U.S. patent application number 15/331526 was filed with the patent office on 2017-02-09 for particle removal during fabrication of electrochromic devices.
The applicant listed for this patent is View, Inc.. Invention is credited to Robert T. Rozbicki.
Application Number | 20170038658 15/331526 |
Document ID | / |
Family ID | 58052570 |
Filed Date | 2017-02-09 |
United States Patent
Application |
20170038658 |
Kind Code |
A1 |
Rozbicki; Robert T. |
February 9, 2017 |
PARTICLE REMOVAL DURING FABRICATION OF ELECTROCHROMIC DEVICES
Abstract
Electrochromic devices are fabricated using a particle removal
operation that reduces the occurrence of electronically conducting
layers and/or electrochromically active layers from contacting
layers of the opposite polarity and creating a short circuit in
regions where defects form. In some embodiments, the particle
removal operation is not a lithiation operation. In some
embodiments, the particle removal operation is performed at an
intermediate stage during the deposition of either an
electrochromic layer or a counter electrode layer.
Inventors: |
Rozbicki; Robert T.;
(Germantown, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
View, Inc. |
Milpitas |
CA |
US |
|
|
Family ID: |
58052570 |
Appl. No.: |
15/331526 |
Filed: |
October 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US2015/026150 |
Apr 16, 2015 |
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15331526 |
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14885734 |
Oct 16, 2015 |
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PCT/US2015/026150 |
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14601141 |
Jan 20, 2015 |
9229291 |
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14885734 |
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13763505 |
Feb 8, 2013 |
9007674 |
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14601141 |
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PCT/US12/57606 |
Sep 27, 2012 |
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13763505 |
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61982427 |
Apr 22, 2014 |
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61541999 |
Sep 30, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 14/08 20130101;
G02F 1/1533 20130101; G02F 1/153 20130101; H01J 37/32 20130101;
C23C 14/028 20130101; G02F 1/1523 20130101; G02F 2001/1536
20130101; H01J 37/3417 20130101; G02F 1/1524 20190101; C23C 14/0635
20130101; C23C 14/34 20130101; G02F 1/133345 20130101; H01J 37/3429
20130101; C23C 14/021 20130101; G02F 1/155 20130101; G02F 2001/1316
20130101; H01J 37/32853 20130101; C23C 14/588 20130101; C23C 14/081
20130101; C23C 14/083 20130101; H01J 37/32733 20130101; G02F
2001/1555 20130101; C23C 14/0652 20130101; C23C 14/086 20130101;
G02F 1/1309 20130101; C23C 14/0676 20130101; C23C 14/5886
20130101 |
International
Class: |
G02F 1/153 20060101
G02F001/153; H01J 37/32 20060101 H01J037/32; G02F 1/13 20060101
G02F001/13; G02F 1/155 20060101 G02F001/155; G02F 1/15 20060101
G02F001/15 |
Claims
1. A method of fabricating an electrochromic device, the method
comprising: providing a substrate having a first transparent
electronically conductive layer comprising a first transparent
electronically conductive material; forming an electrochromic stack
over the substrate having the first transparent electronically
conductive layer, wherein forming the stack comprises: forming an
electrochromic layer comprising an electrochromic material; and
forming a counter electrode layer comprising a counter electrode
material; forming a second transparent electronically conductive
layer over the electrochromic stack, the second transparent
electronically conductive layer comprising a second transparent
electronically conductive material, whereby the first and second
transparent electronically conductive layers sandwich the
electrochromic stack; and performing a particle-removal operation
to reduce the number of defects in the formed electrochromic
device, wherein the particle-removal operation is performed at any
time before both the electrochromic layer and the counter electrode
layer are fully-formed.
2. The method of claim 1, wherein the particle removal operation
reduces the number of visible short-related pinhole in the formed
electrochromic device.
3. The method of claim 1, wherein: the first transparent
electronically conductive material is selected from the group
consisting of fluorinated tin oxide and indium-doped tin oxide; and
the second transparent electronically conductive material is
indium-doped tin oxide.
4. The method of claim 1, wherein the particle-removal operation is
performed before starting to form either the electrochromic or
counter electrode layers.
5. The method of claim 1, wherein the particle-removal operation is
performed after the electrochromic layer is formed but before
starting to form the counter electrode layer.
6. The method of claim 1, wherein the particle-removal operation is
performed after the counter electrode layer is formed but before
starting to form the electrochromic layer.
7. The method of claim 1, wherein the particle-removal operation is
performed after starting to form the electrochromic layer but
before the electrochromic layer is fully formed.
8. The method of claim 1, wherein the particle-removal operation is
performed after starting to form the counter electrode layer but
before the counter electrode layer is fully formed.
9. The method of claim 1, wherein the particle-removal operation
comprises a technique selected from the group consisting of contact
cleaning, irradiation, heat treatment, plasma treatment, contact
with supercritical fluid, acoustic vibration, and contact with
flowing ionized air.
10. The method of claim 1, wherein the particle-removal operation
comprises contact cleaning, and wherein the contact cleaning
removes particles from the surface of the partially-formed
electrochromic device by static electricity and/or adhesion.
11. The method of claim 10, wherein the contact cleaning comprises
contacting the surface of the partially-formed electrochromic
device with one or more rollers, strips, or brushes.
12. The method of claim 1, wherein the particle-removal operation
comprises irradiating the surface of the partially-formed
electrochemical device, and wherein the irradiation produces a
volumetric expansion of the particles to be removed relative to the
surrounding portions of the partially-formed electrochromic device
such that these particles are ejected from the surface of the
partially-formed electrochromic device.
13. The method of claim 1, wherein the particle-removal operation
comprises contacting the surface of the partially-formed
electrochromic device with a plasma.
14. The method of claim 13: wherein the plasma contact produces a
build-up of electrical charge in the particles to be removed; and
wherein the particle-removal operation further comprises applying a
voltage to an outer surface of the partially-formed electrochromic
device such that the charged particles to be removed are ejected
from the surface by repulsive electrostatic forces.
15. The method of claim 13, wherein the plasma is a fluorine and/or
oxygen plasma which etches away a film from the surface of the
partially-formed electrochromic device such that particles are
dislodged and/or removed with the film.
16. The method of claim 1, wherein the particle-removal operation
comprises a heat treatment of the partially-formed electrochromic
device.
17. The method of claim 16, wherein the heat treatment comprises
heating the particles to be removed so as to cause the particles to
volumetrically expand relative to the surrounding portions of the
partially-formed electrochromic device such that the particles are
ejected from the surface of the partially-formed electrochromic
device.
18. The method of claim 17, wherein the heat-treatment comprises a
heating technique selected from: irradiation with UV light,
proximity to a resistive heating element, and exposure to a heated
gas.
19. The method of claim 1, wherein the particle-removal operation
comprises dislodging or burning away particles from the surface of
the partially-formed electrochromic device with laser
radiation.
20. The method of claim 19, wherein the laser radiation is
collimated into a flat beam which grazes the surface of the
partially-formed electrochromic device.
