., "Single-chain antigen-binding
proteins." Science 242.4877 (1988): 423-427; and Huston, James S.,
et al., "Protein engineering of antibody binding sites: recovery of
specific activity in an anti-digoxin single-chain Fv analogue
produced in Escherichia coli." Proceedings of the National Academy
of Sciences 85.16 (1988): 5879-5883). Such single chain antibodies
are also intended to be encompassed within the term "antigen
binding fragment." These antigen binding fragments are obtained
using conventional techniques known to those of skill in the art,
and the fragments are screened for utility in the same manner as
are intact antibodies.
[0048] Antigen binding fragments can also be incorporated into
single domain antibodies, maxibodies, minibodies, single domain
antibodies, intrabodies, diabodies, triabodies, tetrabodies, v-NAR,
and bis-scFv (see, e.g., Holliger, Philipp, and Peter J. Hudson,
"Engineered antibody fragments and the rise of single domains."
Nature Biotechnology 23.9 (2005): 1126). Antigen binding fragments
can be grafted into scaffolds based on polypeptides such as
fibronectin type III (Fn3) (see U.S. Pat. No. 6,703,199, which
describes fibronectin polypeptide monobodies).
[0049] Antigen binding fragments can be incorporated into single
chain molecules including a pair of tandem Fv segments
(VH-CH1-VH-CH1) which, together with complementary light chain
polypeptides, form a pair of antigen binding regions (Zapata,
Gerardo, et al., "Engineering linear F(ab')2 fragments for
efficient production in Escherichia coli and enhanced
antiproliferative activity." Protein Engineering, Design and
Selection 8.10 (1995): 1057-1062 and U.S. Pat. No. 5,641,870).
[0050] In some embodiments, the term "monoclonal antibody" or
"monoclonal antibody composition" refers to polypeptides, including
antibodies and antigen binding fragments that have substantially
identical amino acid sequence or are derived from the same genetic
source. This term also includes preparations of antibody molecules
of single molecular composition. A monoclonal antibody composition
displays a single binding specificity and affinity for a particular
epitope.
[0051] In some embodiments, the term "nanoparticles" refers to
atomic, molecular or macromolecular particles in the length scale,
for example, of approximately 1 to 100 nm. Novel and
differentiating properties and functions of nanoparticles are
observed or developed at a critical length scale of matter, such as
less than 100 nm. Nanoparticles can be used in constructing
nanoscale structures and can be integrated into larger material
components, systems, and architectures. In some embodiments, the
critical length scale for novel properties and phenomena involving
nanoparticles can be under 1 nm (e.g., manipulation of atoms at
approximately 0.1 nm) or it can be larger than 100 nm (e.g.,
nanoparticle reinforced polymers have the unique feature at
approximately 200 to 300 nm as a function of the local bridges or
bonds between the nanoparticles and the polymer).
[0052] In some embodiments, the term "nucleation composition"
refers to a substance or mixture that includes one or more nuclei
capable of growing into a crystal under conditions suitable for
crystal formation. A nucleation composition can, for example, be
induced to undergo crystallization by evaporation, changes in
reagent concentration, adding a substance such as a precipitant,
seeding with a solid material, mechanical agitation, or scratching
of a surface in contact with the nucleation composition.
[0053] In some embodiments, the term "particulate" refers to a
cluster or agglomeration of particles such as atoms, molecules,
ions, dimers, polymers, or biomolecules. Particulates can include
solid matter or be substantially solid, but they can also be porous
or partially hollow. They can contain a liquid or gas. In addition,
particulates can be homogeneous or heterogeneous; that is, they can
include one or more substances or materials.
[0054] In some embodiments, the term "polymer" refers to any
substance or compound that is composed of two or more building
blocks (`mers`) that are repetitively linked to each other. For
example, a "dimer" is a compound in which two building blocks have
been joined together. Polymers include both condensation and
addition polymers. Examples of condensation polymers include
polyamide, polyester, protein, wool, silk, polyurethane, cellulose,
and polysiloxane. Examples of addition polymers are polyethylene,
polyisobutylene, polyacrylonitrile, poly(vinyl chloride), and
polystyrene. Other examples include polymers having enhanced
electrical or optical properties (e.g., a nonlinear optical
property) such as electroconductive or photorefractive polymers.
Polymers include both linear and branched polymers.
[0055] FIG. 1 illustrates an overview of components that can be
included in a sensor system 100. Sensor system 100 can include a
bioFET sensor array 102 coupled with a biometric fingerprint sensor
108 configured to authenticate the use of bioFET sensor array 102
(e.g., by a user). Such authentication with biometric fingerprint
sensor 108 can allow (e.g., the use to have) personalized sensor
systems with bioFET sensor arrays like bioFET sensor array 102 for
secure bio-sensing and/or secure transmission of bio-sensing
measurements to a storage system (e.g., medical record systems or
Health Savings Accounts (HSAs)).
[0056] BioFET sensor array 102 can include at least one sensing
element for detecting a biological or chemical analyte and a fluid
delivery system 104 configured to deliver one or more fluid samples
to bioFET sensor array 102. Fluid delivery system 104 can be a
microfluidic well positioned above bioFET sensor array 102 to
contain a fluid over bioFET sensor array 102. Fluid delivery system
104 can also include microfluidic channels for delivering various
fluids to bioFET sensor array 102. Fluid delivery system 104 can
include any number of valves, pumps, chambers, channels designed to
deliver fluid to bioFET sensor array 102. BioFET sensor array 102
can include a repeating layout of sensors across a surface. For
example, bioFET sensors can be arranged in a two-dimensional array
of rows and columns across the surface.
[0057] BioFET sensor array 102 can include an array of bioFET
sensors, where one or more of the bioFET sensors in the array can
be functionalized to detect a particular target analyte. Different
ones of the bioFET sensors can be functionalized using different
capture reagents for detecting different target analytes. Further
details regarding an example bioFET sensor are provided below. The
bioFET sensors can be arranged in a plurality of rows and columns,
forming a 2-dimensional array of bioFET sensors. In some
embodiments, each row of bioFET sensors can be functionalized using
a different capture reagent. In some embodiments, each column of
bioFET sensors can be functionalized using a different capture
reagent. In some embodiments, different sectors of the
2-dimensional array can be functionalized with different capture
reagents.
[0058] A readout circuit 106 can be configured to measure signals
from the bioFET sensors in bioFET sensor array 102, to generate a
quantifiable sensor signal indicative of the amount of a certain
analyte present in a target solution, and to output the
quantifiable sensor signal to a controller 110 and/or a display
device (not shown), according to some embodiments.
[0059] Biometric fingerprint sensor 108 can include an array of
sensor regions and can be configured to sense a fingerprint pattern
of a user based on piezoelectric or capacitive sensing. The
piezoelectric or capacitive sensing of the fingerprint pattern can
be based on the spatial pattern of the pressure applied by the
user's fingerprint on the array of sensor regions. The pressure
pattern on the array of sensor regions can correspond to the
pattern of the fingerprint's ridges and valleys. Biometric
fingerprint sensor 108 can be configured to convert the applied
pressure into electrical signals indicative of the pattern of the
fingerprint's ridges and valleys.
[0060] A controller 110 can be configured to send and receive
electrical signals to both bioFET sensor array 102 and readout
circuit 106 to perform bio- or chemical-sensing measurements.
Controller 108 can also be configured to send electrical signals
(not shown) to fluid delivery system 104 to, for example, actuate
one or more valves, pumps, or motors. Controller 110 can be further
configured to receive the electrical signals from biometric
fingerprint sensor 108 to authenticate the fingerprint pattern of
the user and to activate bioFET sensor array 102 based on the
authentication. Controller 108 can use authentication data to
securely transfer measurements from bioFET sensor array 102 to
storage systems. Controller 108 can include one or more processing
devices, such as a microprocessor, and can be programmable to
control the operation of biometric fingerprint sensor 110, readout
circuit 106, and/or bioFET sensor array 102. The various electrical
signals that can be sent and received from bioFET sensor array 102
will be discussed in more detail below.
[0061] Embodiments described herein relate to measuring signals
from one or more bioFET sensors, or arrays of bioFET sensors, in a
differential manner to reduce common noise between the bioFET
sensors. Accomplishing this goal can include controlling the fluid
delivery to two separate bioFET sensors, or arrays of bioFET
sensors, and differentially reading out the measured signals from
each of the bioFET sensors, or arrays of bioFET sensors. This
section describes an example embodiment of a bioFET sensor that can
be used in the embodiments of the present application.
