U.S. patent application number 17/108421 was filed with the patent office on 2021-03-18 for chip-scale sensing device for low density material and method of making same.
The applicant listed for this patent is InSyte Systems, Inc.. Invention is credited to Jerome Chandra Bhat, Jim Chih-Min Cheng, Richard Ian Olsen.
Application Number | 20210080425 17/108421 |
Document ID | / |
Family ID | 1000005248532 |
Filed Date | 2021-03-18 |
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United States Patent
Application |
20210080425 |
Kind Code |
A1 |
Bhat; Jerome Chandra ; et
al. |
March 18, 2021 |
CHIP-SCALE SENSING DEVICE FOR LOW DENSITY MATERIAL AND METHOD OF
MAKING SAME
Abstract
An electrochemical sensor device that is efficiently and
economically produced at the chip level for a variety of
applications is disclosed. In some aspects, the device is made on
or using a wafer technology whereby a sensor chamber is created by
said wafer and a gas port allows for a working electrode of the
sensor to detect certain gases. Large scale production is possible
using wafer technology where individual sensors are produced from
one or more common wafers. Integrated circuits are made in or on
the wafers in an integrated way so that the wafers provide the
substrate for the integrated circuitry and interconnects as well as
providing the definition of the chambers in which the gas sensors
are disposed.
Inventors: |
Bhat; Jerome Chandra; (Palo
Alto, CA) ; Cheng; Jim Chih-Min; (Fremont, CA)
; Olsen; Richard Ian; (Truckee, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InSyte Systems, Inc. |
Newark |
CA |
US |
|
|
Family ID: |
1000005248532 |
Appl. No.: |
17/108421 |
Filed: |
December 1, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16254241 |
Jan 22, 2019 |
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17108421 |
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62620963 |
Jan 23, 2018 |
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62620372 |
Jan 22, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 27/304 20130101;
G01N 27/4078 20130101; G01N 27/404 20130101; G01N 27/407 20130101;
G01N 27/4166 20130101 |
International
Class: |
G01N 27/407 20060101
G01N027/407; G01N 27/404 20060101 G01N027/404; G01N 27/30 20060101
G01N027/30; G01N 27/416 20060101 G01N027/416 |
Claims
1. A chip-level electrochemical sensing device, comprising: a base
wafer having externally- and internally-facing sides, said base
wafer further having a plurality of through-vias penetrating said
base wafer and extending between the internally- and
externally-facing sides thereof; a cap wafer disposed over the
internally-facing side of said base wafer; a sensor chamber at
least partially defined by said internally-facing side of said base
wafer and said cap wafer; a gas port formed by a first of said
plurality of through-vias, the gas port providing gas communication
between said externally- and internally-facing sides of the base
wafer to allow a gas on the externally-facing side of the base
wafer to pass through said gas port into said sensor chamber; an
electrochemical sensor disposed in said sensor chamber, the
electrochemical sensor responsive to a property of said gas and
comprising: a working electrode exposed to said gas entering the
sensor chamber through said gas port; a second electrode; a third
electrode; a solid electrolyte that couples the working electrode,
the second electrode, and the third electrode; and a gasket that
defines first and second sub-chambers in the sensor chamber, the
working electrode and the second electrode disposed in the first
sub-chamber and the third electrode disposed in the second
sub-chamber, the gasket at least partially gas-isolating the
working and second electrodes from the third electrode; a first
conducting through-via electrically coupling said working electrode
to a first electrical contact on the externally-facing side of said
base wafer, the first conducting through-via comprising a second of
said plurality of through-vias; a second conducting through-via
electrically coupling said second electrode to a second electrical
contact on the externally-facing side of said base wafer, the
second conducting through-via comprising a third of said plurality
of through-vias; a third conducting through-via electrically
coupling said third electrode to a third electrical contact on the
externally-facing side of said base wafer, the third conducting
through-via comprising a fourth of said plurality of through-vias;
a plurality of electrical connections that carry electrical signals
to and from said device; and an integrated circuit constructed on
or in the base wafer or the cap wafer, said integrated circuit
electrically coupled to said plurality of electrical
connections.
2. The device of claim 1, wherein the gasket fully gas-isolates the
working and second electrodes from the third electrode.
3. The device of claim 1, wherein the gasket is cured from a
liquid.
4. The device of claim 1, wherein the second electrode comprises a
counter electrode.
5. The device of claim 4, wherein the third electrode comprises a
reference electrode.
6. The device of claim 1, wherein the gasket is a first gasket and
the device further comprises a second gasket that defines a third
sub-chamber in the sensor chamber, the second electrode disposed in
the third sub-chamber, the second gasket at least partially
gas-isolating the second electrode from the working electrode
and/or the third electrode.
7. The device of claim 6, wherein the second gasket fully
gas-isolates the second electrode from the working electrode and/or
the third electrode.
8. The device of claim 1, wherein said sensor chamber is at least
partially defined by a recess in the internally-facing side of said
base wafer and/or in an internally-facing side of said cap
wafer.
9. The device of claim 1, wherein the working and second electrodes
are disposed between said electrolyte and said internally-facing
side of the base wafer.
10. The device of claim 1, further comprising a gas-permeable
filter disposed over the gas port to filter the gas passing through
said gas port.
11. The device of claim 1, wherein said sensor chamber is further
defined by sidewalls that separate the base and cap wafers, the
sidewalls comprising a spacer wafer having a thickness that
separates the base and cap wafers.
12. The device of claim 1, wherein: the electrochemical sensor
further comprises a fourth electrode, and the solid electrolyte
couples the working electrode, the second electrode, the third
electrode, and the fourth electrode.
13. The device of claim 12, wherein the fourth electrode is
disposed in the second sub-chamber whereby the gasket at least
partially gas-isolates the working and second electrodes from the
third and fourth electrodes.
14. The device of claim 12, wherein: the gasket further defines a
third sub-chamber in the sensor chamber, and the fourth electrode
is disposed in the third sub-chamber, whereby the gasket at least
partially gas-isolates (a) the working and second electrodes, (b)
the third electrode, and (c) the fourth electrode from one
another.
15. A method for making a chip-level electrochemical sensor device,
comprising: forming a sensor chamber between a base wafer and a cap
wafer, the base wafer and the cap wafer each having an
internally-facing side that at least partially defines the sensor
chamber; forming a working electrode, a second electrode, and a
third electrode in the sensor chamber; placing a solid electrolyte
in the sensor chamber, the sold electrolyte in contact with said
working electrode, said second electrode, and said third electrode;
depositing a liquid gasket material in the sensor chamber; curing
the liquid gasket material to form a solid gasket that defines
first and second sub-chambers in the sensor chamber, the working
electrode and second electrode disposed in the first sub-chamber
and the third electrode disposed in the second sub-chamber, the
solid gasket at least partially gas-isolating the working and
second electrodes from the third electrode; defining a gas port
through-via in said base wafer or said cap wafer, the gas port via
allowing movement of a gas from an exterior of said device to the
first sub-chamber; forming a first conducting through-via in said
base wafer or said cap wafer, the first conducting through-via
electrically coupled to said working electrode; forming a second
conducting through-via in said base wafer or said cap wafer, the
second conducting through-via electrically coupled to said second
electrode; forming a third conducting through-via in said base
wafer or said cap wafer, the third conducting through-via
electrically coupled to said third electrode; and forming
electrical connections between the first, second, and third
conducting through-vias and external connections points.