21. The method of claim 20, wherein the laser radiation is
raster-scanned over the surface of the partially-formed
electrochromic device.
22. The method of claim 1, wherein the electrochromic material of
the electrochromic layer is cathodically-coloring, wherein the
counter electrode material of the counter electrode layer is
anodically-coloring, and wherein the electrochromic layer is formed
before forming the counter electrode layer.
23. The method of claim 22, wherein the cathodically-coloring
electrochromic material comprises a tungsten oxide, and the
anodically-coloring electrochromic material comprises a nickel
tungsten oxide.
24. The method of claim 23, wherein forming the electrochromic
stack further comprises forming an additional layer comprising
tungsten oxide having a different tungsten to oxygen ratio than the
tungsten oxide comprising the other cathodically-coloring
electrochromic material.
25. The method of claim 1, further comprising depositing lithium
into the electrochromic stack.
26. The method of claim 1, wherein the electrochromic stack is
formed on the substrate while the substrate is oriented
vertically.
27. The method of claim 1, wherein the electrochromic stack is
formed on the substrate while the substrate is oriented
horizontally.
28. An apparatus for fabricating an electrochromic device, the
apparatus comprising: (a) an integrated deposition system for
forming an electrochromic stack on a substrate, the system
comprising: (i) a first deposition station containing a first
target comprising a first material for depositing a layer of an
electrochromic material on a substrate when the substrate is
positioned in the first deposition station; (ii) a second
deposition station containing a second target comprising a second
material for depositing a layer of a counter electrode material on
the substrate when the substrate is positioned in the second
deposition station; and (iii) a particle-removal device for
removing particles from the surface of the substrate and/or the
surface of the electrochromic stack before it is fully-formed; and
(b) a controller comprising: program instructions for passing the
substrate through the first and second deposition stations in a
manner that sequentially deposits a stack on the substrate, the
stack comprising the layer of electrochromic material and the layer
of counter electrode material; and program instructions for
operating the particle-removal device to remove particles from the
surface of the substrate and/or the surface of the electrochromic
stack before it is fully-formed.
29. The apparatus of claim 28, wherein the program instructions
comprise instructions for operating the particle-removal device to
remove particles before the layer of electrochromic material is
fully-formed.
30. The apparatus of claim 28, wherein the program instructions
comprise instructions for operating the particle-removal device to
remove particles before the counter electrode layer is fully
formed.
31. The apparatus of claim 28, wherein operation of the
particle-removal device reduces the number of visible short-related
pinhole defects in the fabricated electrochromic device to a level
no greater than about 0.005 per square centimeter.
32. The apparatus of claim 28, wherein the integrated deposition
system further comprises: (iv) a third deposition station
containing a third target comprising a third material, wherein the
third deposition station is configured to deposit an electrode
layer on the electrochromic stack when the substrate having the
electrochromic stack is positioned in the third deposition station,
and wherein the electrode layer comprises a transparent
electronically conductive material.
33. The apparatus of claim 28, further comprising a substrate
holder configured to provide the substrate in a vertical
orientation when positioned for deposition in the first and second
deposition stations.
34. The apparatus of claim 33, wherein the apparatus is further
configured to provide the substrate in a vertical orientation when
positioned at the particle-removal device.
35. The apparatus of claim 28, further comprising a substrate
holder configured to provide the substrate in a horizontal
orientation when positioned for deposition in the first and second
deposition stations.
36. The apparatus of claim 35, wherein the apparatus is further
configured to provide the substrate in a horizontal orientation
when positioned at the particle-removal device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of PCT/US15/26150,
entitled "PARTICLE REMOVAL DURING FABRICATION OF ELECTROCHROMIC
DEVICES", filed Apr. 16, 2015, which claims benefit to U.S.
Provisional Patent Application No. 61/982,427, entitled "PARTICLE
REMOVAL DURING FABRICATION OF ELECTROCHROMIC DEVICES", filed Apr.
22, 2014; this application is also a continuation-in-part of Ser.
No. 14/885,734, titled "DEFECT-MITIGATION LAYERS IN ELECTROCHROMIC
DEVICES," filed on Oct. 16, 2015, which is a continuation of U.S.
patent application Ser. No. 14/601,141, titled "DEFECT-MITIGATION
LAYERS IN ELECTROCHROMIC DEVICES," filed on Jan. 20, 2015, now U.S.
Pat. No. 9,229,291, issued Jan. 5, 2016, which is a continuation of
U.S. patent application Ser. No. 13/763,505, titled
"DEFECT-MITIGATION LAYERS IN ELECTROCHROMIC DEVICES," filed on Feb.
8, 2013, now U.S. Pat. No. 9,007,674, issued Apr. 14, 2015, which
is a continuation-in-part of PCT Application No. PCT/US12/57606,
titled "IMPROVED OPTICAL DEVICE FABRICATION," filed on Sep. 27,
2012, which claims the benefit of priority to U.S. Provisional
Application No. 61/541,999, titled "OPTICAL DEVICE FABRICATION,"
filed on Sep. 30, 2011; all of which applications are herein
incorporated by reference.
BACKGROUND
[0002] Electrochromism is a phenomenon in which a material exhibits
a reversible electrochemically-mediated change in an optical
property when placed in a different electronic state, typically by
being subjected to a voltage change. The optical property is
commonly one or more of color, transmittance, absorbance, and
reflectance. Electrochromic materials may be incorporated into, for
example, windows and mirrors. The color, transmittance, absorbance,
and/or reflectance of such windows and mirrors may be changed by
inducing a change in the electrochromic material. However, advances
in electrochromic technology, apparatus, and related methods of
making and/or using them, are needed because conventional
electrochromic windows suffer from, for example, high defectivity
and low versatility.
SUMMARY
[0003] Disclosed herein is an electrochromic device design and
process for producing electrochromic devices. In some embodiments,
the methods employ a particle removal operation which reduces the
likelihood that electronically conducting layers and/or
electrochromically active layers will contact layers of the
opposite polarity and creating a short circuit in regions where
defects form. In some embodiments, the particle removal operation
is not a lithiation operation. In some embodiments, the particle
removal operation is performed at an intermediate stage during the
deposition of either an electrochromic layer or a counter electrode
layer.
[0004] One aspect of the disclosure concerns methods of fabricating
an electrochromic device, which methods may be characterized by:
(a) providing a substrate having a first transparent electronically
conductive layer comprising a first transparent electronically
conductive material; (b) forming an electrochromic stack over the
substrate having the first transparent electronically conductive
layer; (c) forming a second transparent electronically conductive
layer over the electrochromic stack, the second transparent
electronically conductive layer including a second transparent
electronically conductive material, whereby the first and second
transparent electronically conductive layers sandwich the
electrochromic stack; and (d) performing a particle-removal
operation to reduce the number of defects in the formed
electrochromic device, wherein the particle-removal operation is
performed at any time before both the electrochromic layer and the
counter electrode layer are fully-formed. Forming the stack may
include the following operations: (i) forming an electrochromic
layer comprising an electrochromic material; and (ii) forming a
counter electrode layer comprising a counter electrode
material.