[0062] One example type of bioFET sensor that can be used in bioFET
sensor array 102 (FIG. 1) is the dual gate back-side sensing FET
sensor. Dual gate back-side FET sensors utilize semiconductor
manufacturing techniques and biological capture reagents to form
arrayed sensors. While MOSFETs can have a single gate electrode
connected to a single electrical node, the dual gate back-side
sensing FET sensor can have two gate structures, each of which is
connected to a different electrical node. A first one of the two
gate structures is referred to as a "front-side gate," and the
second one of the two gate structures is referred to as a
"back-side gate." Both the front-side gate and the back-side gate
are configured such that, in operation, each one can be
electrically charged and/or discharged and thereby each can
influence the electric field between the source/drain terminals of
the dual gate back-side sensing FET sensor. The front-side gate can
be electrically conductive, separated from a channel region by a
front-side gate dielectric, and can be configured to be charged and
discharged by an electrical circuit to which it is coupled. The
back-side gate can be separated from the channel region by a
back-side gate dielectric and can include a bio-functionalized
sensing layer disposed on the back-side gate dielectric. The amount
of electric charge on the back-side gate can be a function of
whether a bio-recognition reaction has occurred. In the operation
of the dual gate back-side sensing FET sensors, the front-side gate
can be charged to a voltage within a predetermined range of
voltages. The voltage on the front-side gate can determine a
corresponding conductivity of the FET sensor's channel region. A
relatively small amount of change to the electric charge on the
back-side gate can change the conductivity of the channel region.
It is this change in conductivity that can indicate a
bio-recognition reaction.
[0063] One advantage of the dual gate back-side sensing FET sensors
is the prospect of label-free operation. Specifically, the dual
gate back-side sensing FET sensors can enable the avoidance of
costly and time-consuming labeling operations such as the labeling
of an analyte with, for instance, fluorescent or radioactive
probes.
[0064] FIG. 2 illustrates a dual gate back-side sensing FET sensor
200, according to some embodiments. In some embodiments, dual gate
back-side sensing FET sensor 200 can represent the bioFET sensors
of bioFET sensor array 102 (FIG. 1). Dual gate back-side sensing
FET sensor 200 can include a gate electrode 202 formed on a surface
of a semiconductor substrate 214 and separated therefrom by an
intervening gate dielectric 215 disposed on semiconductor substrate
214. A dielectric layer 211 including a plurality of interconnect
layers (not shown) can be provided over one side of semiconductor
substrate 214. Semiconductor substrate 214 also referred to as
active layer 214 can be doped with n-type and/or p-type dopants.
Semiconductor substrate 214 can include a source region 204, a
drain region 206, and a channel region 208 between source region
204 and drain region 206. In some embodiments, semiconductor
substrate 214 can have a thickness in a range from about 100 nm to
about 130 nm. Gate electrode 202, source region 204, drain region
206, and channel region 208 can be formed using suitable CMOS
process technology. Gate electrode 202, source region 204, drain
region 206, and channel region 208 can form a FET. An isolation
layer 210 can be disposed on the opposing side of semiconductor
substrate 214 from gate electrode 202. In some embodiments,
isolation layer 210 can have a thickness of about 1 .mu.m. In this
disclosure side 214f of semiconductor substrate 214 over which gate
electrode 202 is disposed is referred to as the "front-side" of
semiconductor substrate 214. Similarly, side 214b of semiconductor
substrate 214 on which isolation layer 210 is disposed is referred
to as the "back-side."
[0065] An opening 212 can be provided in isolation layer 210.
Opening 212 can be substantially aligned with gate electrode 202.
In some embodiments, opening 212 can be larger than gate electrode
202 and can extend over multiple dual gate back-side sensing FET
sensors. An interface layer 224 can be disposed in opening 212 on
the surface of channel region 208. The region of opening 212 lined
with interface layer 224 along its sidewalls can form a sensing
well 213. Interface layer 224 within sensing well 213 can be
operable to provide an interface for positioning and immobilizing
one or more capture reagents 226 that act as surface receptors for
detection of biomolecules or bio-entities.
[0066] Dual gate back-side sensing FET sensor 200 can further
include electrical contacts 216 and 218 to drain region 206 and
source region 204, respectively. A front-side gate contact 220 can
be made to gate electrode 202, while a back-side gate contact 222
can be made to channel region 208. It should be noted that
back-side gate contact 222 does not need to physically contact
semiconductor substrate 214 or any interface layer over
semiconductor substrate 214. Thus, while a FET can use a gate
contact to control conductance of the semiconductor between the
source and drain (e.g., the channel), dual gate back-side sensing
FET sensor 200 can allow capture reagents 226 formed on a side
opposing gate electrode 202 to control the conductance, while gate
electrode 202 can provide another region to control the
conductance. Therefore, dual gate back-side sensing FET sensor 200
can be used to detect one or more specific biomolecules or
bio-entities in the environment around and/or in opening 212, as
discussed in more detail using various examples herein.
[0067] Dual gate back-side sensing FET sensor 200 can be connected
to: additional passive components such as resistors, capacitors,
inductors, and/or fuses; other active components, including
p-channel field effect transistors (PFETs), n-channel field effect
transistors (NFETs), metal-oxide-semiconductor field effect
transistors (MOSFETs), high voltage transistors, and/or high
frequency transistors; other suitable components; or combinations
thereof. Additional features can be added in dual gate back-side
sensing FET sensor 200, and some of the features described can be
replaced or eliminated, for additional embodiments of dual gate
back-side sensing FET sensor 200.
[0068] FIG. 3 illustrates a schematic of a portion of an
addressable array 300 of bioFET sensors 304 connected to bit lines
306 and word lines 308, according to some embodiments. The terms
bit lines and word lines are used herein to indicate similarities
to array construction in memory devices, however, there is no
implication that memory devices or a storage array necessarily be
included in the array. Addressable array 300 can have similarities
to that employed in other semiconductor devices, such as dynamic
random access memory (DRAM) arrays. For example, dual gate
back-side sensing FET sensor 200 (FIG. 2) can be formed in a
position that a capacitor would be found in a DRAM array.
Addressable array 300 is exemplary and other configurations are
possible.
[0069] FETs 302 can be configured to provide an electrical
connection between a drain region of bioFET sensor 304 and bit line
306. In this way, FETs 302 can be analogous to access transistors
in a DRAM array. In some embodiments, each of bioFET sensors 304
can be similar to a dual gate back-side sensing FET sensor 200 and
each can include a sensing gate provided by a receptor material
disposed on a dielectric layer overlying a FET channel region
disposed at a reaction site, and a control gate provided by a gate
electrode (e.g., polysilicon) disposed on a dielectric layer
overlying the FET channel region.
[0070] Addressable array 300 shows an array formation designed to
detect small signal changes provided by biomolecules or
bio-entities introduced to bioFET sensors 304. The arrayed format
using bit lines 306 and word lines 308 allows for a smaller number
of input/output pads since common terminals of different FETs in
the same row or column are tied together. Amplifiers can be used to
enhance the signal strength to improve the detection ability of the
device having the circuit arrangement of addressable array 300. In
some embodiments, when voltage is applied to particular word lines
308 and bit lines 306, the corresponding access transistors 302 can
be turned ON (e.g., like a switch). When the gate of the associated
bioFET sensor 304 (e.g., such as back-side gate 222 of dual gate
back-side sensing FET sensor 200) has its charge affected by the
bio-molecule presence, a threshold voltage of bioFET sensor 304 is
changed, thereby modulating the current (e.g., I.sub.ds) for a
given voltage applied to back-side gate 222. The change of the
current (e.g., I.sub.ds) or threshold voltage (V.sub.t) can serve
to indicate detection of the relevant biomolecules or
bio-entities.
[0071] FIG. 4 illustrates an addressable array 400 of dual gate
back-side sensing FET sensors and heater. Addressable array 400 can
include access transistor 302 and bioFET sensor 304 arranged as an
array 401 of individually addressable pixels 402. In some
embodiments, each of bioFET sensors 304 can be similar to a dual
gate back-side sensing FET sensor 200. Array 401 can include any
number of pixels 402. For example, array 401 can include
128.times.128 pixels. Other arrangements can include 256.times.256
pixels or non-square arrays such as 128.times.256 pixels.
[0072] Each pixel 402 can include access transistor 302 and bioFET
sensor 304 along with other components that can include one or more
heaters 408 and a temperature sensor 410. In some embodiments,
access transistor 302 can be an n-channel FET. An n-channel FET 412
can also act as an access transistor for temperature sensor 410. In
some embodiments, the gates of FETs 302 and 412 can be connected,
though this is not required. Each pixel 402 (and its associated
components) can be individually addressed using column decoder 404
and row decoder 406. In some embodiments, each pixel 402 can have a
size of about 10 .mu.m by about 10 .mu.m, about 5 .mu.m by about 5
.mu.m, or about 2 .mu.m by about 2 .mu.m.
[0073] Column decoder 406 and row decoder 404 can be used to
control the ON/OFF state of both n-channel FETs 302 and 412 (e.g.,
voltage is applied to the gates of FETs 302 and 412 together, and
voltage is applied to the drain regions of FETs 302 and 412
together). Turning ON n-channel FET 302 can provide a voltage to a
source/drain region of bioFET sensor 304. When bioFET sensor 304 is
ON, a current I.sub.ds can flow through bioFET sensor 304 and can
be measured.