16. The method of claim 15, wherein the solid gasket fully
gas-isolates the working and second electrodes from the third
electrode.
17. The method of claim 15, wherein the second electrode comprises
a counter electrode and the third electrode comprises a reference
electrode.
18. The method of claim 15, wherein the solid gasket defines a
third sub-chamber in the sensor chamber, the second electrode
disposed in the third sub-chamber.
19. The method of claim 15, wherein said base wafer and/or said cap
wafer comprise a silicon wafer.
20. The method of claim 15, further comprising placing a spacer
wafer between the base and cap wafers to form sidewalls of the
sensor chamber.
21. The method of claim 15, further comprising: forming a fourth
electrode in the sensor chamber; and placing the solid electrolyte
in contact with said fourth electrode.
22. The method of claim 21, further comprising placing the fourth
electrode in the second sub-chamber whereby the solid gasket at
least partially gas-isolates the working and second electrodes from
the third and fourth electrodes.
23. The method of claim 22, wherein the solid gasket further
defines a third sub-chamber in the sensor chamber, and the method
further comprises placing the fourth electrode in the third
sub-chamber, whereby the solid gasket at least partially
gas-isolates (a) the working and second electrodes, (b) the third
electrode, and (c) the fourth electrode from one another.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/254,241, titled "Chip-Scale Sensing Device
for Low Density Material," filed on Jan. 22, 2019, which claims
priority to U.S. Provisional Application No. 62/620,372, titled
"Chip-Scale Sensing Device for Low Density Material," filed on Jan.
22, 2018, and to U.S. Provisional Application No. 62/620,963,
titled "Low Impedance Sensor for Low Density Material," filed on
Jan. 23, 2018. Each of the foregoing applications is hereby
incorporated by reference.
TECHNICAL FIELD
[0002] This invention relates to the design and manufacture of
sensor devices that sense or identify low density materials, e.g.,
gasses by an electrochemical cell integrated with a sensing circuit
in a chip-scale package.
BACKGROUND
[0003] Given the changes in the earth's atmosphere, precipitated by
industrialization and natural sources, as well as the dramatically
increasing number of household and urban pollution sources, the
need for accurate and continuous air quality monitoring has become
necessary to both identify the sources and warn consumers of
impending danger. Tantamount to making real-time monitoring and
exposure assessment a reality is the ability to deliver, low cost,
small form factor, and low power devices which can be integrated
into the broadest range of platforms and applications.
[0004] There are multiple methods of sensing distinct low-density
materials such as gasses. Common methods include nondispersive
infrared spectroscopy (NDIR), the use of metal oxide sensors, the
use chemiresistors, and the use of electrochemical sensors. The
present invention pertains to electrochemical sensors.
[0005] One drawback with a conventional electrochemical sensor is
that its size (e.g., volume of electrolyte and size of electrodes)
is relatively large so that it takes a long time to stabilize when
subjected to the target gas. Further, since the change in current
in response to a gas is small, there is a low signal to noise
ratio, and there are losses and RF coupling due to metal traces
leading to processing circuitry external to the sensor, further
reducing the signal to noise ratio. Additionally, the
electrochemical cell body is typically a polymer that cannot
withstand temperatures above 150.degree. C., and the electrolyte
comprises an aqueous acid that cannot withstand temperatures above
approximately 100.degree. C. This prevents the electrical contacts
from being soldered to a printed circuit board by reflowing the
solder (typically at 180-260.degree. C.) and prevents the used of
some heat-cured conductive adhesives such as silver-containing
epoxies, or anisotropic conductive films or pastes (typically at
cured at 120-150.degree. C.).
[0006] There are multiple methods of sensing distinct low-density
materials such as gasses. Common methods include nondispersive
infrared spectroscopy (NDIR), the use of metal oxide sensors, the
use chemiresistors, and the use of electrochemical sensors. Some
electrochemical sensors are also known to those skilled in the art.
In this application, we describe the further miniaturization of
such an integrated electrochemical system via the application of
wafer-level packaging, panel-level packaging, and chip-scale
packaging techniques.
[0007] This disclosure provides a number of designs, features,
novel devices and methods for making and using the same.
SUMMARY
[0008] The following description and drawings set forth certain
illustrative implementations of the disclosure in detail, which are
indicative of several exemplary ways in which the various
principles of the disclosure may be carried out. The illustrative
examples, however, are not exhaustive of the many possible
embodiments of the disclosure. Other objects, advantages and novel
features of the disclosure will be set forth in the following
detailed description of the disclosure when considered in
conjunction with the drawings.
[0009] One or more embodiments are directed to a chip-level
electrochemical sensing device, comprising a base wafer having an
externally facing side and an internally facing side, said
internally facing side partially defining a sensor chamber, said
base wafer further having a plurality of through vias penetrating
said base wafer and extending between the internally and externally
facing sides thereof; at first one of said through vias comprising
a gas port that allows gas communication between said externally
and internally facing sides of the base wafer, and specifically
allowing a gas on the externally facing side of the base wafer to
pass through said gas port through via into said sensor chamber; an
electrochemical sensor responsive to a property of said gas,
disposed in said sensor chamber; the electrochemical sensor
comprising a first electrode and a second electrode, wherein the
first and second electrodes coupled by an electrolyte, and wherein
the first electrode is exposed to said gas entering the sensor
chamber through said gas port; a second one of said through vias
comprising a conducting through via electrically coupling said
first electrode of the electrochemical sensor to a first electrical
contact on the externally facing side of said base wafer; a third
one of said vias comprising a conducting through via electrically
coupling said second electrode of the electrochemical sensor to a
second electrical contact on the externally facing side of said
base wafer; and at least one set of electrical connections that
carry electrical signals to and from said device; and an integrated
circuit constructed on or in any of the base wafer and cap wafer,
said integrated circuit electrically coupled to said set of
electrical connections.
[0010] Other embodiments are directed to an article of manufacture,
comprising a common base wafer and a common cap wafer, into which a
plurality of integrated circuits are packaged, and onto which a
plurality of electrochemical sensor devices are created; each of
said plurality of sensor devices comprising a plurality of
electrodes disposed within respective sensor chambers at least
partially defined by the base wafer and the cap wafer and sidewalls
separating said cap wafer and base wafer; each of said plurality of
sensor devices further comprising an electrolyte material
contacting each of said sensor device's respective plurality of
sensor electrodes; and wherein at least one sensor electrode of
each sensor device comprises a working electrode in gas
communication with an external environment of said device by way of
a respective gas port through via in one of said base and cap
wafers so as to provide gas coupling between the working electrode
and the external environment, while being gas-isolated from other
electrodes within the same sensor device.