[0005] In some implementations, the particle-removal operation is
performed before starting to form either the electrochromic or
counter electrode layers. In other implementations, the
particle-removal operation is performed after the electrochromic
layer is formed but before starting to form the counter electrode
layer. In still other implementations, the particle-removal
operation is performed after the counter electrode layer is formed
but before starting to form the electrochromic layer. Still
further, the particle-removal operation may be performed after
starting to form the electrochromic layer but before the
electrochromic layer is fully formed. Still further, the
particle-removal operation is performed after starting to form the
counter electrode layer but before the counter electrode layer is
fully formed.
[0006] In some embodiments, the particle removal operation reduces
the number of visible short-related pinhole in the formed
electrochromic device. Some examples of the particle-removal
operation include contact cleaning, irradiation, heat treatment,
plasma treatment, contact with supercritical fluid, acoustic
vibration, and contact with flowing ionized air.
[0007] In some examples where the particle-removal operation
includes contact cleaning, the contact cleaning removes particles
from the surface of the partially-formed electrochromic device by
static electricity and/or adhesion. For example, the contact
cleaning may involve contacting the surface of the partially-formed
electrochromic device with one or more rollers, strips, or
brushes.
[0008] In some cases, the particle-removal operation involves
irradiating the surface of the partially-formed electrochemical
device. The irradiation may produce a volumetric expansion of the
particles to be removed relative to the surrounding portions of the
partially-formed electrochromic device such that these particles
are ejected from the surface of the partially-formed electrochromic
device.
[0009] In certain embodiments, the particle-removal operation
includes contacting the surface of the partially-formed
electrochromic device with a plasma. As an example, the plasma
contact produces a build-up of electrical charge in the particles
to be removed, and then the particles are ejected by applying a
voltage to an outer surface of the partially-formed electrochromic
device. In some implementations, the plasma is a fluorine and/or
oxygen plasma which etches away a film from the surface of the
partially-formed electrochromic device such that particles are
dislodged and/or removed with the film.
[0010] In certain embodiments, the particle-removal operation
includes a heat treatment of the partially-formed electrochromic
device. The heat treatment may involve heating the particles to be
removed so as to cause the particles to volumetrically expand
relative to the surrounding portions of the partially-formed
electrochromic device and thereby eject the particles from the
surface of the partially-formed electrochromic device. In some
implementations, the heat-treatment includes a heating technique
selected from: irradiation with UV light, proximity to a resistive
heating element, and exposure to a heated gas.
[0011] In another example, the particle-removal operation includes
dislodging or burning away particles from the surface of the
partially-formed electrochromic device with laser radiation. In
some cases, the laser radiation is collimated into a flat beam
which grazes the surface of the partially-formed electrochromic
device. In some examples, the laser radiation is raster-scanned
over the surface of the partially-formed electrochromic device.
[0012] In certain embodiments, the electrochromic material of the
electrochromic layer is cathodically-coloring, and the counter
electrode material of the counter electrode layer is
anodically-coloring. In some examples, the electrochromic layer is
formed before forming the counter electrode layer. In such
processes, the cathodically-coloring electrochromic material may
include a tungsten oxide, and the anodically-coloring
electrochromic material may include a nickel tungsten oxide. In
some examples, the method of forming the electrochromic layer
includes forming an additional layer containing tungsten oxide
having a different tungsten to oxygen ratio than the tungsten oxide
comprising the other cathodically-coloring electrochromic
material.
[0013] In some implementations, the method additionally includes
depositing lithium into the electrochromic stack. In some cases,
the first transparent electronically conductive material is
selected from fluorinated tin oxide and indium-doped tin oxide, and
the second transparent electronically conductive material is an
indium-doped tin oxide.
[0014] In some implementations, the electrochromic stack is formed
on the substrate while the substrate is oriented vertically. In
some implementations, the electrochromic stack is formed on the
substrate while the substrate is oriented horizontally.
[0015] Another aspect of the disclosed embodiments concerns
apparatus for fabricating an electrochromic device. Such apparatus
may be characterized by the following features: (a) an integrated
deposition system for forming an electrochromic stack on a
substrate, and (b) a controller including instructions for (i)
passing the substrate through the integrated deposition system and
(ii) operating a particle-removal device to remove particles from
the surface of the substrate and/or the surface of the
electrochromic stack before it is fully-formed. The integrated
deposition system includes (i) a first deposition station
containing a first target comprising a first material for
depositing a layer of an electrochromic material on a substrate
when the substrate is positioned in the first deposition station;
(ii) a second deposition station containing a second target
comprising a second material for depositing a layer of a counter
electrode material on the substrate when the substrate is
positioned in the second deposition station; and (iii) the
particle-removal device for removing particles from the surface of
the substrate and/or the surface of the electrochromic stack before
it is fully-formed. The instructions for passing the substrate
through the deposition system contain instructions for passing the
substrate through the first and second deposition stations in a
manner that sequentially deposits a stack on the substrate, the
stack comprising the layer of electrochromic material and the layer
of counter electrode material
[0016] In some designs, the integrated deposition system further
includes (iv) a third deposition station containing a third target
comprising a third material. The third deposition station is
configured to deposit an electrode layer on the electrochromic
stack when the substrate having the electrochromic stack is
positioned in the third deposition station. The electrode layer may
include a transparent electronically conductive material.
[0017] The apparatus may additionally include a substrate holder
configured to provide the substrate in a vertical orientation when
positioned for deposition in the first and second deposition
stations. In some cases, the apparatus is configured to provide the
substrate in a vertical orientation when positioned at the
particle-removal device.
[0018] In some embodiments, the apparatus additionally includes a
substrate holder configured to provide the substrate in a
horizontal orientation when positioned for deposition in the first
and second deposition stations. In some implementations, the
apparatus is further configured to provide the substrate in a
horizontal orientation when positioned at the particle-removal
device.
[0019] In certain embodiments, the program instructions include
instructions for operating the particle-removal device to remove
particles before the layer of electrochromic material is
fully-formed. In other embodiments, the program instructions
include instructions for operating the particle-removal device to
remove particles before the counter electrode layer is fully
formed.
[0020] In some designs, the operation of the particle-removal
device reduces the number of visible short-related pinhole defects
in the fabricated electrochromic device to a level no greater than
about 0.005 per square centimeter.
[0021] These and other features and advantages of the disclosed
embodiments will be described in more detail below with reference
to the associate drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0022] FIGS. 1A and 1B depict the structure and function of
electrochromic devices.
[0023] FIG. 2 depicts a particle defect in an electrochromic
device.
[0024] FIGS. 3A-3D depict aspects of formation and remediation of a
pop-off defect.
[0025] FIG. 4 is a scanning electron micrograph of an
electrochromic device which does not contain any shorts or pop off
defects.
[0026] FIG. 5A is a flow chart of a baseline process for forming an
electrochromic device that may be modified by introduction of one
or more particle removal operations.