[0074] Heater 408 can be used to locally increase a temperature
around bioFET sensor 304. Heater 408 can be constructed using any
known technique, such as forming a metal pattern with a high
current running through it. Heater 408 can also be a thermoelectric
heater/cooler, like a Peltier device. Heater 408 can be used during
certain biological tests such as to denature DNA or RNA or to
provide a binding environment for certain biomolecules. Temperature
sensor 410 can be used to measure the local temperature around
bioFET sensor 304. In some embodiments, a control loop can be
created to control the temperature using heater 408 and the
feedback received from temperature sensor 410. In some embodiments,
heater 408 can be a thermoelectric heater/cooler configured to
provide local active cooling to the components within pixel
402.
[0075] FIG. 5A illustrates a cross-sectional view of a
semiconductor device 500, according to some embodiments. The
cross-sectional view of semiconductor device 500 is shown for
illustration purposes and may not be drawn to scale. Semiconductor
device 500 can include a bioFET sensor 528, a biometric fingerprint
sensor 530, a temperature sensor 532, and a heater 534 disposed on
a carrier substrate 536. The discussion of dual gate back-side
sensing FET sensor 200 applies to bioFET sensor 528 unless
mentioned otherwise. The elements of FIG. 5A with the same
annotations as elements in FIG. 2 are described above. Though one
bioFET sensor 530 is shown in FIG. 5A, semiconductor device 500 can
include an array of bioFET sensors 530. In some embodiments,
biometric fingerprint sensor 530, temperature sensor 532, and
heater 534 can be an implementation of biometric fingerprint sensor
108 (FIG. 1), temperature sensor 410 (FIG. 4), and heater 408 (FIG.
4), respectively. The discussion of biometric fingerprint sensor
108, temperature sensor 410, and heater 408 applies to biometric
fingerprint sensor 530, temperature sensor 532, and heater 534,
respectively, unless mentioned otherwise.
[0076] BioFET sensor 528 can include gate electrode 202, source
region 204, drain region 206, and channel region 208, where source
region 204 and drain region 206 are formed within semiconductor
substrate 214. In some embodiments, semiconductor substrate 214 can
be formed from a single semiconductor crystal, such as crystalline
silicon. Alternatively, semiconductor substrate 214 can include (i)
an elementary semiconductor, such as germanium; (ii) a compound
semiconductor including silicon carbide, gallium arsenide, gallium
phosphide, indium phosphide, indium arsenide, and/or indium
antimonide; (iii) an alloy semiconductor including silicon
germanium carbide, silicon germanium, gallium arsenic phosphide,
gallium indium phosphide, gallium indium arsenide, gallium indium
arsenic phosphide, aluminum indium arsenide, and/or aluminum
gallium arsenide; or (iv) a combination thereof. Further,
semiconductor substrate 214 can be doped with p-type dopants (e.g.,
boron, indium, aluminum, or gallium) or n-type dopants (e.g.,
phosphorus or arsenic). In some embodiments, semiconductor
substrate 214 can have a vertical dimension along a Z-axis in a
range from about 5 nm to about 200 nm.
[0077] Gate electrode 202, source region 204, drain region 206, and
channel region 208 form a FET. BioFET sensor 528 can be coupled to
additional circuitry (not shown) fabricated within semiconductor
substrate 214. The additional circuitry can include any number of
MOSFET devices, resistors, capacitors, and/or inductors to form
circuitry to aid in the operation of bioFET sensor 528. The
additional circuitry can represent readout circuit 106 of FIG. 1
used to measure a signal from bioFET sensor 528 that is indicative
of analyte detection. The additional circuitry can include
amplifiers, analog to digital converters (ADCs), digital to analog
converters (DACs), voltage generators, logic circuitry, and/or DRAM
memory, to name a few examples.
[0078] BioFET sensor 528 can further include interface layer 224
disposed on isolation layer 210 and within opening 212 over channel
region 208. In some embodiments, isolation layer 210 can include a
dielectric material, such as silicon oxide. In some embodiments,
isolation layer 210 can have a vertical dimension along a Z-axis in
a range from about 1 nm to about 500 nm. In some embodiments,
interface layer 224 can have a thickness on channel region 208 in a
range from about 20 .ANG. to about 40 .ANG.. Interface layer 224
can include a high-k dielectric material, such as hafnium silicate,
hafnium oxide (HfO.sub.2), zirconium oxide (ZrO.sub.2), aluminum
oxide (Al.sub.2O.sub.3), tantalum pentoxide (Ta.sub.2O.sub.5),
hafnium dioxide-alumina (HfO.sub.2--Al.sub.2O.sub.3) alloy, or any
combinations thereof. Interface layer 224 can act as a support for
the attachment of capture reagents 226. A solution 540 can be
provided over the reaction site of bioFET sensor 528. Solution 540
can be a buffer solution with capture reagents, target analytes,
wash solution, or any other biological or chemical species. In some
embodiments, solution 540 can be provided within a microfluidic
channel 542 of semiconductor device 500 disposed on the portion of
interface layer 224 extending over isolation layer 210.
[0079] In some embodiments, bioFET sensor 528 can be coupled to a
multi-layer interconnect (MLI) structure 538 disposed within
dielectric layer 211 of semiconductor device 500. Dielectric layer
211 can be disposed on carrier substrate 536 and can be an
inter-layer dielectric or ILD layer and/or composed of multiple ILD
sub-layers. In some embodiments, dielectric layer 211 can include
an oxide or a nitride material. In some embodiments, dielectric
layer 211 can have a vertical dimension along a Z-axis in a range
from about 50 nm to about 5000 nm. MLI structure 538 can include a
plurality of conductive lines 538A electrically connected to each
other through conductive vias or plugs 538B. In some embodiments,
conductive lines 538A can include aluminum and/or copper, and
conductive vias or plugs 538B can include tungsten or copper. MLI
structure 538 can be configured to provide electrical connection to
bioFET sensor 528 with various doped regions and/or devices formed
within semiconductor substrate 214.
[0080] Biometric fingerprint sensor 530 can include an array of
sensor regions 530A-530C with a common bottom electrode 546
disposed on isolation layer 210, which is disposed on semiconductor
substrate 214. Each of sensor regions 530A-530C can further include
a top electrode 544 and a sensing material 548. In some
embodiments, each sensing material 548 can be disposed on bottom
electrode 546 at a pitch distance of about 1 .mu.m to about 500
.mu.m. In some embodiments, sensing material 548 can be a
piezoelectric material, such as lead zirconate titanate (also
referred to as PZT), aluminum nitride (AlN), or zinc oxide (ZnO)
for piezoelectric biometric fingerprint sensor 530 or a high-k
dielectric material, such as hafnium oxide (HfO.sub.2), titanium
oxide (TiO.sub.2), hafnium zirconium oxide (HfZrO), tantalum oxide
(Ta.sub.2O.sub.3), hafnium silicate (HfSiO.sub.4), zirconium oxide
(ZrO.sub.2), zirconium silicate (ZrSiO.sub.2), or any combination
thereof for capacitive biometric fingerprint sensor 530. In some
embodiments, sensing material 548 can have a vertical dimension
along a Z-axis in a range from about 100 nm to about 2000 nm. Top
and bottom electrodes 544 and 546 can include conductive materials,
such as platinum (Pt), gold (Au), zinc (Zn), copper (Cu), aluminum
(Al), lead (Pb), tungsten (W), tin (Sn), iron (Fe), nickel (Ni),
lithium (Li), or a metal with a high temperature coefficient of
resistance (e.g., greater than about 1.times.10.sup.-3/.degree.
C.). In some embodiments, each of top and bottom electrode 544 and
546 can have a vertical dimension along a Z-axis in a range from
about 20 nm to about 500 nm. The vertical dimension of top
electrode 544 within this range can provide a flexible top
electrode for sensing the pressure applied by a user's fingerprint
on sensing material 548 of the array of sensor regions 530A-530C.
The vertical dimension of top electrode 544 outside the range of
about 20 nm to about 500 nm can reduce the flexibility of top
electrode 544 and thus reduce the sensitivity of biometric
fingerprint sensor 530.
[0081] Biometric fingerprint sensor 530 can further include a
sensing layer 550 disposed on the array of sensor regions
530A-530C. Sensing layer 550 can also be disposed between adjacent
sensor regions of the array of sensor regions 530A-530C to
electrically isolate them from each other. Sensing layer 550 can
include high-k materials, such as hafnium oxide (HfO.sub.2),
titanium oxide (TiO.sub.2), hafnium zirconium oxide (HfZrO),
tantalum oxide (Ta.sub.2O.sub.3), hafnium silicate (HfSiO.sub.4),
zirconium oxide (ZrO.sub.2), zirconium silicate (ZrSiO.sub.2),
silicon oxide (SiO.sub.2), silicon nitride, yttrium oxide
(Y.sub.2O.sub.3), lanthanum oxide (La.sub.2O.sub.3), or any
combination thereof. In some embodiments, sensing layer 550 can
have a vertical dimension along a Z-axis in a range from about 1 nm
to about 100 nm. The vertical dimension of sensing layer 550 within
this range can provide a flexible insulating layer that is
sensitive to the pressure applied by the user's fingerprint on top
electrodes 544.