[0011] Yet other embodiments are directed to a method for making a
chip-level electrochemical sensor device, comprising forming a
plurality of wafers including a base wafer and cap wafer, each of
the cap and base wafers having an internally-facing side and an
externally facing side; forming through vias in one or more of said
cap and base wafers, including at least one gas port through via
allowing movement of a gas from an exterior of said device to an
interior space therein; forming a plurality of electrochemical
sensor electrodes, including a working electrode, in a sensor
chamber defined by said cap and base wafers, said working electrode
being disposed in a portion of the sensor chamber in gas
communication with the exterior of the device by way of said gas
port through via; placing an electrolyte in contact with each of
said plurality of sensor electrodes within the sensor chamber;
isolating a volume within said sensor chamber comprising said
working electrode to prevent or reduce a movement of gas between
said portion of the sensor chamber containing the working electrode
and other portions of the sensor chamber; and forming electrical
connections in said cap and base wafers so as to electrically
connect the plurality of electrodes to one another or to external
connections points.
[0012] Still other embodiments are directed to a chip-scale gas
sensor, comprising a cap wafer; a base wafer; a spacer wafer
disposed between the cap and base wafers and together with the cap
and base wafers defining a sensor chamber; a solid or semi-solid
electrolyte within said sensor chamber; a plurality of sensor
electrodes within said sensor chamber, each of said sensor
electrodes in contact with the solid or semi-solid electrolyte; a
gas port through via in any of said cap and base wafers; a gas
blocking gasket coupled to said electrolyte; and an application
specific integrated circuit (ASIC) integrated into either of said
cap or base wafers. The gas port through via may have a gas filter
applied thereto which filters, blocks or otherwise affects a gas
moving through the gas port.
[0013] Therefore, in various aspects, an electrochemical sensor
device that is efficiently and economically produced at the chip
level for a variety of applications is disclosed. In some aspects,
the device is made on or using a wafer technology whereby a sensor
chamber is created by said wafer and a gas port allows for a
working electrode of the sensor to detect certain gases. Large
scale production is possible using wafer technology where
individual sensors are produced from one or more common wafers.
Integrated circuits are made in or on the wafers in an integrated
way so that the wafers provide the substrate for the integrated
circuitry and interconnects as well as providing the definition of
the chambers in which the gas sensors are disposed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] For a fuller understanding of the nature and advantages of
the present technology, reference is made to the following detailed
description of preferred embodiments and in connection with the
accompanying drawings, in which:
[0015] FIG. 1 illustrates a cross-sectional view of an embodiment
of a chip-scale package sensor module comprising a cavity package,
electrodes, electrolyte, a sensing circuit, and electrical
interconnects;
[0016] FIG. 2 illustrates a cross-sectional view of an alternative
embodiment of a chip-scale package sensor module comprising a
cavity package, electrodes, electrolyte, a sensing circuit, and
electrical interconnects;
[0017] FIG. 3 illustrates a cross-sectional view of an alternative
embodiment of a chip-scale package sensor module comprising a
cavity package, electrodes, electrolyte, a sensing circuit, and
electrical interconnects;
[0018] FIG. 4 illustrates a cross-sectional view of an alternative
embodiment of a chip-scale package sensor module comprising a
cavity package, electrodes, electrolyte, a sensing circuit, and
electrical interconnects;
[0019] FIG. 5 illustrates a cross-sectional view of an alternative
embodiment of a chip-scale package sensor module comprising a
cavity package, electrodes, electrolyte, a sensing circuit, and
electrical interconnects;
[0020] FIG. 6 illustrates a cross-sectional view of an alternative
embodiment of a chip-scale package sensor module comprising a
cavity package, electrodes, electrolyte, a sensing circuit, and
electrical interconnects;
[0021] FIG. 7 illustrates an exemplary method for making said
devices; and
[0022] FIG. 8 illustrates multiple sensor devices formed from a
common wafer set, including optionally having a multi-sensor device
with multiple sensors therein.
DETAILED DESCRIPTION
[0023] In an electrochemical sensor, a sensor electrode (also known
as a working electrode) contacts a suitable electrolyte. The sensor
electrode typically comprises a catalytic metal that reacts with
the target gas and electrolyte to release or accept electrons,
which creates a characteristic current in the electrolyte when the
electrode is properly biased and when used in conjunction with an
appropriate counter-electrode. The current is generally
proportional to the amount of target gas contacting the sensor
electrode. By using a sensor electrode material and bias that is
targeted to the particular gas to be detected and sensing the
current, the concentration of the target gas in the ambient
atmosphere can be determined.
[0024] One or more embodiments of the present invention are
directed to an electrochemical sensing device, which is preferably
a chip-level device and manufactured on a semiconductor-based
architecture such as using a silicon-based wafer like those used in
the integrated circuit industry. However, ceramic or other
substrates can also be employed as a base wafer in the present
designs. The present device is therefore compact in size, easy and
inexpensive to manufacture in large numbers, and can have wide
applications beyond prior sensor designs. In an aspect, the present
sensor devices can be used to detect certain gases in an atmosphere
or environment of the sensor devices. Many configurations can be
designed based on the current disclosure. The present disclosure
can utilize a number of different electrochemical sensors, which
may include examples described in Publication 2017/0336434,
incorporated herein by reference, directed to integration of an
electrochemical cell with an electronic circuit in a small
form-factor package. Some specific preferred embodiments are
presented below, but those skilled in the art will appreciate how
to extend this disclosure, using a variety of materials, dimensions
and arrangements that are all comprehended by this disclosure and
its appended claims.
[0025] FIG. 1 shows a cross section of an exemplary electrochemical
sensor device 100. The device 100 is generally constructed on a
base wafer 110. The base wafer 110, can be made of any suitable
composition, and as will be explained below, generally allows for
construction of and fabrication of components, circuitry and parts
on said base wafer 110. In some embodiments, the base wafer 110 is
a semiconducting or semiconductor-based wafer such as a silicon
wafer. In other embodiments the base wafer 110 comprises a ceramic
wafer or a printed circuit board (PCB) panel. Where a ceramic wafer
is used for a cap or base herein, any coupled IC components are
mounted onto such ceramic layers, while in other embodiments, an IC
may be integrated into a surface region of a wafer. The base wafer
can be shaped to have a flat or contoured surface. For example,
base wafer 110 generally has a thickness and describes a planar
slab or disc with two opposing faces. In this example, we call the
face of base wafer 110 directed to the outside of the device 100
the externally facing side 112, while its face directed to the
inside of device 100 is referred to as the base wafer's internally
facing side 114. The externally facing side 112 of base wafer 110
in this example is generally planar or flat. The internally facing
side 114 of the base wafer 110 can be carved, etched, sand blasted,
molded, cast, printed, machined, deposited, or otherwise formed by
any known means of shaping as shown. In some examples, the shape of
the internally facing side 114 of the base wafer can be created by
deposition of additional layers on top of a flat base wafer to
obtain the contoured or shaped cross section desired.
[0026] Some embodiments utilize co-fired ceramic wafers for the
base and/or lid units. These may be made by: 1. Preparing
individual ceramic sheets, slabs or layers, 2. Forming the through
vias (electrical conducting filled vias or gas port vias) into one
or more layers, 3. Printing electrical interconnect traces on the
layers, e.g., to fill the electrically-conducting vias, 4. Aligning
the layers with respect to one another, and 5. Co-firing the layers
together. This process can be used as reasonable for any given
embodiment disclosed herein.