[0027] FIGS. 5B and 5C are flow charts of processes that
incorporate particle removal operations at specified stages in the
sequence of device fabrication operations.
[0028] FIG. 5D is a flow chart of a process in accordance with
certain embodiments in which a particle removal operation is
performed at an intermediate point during the deposition of a
second electrochromic layer.
[0029] FIG. 5E is a flow chart of a process in accordance with
certain embodiments in which two particle removal operations are
performed.
[0030] FIGS. 6A and 6B are illustrations of apparatus that may be
used to fabricate electrochromic devices on substrates in vertical
and horizontal configurations, respectively.
DETAILED DESCRIPTION
[0031] The present disclosure concerns methods and apparatus for
reducing difficulties created by defects in electrochromic devices.
Certain types of defects introduce short circuits across the
electrochromic device electrodes that produce particularly
unattractive blemishes in electrochromic products. Despite efforts
to clean and remove particulates on substrates prior to fabrication
of electrochromic devices thereon, some particles are formed as a
part of the fabrication process, e.g., during sputter deposition
particulates can be formed from various hardware in the sputter
environment. Spurious particles can deposit onto the substrate
during movement through and between sputter environments. This is
especially true of horizontally oriented substrates. Vertical
orientation of the substrate helps to reduce such deposition, but
still some particles contaminate the substrate during fabrication
nonetheless. Various disclosed embodiments concern the use of a
particle removal operation during fabrication of the electrochromic
device stack. This additional operation serves to prevent formation
of a short circuit if a particle has been ejected from the device
stack during fabrication. The problem of shorting associated with
particle ejection is described below in the context of FIGS. 3A-3D.
In certain embodiments, the particle-removal operation is performed
at any time before both of the electrochromic layer and the counter
electrode layer are fully-formed.
[0032] Before turning to a more detailed description of particle
removal techniques and processes incorporating such techniques,
examples of electrochromic device structure and fabrication will be
presented. FIGS. 1A and 1B are schematic cross-sections of an
electrochromic device, 100, showing a common structural motif for
such devices. Electrochromic device 100 includes a substrate 102, a
conductive layer (CL) 104, an electrochromic layer (EC) 106, an
optional ion conducting (electronically resistive) layer (IC) 108,
a counter electrode layer (CE) 110, and another conductive layer
(CL) 112. Elements 104, 106, 108, 110, and 112 are collectively
referred to as an electrochromic stack, 114. A voltage source, 116,
operable to apply an electric potential across electrochromic stack
112 effects the transition of the electrochromic device from, e.g.,
a bleached state (refer to FIG. 1A) to a colored state (refer to
FIG. 1B).
[0033] The order of layers may be reversed with respect to the
substrate. That is, the layers may be in the following order:
substrate, conductive layer, counter electrode layer, ion
conducting layer, electrochromic material layer, and conductive
layer. The counter electrode layer may include a material that is
electrochromic or not. If both the electrochromic layer and the
counter electrode layer employ electrochromic materials, one of
them should be a cathodically coloring material and the other
should be an anodically coloring material. For example, the
electrochromic layer may employ a cathodically coloring material
and the counter electrode layer may employ an anodically coloring
material. This is the case when the electrochromic layer is a
tungsten oxide and the counter electrode layer is a nickel tungsten
oxide.
[0034] The conductive layers commonly comprise transparent
conductive materials, such as metal oxides, alloy oxides, and doped
versions thereof, and are commonly referred to as "TCO" layers
because they are made from transparent conducting oxides. In
general, however, the transparent layers can be made of any
transparent, electronically conductive material that is compatible
with the device stack. Some glass substrates are provided with a
thin transparent conductive oxide layer such as fluorinated tin
oxide, sometimes referred to as "TEC."
[0035] Device 100 is presented for illustrative purposes only, in
order to facilitate understanding of the context of embodiments
described herein. Methods and apparatus described herein are used
to identify and reduce defects in electrochromic devices,
regardless of the structural arrangement of the electrochromic
device.
[0036] During normal operation, an electrochromic device such as
device 100 reversibly cycles between a bleached state and a colored
state. As depicted in FIG. 1A, in the bleached state, a potential
is applied across the electrodes (transparent conductor layers 104
and 112) of electrochromic stack 114 to cause available ions (e.g.
lithium ions) in the stack to reside primarily in the counter
electrode 110. If electrochromic layer 106 contains a cathodically
coloring material, the device is in a bleached state. In certain
electrochromic devices, when loaded with the available ions,
counter electrode layer 110 can be thought of as an ion storage
layer.
[0037] Referring to FIG. 1B, when the potential on the
electrochromic stack is reversed, the ions are transported across
ion conducting layer 108 to electrochromic layer 106 and cause the
material to enter the colored state. Again, this assumes that the
optically reversible material in the electrochromic device is a
cathodically coloring electrochromic material. In certain
embodiments, the depletion of ions from the counter electrode
material causes it to color also as depicted. In other words, the
counter electrode material is anodically coloring electrochromic
material. Thus, layers 106 and 110 combine to synergistically
reduce the amount of light transmitted through the stack. When a
reverse voltage is applied to device 100, ions travel from
electrochromic layer 106, through the ion conducting layer 108, and
back into counter electrode layer 110. As a result, the device
bleaches.
[0038] Some pertinent examples of electrochromic devices are
presented in the following US patent applications, each
incorporated by reference in its entirety: U.S. patent application
Ser. No. 12/645,111, filed Dec. 22, 2009; U.S. patent application
Ser. No. 12/772,055, filed Apr. 30, 2010; U.S. patent application
Ser. No. 12/645,159, filed Dec. 22, 2009; U.S. patent application
Ser. No. 12/814,279, filed Jun. 11, 2010; U.S. patent application
Ser. No. 13/462,725, filed May 2, 2012; and U.S. patent application
Ser. No. 13/763,505, filed Feb. 8, 2013.
[0039] Electrochromic devices such as those described in relation
to FIGS. 1A and 1B are used in, for example, electrochromic
windows. For example, substrate 102 may be architectural glass upon
which electrochromic devices are fabricated. Architectural glass is
glass that is used as a building material. Architectural glass is
typically used in commercial buildings, but may also be used in
residential buildings, and typically, though not necessarily,
separates an indoor environment from an outdoor environment. In
certain embodiments, architectural glass is at least 20 inches by
20 inches, and can be much larger, e.g., as large as about 72
inches by 120 inches.
[0040] As larger and larger substrates are used for electrochromic
windows it is desirable to minimize defects in the electrochromic
device, because otherwise the performance and visual quality of the
electrochromic windows will suffer. The embodiments described
herein may mitigate defectivity in electrochromic windows.
[0041] In some embodiments, electrochromic glass is integrated into
an insulating glass unit (IGU). An insulating glass unit includes
multiple glass panes assembled into a unit, generally with the
intention of maximizing the thermal insulating properties of a gas
contained in the space formed by the unit while at the same time
providing clear vision through the unit. Insulating glass units
incorporating electrochromic glass are similar to insulating glass
units currently known in the art, except for electrical terminals
for connecting the electrochromic glass to voltage source.