[0082] In some embodiments, as shown in FIG. 5B, biometric
fingerprint sensor 530 can optionally include a coupling layer 552
disposed on sensing layer 550, a cover plate 554 disposed on
coupling layer 552, and an array of cavities 556 on back side of
biometric fingerprint sensor 530. Coupling layer 552 can include a
polymeric material and can have a vertical dimension along a Z-axis
in a range from about 1 .mu.m to about 1000 .mu.m. Coupling layer
552 can be configured to provide additional flexibility to the
underlying sensing layer 550 and/or top electrodes 544 for
increased sensitivity to the pressure applied by the user's
fingerprint on sensing material 548 of the array of sensor regions
530A-530C. Cover plate 554 can include sapphire glass or other
suitable protective material for protecting coupling layer 552 when
pressure applied by the user's fingerprint on biometric fingerprint
sensor 530. In some embodiments, cover plate 554 can have a
vertical dimension along a Z-axis in a range from about 1000 .mu.m
to about 40000 .mu.m. In some embodiments, each cavity 556 can have
a vertical dimension along a Z-axis in a range from about 300 .mu.m
to about 1000 .mu.m and a horizontal dimension along an X-axis in a
range from about 1 .mu.m to about 500 .mu.m. The array of cavities
556 can be configured to create a resonating cavity for increasing
amplitude of ultrasound generated by biometric fingerprint sensor
530.
[0083] Though three sensor regions 530A-530C is shown in FIGS.
5A-5B, biometric fingerprint sensor 530 can include a 2-dimensional
array of sensor regions similar to sensor region 530A-530C as shown
in FIG. 6. FIG. 6 illustrates a plan view of a 2-dimensional array
600 having nine sensor regions 11-33, where each row (along an
X-axis) of sensor regions can be similar to the array of sensor
regions 530A-530C and the cross-sectional view of the array of
sensor regions 530A-530C can be along line A-A of FIG. 6. The
discussion of the array of sensor regions 530A-530C applies to each
row of sensor regions of array 600 unless mentioned otherwise. In
FIG. 6, only sensing material 548 are shown to represent sensor
regions 11-33 and top and bottom electrodes 544 and 546 are not
shown for clarity.
[0084] In array 600, top electrodes 544 of each column (along a
Y-axis) of array 600 can be connected to a voltage source
represented by T1, T2, and T3, and bottom electrode 546 of each row
(along an X-axis) of array 600 can be connected to a voltage source
represented by B1, B2, and B3. Bottom electrode 546 can be common
for sensor regions along each row, and not along each column of
array 600. During operation of biometric fingerprint sensor 530,
each sensor regions of array 600 can be sequentially or in any
order activated by suppling voltage from its corresponding voltage
sources. For example, sensor region 11 can be activated by
supplying voltage from voltage sources T1 and B1, and sensor region
12 can be activated by supplying voltage from voltage sources T2
and B1. In some embodiments, the voltage supplied by voltage
sources T1-T3 can be greater than that supplied by voltage sources
B1-B3. In some embodiments, the voltage supplied by voltage sources
T1-T3 can be in a range from about 0.5 V to about 5 V. In some
embodiments, voltage sources B1-B3 can be at ground potential and
bottom electrodes 546 can be grounded during operation of biometric
fingerprint sensor 530. In some embodiments, voltages supplied to
bioFET sensor 528, biometric fingerprint sensor 530, and
temperature sensor 532 during their operation different from each
other. In some embodiments, the voltage supplied to bioFET sensor
528 during its operation can range from about 0.5 V to about 2.5 V
and the voltage supplied to temperature sensor 532 during its
operation can range from about 0.5 V to about 2 V.
[0085] Referring back to FIG. 5A, temperature sensor 532 can
include a sensing electrode 558 disposed on isolation layer 210,
which is disposed on semiconductor substrate 214. Temperature
sensor 532 can be configured to measure the temperature of devices
(e.g., bioFET sensor 528) within semiconductor substrate 214 and/or
solutions (e.g., solution 540) within opening 212 based on the
variations in resistance of sensing electrode 558 with variations
in temperature. Sensing electrode 558 can include a material with a
stable resistance-temperature relationship, which can be the amount
of resistance change of the material per degree of temperature
change. In some embodiments, this material can include Pt, Au, Zn,
Cu, Al, Pb, W, Sn, Fe, Ni, Li, or a metal with a high temperature
coefficient of resistance (e.g., greater than about
1.times.10.sup.-3/.degree. C.).
[0086] Heater 534 can include resistive elements coupled to a
suitable current supply. In some embodiments, heater 534 can be
supplied with current through MLI structure 538. In some
embodiments, heater 534 can include doped polysilicon and/or can
have the same dopant concentration profile as semiconductor
substrate 214.
[0087] FIG. 7 is a flow diagram of a method 700 for fabricating
semiconductor device 500 as described with reference to FIGS.
5A-5B, according to some embodiments. For illustrative purposes,
the operations illustrated in method 700 will be described with
reference to the example fabrication process for fabricating
semiconductor device 500 as illustrated in FIGS. 8-18. FIGS. 8-18
are cross-sectional views of semiconductor device 500 at various
stages of its fabrication process. Operations can be performed in a
different order or not performed depending on specific
applications. It should be noted that method 700 may not produce a
complete semiconductor device 500. Accordingly, it is understood
that additional processes can be provided before, during, and after
method 700, and that some other processes may only be briefly
described herein. Elements in FIGS. 8-18 with the same annotations
as elements in FIGS. 5A-5B are described above.
[0088] In operation 705, a transistor and a multi-layer
interconnect (MLI) structure are formed on a substrate. For
example, as described with reference to FIG. 8, a field effect
transistor (FET) 801 and MLI structure 538 can be formed on a
substrate 860. The process for forming FET 801 on substrate 860 can
include forming substrate 860, forming gate electrode 202, and
forming source and drain regions 204 and 206.
[0089] The process for forming substrate 860 can include forming a
silicon-on-insulator (SOI) substrate that can include semiconductor
substrate 214 (also referred to as active layer 214), a buried
oxide layer 210*, which can form isolation layer 210 in subsequent
processing, and a bulk semiconductor 810. In some embodiments, the
SOI substrate can be formed through separation by implanted oxygen
(SIMOX). The process for forming gate electrode 202 can include
depositing a dielectric material for gate dielectric 215 on
semiconductor substrate 214 and a conductive material for gate
electrode 202 on gate dielectric 215, followed by patterning and
etching of the deposited materials.
[0090] The dielectric material for gate dielectric 215 can include
(i) silicon oxide, silicon nitride, and/or silicon oxynitride, (ii)
a high-k dielectric material, such as HfO.sub.2, TiO.sub.2, HfZrO,
Ta.sub.2O.sub.3, HfSiO.sub.4, ZrO.sub.2, and ZrSiO.sub.2, (iii) a
high-k dielectric material having oxides of lithium (Li), beryllium
(Be), magnesium (Mg), calcium (Ca), strontium (Sr), scandium (Sc),
yttrium (Y), zirconium (Zr), aluminum (Al), lanthanum (La), cerium
(Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium
(Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho),
erbium (Er), thulium (Tm), ytterbium (Yb), or lutetium (Lu), or
(iv) a combination thereof and can be formed by CVD, atomic layer
deposition (ALD), physical vapor deposition (PVD), e-beam
evaporation, or other suitable processes.
[0091] In some embodiments, the conductive material for gate
electrode 202 can include Ti, silver (Ag), Al, titanium aluminum
nitride (TiAlN), tantalum carbide (TaC), tantalum carbo-nitride
(TaCN), tantalum silicon nitride (TaSiN), manganese (Mn), Zr,
titanium nitride (TiN), tantalum nitride (TaN), ruthenium (Ru),
molybdenum (Mo), tungsten nitride (WN), copper (Cu), tungsten (W),
cobalt (Co), nickel (Ni), titanium carbide (TiC), titanium aluminum
carbide (TiAlC), tantalum aluminum carbide (TaAlC), metal alloys,
and/or combinations thereof and can be formed by ALD, PVD, CVD, or
other suitable deposition processes.
[0092] The process for forming gate electrode 202 can be followed
by the process for forming source and drain regions 204 and 206,
which can include doping regions of semiconductor substrate 214
with n-type or p-type dopants. After the process for forming source
and drain regions 204 and 206, MLI structure 538 can be formed on
substrate 860. The process for forming MLI structure 538 can
include sequentially forming multiple layers, each of which can
include conductive lines 538A and conductive vias 538B in a stack
of dielectric layers that subsequently form interlayer dielectric
(ILD) layer 211 as shown in FIG. 8. The multiple layers can be
deposited by CVD, PVD, ALD, plating, or spin-on coating. Conductive
lines 538A can include Cu, Al, W, Ta, Ti, Ni, Co, metal silicide,
metal nitride, polysilicon, or any combinations thereof. The
dielectric layers of ILD 211 can include silicon oxide, fluorinated
silicon glass (FGS), silicon oxycarbide (SiOC), and/or other
insulating materials. MLI may be formed by suitable processes
typical in CMOS fabrication, such as CVD, PVD, ALD, plating,
spin-on coating, and/or other processes. In some embodiments,
heater 534 can be formed by the process for forming MLI structure
538.