[0027] A cap wafer, lid or other cover 170 is disposed against the
internally facing side 114 of the base wafer 110 to crate, together
with the base wafer a sensor chamber 132 housing the present
electrochemical sensor 130. The cap wafer 170 can be a wafer-level,
panel-level or die-level member, and like the base wafer, may
comprise any suitable composition including glass, silicon, ceramic
or polymer. As can be seen, the sensor chamber 132 can be in part
described by an internal face 172 of said cap wafer 170. The cap
wafer's internally facing side or face 172 can also be carved,
etched, sand blasted, molded, cast, printed, machined or deposited
using appropriate methods to create or co-define the sensor chamber
132 that houses electrochemical sensor 130.
[0028] In an aspect, the sensor chamber 132 can be at least in part
defined by the interior sides of the base wafer 110 and cap wafer
or lid 170. The sensor chamber 132 can be almost entirely sealed to
the outside environment, with the exception of a gas port 120
formed as a through-via in said base wafer 110. The gas port and
other through vias 120, 122, 124 extend through the base wafer 110
and specifically, penetrate the base wafer and extend from its
externally facing side to its internally facing side. The gas port
through via 120 would thus be a way or only way for the gas to pass
in/out of the sensor chamber 132. In some embodiments, an optional
filter 190 can be placed in or against the gas port through via 120
to selectively filter materials passing through the gas port 120.
For example, the filter may be gas permeable, but may be configured
and arranged to block or reduce the passage of solid particles
greater than a given size, or to block the passage of liquids,
certain gases, and so on. In some examples, the filter 190 may
adsorb or absorb certain gasses or materials. In some examples, the
filter 190 may catalyze certain gases or materials to stop or
reduce their propagation through the filter. Filters such as those
disclosed in Provisional Applications 62/730,076 and 62/750,926,
which are incorporated herein by reference, may be used as a basis
for some filter 190 designs and compositions. But such designs may
be adapted, added or omitted in the present embodiments as best
suits a specific purpose.
[0029] Inside the sensor device 100, and more specifically, inside
sensor chamber 132 are disposed a plurality of sensor electrodes
134, 136 being part of electrochemical sensor 130. The sensor 130
is responsive to a gas or a property of a gas or a component or
material in said gas and delivers an electrical response output or
measurable signal responsive to the presence of said gas or gas
property. The number of electrodes per sensor 130 can vary and may
include three, four or more electrodes. The electrodes include a
first working electrode 134 in gas communication with the
environment of the device through gas port through via 120. That
is, gases in the environment of the device 100 can pass through the
gas port 120 and come into contact with the electrochemical sensor
130 by way of its working electrode 134. Gas port 120 can be
considered a gas diffusion aperture as it can allow for diffusion
of a gas between the external and internal sides of base wafer
110.
[0030] Each of the electrodes 134, 136 are contacting or coupled to
an electrolyte 140. While in gas isolation from one another by way
of a gasket or other blocking material 180, the electrodes 134, 136
are coupled at least on one side by the electrolyte material 140.
In the embodiment shown, the electrolyte 140 comprises a layer or
slab of some general thickness, and the electrodes 136, 134 are
disposed on a same (e.g., lower) face of the electrode 140
material. We note that a plurality of electrodes, including at
least a working electrode and another electrode are used. Various
embodiments can employ 3-terminal or 3 electrode designs,
4-terminal or 4 electrode designs, and other designs.
[0031] In some embodiments, one or more of the electrodes, e.g. the
working electrode 140, may comprise a porous material such as a
carbon paper, a carbon cloth, or any other porous,
electrically-conducting matrix and a catalyst such as platinum,
palladium, ruthenium, rhodium, silver, nickel, iron, vanadium,
other transition metals and alloys thereof; aluminosilicates,
alumina, boron nitrides, other semiconductor catalysts, and
mixtures thereof.
[0032] The electrolyte material may be a solid or a semi-solid
material. In other embodiments, the electrodes can be disposed on
opposite sides of electrolyte 140 as shown. This disclosure
illustrates and describes a few such embodiments in detail by way
of illustration only. Those skilled in the art will appreciate that
various ways of arranging the electrodes about the electrolyte are
possible, and these ways are comprehended by this disclosure and
claims as well.
[0033] While some of the present embodiments and exemplary
illustrations (e.g., FIG. 1) show the electrolyte layer as
`floating` or disposed freely within the sensor cavity in the
device, other embodiments (e.g., FIG. 2) can have the electrolyte
extending in thickness so as to touch an internal surface of the
proximal wafer. A thicker electrolyte layer that is in contact with
its proximal wafer can thus provide mechanical compression by the
wafer against the electrolyte to press it against the internal
components and better seal the working electrode chamber. The
wafers can sandwich the contents of the sensor chamber with an
appropriate compression force to hold the contents securely and
better seal them. However, those skilled in the art will understand
that an adhesive or epoxy can be used to connect some or all of the
components of the devices to keep them in place in examples where
the electrolyte is not pressed against a wafer surface.
[0034] In an aspect of the electrolytes described in the present
embodiment and others, the electrolyte may comprise a sieve or
sieve-like material, or have a structure and composition causing
the electrolyte layer to act as a sieve. More particularly, the
electrolyte in some embodiments may act as a selective sieve that
is design and configured to block certain materials but not others,
e.g., certain gases but not others.
[0035] Other silicon through vias, e.g., 122, 124 can be formed in
the base wafer 110. These through vias can be filled with a
conductor so carry an electrical signal between the inside and
outside surfaces of the base wafer 110. Specifically, aside from
the first (gas port) through via 120, a second (conducting) through
via 122 can be established to contact the first (working) electrode
134. And a third (conducting) through via 124 can be established to
contact the second (counter) electrode. It should be noted that in
any of the present embodiments, the electrically-conducting through
vias may preferably be filled with a conducting material so as to
prevent unwanted gas passage therethrough. If an
electrically-conducting via is not filled with the conductor, e.g.,
the conducting material only coats the internal sides of the via,
then another material such as a polymeric or similar solid or
semi-solid material can be used to plug or fill any gas passages in
the electrical through vias.
[0036] On the outside, or externally facing side 112 of base wafer
110, other components may be disposed and arranged. First and
second electrical contacts 162, 164 can be formed, deposited or
manufactured to make electrical contact with the respective
conducting through vias 122 and 124. In some examples, solder bumps
163 and 165 can be placed on or in electrical contact with first
and second electrical contacts 162, 164 to give the whole device
100 a suitable electrical interface to a greater system in which
the device is installed, such as on a printed circuit board, or in
a mobile or stationary computing or communication apparatus (e.g.,
smart phone). The figure shows a board 102 on which the sensor
device is disposed, said board 102 built to make electrical
connection by way of solder bumps 163, 164. If the device 100 is
mounted on or attached to some substrate or circuit board 102, a
hole 104 may be formed in this board 102 to allow gas diffusion
therethrough and into gas port through via 120. The optional filter
190 may then be moved to cover an entry/exit of either gas port
through via 120 as shown, or alternatively to cover an entry/exit
of hole 104. These examples are not meant to limit the range of
applications in which the device 100 may be utilized but are
provided for illustrative purposes of some embodiments and
preferred examples.