Defectivity in Electrochromic Devices
[0042] As used herein, the term "defect" refers to a defective
point or region of an electrochromic device. Typically, defects are
electrical shorts or pinholes. Further, defects may be
characterized as visible or non-visible. In general, a defect in an
electrochromic device, and sometimes an area around the defect,
does not change optical state (e.g., color) in response to an
applied potential that is sufficient to cause non-defective regions
of the electrochromic device to color or otherwise change optical
state. Often a defect will be manifest as visually discernible
anomalies in the electrochromic window or other device. Such
defects are referred to herein as "visible" defects. Other defects
are so small that they are not visually noticeable to the observer
in normal use (e.g., such defects do not produce a noticeable light
point or "pinhole" when the device is in the colored state during
daytime).
[0043] A short is a localized electronically conductive pathway
spanning the ion conducting layer (e.g., an electronically
conductive pathway between the two transparent conducting layers).
Typically, a defect causing a visible short will have a physical
dimension on the order of tens micrometers, sometimes less, which
is a relatively small defect from a visual perspective. However,
these relatively small defects result in a visual anomaly, the
"halo", in the colored electrochromic window that are, for example,
about 1 centimeter in diameter, sometimes larger. Halos can be
reduced significantly by isolating the defect, for example by
circumscribing the defect via a laser scribe or by ablating the
material directly without circumscribing it. For example, a
circular, oval, triangular, rectangular, or other shaped perimeter
is ablated around the shorting defect thus electrically isolating
it from the rest of the functioning device. The circumscription may
be only tens, a hundred, or up to a few hundred micrometers in
diameter. By circumscribing, and thus electrically isolating the
defect, the visible short will resemble only a small point of light
to the naked eye when the window is colored and there is sufficient
light on the other side of the window. When ablated directly,
without circumscription, there remains no EC device material in the
area where the electrical short defect once resided. Rather, there
is a hole through the device and at the base of the hole is, for
example, the float glass or the diffusion barrier or the lower
transparent electrode material, or a mixture thereof. Since these
materials are all transparent, light may pass through the base of
the hole in the device. Depending on the diameter of a
circumscribed defect, and the width of the laser beam,
circumscribed pinholes may also have little or no electrochromic
material remaining within the circumscription (as the
circumscription is typically, though not necessarily, made as small
as possible). Such mitigated short defects manifest as pin points
of light against the colored device, thus these points of light are
commonly referred to as "pinholes." Isolation of an electrical
short by circumscribing or direct ablation would be an example of
an intentionally-made pinhole formed to convert a halo into a much
smaller visual defect. Pinholes may also arise as a natural result
of defects in the optical device, e.g. where a particle embedded in
the complete device pops off to remove a portion of the device
where there are no associated electrical shorts across the device
electrodes. In either case, they are to be avoided if possible.
[0044] A pinhole is a region where one or more layers of the
electrochromic device are missing or damaged so that
electrochromism is not exhibited. Pinholes are not electrical
shorts, and, as described above, they may be the result of
mitigating an electrical short in the device. In certain
embodiments, a pinhole has a defect dimension of between about 25
micrometers and about 300 micrometers, typically between about 50
micrometers and about 150 micrometers, thus it is much harder to
discern visually than a halo. Typically, in order to reduce the
visible perception of pinholes resulting from mitigation of halos,
one will limit the size of a purposely-created pinhole to about 100
micrometers or less.
[0045] In some cases, an electrical short is created by a
conductive particle lodging in and/or across the ion conducting
layer, thereby causing an electronic path between the counter
electrode layer and the electrochromic layer or the transparent
conducting layer associated with either one of them. A defect may
also be caused by a particle on the substrate on which the
electrochromic stack is fabricated. When such a particle causes
layer delamination due to stresses imparted by the particle, this
is sometimes called "pop-off" In other instances, the layers do not
adhere to the substrate properly and delaminate, interrupting the
flow of ions and/or electrical current within the device. These
types of defects are described in more detail below in relation to
FIGS. 2 and 3A-3D. A delamination or pop-off defect can lead to a
short if it occurs before a transparent conducting layer or
associated EC or CE layer is deposited. In such cases, the
subsequently deposited transparent conducting layer or EC/CE layer
will directly contact an underlying transparent conducting layer or
CE/EC layer providing direct electronic conductive pathway. A few
examples of defect sources are presented in the table below. The
table below is intended to provide examples of mechanisms that lead
to the different types of visible and non-visible defects. It is
not exhaustive. Additional factors exist which may influence how
the EC window responds to a defect within the stack. t,?
[0046] It is believed that problematic shorts are frequently those
in which a particle contacts the partially fabricated device
before, during, or immediately after a first electrochromic layer
is deposited on a substrate, and then remains in place until
immediately before, during or after deposition of the second
transparent conductive layer. As explained more fully below, such
shorts may be the result of particles attached to the substrate
upon entry into the electrochromic deposition chamber, or particles
that become attached during deposition of a cathodic electrochromic
layer such as a layer of tungsten oxide or become attached
immediately after deposition of the first electrochromic layer but
before any substantial amount of the next electrochromic layer is
deposited. As explained, the substrate may or may not have a
transparent conductive layer provided thereon when the substrate
enters the deposition apparatus. Problematic shorts may also be
introduced by particles that contact the partially fabricated
device during lithiation, such as lithiation performed after or
during deposition of the second electrochromic layer.
[0047] As noted above, in the case of a visible short the defect
will appear as a light central region (when the device is in the
colored state) with a diffuse boundary such that the device
gradually darkens with distance from the center of the short. If
there are a significant number of electrical shorts (visible or
non-visible) concentrated in an area of an electrochromic device,
they may collectively impact a broad region of the device whereby
the device cannot switch in such region. This is because the
potential difference between the EC and CE layers in such regions
cannot attain a threshold level required to drive ions across the
ion conductive layer. It should be understood that leakage current
may result from sources other than short-type defects. Such other
sources include broad-based leakage across the ion conducting layer
and edge defects such as roll off defects and scribe line defects.
The emphasis here is on leakage caused only by points of electrical
shorting across the ion conducting layer in the interior regions of
the electrochromic device. These shorts cause visible defects that
should be minimized for the electrochromic pane to be acceptable
for use in an electrochromic window. Conventionally, the visual
defects are identified and mitigated after device fabrication, e.g.
prior to assembly of the pane into an IGU, in an IGU prior to
installation of the IGU in an architectural facade or after
installation of the IGU using a portable defect mitigation
apparatus (e.g. as described in U.S. patent application Ser. No.
13/610,612 filed Sep. 14, 2011 and Ser. No. 13/859,623 filed Apr.
9, 2013, both incorporated herein by reference in their
entireties). However, these are time consuming procedures and thus
add expense which is to be avoided if possible. Embodiments
described herein reduce particles and thus particle-related defects
during fabrication of the electrochromic device, which allows for
less post-fabrication mitigation.