[0093] Referring to FIG. 7, in operation 710, sensor regions of a
biometric fingerprint sensor and a sensing electrode of a
temperature sensor are formed on a back-side of a semiconductor
substrate. For example, as described with reference to FIGS. 9-12,
sensor regions 530A-530C of biometric fingerprint sensor 530 and
sensing electrode 558 of temperature 532 can be formed on back-side
214b of semiconductor substrate 214.
[0094] The process for forming sensor regions 530A-530C can include
(i) bonding carrier substrate 536 to front-side 214f of
semiconductor substrate 214, (ii) removing bulk semiconductor 810,
(iii) depositing materials for bottom electrode 546, sensing
material 548, and top electrodes 544, and (iv) patterning and
etching the deposited materials.
[0095] Referring to FIG. 9, the bonding of carrier substrate 536 to
front-side 214f can include using a wafer bonding process, such as
fusion bonding, anodic bonding, eutectic bonding, or a suitable
wafer bonding process, to bond back surface 563a of carrier
substrate 536 to ILD top surface 211a of ILD layer 211. In the case
of fusion bonding, the wafer bonding process can include bringing
carrier substrate 536 and ILD top surface 211a into physical
contact, followed by an annealing process that forms a bond (e.g.,
Si/Si bond, oxide/oxide bond, or oxide/Si bond) between carrier
substrate 536 and ILD top surface 211a. The annealing process can
be performed at a temperature ranging from about 200.degree. C. to
about 480.degree. C. The fusion bonding process can further include
applying a force on top surface 536a of carrier substrate 536 for a
period of time before or during the annealing process. The force
can range from about 0.1 N to about 5 N, and the period of time can
range from about 10 seconds to about 10 minutes. In some
embodiments, carrier substrate 536 can be bonded to ILD top surface
211a with a polysilicon layer as a bonding interface between back
surface 563a and ILD top surface 211a. In some embodiments, carrier
substrate 536 can include silicon, glass, and/or quartz.
[0096] Referring to FIGS. 9 and 10, the wafer bonding process can
be followed by a wafer thinning process to remove bulk
semiconductor 810 and expose buried oxide layer 210*, which forms
isolation layer 210 on semiconductor substrate 214. Prior to the
wafer thinning process, the structure of FIG. 9 can be flipped
vertically along an X-axis. The wafer thinning process can include
a grinding process, a polishing process, and/or an etching process
performed on exposed surface 810s of bulk semiconductor 810 of FIG.
9's structure.
[0097] The grinding process can include grinding on surface 810s of
bulk semiconductor 810 with a grinding tool for a period of time
ranging from about 30 seconds to about 10 minutes until surface
210s of isolation layer 210 is exposed as shown in FIG. 10. The
polishing process can include performing a CMP process on surface
810s of bulk semiconductor 810 until surface 210s of isolation
layer 210 is exposed as shown in FIG. 10. The etching process can
include a dry etch (e.g., a plasma etch) or a wet etch process. The
wet etch process can include etching surface 810s of bulk
semiconductor 810 with an etchant having hydrofluoric acid (HF),
nitric acid (HNO.sub.3), or a combinations thereof until surface
210s of isolation layer 210 is exposed as shown in FIG. 10. In some
embodiments, the etchant can include HNO.sub.3 with a concentration
in a range from about 50% to about 90%. In some embodiments, the
etchant can include HNO.sub.3 with a concentration in a range from
about 10% to about 50% mixed with hydrofluoric acid (HF) with a
concentration in a range from about 10% to about 50%. In some
embodiments, bulk semiconductor 810 can be removed by using the
grinding process, followed by the polishing process, and then the
etching process.
[0098] In the structure of FIG. 10, isolation layer 210 can have a
vertical dimension 210t along a Z-axis in a range from about 1 nm
to about 500 nm, semiconductor substrate 214 can have a vertical
dimension 214t in a range from about 5 nm to about 200 nm, ILD
layer 211 can have a vertical dimension 211t in a range from about
50 nm to about 5000 nm, and carrier substrate can have a vertical
dimension 536t in a range from about 400 .mu.m to about 1000
.mu.m.
[0099] Referring to FIG. 11, the process for removing bulk
semiconductor 810 can be followed by a process for depositing a
conductive material layer 546* on isolation layer 210 for
simultaneous formation of bottom electrode 546 and sensing
electrode 558 in subsequent processing (shown in FIG. 12),
according to some embodiments. The deposition of conductive
material layer 546* can be followed by a process for depositing a
piezoelectric material layer 548* or dielectric material layer 548*
on conductive material layer 546* for subsequent formation of
sensing material 548 (shown in FIG. 12). The deposition of layer
548* can be followed by a process for depositing a conductive
material layer 544* on layer 548* for subsequent formation of top
electrodes 544 (shown in FIG. 12).
[0100] The process for depositing conductive material layers 544*
and 546* can include depositing conductive materials, such as Pt,
Au, Zn, Cu, Al, Pb, W, Sn, Fe, Ni, Li, or a metal with a high
temperature coefficient of resistance using deposition methods,
such as e-gun evaporation or sputtering. In some embodiments, the
process for depositing conductive material layers 544* and 546* can
include depositing conductive materials, such as, silver (Ag) or
silver chloride (AgCl) using e-gun evaporation, sputtering,
electroplating, or screen printing. In some embodiments, the
process for depositing conductive material layers 544* and 546* can
further include depositing layers 544* and 546* each with a
vertical dimension along a Z-axis in a range from about 20 nm to
about 500 nm.
[0101] The process for depositing piezoelectric material layer 548*
can include depositing a piezoelectric material, such as PZT, AlN,
or ZnO, for piezoelectric biometric fingerprint sensor 530. The
process for depositing dielectric material layer 548* can include
depositing a high-k dielectric material, such as HfO.sub.2,
TiO.sub.2, HfZrO, Ta.sub.2O.sub.3, HfSiO.sub.4, ZrO.sub.2,
ZrSiO.sub.2, or any combinations thereof, for capacitive biometric
fingerprint sensor 530. Piezoelectric material layer 548* can be
deposited using deposition methods, such as sol-gel, physical vapor
deposition (PVD), or chemical vapor deposition (CVD) at temperature
ranging from about 80.degree. C. to about 100.degree. C. Dielectric
material layer 548* can be deposited using PVD or CVD. In some
embodiments, the process for depositing layer 548* can further
include depositing layer 548* with a vertical dimension along a
Z-axis in a range from about 100 nm to about 2000 nm.
[0102] Referring to FIG. 12, bottom electrode 546, top electrodes
544, sensing material 548, and sensing electrode 558 can be formed
after patterning and etching the conductive material layers 544*
and 546* and layer 548*. The etching process can include a lift-off
process, ion beam etching, reactive ion etching, wet etching, or
any combinations thereof. In some embodiments, the etching process
can be performed at a temperature ranging from room temperature
(e.g., 27.degree. C.) to about 100.degree. C. In some embodiments,
each sensing material 548 can be disposed on bottom electrode 546
at a pitch distance P.sub.1 of about 1 .mu.m to about 500
.mu.m.
[0103] Referring to FIG. 7, in operation 715, a sensing well is
formed on the back-side of the semiconductor substrate. For
example, as described with reference to FIGS. 13-15, sensing well
213 can be formed on back-side 214b of semiconductor substrate 214.
The process for forming sensing well 213 can include (i) forming
opening 212, (ii) depositing a high-k dielectric material layer
224*, and (iii) patterning and etching of layer 224*. Opening 212
can be formed by patterning and etching a portion of isolation
layer 210 overlying FET 801 on back-side 214b to expose channel
region 208 and portions of source region 204 and drain region 206.
The patterning and etching of the portion of isolation layer 210
can include using photolithography processes followed by an etching
process, such as a dry etch, wet etch, plasma etch, and/or
combinations thereof. In some embodiments, the patterning and
etching processes can include forming opening 212 with a horizontal
dimension along an X-axis in a range from about 5 nm to about 5
mm.
[0104] Referring to FIG. 14, following the forming of opening 212,
high-k dielectric material layer 224* can be blanket deposited on
the structure of FIG. 13. The blanket depositing can include
depositing a high-k material, such as HfO.sub.2, TiO.sub.2, HfZrO,
Ta.sub.2O.sub.3, HfSiO.sub.4, ZrO.sub.2, ZrSiO.sub.2, SiO.sub.2,
SiN, Y.sub.2O.sub.3, La.sub.2O.sub.3, or any combinations thereof,
using a deposition method, such as PVD, CVD, or ALD. In some
embodiments, the blanket depositing can further include depositing
high-k dielectric material layer 224* with a vertical dimension
along a Z-axis in a range from about 1 nm to about 100 nm.
[0105] Referring to FIG. 15, the patterning and etching of high-k
dielectric material layer 224* can simultaneously form sensing well
213 of bioFET sensor 528 and sensing layer 550 of biometric
fingerprint sensor 530. The etching process can include a lift-off
process, ion beam etching, reactive ion etching, wet etching, or
any combinations thereof. In some embodiments, the etching process
can be performed at a temperature ranging from room temperature
(e.g., 27.degree. C.) to about 100.degree. C.