[0037] In addition, the device 100 can include or be coupled to an
integrated circuit or ASIC or other circuitry (IC 150) disposed on
a surface 112 of base wafer 110. Those skilled in the art will
understand that IC 150 can be built on said surface 112 or can be
placed in some other location with respect to the sensor device so
as to be in communication therewith. The IC 150 can provide a
number of functions to the device 100 including processing
functions, data storage functions, communication functions and so
on as suits a given implementation. In some embodiments, IC 150 can
serve as an interface to a system incorporating sensor device 100,
for example in a mobile communication or computing device. As
stated before, the IC 150 can be disposed onto or manufactured in
surface 112 depending on the application and on the material from
which base wafer 110 is made. In some embodiments, the IC or ASIC
or other circuit above may not be limited to being integrated into
ax exterior surface of the device and may be integrated into or
onto an internal or other portion of the device.
[0038] In an aspect, the IC 150 is used to drive the sensor device
cell. In another aspect the IC 150 is used to sense a current
generated by the sensor cell in the presence of a detected gas of
interest. In the case of multi-electrode sensor devices (e.g.,
3-electrodes) the IC 150 can bias the cell appropriately by
applying a bias voltage to the reference electrode for example.
[0039] Regarding the external attachment and construction of the
devices described herein, e.g., device 100 and the other present
embodiments, the substrate or circuit board 102 may be substituted
with any appropriate cover, layer or casing that acts to protect
device 100. In some examples, the devices are made water-proof or
water-resistant or impervious to external contamination. In some
examples, the layer 102 comprises a cover or housing can facilitate
simple manufacturing processes that result in IP6x-compliant sensor
devices.
[0040] As can be seen, the resulting arrangement of device 100 can
yield a capped enclosure or chamber, on a silicon or similar base
wafer, with a sensor 130 disposed in said enclosure or sensor
chamber. The sensor chamber can be defined by recesses in one or
both of the base and cap wafers, or by separating the base and cap
wafers with a suitable spacer. Within the sensor chamber, a
plurality of cavities can be defined by the gaskets or other
internal structures that form separate cavities for the electrodes.
One such cavity is made to have gas communication with the exterior
environment around the device so that a gas in the environment can
contact the working electrode 134 and allow for sensing of the
gas.
[0041] We will present other exemplary embodiments below, in which
two or more electrodes of an electrochemical sensor are contained
in a sensor chamber as described. The various designs and
embodiments can include additional electrodes in contact with the
electrolyte material, and the various designs can differ in their
arrangement of the placement of the electrodes, the method of
spacing the base and cap wafers, etc. to suit a given application.
For example, the base and cap wafers in some embodiments are
etched, carved, formed or otherwise shaped to define the sensor
chamber between said wafers. However, the base and/or cap wafers
may, alternatively, be substantially flat or slab or disc shaped,
but spaced apart using a spacer wafer or material such as glass or
silicon, having optional through vias (through silicon or through
glass vias) to make the needed connections through these
layers.
[0042] In the instantiation in FIG. 1, a segment of the surface of
the base wafer 110 forming the partially-enclosed cavity has been
recessed, for example, by etching. For a given required height of
the partially-enclosed cavity, partial recessing of the base wafer
in this manner enables the recess in the cap wafer to be reduced,
potentially facilitating formation of the cap. However, depending
on the method of formation of the cap, forming a deep recess in the
cap may be straightforward. In this case, recessing of the base
wafer may offer no particular advantage and may be omitted.
[0043] In an alternative instantiation, the IC 150 may be located
on the same surface of the silicon base wafer 110 on which the
electrodes are attached. In this scheme, it may be protected from
the contents of the electrochemical cell by the application of one
or more appropriate dielectric or other chemically-resistant
layers. While a number of design options are possible, those
skilled in the art will understand that the IC 150 may be
integrated into the base wafer 110, but may also be constructed
thereon, for example if the base wafer is made of ceramic
[0044] The present sensor devices can be manufactured using some or
many steps from within the relevant industry, but also using novel
steps, especially as to the sequence and nature thereof. These
steps can include one or more optional steps, so they may not all
be required. Also, the order of performing the steps can vary as
appropriate for a given device and process, so the steps herein are
listed in an exemplary and illustrative way only. With regard to
the device 100 of FIG. 1, it may be constructed using the following
method, which is also hereby presented as a novel aspect of this
invention: The cap wafer and base wafer are formed; the base wafer
is optionally cavity etched; the through vias described are then
formed in the appropriate wafer; the cavity or sensor chamber side
interconnects are formed and established; the outside electrodes
(for connection to external circuits) are formed; electrodes and/or
contact points are disposed as necessary to connect the relevant
electrical components; an optional gasket is put in place to
establish optional sub-chambers within the sensor chamber; the
electrolyte material (in some embodiments a slab or layer of
electrolyte) is put against the electrodes in the sensor chamber;
attach the cap wafer, die level or panel to the lower parts;
install optional solder bump wafer; install optional gas filter
over the gas port; test the wafer and/or device; and singulate the
wafer(s) to make individual components by cutting or dicing the
wafers. Testing may be performed before and/or after
singulation.
[0045] FIG. 2 describes another embodiment of an electrochemical
sensor device 200 according to this invention. In this embodiment,
the partially-enclosed sensor chamber 232 is defined using two
substantially planar or flat wafers, e.g., base wafer 210 and cap
wafer 270 as well as one or more spacers 275. The spacers may
comprise a spacer wafer 275 bonded, adhered or attached to each of
the opposing base wafer 110 and cap wafer 270, shown below and
above the spacer 275 in the figure.
[0046] The spacer wafer 275 (and other wafers or panels described
herein) may have a relatively large form factor and include
through-vias in the spacer wafer, made for example by dry etching,
wet etching or sand blasting or other subtractive manufacturing
processes. Alternatively, the spacer wafer 275 may be cast, molded,
stamped, milled, drilled, machined, or printed with the
through-vias formed as part of the forming process such that no
additional processing is required to form the vias. Where co-fired
ceramic panels or wafers are used, the wafer may be formed as
described herein.
[0047] The electrochemical sensor 130 here is disposed in a sensor
chamber 232 defined at least in part by each of the
lower/internally facing side 272 of cap wafer 270, the
upper/internally facing side 214 of base wafer 210 and the
spacer(s) 275. The base wafer 210 has a lower/externally facing
side 212. As before, a gas port 220 or gas diffusion aperture is
formed with a through via in base wafer 210, while conducting or
conductor-filled through vias 222, 224 connect the internal sensor
electrodes 234, 236 to the outside world. The interconnection and
use of the device 200 is similar to or the same as described above
with respect to earlier embodiment 100.