[0048] FIG. 2 is a schematic cross-section of an electrochromic
device, 200, with a particle, 205, in the ion conducting layer
causing a localized defect in the device. In this example,
electrochromic device 200 includes the same layers as described in
relation to FIGS. 1A and 1B. Voltage source 116 is configured to
apply a potential to electrochromic stack 114 as described above,
through suitable connections (e.g., bus bars) to conductive layers
104 and 112.
[0049] In this example, ion conducting layer 108 includes a
conductive particle, 205, or other artifact causing a defect.
Conductive particle 205 results in a short between electrochromic
layer 106 and counter electrode layer 110. In this example,
particle 205 spans the thickness of the IC layer 108. Particle 205
physically impedes the flow of ions between electrochromic layer
106 and counter electrode layer 110, and also, due to its
electrical conductivity, allows electrons to pass locally between
the layers, resulting in a transparent region 210 in electrochromic
layer 106 and a transparent region 220 in counter electrode layer
110. Transparent region 210 exists when the remainder of layers 110
and 106 are in the colored state. That is, if electrochromic device
200 is in the colored state, conductive particle 205 renders
regions 210 and 220 of the electrochromic device unable to enter
into the colored state. Sometimes such visible defect regions are
referred to as "constellations" or "halos" because they appear as a
series of bright spots (or stars) against a dark background (the
remainder of the device being in the colored state). Humans will
naturally direct their attention to the halos and often find them
distracting or unattractive. Embodiments described herein reduce
such visible defects. Pinhole defects may or may not be deemed
worthy of repair, as they can be nearly indiscernible to the naked
eye by most observers.
[0050] As mentioned above, visible short defects can also be caused
by particles popping off, e.g. during or after fabrication of the
electrochromic device, thereby creating damaged areas in the
electrochromic stack, through one or more layers of the stack.
Pop-off defects are described in more detail below.
[0051] FIG. 3A is a schematic cross-section of an electrochromic
device, 300, with a particle 305 or other debris on conductive
layer 104 prior to depositing the remainder of the electrochromic
stack. Electrochromic device 300 includes the same components as
electrochromic device 100. Particle 305 causes the layers in the
electrochromic stack 114 to bulge in the region of particle 305,
due to conformal layers 106-110 being deposited sequentially over
particle 305 as depicted (in this example, conductive layer 112,
e.g. TCO, has not yet been deposited). While not wishing to be
bound by a particular theory, it is believed that layering over
such particles embedded within the device layers, given the
relatively thin and conformal nature of these layers, can cause
stress in the area where the bulges are formed. More particularly,
in each layer, around the perimeter of the bulged region, there can
be defects in the layer, e.g. in the lattice arrangement or on a
more macroscopic level, cracks or voids. One consequence of these
defects may be, for example, an electrical short between
electrochromic layer 106 and counter electrode layer 110 and/or
loss of ion conductivity in layer 108. When the particle is larger,
roll off of deposited layers, particularly TCO materials, under the
particle is another potential source of shorting. These defects are
not depicted in FIG. 3A, however.
[0052] Referring to FIG. 3B, another consequence of defects caused
by particle 305 is called a "pop-off" In this example, prior to
deposition of conductive layer 112, a portion above the conductive
layer 104 in the region of particle 305 breaks loose, carrying with
it portions of electrochromic layer 106, ion conducting layer 108,
and counter electrode layer 110. The "pop-off" is piece 310, which
includes particle 305, a portion of electrochromic layer 106, as
well as ion conducting layer 108 and counter electrode layer 110.
The result is an exposed area of conductive layer 104 at the bottom
of the trench left when piece 310 popped out of the layered stack
of materials. It is believed that certain process operations tend
to promote pop-offs. For example expansion and contraction of the
material layers may promote pop-offs due to associated stress in
the material layers. It is believed that lithium intercalation into
the layers can induce stress in the layers. FIG. 3C depicts a
"large" format particle 320 formed in stack 300. Such a particle
spans the thickness of multiple layers (in this example
electrochromic layer 106, ion conducting layer 108, and counter
electrode layer 110). While portions of layers 106, 108, and 110
form on top of particle 320, they effectively form part of the
particle itself. Particle 320 protrudes above the top of the layers
during deposition, including protruding above layer 110. In some
cases, particle 320 naturally pops off without the application of a
particle ejection promoting step such as lithiation. In other
cases, particle 320 is removed by use of a particle removal
operation purposely applied to remove particles. Examples of such
operations are described below and include contact adhesion
techniques, electrostatic approaches, and thermal or pressure
treatments, as well as lithiation, the latter serving to supply the
device with lithium ions and also to induce stress in the device
layers in order to remove particles.
[0053] In some cases, a short type defect is produced underneath an
overhanging area of particle 320. Such defect may result from
roll-off of the subsequently deposited layers, one after the other.
For example, the first electrochromic layer 106 may extend only a
limited distance under the particle overhang, while ion conducting
layer 108 extends a little further under the overhang, counter
electrode 110 extends still a little further, and finally, the
second transparent conductive layer extends ever further, such that
its edge contacts the underlying first transparent conductive
layer, see FIG. 3C. This conductive layer to conductive layer
contact produces a short-type defect. The short exists regardless
of whether particle 320 ever pops off or is otherwise dislodged. In
such instances, this electrical shorting type defect would have to
be circumscribed by laser to isolate the short and thereby remove
the halo effect and leave a pinhole defect.
[0054] Referring to FIG. 3D, after pop-off an open trench, 350,
exists in the device stack. Once conductive layer 112 is deposited,
an electrical short is formed where conductive layer 112 comes in
contact with conductive layer 104. This electrical short would
leave a transparent region in electrochromic device 300 when it is
in the colored state, similar in appearance to the visual defect
created by the short described above in relation to FIG. 2.
[0055] Pop-off defects due to particles or debris on the substrate,
ion conducting layer, and on the counter electrode layer may also
cause pinhole defects. Also, if a contaminate particle is large
enough and does not cause a pop-off, it might be visible when the
electrochromic device is in the bleached state.
[0056] The description above, as described in relation to FIGS. 1A,
1B, 2, and 3A-D, presumes that there is a distinct ion conducting
(electronically resistive) layer sandwiched between an
electrochromic layer and a counter electrode layer in
electrochromic devices. The description is only meant to be
illustrative of how a particle can create a short related defect.
That is, there are electrochromic devices where a distinct
electronically resistive and ion conducting layer does not exist,
but rather an interfacial region that serves as an ion conductive
layer exists at the interface of the electrochromic and counter
electrode layers. Electrochromic devices having this architecture
are described in U.S. patent application Ser. No. 12/772,055 filed
Apr. 30, 2010, Ser. No. 12/772,075 filed Apr. 30, 2010, Ser. No.