[0106] As shown in FIG. 15, bioFET sensor 528, biometric
fingerprint sensor 530, and temperature sensor 558 can be
simultaneously formed at the end of operation 715. Such
simultaneous formation of different sensors in a semiconductor
device can reduce the number of process steps compared to the
number of process steps required if the fabrication processes of
theses sensors are not integrated. Thus, integration of the sensor
fabrication processes can reduce manufacturing cost and improve
manufacturing yield.
[0107] Referring to FIG. 7, in operation 720, a contact opening is
formed on the MLI structure. For example, as described with
reference to FIG. 15, a contact opening 1562 can be formed on MLI
structure 538. Contact opening 1562 can formed by patterning and
etching portions of layers (e.g., isolation layer 210,
semiconductor substrate 214, and/or ILD layer 211) overlying a
conductive line 538A of MLI structure 538. The patterning process
can include using photolithography processes followed by suitable
wet, dry or plasma etching processes. In some embodiments, the
etching process can include a lift-off process, ion beam etching,
reactive ion etching, wet etching, or any combinations thereof. In
some embodiments, the etching process can be performed at a
temperature ranging from room temperature (e.g., 27.degree. C.) to
about 100.degree. C.
[0108] Referring to FIG. 7, in operation 725, an array of cavities
are formed on a back-side of the biometric fingerprint sensor and a
cover plate is deposited on the sensor regions. For example, as
described with reference to FIGS. 16-17, array of cavities 556 can
be formed on back-side of biometric fingerprint sensor 530, and
cover plate 554 can be formed on coupling layer 552 disposed on
sensor regions 530A-530C.
[0109] The array of cavities 556 can be formed by thinning carrier
substrate 536 to form carrier substrate 536* followed by an etching
process to remove portions of carrier substrate 536*, ILD layer
211, and semiconductor substrate 214 underlying corresponding
sensor regions 530A-530C. Each cavity 556 can be substantially
aligned to each of sensor regions 530A-530C.
[0110] The thinning process can include a grinding process, a
polishing process, and/or an etching process performed on surface
536a of carrier substrate 536 (FIG. 15) to form carrier substrate
536* (FIG. 16) with its vertical dimension along a Z-axis reduced
by about 100 .mu.m to about 600 .mu.m compared to the vertical
dimension of carrier substrate 536. In some embodiments, carrier
substrate 536 can be thinned down by using a grinding process,
followed by a polishing process, and then an etching process.
Following the thinning process, the array of cavities 556 can be
formed by etching the portions of carrier substrate 536*, ILD layer
211, and semiconductor substrate 214 underlying the corresponding
sensor regions 530A-530C with a deep reaction ion etching. In some
embodiments, each cavity 556 can have a vertical dimension along a
Z-axis in a range from about 300 .mu.m to about 1000 .mu.m and a
horizontal dimension along an X-axis in a range from about 1 .mu.m
to about 500 .mu.m.
[0111] Referring to FIG. 17, following the etching process,
coupling layer 552 and cover plat 554 can be selectively deposited
on insulating layer 552 using an embossing process or a glue
bonding process. Coupling layer 552 can include a polymeric
material and can have a vertical dimension along a Z-axis in a
range from about 1 .mu.m to about 1000 .mu.m. Cover plate 554 can
include sapphire glass or other suitable protective material for
protecting coupling layer 552 when pressure applied (e.g., by the
user's fingerprint) on biometric fingerprint sensor 530. In some
embodiments, cover plate 554 can have a vertical dimension along a
Z-axis in a range from about 1000 .mu.m to about 40000 .mu.m.
[0112] In some embodiments, operation 725 can be optional and
operation 720 can be followed by operation 730.
[0113] Referring to FIG. 7, in operation 730, a microfluidic
channel is formed around the sensing well. For example, as
described with reference to FIG. 18, microfluidic channel 542 can
be formed on back-side 214b of semiconductor substrate 214 and
around sensing well 213. The process for forming microfluidic
channel 542 can include soft lithography using polydimethylsiloxane
(PDMS), wafer bonding methods, and/or other suitable methods.
General Biological Applications
[0114] BioFETs of the present disclosure can be used to determine
the presence or absence of a target analyte. In some aspects, the
bioFETs can detect and measure absolute or relative concentrations
of one or more target analytes. The bioFETs can also be used to
determine static and/or dynamic levels and/or concentrations of one
or more target analytes, providing valuable information in
connection with biological and chemical processes. The bioFETs can
further be used to monitor enzymatic reactions and/or non-enzymatic
interactions including, but not limited to, binding. As an example,
the bioFETs can be used to monitor enzymatic reactions in which
substrates and/or reagents are consumed and/or reaction
intermediates, byproducts, and/or products are generated. An
example of a reaction that can be monitored using a bioFET of the
present disclosure is nucleic acid synthesis to, for example,
ascertain nucleic acid sequence.
[0115] Types of target analytes for use in the embodiments of the
present disclosure can be of any nature provided there exists a
capture reagent that binds to it selectively and in some instances
specifically. Target analytes can be present in the test sample or,
for example, generated following contact of the test sample with
the sensing layer of a dual gate back-side sensing bioFET or with
other reagents in the solution in contact with the sensing layer of
a dual gate back-side sensing bioFET. Thus, types of target
analytes include, but are not limited to, hydrogen ions (protons)
or other ionic species, non-ionic molecules or compounds, metals,
metal coordination compounds, nucleic acids, proteins, lipids,
polysaccharides, and small chemical compounds such as sugars,
drugs, pharmaceuticals, chemical combinatorial library compounds,
and the like. Target analytes can be naturally occurring or can be
synthesized in vivo or in vitro. Target analytes can indicate that
a reaction or interaction has occurred, or indicate the progression
thereof. Target analytes measured by a bioFET according to the
present disclosure are not, however, limited and can include any of
a variety of biological or chemical substances that provide
relevant information regarding a biological or chemical process
(e.g., binding events such as nucleic acid hybridization and other
nucleic acid interactions, protein-nucleic acid binding,
protein-protein binding, antigen-antibody binding, receptor-ligand
binding, enzyme-substrate binding, enzyme-inhibitor binding, cell
stimulation and/or triggering, interactions of cells or tissues
with compounds such as pharmaceutical candidates, and the like). It
is to be understood that the present disclosure further
contemplates detection of target analytes in the absence of a
receptor, for example, detection of PPi and Pi in the absence of
PPi or Pi receptors. Any binding or hybridization event that causes
a change to the transconductance of the dual gate back-side sensing
bioFET changes the current that flows from the drain to the source
of the sensors described herein and can be detected according to
some embodiments.
[0116] For detection of various target analytes, the sensing
surfaces of the dual gate back-side sensing bioFETs of the present
disclosure can be coated with a capture reagent for the target
analyte that binds selectively to the target analyte of interest or
in some instances to a genus of analytes to which the target
analyte belongs. A capture reagent that binds selectively to a
target analyte is a molecule that binds preferentially to that
analyte (i.e., its binding affinity for that analyte is greater
than its binding affinity for any other analyte). Binding
affinities for the analyte of interest can be at least about
2-fold, at least about 3-fold, at least about 4-fold, at least
about 5-fold, at least about 6-fold, at least about 7-fold, at
least about 8-fold, at least about 9-fold, at least about 10-fold,
at least about 15-fold, at least about 20-fold, at least about
25-fold, at least about 30-fold, at least about 40-fold, at least
about 50-fold, at least about 100-fold, at least about 500-fold, or
at least about 1000-fold more than its binding affinity for any
other analyte. In addition to relative binding affinity, the
capture reagent has an absolute binding affinity that is
sufficiently high to efficiently bind the target analyte of
interest (i.e., it has a sufficient sensitivity). Capture reagents
for use in the methods and systems of the present disclosure can
have binding affinities in the femtomolar, picomolar, nanomolar, or
micromolar ranges and can be reversible.
[0117] The capture reagent can be of any nature (e.g., a chemical,
a nucleic acid, a peptide, a lipid, or a combination thereof). The
present disclosure contemplates capture reagents that are
ionophores, which bind selectively to an ionic species, whether
anionic or cationic. In some embodiments, an ionophore is the
capture reagent and the ion to which it binds is the target
analyte. Ionophores include art-recognized carrier ionophores
(i.e., small lipid-soluble molecules that bind to a particular ion)
derived from, for example, a microorganism. In some embodiments,
the capture reagent is polysiloxane, valinomycin, or salinomycin
and the ion to which it binds is potassium. In some embodiments,
the capture reagent is monensin, nystatin, or SQI-Pr, and the ion
to which it binds is sodium. And in other embodiments, the capture
reagent is ionomycin, calcimycine (A23187), or CA 1001 (ETH 1001),
and the ion to which it binds is calcium. In other aspects, the
present disclosure contemplates capture reagents that bind to more
than one ion. For example, beauvericin can be used to detect
calcium and/or barium ions, nigericin can be used to detect
potassium, hydrogen and/or lead ions, and gramicidin can be used to
detect hydrogen, sodium, and/or potassium ions.