[0048] The sensor device 200 can be manufactured using some or many
steps from within the relevant industry, but also using novel
steps, especially as to the sequence and nature thereof. These
steps can include one or more optional steps, so they may not all
be required. Also, the order of performing the steps can vary as
appropriate for a given device and process, so the steps herein are
listed in an exemplary and illustrative way only. With regard to
the device 200 of FIG. 2, it may be constructed using the following
method, which is also hereby presented as a novel aspect of this
invention: The base or IC wafer is formed; the through vias
described are then formed in the appropriate wafer; the cavity or
sensor chamber side interconnects are formed and established; the
spacer wafer or plate is established or installed or attached;
electrodes and/or contact points are disposed as necessary to
connect the relevant electrical components; an optional gasket is
put in place to establish optional sub-chambers within the sensor
chamber; the electrolyte material (in some embodiments a slab or
layer of electrolyte) is put against the electrodes in the sensor
chamber; attach the cap wafer, die level or panel to the lower
parts; install optional solder bump wafer; install optional gas
filter over the gas port; test the wafer and/or device; and
singulate the wafer(s). Other steps as described in the context of
other embodiments herein may be included, omitted, substituted or
performed in any order that suits a given embodiment as would be
appreciated by one of ordinary skill in the art.
[0049] FIG. 3 illustrates another electrochemical sensor device
300, which can be manufactured and used according to the present
disclosure. Again, a pair of generally parallel wafers or
substrates (IC die wafer 310 and cap or lid wafer 370) partially
define an internal space that acts as a sensor chamber 332. The
sensor chamber 332 is also partially defined by spacer wafers or
panels 315, which give some separation between the base wafer 310
and cap wafer 370. The wafers 310 and/or 370 may optionally be
etched, machined, cut or shaped as described earlier to optionally
form deeper recesses to enlarge or partially define the sensor
chamber 332. In FIGS. 3, 5, 6, electrical through vias are required
within the spacer wafer. Hence the spacer wafer design and
construction may vary and may include electrically-conducting vias
and the fabrication of the spacer wafers may include steps of
forming and/or filling the conducting vias therein.
[0050] The electrolyte material 340 is disposed within the sensor
chamber 332. Electrolyte material 340 may comprise a single-phase
solid or semi-solid electrolyte. The electrolyte may alternatively
comprise a matrix such as a polymer matrix imbibed with a
electrolyte--and capable of performing the functions of an ion
bridge between the various electrodes. Example matrix materials
comprise polybenzimidazole (PBI) or its derivatives, TPS or its
derivates, perfluorosulfonicacid, Nafion or its derivatives,
co-polymers or blends of the above materials with other polymers
such as polytetrafluoroethylene (PTFE), any suitable material able
of performing as a proton exchange membranes (PEM) or any other
material suitable to the function--such as any material which might
be used in the manufacture of a PEM for a fuel cell. Examples of
imbibed electrolytes include sulfuric acid, phosphoric acid, or any
inorganic or acid suitable for providing ionic conductivity between
electrodes in an electrochemical cell. Electrolytes may also
include zwitterionic materials. Contacting said electrolyte 340 are
a plurality of sensor electrodes 334, 335, 336, 337. Those skilled
in the art will understand that a number of configurations of this
device are possible, but we present here one or more preferred
embodiments for illustration.
[0051] The cap wafer 370 in this embodiment has one gas port
through via 320 passing through the thickness of wafer 370 to allow
diffusion of a gas from an outside environment into the gas port to
be sensed by a first sensor electrode 335 that used as a working
electrode. Optionally, filter 190 can be used to filter gases
passing therethrough. Counter electrodes and other electrodes 334,
336, 337 are in contact with the same electrolyte material 340
contacting the working electrode 335.
[0052] An integrated circuit (IC) 350 is disposed on a surface of
the base wafer 310. The IC can provide an interface, logic or other
function as described herein and known to those skilled in the art.
To achieve electrical connection between the sensor electrodes and
the IC 350, a plurality of through vias 321 are provided that
penetrate the wafers, including the spacer wafers 315 so as to
reach from the electrode contacts 338 to IC 350. The spacers 315
may comprise silicon, glass, or another material such as co-fired
ceramic, ceramic with vias and contacts formed after firing, or
printed circuit board (PCB).
[0053] The drawing is simplified to show what is necessary to
appreciate the construction of the embodiment, and so not every
through via is separately numbered in these examples, nor is every
electrical contact point. But those reading this disclosure will
appreciate that like-constructed components are provided as shown
and operate as described herein. Conducting contact points or
layers 322 are provided as needed to electrically connect the
various members of device 300 where suitable. Also, the device 300
can be mounted to a PCB or flexible circuit board or similar
sub-unit of a larger system, and can receive and/or transmit
electrical signals through electrical contact 362 and solder bumps
or other pin connections 363.
[0054] One or more electrodes can be gas isolated from the others
using gasket material 380, which can further effectively subdivide
the sensor chamber 332 into more than one sub-chamber or electrode
space 333 within said sensor chamber. This aspect is true for other
embodiments presented in this disclosure, and it is possible to
consider the one or more sub-chambers or electrode spaces within
the overall sensor chamber based on the gasket 380 or other
dividing materials between the respective sub-chambers 333. Various
gasketing features are disclosed in the present document, which can
apply to one or more of the invention's embodiments.
[0055] The gaskets referred to herein, for example 180, 380 (et al)
may be deposited as a liquid that cures once in place or may be
pre-formed according to the shape and dimensions needed, which
pre-formed gaskets are then picked and placed into position within
the sensor device.
[0056] The gaskets 180, 380 (et al) substantially block or exclude
gases from passing across a barrier defined by the gaskets. In some
aspects, the gaskets 180, 380 (et al) may comprise a fully airtight
and gas-isolating seal. But in alternative embodiments, the gaskets
180, 380 (et al) could be designed and arranged to permit slight
leakage of certain gases, e.g., small molecule gases like oxygen or
hydrogen and others, while blocking passage of larger gas molecules
such as carbon monoxide or carbon dioxide and others. In an
example, the gasket material may be designed and configured to
allow some water vapor gas to pass across the gasket material.
[0057] The sensor device 300 can be manufactured using some or many
steps from within the relevant industry, but also using novel
steps, especially as to the sequence and nature thereof. These
steps can include one or more optional steps, so they may not all
be required. Also, the order of performing the steps can vary as
appropriate for a given device and process, so the steps herein are
listed in an exemplary and illustrative way only. With regard to
the device 300 of FIG. 3, it may be constructed using the following
method, which is also hereby presented as a novel aspect of this
invention: The base or IC wafer is formed; we optionally etch the
cavity or sensor chamber; the through vias described are then
formed in the appropriate wafer; the cavity or sensor chamber side
interconnects are formed and established; the spacer wafer or plate
is established or installed or attached, e.g., by bonding it at the
proper locations; electrodes and/or contact points are disposed as
necessary to connect the relevant electrical components; an
optional gasket is put in place to establish optional sub-chambers
within the sensor chamber; the electrolyte material (in some
embodiments a slab or layer of electrolyte) is put against the
electrodes in the sensor chamber; attach the cap wafer, die level
or panel to the lower parts, which can include forming the cap
wafer with its gas port via and attaching respective conducting
contacts or electrodes to the cap wafer; install optional solder
bump wafer; install optional gas filter over the gas port; test the
wafer and/or device; and singulate the wafer(s). As discussed with
respect to related embodiments herein, other steps can be included
or omitted as suits a given implementation. For embodiments having
multiple adjacent or bonded wafer elements, a conductive bond
section using electrically conducting bonding agents can be used.