12/814,277 filed Jun. 11, 2010, Ser. No. 12/814,279 filed Jun. 11,
2010 and Ser. No. 13/166,537 filed Jun. 22, 2011, each entitled,
"Electrochromic Devices," each having inventors Wang et al., and
each incorporated by reference herein in their entirety. Thus
particles can cause shorting defects in these devices as well,
e.g., where the particle exists at and/or crosses the interface
between the electrochromic and counter electrode layers and/or
creates pop-off type defects as described. Such devices are also
susceptible to other defect types described herein, despite not
having a distinct IC layer as in conventional devices.
[0057] Thus, three types of defects are of primary concern with
regard to electrochromic windows: (1) visible pinholes, (2) visible
shorts, and (3) non-visible shorts. A visible pinhole will have a
defect dimension of at least about 100 .mu.m, and manifest as a
very small point of light when the window is colored, sometimes
unnoticeable at first glance, but visible upon scrutiny. Typically,
though not necessarily, a visible short will have defect dimension
of at least about 3 micrometers resulting in a region, e.g. of
about 1 cm in diameter, which as mentioned is sometimes referred to
as a "halo," where the electrochromic effect is perceptibly
diminished. These halo regions can be reduced significantly by
isolating the defect causing the visible short so that to the naked
eye the visible short will resemble only a visible pinhole.
Non-visible shorts can affect switching performance of the
electrochromic device, by contributing to the overall leakage
current of the device, but do not create discernible points of
light or halos when the window is in a colored state.
[0058] Visible shorts produce a halo when the device is darkened. A
halo is a region in the device where an electrical short across the
electrochromic stack causes an area around the short to drain
current into the short and therefore the area surrounding the short
is not darkened, because the requisite electrical potential and ion
arrangement is not established in this region. As mentioned, these
regions can be up to about 1 cm in diameter, and thus present a
problem by making the electrochromic window, when colored,
unattractive to the observer. This frustrates the purpose of having
windows that can operate in a colored mode.
[0059] Conventionally visible short defects are mitigated after
fabrication of the electrochromic device, but while still in the
production facility, for example, prior to fabrication into an
insulated glass unit. For example, individual electrochromic panes
are characterized by first applying temporary bus bars and then
coloring the electrochromic device. Visual defects such as halos
are identified and then mitigated, for example, laser circumscribed
to isolate them and remove the halo effect, which leaves smaller,
less discernible, pinhole defects. Alternatively, or in addition,
mitigation of defects may be done on the IGU assembly. As described
above, conventionally, at least two, large, dedicated apparatus,
are used to carry out identification and mitigation of visual
defects. However, defects can form in the electrochromic devices
after the devices leave the production facility due to, for
example, the inherent stresses in electrochromic devices (e.g. see
above) and/or stresses applied to the windows during normal use
such as installation, pressure differential between interior and
exterior space, impacts that do not break the window pane and the
like. Conventionally, for electrochromic windows already installed
in a vehicle or building, mitigating such defects would not be
done, rather the unit would be replaced in the field. This can be
very expensive.
[0060] As mentioned, the methods and devices herein mitigate the
visual perception of defects. In one embodiment, the number of
visible pinhole defects is no greater than about 0.04 per square
centimeter. In another embodiment, the number of visible pinhole
defects is no greater than about 0.02 per square centimeter, and in
more specific embodiments, the number of such defects is no greater
than about 0.01 per square centimeter. In one embodiment, the
number of short-related defects visible when the device is colored
is no greater than about 0.005 per square centimeter. In another
embodiment, the number of short-related defects visible when the
device is colored is no greater than about 0.003 per square
centimeter, and in more specific embodiments, the number of such
defects is no greater than about 0.001 per square centimeter. In a
further embodiment, the number of short-related defects visible
when the device is colored is no greater than about 0.0005 per
square centimeter. In one embodiment, the total number of visible
defects, pinholes and short-related pinholes created from isolating
visible short-related defects, is less than about 0.1 defects per
square centimeter, in another embodiment less than about 0.08
defects per square centimeter, in another embodiment less than
about 0.05 defects per square centimeter, in another embodiment
less than about 0.01 defects per square centimeter, and in another
embodiment less than about 0.045 defects per square centimeter
(less than about 450 defects per square meter of window). In some
cases, the total number of visible defects, pinholes and
short-related pinholes created from isolating visible short-related
defects, is less than about 0.005 defects per square
centimeter.
[0061] In some embodiments, the number of non-visible electrical
short defects results in leakage currents of less than 20
.mu.A/cm.sup.2 at .+-.2V bias. In one embodiment, the number of
non-visible electrical short defects results in leakage currents of
less than 10 .mu.A/cm.sup.2 at .+-.2V bias. In one embodiment, the
number of non-visible electrical short defects results in leakage
currents of less than 5 .mu.A/cm.sup.2 at .+-.2V bias. In one
embodiment, the number of non-visible electrical short defects
results in leakage currents of less than 2 .mu.A/cm.sup.2 at .+-.2V
bias. In one embodiment, the number of non-visible electrical short
defects results in leakage currents of less than 1 .mu.A/cm.sup.2
at .+-.2V bias. These values apply across the entire face of the
electrochromic device (i.e., there is no region of the device
(anywhere on the device) having a defect density greater than the
recited value).
[0062] In some embodiments, the electrochromic device has no
visible defects greater than about 1.6 mm in diameter (the largest
transverse dimension of the defect). In another embodiment, the
device has no visible defects greater than about 0.5 mm in
diameter, and in another embodiment the device has no visible
defects greater than about 100 .mu.m in diameter.
[0063] FIG. 4 is a scanning electron micrograph (SEM) of an
electrochromic device having a first transparent conductor layer
(TCO) 481 disposed on a substrate, an electrochromic layer 483
disposed on top of TCO 481, an ion conductor layer 485 disposed on
the electrochromic layer, a counter electrode layer 487 disposed on
the ion conductor layer, and a second transparent conductor layer
(TCO) 489. The portion of device shown does not have any pop off
defects or shorts. This is an example of a "clean" structure that
will be produced by a method employing a particle removal
operation.
[0064] Process Examples
[0065] As explained, a deposited particle removal operation is
performed at some point in the device fabrication process. It is
typically performed between formation of the first and second
transparent conductive layers. In certain embodiments, the particle
removal operation is performed immediately prior to a process step
that has a significant likelihood of producing a particle ejection.
In certain embodiments, the particle removal operation is performed
immediately after a process step that is likely to present
particles in a partially fabricated device but before a process
step that has a significant likelihood of producing a particle
ejection. An example of a process step that is likely to eject a
particle is the introduction of lithium metal into the device
stack.
[0066] A device fabrication process 501 is depicted in FIG. 5A and
represents a baseline process that may be modified to include one
or more particle removal operations. Process 501 begins with an
operation 503 where a processing facility or a pre-processing
apparatus receives a substrate. As explained, the substrate may be
a window, a mirror, or the like. In some implementations, the
substrate provided by a substrate vendor contains a transparent
conductive oxide layer pre-formed. In other implementations, the
substrate is provided without the transparent conductive oxide
layer, in which case, the device fabrication process includes a
separate operation of forming the transparent conductive layer on
the substrate.