[0118] Test samples can be from a naturally occurring source or can
be non-naturally occurring. Naturally-occurring test samples
include, without limitation, bodily fluids, cells, or tissues to be
analyzed for diagnostic, prognostic and/or therapeutic purposes.
The test sample can include any of cells, nucleic acids, proteins,
sugars, lipids, and the like. In various embodiments, test samples
can include chemical or biological libraries to be screened for the
presence of agents with particular structural or functional
attributes. Samples can be a liquid or dissolved in a liquid and of
small volume and, as such, are amenable to high-speed, high-density
analysis such as analyte detection using microfluidics.
[0119] Examples of bioFETs contemplated by various embodiments
discussed herein include, but are not limited to, chemical FETS
(chemFETs), ion sensitive FETs (ISFETs), immunologic FETs
(ImmunoFETs), genetic FETs (GenFETs or DNA-FETs), enzyme FETs
(EnFETs), receptor FETs, cell-based FETs, cell-free FETs, and
liquid biopsy FETs. Thus, the bioFETs described herein can be used
to detect target analytes with capture reagents and, as such,
define the bioFET type that are not mutually exclusive. As a
non-limiting example, a liquid biopsy FET can detect cell-free DNA
and can also be referred to as a cell-free FET or a DNA-FET. See,
e.g., Sakata et al. "Potentiometric Detection of Single Nucleotide
Polymorphism by Using a Genetic Field-effect transistor,"
Chembiochem 6 (2005): 703-10; Uslu et al. "Labelfree fully
electronic nucleic acid detection system based on a field-effect
transistor device," Biosens Bioelectron 19 (2004): 1723-31; Sakurai
et al. "Real-time monitoring of DNA polymerase reactions by a micro
ISFET pH sensor," Anal Chem 64.17 (1992): 1996-1997.
[0120] For example, some embodiments provide a method for detecting
a nucleic acid that includes contacting probe nucleic acids bound
to a surface of a back-side sensing layer of a dual gate back-side
sensing bioFET with a sample and detecting binding of a nucleic
acid from the sample to one or more regions of the probe nucleic
acids. Such a nucleic acid detecting bioFET can also be referred to
as a GenFET or DNA-FET.
[0121] In other aspects, some embodiments provide a method for
detecting a protein that includes contacting probe protein
molecules bound to a surface of a back-side sensing layer of a dual
gate back-side sensing bioFET with a sample and detecting binding
of a protein from the sample to one or more regions of the probe
protein molecules. GenFETs and DNA-FETs can be used to detect the
protein.
[0122] In other aspects, some embodiments provide a method for
detecting a nucleic acid that includes contacting probe protein
molecules bound to a surface of a back-side sensing layer of a dual
gate back-side sensing bioFET with a sample and detecting binding
of a nucleic acid from the sample to one or more regions of the
probe protein molecules. In yet other aspects, some embodiments
provide a method for detecting an antigen that includes contacting
probe antibodies bound to a back-side sensing layer of a dual gate
back-side sensing bioFET with a sample and detecting binding of an
antigen from the sample to one or more regions of the probe
antibodies. Such protein or antibody binding bioFETs can also be
referred to as ImmunoFETs.
[0123] In other aspects, some embodiments provide a method for
detecting an enzyme substrate or inhibitor that includes contacting
probe enzymes bound to a surface of a back-side sensing layer of a
dual gate back-side sensing bioFET with a sample and detecting
binding of an entity from (or generation of an enzymatic product
in) the sample to one or more regions of the probe enzymes. In yet
other aspects, some embodiments provide a method for detecting an
enzyme that includes contacting enzyme substrates or inhibitors
bound to a surface of a back-side sensing layer of a dual gate
back-side sensing bioFET with a sample and detecting binding of an
entity from (or generation of an enzymatic product in) the sample
to one or more of the enzyme substrates or inhibitors. Such an
enzyme based bioFET can also be referred to as an EnFET.
[0124] In other aspects, some embodiments provide a method for
detecting protein-small molecule (e.g., organic compound)
interactions that includes contacting small molecules bound to a
surface of a back-side sensing layer of a dual gate back-side
sensing bioFET with a sample and detecting binding of proteins from
the sample to one or more regions of the probe small molecules. In
yet other aspects, some embodiments provide a method for detecting
nucleic acid-small-molecule (e.g., organic compound) interactions
that includes contacting small molecules bound to a surface of a
back-side sensing layer of a dual gate back-side sensing bioFET
with a sample and detecting binding of nucleic acids from the
sample to one or more regions of the probe small molecules. In
either detection method, the sample can include small molecules and
the capture reagents bound to the surface of the back-side sensing
layer can be either nucleic acids or proteins. In other aspects,
the target analytes of interest are heavy metals and other
environmental pollutants, and/or the bioFET arrays are specifically
configured to detect the presence of different pollutants. Such
small molecule or chemical-sensing bioFETs can also be referred to
as chemFETs.
[0125] In other aspects, some embodiments provide a method for
detecting hydrogen ions and/or changes in H+ concentration (i.e.,
changes in pH). Such ion-sensing bioFETs can also be referred to as
ISFETs.
[0126] The systems and methods described herein can also be used to
aid in the identification and treatment of disease. For example,
some embodiments provide a method for identifying a sequence
associated with a particular disease or for identifying a sequence
associated with a response to a particular active ingredient or
treatment or prophylactic agent that includes contacting a capture
reagent (e.g., a nucleic acid probe) bound to a surface of a
back-side sensing layer of a dual gate back-side sensing bioFET
with a sample, and detecting binding of nucleic acids (e.g.,
including a variant or lacking nucleic acids otherwise contained in
a corresponding wild-type nucleic acid sequence) from the sample to
one or more regions of the capture reagent. Such bioFETs can also
be referred to as GenFETs, DNA-FETs, or liquid biopsy FETs.
Further Applications
[0127] Several additional applications of the dual gate back-side
sensing bioFETs described herein are contemplated. For example, the
sensing layer of a dual gate back-side sensing bioFET provides
real-time, label-free quantification and analysis for a variety of
biological, chemical, and other applications including, but not
limited to, gene expression analysis, comparative genome
hybridization (CGH), array-based exon enrichment processes, protein
sequencing, tissue microarrays, and cell culture. In some
embodiments, the dual gate back-side sensing bioFET can be used to
screen samples including, but not limited to, bodily fluids and/or
tissues such as blood, urine, saliva, CSF, or lavages or
environmental samples such as water supply samples or air samples,
for the presence or absence of a substance. For example, the arrays
can be used to determine the presence or absence of pathogens
(e.g., food-borne or infectious pathogens) such as viruses,
bacteria, or parasites based on target genomic, proteomic, and/or
other elements. The arrays can also be used to identify the
presence or absence or characterize cancer cells or cells that are
indicative of another condition or disorder, in a subject.
Additional applications for use of the dual gate back-side sensing
bioFETs described herein include those described in U.S. Pat. Nos.
8,349,167 (Gene expression analysis, comparative genome
hybridization (CGH), array-based exon enrichment processes);
8,682,592 (Non-Invasive Prenatal Diagnosis(NIP D), DNA/RNA
contamination, SNP identification); 9,096,899 (Method of amplifying
and sequencing DNA within a flow cell is provided); 9,340,830
(Analyzing a tumor sample); 9,329,173 (Automated system for testing
for Salmonella enterica bacteria); 9,341,529 (Method for
manufacturing a pressure sensor); U.S. Pub. Appl. Nos.
2015/0353920; 2015/0355129 (Chemical and biological substances
detection in bodily fluid); 2016/0054312 (Chemically differentiated
sensor array for sample analysis); 2016/0040245 (Identification and
molecular characterization of the CTCs associated with
neuroendocrine prostate cancer (NEPC).
[0128] In some embodiments, the dual gate back-side sensing bioFETs
can be used to obtain single cell gene expression profiles from one
or more cells in a cellular sample of interest, for example, in
heterogeneous cellular samples. Such samples often exhibit a high
degree of variation in their gene/biomarker expression levels
(e.g., due to the cell cycle, environment, and stochastic mechanism
of transcription/translation), even among individual cells that
have the same phenotype. The dual gate back-side sensing bioFETs
enable interrogation of the expression profile of each cell in the
sample. In certain aspects, the subject methods for single-cell
molecular profiling obviate the need for separating cells of
interest from a heterogeneous cellular sample with individual
profiling available at each dual gate back-side sensing bioFET.
Direct molecular profiling in heterogeneous cell samples is
advantageous for clinical diagnostic and biomarker discovery
applications. In certain aspects, the dual gate back-side sensing
bioFETs are used in molecular profiling and cellular subtyping of
heterogeneous original or enriched disease tissue and biological
fluid samples, for example, biopsy tumor samples, endothelial cells
from cardiovascular disease samples, bone marrow samples, lymph
node samples, lymph, amniotic fluid, brain samples from different
neurological disorders, lung pathological samples, and/or any other
heterogeneous disease tissue sample of interest. Thus, for example,
the dual gate back-side sensing bioFETs are used in the molecular
profiling of normal biological tissue and biological fluid samples,
to elucidate, for example, the mechanisms of differentiation,
immune responses, cell-cell communication, or brain
development.