Also, conducting vias are formed in spacer panels or wafers where
necessary to connect circuit elements above and below the
spacers.
[0058] FIG. 4 extends or modifies the present disclosure and shows
another electrochemical sensor device 400 based on a pair of
substantially parallel and planar wafers, e.g., base wafer or
substrate 310 and lid or cap wafer 470. In this instantiation, the
partially-enclosed sensor chamber 432 is formed without the need
for a separate spacer member between the two foregoing wafers. One
or both of wafers 310 and 470 may comprise a multi-layer co-fired
ceramic or PCB, or any other appropriate laminate structure. The
top (cap) wafer 470 has the gas port through via 420 therein,
optionally filtered by filter 190 as mentioned before. Conducting
vias and contacts 421, 422 may be created in the wafer structures
as described before. In some embodiments, the lateral elements 438
may be formed on the topside of the lid wafer and not part-way
through the thickness of the lid as shown in the figure.
[0059] In some embodiments, glass or silicon wafers or panels are
used. Here, interconnects embedded in the silicon or glass wafers
may not be possible or economically justified. Instead, in an
aspect, the electrical interconnects may be performed only on the
top-side or bottom-side of the cap wafer, or a combination of the
foregoing. In other embodiments, co-fired ceramic panels or wafers
are used, in which embedded interconnects may be employed, in a PCB
or 3D printed substrate architecture.
[0060] The sensor device 400 can be manufactured using some or many
steps from within the relevant industry, but also using novel
steps, especially as to the sequence and nature thereof. These
steps can include one or more optional steps, so they may not all
be required. Also, the order of performing the steps can vary as
appropriate for a given device and process, so the steps herein are
listed in an exemplary and illustrative way only. With regard to
the device 400 of FIG. 4, it may be constructed using the following
method, which is also hereby presented as a novel aspect of this
invention: The base or IC wafer is formed; we optionally etch the
cavity or sensor chamber; the through vias (e.g., silicon or glass
vias) described are then formed in the appropriate wafer; the
cavity or sensor chamber side interconnects are formed and
established; electrodes and/or contact points are disposed as
necessary to connect the relevant electrical components; an
optional gasket is put in place to establish optional sub-chambers
433 within the sensor chamber; the electrolyte material (in some
embodiments a slab or layer of electrolyte) is put against the
electrodes in the sensor chamber; attach the cap wafer, die level
or panel to the lower parts, which can include forming the cap
wafer with its gas port via and attaching respective conducting
contacts or electrodes to the cap wafer; install optional solder
bump wafer; install optional gas filter over the gas port; test the
wafer and/or device; and singulate the wafer(s).
[0061] FIG. 5 Illustrates yet another embodiment of an
electrochemical sensor device 500 wherein the base wafer 510 is
formed from a glass wafer with glass through vias and electrical
redistribution. A silicon wafer with silicon through vias and
electrical redistribution, a PCB panel or a ceramic panel with vias
and electrical connections may alternatively be used. In this
instantiation, the cap wafer 570 of the partially-enclosed sensor
chamber 532 comprises the IC die and a gas port through via 520. A
spacer layer or wafer or plate 515 is used to define the height of
the partially-enclosed cavity 532 and provide the electrical
interconnection between the lid and base wafers. As before, one or
more gaskets 580 can subdivide the sensor chamber 532. The
electrodes 535, 534, 536, 537, contact an electrolyte material 540,
and are coupled to the electrical conduction ways illustrated in
the cross section by conducting plates, contacts or similar means
538 that carry electrical current among the respective vias 521
penetrating the structures of device 500.
[0062] It is noted that in all of the present examples an IC (e.g.,
150, 550) may be integrated into one of the wafers as suits a given
application. However, it will be appreciated that the sensor
devices 100, 500 and others may be prepared without an integrated
IC circuit, but rather, connections to an external circuit such as
an IC that is not part of the device could be achieved as well.
[0063] While the illustration shows the working electrode 535 being
gas isolated by gaskets 580, alternative embodiments may add
additional gasketing material between the other electrodes and
their sub-chambers so as to gas-isolate, substantially gas-isolate,
or selectively gas-isolate each of the electrodes from the
other.
[0064] The sensor device 500 can be manufactured using some or many
steps from within the relevant industry, but also using novel
steps, especially as to the sequence and nature thereof. These
steps can include one or more optional steps, so they may not all
be required. Also, the order of performing the steps can vary as
appropriate for a given device and process, so the steps herein are
listed in an exemplary and illustrative way only. With regard to
the device 500 of FIG. 5, it may be constructed using the following
method, which is also hereby presented as a novel aspect of this
invention: The base or IC wafer is formed as a cap wafer; we
optionally etch the cavity or sensor chamber; the gas through via
is established in its respective plate or wafer element; the other
through vias (e.g., silicon or glass vias) described are formed in
the appropriate wafer; the cavity or sensor chamber side
interconnects are formed and established; the glass spacer wafer or
plate is established or installed or attached, e.g., by bonding it
at the proper locations; electrodes and/or contact points are
disposed as necessary to connect the relevant electrical
components; an optional gasket is put in place to establish
optional sub-chambers within the sensor chamber; the electrolyte
material (in some embodiments a slab or layer of electrolyte) is
put against the electrodes in the sensor chamber; attach the glass
base wafer, die level or panel to the other device parts, which can
include forming the base glass wafer with its electrodes and
attaching respective conducting contacts or electrodes thereto;
install optional solder bump wafer; install optional gas filter
over the gas port; test the wafer and/or device; and singulate the
wafer(s).
[0065] FIG. 6 illustrates another cross-sectional embodiment of an
electrochemical sensor device 600. Once again, a plurality of
electrodes 634, 635, 636, 637 are disposed in a sensor chamber 632
at least partially defined by a base wafer or plate or substrate
member 610 and a lid or cap wafer or plate or substrate member 670
including a gas port via 620 connecting a working electrode 635 to
an external gas environment 602, as well as connecting separators
or spacer elements 615, which may be multi-layer ceramic or PCB
package elements with cavities and electrical vias 621 passing
therethrough. In this exemplary embodiment, the base wafer 610 is
formed from a multi-layer ceramic, PCB, or other appropriate
composite material, and the cap wafer 670 comprises an IC die. The
base wafer 610 may alternatively comprise a silicon wafer with
through silicon vias (TSVs) or a glass wafer with through glass
vias (TGVs) as described herein, or other appropriate substrate
providing interconnection between its upper and lower surfaces. As
stated elsewhere, an IC 650 may be manufactured and mounted onto a
suitable wafer on an outer surface thereof (e.g., for glass wafer
applications), or the IC 650 may be made integrated into the wafer
670 if the manufacturing process therefore allows.
[0066] FIG. 7 illustrates an exemplary process or method 700 for
making the present devices, generally, with the example of device
600 being used for illustration. Those skilled in the art will
understand how this illustration equally applies to the other
methods and steps recited herein, and equivalent methods as well.