[0129] In some embodiments, the dual gate back-side sensing bioFETs
are used in obtaining single cell expression profiles in
circulating tumor cells (CTCs). CTCs can derive from metastases and
can recirculate through the bloodstream and lymph to colonize
distinct organs and/or the primary tumor, giving rise to secondary
metastasis. CTCs play a critical role in the metastatic spread of
carcinomas. Therefore, detection of CTCs in blood (liquid biopsy)
or disseminating tumor cells (DTC) in bone marrow can be used to
monitor tumor staging and would improve the identification,
diagnosis, and treatment of cancer patients at high risk of
metastatic relapse. See, e.g., U.S. Pat. Nos. 9,340,830 (Col. 205,
lines 61-64); 9,447,411 (Col. 21, lines 42-54); 9,212, 977 (Col.
19, lines 56-67); 9,347,946 (Col. 9, lines 16-30). In some
embodiments, the dual gate back-side sensing bioFETs are used to
obtain expression and mutation profiles in a cellular sample that
includes CTCs as well as non-target contaminating cell types (e.g.,
leukocytes). See, e.g., U.S. Pat. Nos. 9,340,830 (Col. 1, lines
41-67); 9,447,411 (Col. 2, lines 41-55); 9,212, 977 (Col. 2, lines
48-67; Col. 3 lines 1-10); and 9,347,946 (Col. 9).
[0130] In other embodiments, the dual gate back-side sensing
bioFETs described herein can provide point-of-care, portable,
and/or real-time diagnostic tools. They can, for example, provide
an electronic readout of an enzyme linked immunosorbent assay
(ELISA) or other assays to detect various chemical or biological
substances. The dual gate back-side sensing bioFETs can be
configured to transduce or convert a biochemical binding event or
reaction into an electrical signal, which can be read out. Indirect
detection of a freely diffusing, electronically active species
produced at the site of a bound chemical or biological substance
can be performed utilizing the dual gate back-side sensing bioFETs.
Electronic readout ELISA schemes where an enzyme capable of
producing an electronically active species can be used. In some
embodiments, riboswitches are used to detect metabolites. See,
e.g., Mironov, Alexander S., et al., "Sensing small molecules by
nascent RNA: a mechanism to control transcription in bacteria."
Cell 111.5 (2002): 747-756; Winkler, Wade, Ali Nahvi, and Ronald R.
Breaker, "Thiamine derivatives bind messenger RNAs directly to
regulate bacterial gene expression." Nature 419.6910 (2002):
952-956. In some embodiments, the dual gate back-side sensing
bioFET arrays are used to measure the kinetics of a reaction and/or
compare the activities of enzymes, including substrates, a
co-factor, or another moiety for readout.
[0131] Other applications for the dual gate back-side sensing
bioFET arrays involve the use of molecular recognition sites, where
molecules that specifically recognize particular target molecules
are either identified or designed and applied to the surface of the
array. Previous work with chemFETs has demonstrated the ability of
single individual ISFETs to recognize ions such as potassium.
[0132] In some embodiments, the dual gate back-side sensing bioFET
is used to monitor the presence and/or amount of specific molecules
including, for example, environmental testing of specific toxins
and important elements. Such testing can use molecular recognition
sites to measure both pollution gases and particulate
contamination, where molecules that specifically recognize
particular target molecules are either identified or designed and
applied to the surface of the array. See, e.g., Brzozka et al.
"Enhanced performance of potassium CHEMFETs by optimization of a
polysiloxane membrane," Sensors and Actuators B. Chemical 18, 38-41
(1994); Sibbald et al. "A miniature flow-through cell with a
four-function ChemFET integrated circuit for simultaneous
measurements of potassium, hydrogen, calcium and sodium ions,"
Analytica Chimica Acta. 159, 47-62 (1984); Cobben et al.
"Transduction of selective recognition of heavy metal ions by
chemically modified field effect transistors (CHEMFETs)," Journal
of the American Chemical Society 114, 10573-10582 (1992). In some
embodiments, the dual gate back-side sensing bioFET can be used
with a personal, portable, and wearable detector system. This
system can act as an early warning device indicating to the user
that the pollution levels in their current local environment is at
a level that could cause the user some discomfort or even lead to
breathing problems. This is particularly relevant to people
suffering from respiratory or bronchial or asthma conditions, where
the user needs to take necessary precautions. The dual gate
back-side sensing bioFET has the capability of detecting individual
gases, such as NOx, SO.sub.2 and/or CO, and/or monitoring
temperature and humidity. See U.S. Pub. Appl. Nos. 2014/0361901;
2016/0116434 (Paragraph [0117]). The pollution sensors can, for
example, be referred to as a gas field effective transistor
(gasFET). A gasFET can contain, for example, an FET with a gate
metallization exposed to the surrounding atmosphere. When a gas is
absorbed on the surface, protons can diffuse to the metal gas
interface. This results in a dipole layer which affects the
threshold voltage of the device.
[0133] In some embodiments, the dual gate back-side sensing bioFET
can be used in vivo by introduction into a subject (e.g., in the
brain or other region that is subject to ion flux) and then
analyzing for changes. For example, electrical activity of cells
can be detected by ionic flow. Thus, a bioFET array can be
integrated onto a novel ion-discriminating tissue probe. Other
applications include, for example, cochlear prosthesis and retinal
and cortical implants. See, e.g., Humayun et al. Vision Research
43, 2573-2581 (2003); Normann et al. Vision Research 39, 2577-2587
(1999).
Final Remarks
[0134] The present disclosure provides example structures of a
semiconductor device (e.g., semiconductor device 500) with an array
of bioFET sensors (e.g., sensor 528), a biometric fingerprint
sensor (e.g., sensor 530), and a temperature sensor (e.g., sensor
532) and example methods for fabricating the same. The biometric
fingerprint sensor can be configured to authenticate the
fingerprint pattern of a user and the bioFET sensor can be
activated based on the fingerprint pattern authentication. Such
authentication with the biometric fingerprint sensor can allow the
user to have a personalized sensor system with the array of bioFET
sensors for secure bio-sensing and/or secure transmission of
bio-sensing measurements to the user's storage system (e.g.,
medical record systems or Health Savings Accounts (HSAs)). The
temperature sensor can be configured to measure the temperature
variations in the bioFET sensor during its operation, based on
which the temperature of the bioFET sensor can be adjusted using a
heater (e.g., heater 534).
[0135] The example method for fabricating the semiconductor device
integrates the fabrication processes of the array of bioFET sensor,
biometric fingerprint sensor, and temperature sensor, such that
these sensors can be simultaneously formed on a carrier substrate.
Such integration of the sensor fabrication processes can reduce the
number of process steps and increase manufacturing yield.
[0136] According to some embodiments, a method for fabricating a
semiconductor device includes forming a gate electrode on a first
side of a semiconductor substrate, forming a channel region between
source and drain regions within the semiconductor substrate, and
forming a piezoelectric sensor region on a second side of the
semiconductor substrate. The second side is substantially parallel
and opposite to the first side. The method further includes forming
a temperature sensing electrode on the second side during the
forming of the piezoelectric sensor region, forming a sensing well
on the channel region, and binding capture reagents on the sensing
well.
[0137] According to some embodiments, a method for fabricating a
semiconductor device includes forming a bioFET sensor and a
biometric sensor on a carrier substrate. The method of forming the
bioFET sensor includes forming a gate electrode on a first side of
a semiconductor substrate disposed on the carrier substrate and
forming a channel region between source and drain regions within
the semiconductor substrate. The method of forming the biometric
sensor includes forming a piezoelectric sensor region on a second
side of the semiconductor substrate and depositing a sensing layer
on the piezoelectric sensor region. The second side is
substantially parallel and opposite to the first side.
[0138] According to some embodiments, a semiconductor device
includes a gate electrode disposed on a first side of a
semiconductor substrate, a channel region disposed between source
and drain regions within the semiconductor substrate, and a
piezoelectric sensor region disposed on a second side of the
semiconductor substrate. The second side is substantially parallel
and opposite to the first side. The semiconductor device further
includes a temperature sensing electrode disposed on the second
side, a sensing well disposed on the channel region, and capture
reagents bound to the sensing well.
[0139] It is to be understood that the phraseology or terminology
herein is for the purpose of description and not of limitation,
such that the terminology or phraseology of the present
specification is to be interpreted by the skilled artisan in light
of the teachings and guidance.
[0140] The breadth and scope of the present disclosure should not
be limited by any of the above-described exemplary embodiments but
should be defined in accordance with the subjoined claims and their
equivalents.
[0141] The foregoing disclosure outlines features of several
embodiments so that those skilled in the art can better understand
the aspects of the present disclosure. Those skilled in the art
should appreciate that they can readily use the present disclosure
as a basis for designing or modifying other processes and
structures for carrying out the same purposes and/or achieving the
same advantages of the embodiments introduced herein. Those skilled
in the art should also realize that such equivalent constructions
do not depart from the spirit and scope of the present disclosure,
and that they can make various changes, substitutions, and
alterations herein without departing from the spirit and scope of
the present disclosure.
* * * * *