These steps can include one or more optional steps, so they may not
all be required. As some examples, we have stated that the
application of spacer wafers, gas filters, and gaskets are not
required in each embodiment, and so these and similar acts or
processes can be substituted or omitted or replaced, in a number of
ways. Also, the order of performing the steps can vary as
appropriate for a given device and process, so the steps herein are
listed in an exemplary and illustrative way only. As one example of
this, the testing and singulating or dicing up of a wafer can be
performed in either order, first testing the multi-sensor array on
a wafer as a whole, or alternatively, cutting up, dicing or
singulating the sensors on a wafer into individual sensor devices
that are tested after singulation.
[0067] With regard to the device 600 of FIG. 6 and others, it may
be constructed using the following method, which is also hereby
presented as a novel aspect of this invention: The base or IC wafer
is formed as a cap wafer at 701; the gas through via is established
in its respective plate or wafer element at 702; the other through
vias and cavity-side interconnects (e.g., silicon or glass vias)
are formed at 704; electrodes and/or contact points are disposed as
necessary to connect the relevant electrical components at 706; an
optional gasket is put in place to establish optional sub-chambers
within the sensor chamber at 708; the electrolyte material (in some
embodiments a slab or layer of electrolyte) is put against the
electrodes in the sensor chamber at 710; a spacer wafer is formed
at 712 and a lid or cap wafer at 714; the cap and base wafers are
bonded to one another or to a spacer wafer at 713; the die is
attached to a formed ceramic or PCB package panel having electrodes
attached thereto at 714, 716 and 718; install optional solder bumps
to wafer at 720; install optional gas filter over the gas port at
722; test the wafer/panel and/or device at 724; and singulate the
panel or wafer(s) at 726.
[0068] It can thus be seen that the base and cap wafers of some
embodiments of the present sensor device are separated by a
distinct separator plate or wafer (e.g., in FIGS. 3, 5 and 6),
while in other embodiments, the cap and base wafer are separated by
sidewalls made integrally or monolithically from at least one of
said base and cap wafers (e.g., in FIGS. 1 and 4).
[0069] As discussed elsewhere, it is desired in some embodiments
that the sensor device be IP6x compatible. Referring to FIG. 1, but
applicable generally, the present invention can optionally include
in the filter 190 (et al) design a hydrophobic and/or oleophobic
material to prevent certain contaminants and substances from
entering the sensor chamber spaces. The filter 190 can be porous,
and the porosity can be defined by a general characteristic pore
size and nature to meet required dust (solid particulate) and
waterproofing needs and standards. Additionally, the sides of
filter 190 (e.g., 191) can be sealed to prevent incursion of
outgassing gases from the internal components of the system into
the gas sensor when the filter is mounted against or pressed
against or sealed against an IP6x compatible frame or housing 102.
Optionally, filter 190 may be equipped with a gasket or adhesive
192 to aid in sealing the filter against the frame or housing 102
on which the sensor 100 is mounted. While the figures shows are
simplified representations, those skilled in the art will
understand that the gasket or adhesive 192 is to be applied between
filter 190 and substrate or housing 102.
[0070] In some embodiments, a gasket was described. More generally
a seal can be formed (either from existing structural materials,
e.g., the wafers and/or the electrolyte or using specific gasketing
material). So the gas seal providing the present gas isolation of
one or more electrode chambers from the others may comprise a
gasket or gaskets. It is to be understood that the working
electrode is not the only electrode chamber that could be provided
with a gas port through via. One or more of the other electrodes
may be provided with external gas through a provided gas port
through via as well. Similarly, when sealing the respective one or
more electrode chambers from one another in various optional
examples, the other electrode chambers may be the ones sealed
instead of and/or in addition to the working electrode chamber. For
example, a seal comprising a gasket as described herein can be
applied to, above and/or below the solid or semi-solid electrolyte
so as to gas isolate any or all of the electrodes and electrode
chambers from one another. The gasket can be press-formed or fit
where it is in compression from other members given herein to
provide the gas isolation as stated.
[0071] In some examples a solid or semi-solid electrolyte material
was described. It should be understood that in some or all
embodiments, the electrolyte would be made to resist a certain
amount of mechanical force or pressure, e.g., by not being a fluid
electrolyte, but rather by being a solid or semi-solid material,
which has certain solid/semi-solid material mechanical properties
(e.g., density, stress-strain, hardness, non-pliability and so
forth).
[0072] FIG. 8 illustrates one example of a common wafer 802 on or
in which a plurality of sensor devices 812, 822, 832, 842 as
described above can be formed using manufacturing techniques
described herein. In the example 802, each sensor device is made
with its own integrated circuit 813, 823, 833, 843, respectively.
Then, the devices can be singulated to create four individual
functional electrochemical sensor devices as described herein by
dicing or cutting or otherwise separating them into individual
parts. In other embodiments, such as shown at 804, multi-sensor
devices are provided. For example, one multi-sensor device has four
different electrochemical sensor devices 814a, 814b, 814c and 814d
therein. These have an integrated circuit 815 that can determine
any of several different gasses, for example if each of the
separate sensor devices 814a, 814b, 814c and 814d is sensitive to
one such different gas. In another example, a second multi-sensor
device has four different electrochemical sensor devices 824a-d
having an integrated circuit 823 that can determine any of several
different gasses, for example if each of the separate sensor
devices 824a-d is sensitive to one such different gas. In yet
another example, a third multi-sensor device has four different
electrochemical sensor devices 834a-d having an integrated circuit
813 that can determine any of several different gasses, for example
if each of the separate sensor devices 834a-d is sensitive to one
such different gas. In yet another example, a fourth multi-sensor
device has four different electrochemical sensor devices 844a-d
having an integrated circuit 843 that can determine any of several
different gasses, for example if each of the separate sensor
devices 844a-d is sensitive to one such different gas.
[0073] The present devices can have separate integrated circuits,
or they can share one integrated circuit among more than one sensor
device as needed.
[0074] Having described the invention in detail, those skilled in
the art will appreciate that, given the present disclosure,
modifications may be made to the invention without departing from
the spirit of the inventive concepts described herein. Therefore,
it is not intended that the scope of the invention be limited to
the specific embodiments illustrated and described. For example,
electrochemical electrodes may be placed entirely on any one
surface of the partially-enclosed cavity, or placed on multiple
surfaces of the of the partially-enclosed cavity; the integrated
circuit may comprise a monolithic circuit formed in one of the
packaging elements, or may comprise multiple, dissociated
integrated circuits formed in one or more of the packaging
elements; integrated circuits may be formed in any appropriate
semiconducting material; the sensing module may comprise multiple
electrochemical cells, each cell having a unique combination of
electrodes and electrolyte so as to improve the selectivity and
range of gasses which can be detected; the flow of the outlined
assembly processes may be re-ordered whilst still achieving an
identical or substantially identical outcome; assembly may be
performed at the wafer level, at the coupon level, at the panel
level, at the die level, at the gang-level, via chip-on-wafer
processes, via chip-on-panel processes, or via multiple of these
and other techniques.
* * * * *