[0067] Continuing with the process flow 501, an operation 505
involves the washing or otherwise preparing the substrate for
device fabrication. This preparation may include such operations as
cutting the glass to size, grinding the edges or other portions of
the glass, washing it, tempering it, washing it again, etc. In some
implementations, the preparation operations include first cutting
the glass substrate to size for the final process, then grinding
the edge of the glass, followed by tempering or other strengthening
operation. In some cases, the substrate is washed before and/or
after tempering. Cutting, grinding and similar operations are
described in U.S. patent application Ser. No. 13/456,056, filed
Apr. 25, 2012, which is incorporated herein by reference in its
entirety. Fabrication of the electrochromic device itself begins
after the pre-processing operation 505 is complete.
[0068] If the substrate provided after pre-processing 505 does not
include a thin layer of transparent conductive material thereon,
device fabrication begins by forming such layer. If the substrate
as provided includes such layer, it may not be necessary to perform
the operation. Regardless of how the transparent conductive
material is formed, a first electrochromic layer is deposited on it
in an operation 507. In certain embodiments, the first
electrochromic layer includes a cathodic electrochromic material.
In other embodiments, it includes an anodic electrochromic
material.
[0069] In some cases, the substrate is heated prior to deposition
of the first electrochromic material. The first electrochromic
material layer is typically deposited by a process involving
physical or chemical vapor deposition under vacuum or other
controlled pressure. In a typical embodiment, the process involves
sputtering a target containing elements contained in the
electrochromic layer. However, in alternative embodiments, the
electrochromic layer is deposited under ambient pressure such by a
solution phase reaction.
[0070] In one implementation, the first electrochromic layer
contains a cathodically coloring electrochromic material deposited
in two operations, one providing a sub-layer of the base material
in a first stoichiometry and the second providing another sub-layer
of the base material in a second stoichiometry. As an example, the
cathodically coloring electrochromic material is tungsten oxide,
which has a nominal composition of WO.sub.x. The first deposited
sub-layer may have a composition of tungsten oxide in which the
value of x is about 2.7 to 2.8 and the second deposited sub-layer
may have a composition of tungsten oxide in which x is about 2.85
to 3.5. In one example, the first sub-layer is thicker; for
example, it has a thickness of about 400 nm and the second
sub-layer has a thickness of about 100 nm.
[0071] After the first electrochromic layer is deposited, the
partially fabricated device is optionally lithiated as indicated at
process block 509. The lithiation operation involves delivery of
lithium metal or lithium ions into the first electrochromic layer.
The lithium may be provided by sputtering or other suitable
process. Certain aspects of lithium deposition and the targets used
in lithium deposition processes are described in International
Application No. PCT/US2012/034556, filed Apr. 20, 2012 (designating
the US) and in International Application No. PCT/US2012/042514,
filed Jun. 14, 2012 (designating the US), both of which are
incorporated herein by reference in its entirety.
[0072] The next operation in device fabrication process 501
involves depositing a second electrochromic layer (an example of
the counter electrode layer generally described above). See block
511. As with the deposition of the first electrochromic layer, this
deposition process may be accomplishing using, e.g., physical or
chemical vapor deposition. If the first electrochromic layer
contains a cathodically coloring electrochromic material, then the
second electrochromic layer may contain an anodically coloring
electrochromic material. The opposite is also true. If the first
electrochromic layer contains an anodically coloring electrochromic
material, the second electrochromic layer may contain a
cathodically coloring electrochromic material. In certain
embodiments, the second electrochromic layer contains an anodically
coloring electrochromic material such as nickel oxide or nickel
doped tungsten oxide (sometimes referred to as NiWO). In some
examples, where nickel tungsten oxide serves as the second
electrochromic layer, it is formed to a thickness of between about
200 and 300 nm. In some cases, only one electrochromic layer is
used. Ions are shuttled into and out of the single electrochromic
layer, from and to a non-electrochromic counterelectrode.
[0073] In the example of FIG. 5A, no ion conducting layer is
separately deposited between the first and second electrochromic
layer. In alternative embodiments, an ion conducting layer is
deposited between these layers. Examples of suitable ion conducting
layers include those presented above in the description of FIG.
4.
[0074] After the second electrochromic layer is deposited, the
device, which includes the first and second electrochromic layers,
is lithiated as indicated in operation 513. The lithiation may be
accomplished as described in the context of operation 509. As
mentioned, lithiation operations may promote ejection of particles
previously embedded in the partially fabricated electrochromic
device stack. While not depicted in the process flow of FIG. 5A, a
particle removal operation may be performed after any of the steps
that tend to present particles in the partially fabricated device
and/or before any of the steps that promote ejection of such
particles. Therefore, in certain embodiments, the particle removal
operation may be performed prior to lithiation operation 509 or
prior to lithiation operation 513.
[0075] Returning to the process flow depicted in FIG. 5A, after the
lithiation of the device in 513, the next process operation
deposits a second transparent conductive oxide layer as depicted in
an operation 515. At this point, all structures needed for the
basic electrochromic device have been created. In some embodiments,
there is a subsequent post treatment of the as deposited device in
order to complete the process. See block 517. Examples of suitable
post-treatment include thermal and/or chemical conditioning
operations. Such operations are described in U.S. patent Ser. No.
12/645,111, previously incorporated herein by reference.
[0076] FIGS. 5B-5E present variations on the baseline process
depicted in FIG. 5A. In each case, the basic process flow from FIG.
5A is depicted but with additional or different steps removing
particles at particular points in the process. See e.g., operation
512 in FIG. 5B and operation 510 in FIG. 5C. In FIG. 5B, particle
removal is performed before lithiation operation 513 and after
deposition of the second electrochromic layer (operation 511). In
FIG. 5C, process flow 523, particle removal is performed between
deposition of the first electrochromic layer 507 and deposition of
the second electrochromic layer (operation 511). In various
embodiments, particle removal is performed prior to the first
lithiation operation. As explained, the process is not limited to
this sequence. Other operations that may promote particle ejection
may be preceded by a particle removal operation.
[0077] In some cases, the particle removal operation is performed
intermediate between two operations for depositing the second
electrochromic layer. In other embodiments, the first
electrochromic layer is divided into two portions, with particle
removal performed between the two portions.
[0078] In some embodiments, the second electrochromic layer is a
nickel tungsten oxide, which is deposited as two portions, with
particle removal performed therebetween. However, the first and
second portions of the second electrochromic layer are deposited
under different process conditions. For example, while both
portions may be deposited by a physical vapor deposition technique
employing sputtering from nickel and tungsten targets, the PVD
conditions are different. In some cases, the second portion is
deposited at a lower pressure and/or with lower oxygen
concentrations than the first portion. In some cases, the second
portion of the second electrochromic layer is deposited at a lower
power than the first portion. Further, the atomic ratio of nickel
to tungsten may be lower in the second portion. In other cases, the
atomic ratio of nickel and tungsten is the same in both portions of
the layer.
[0079] In some examples, the ranges of deposition conditions for
first portion of the nickel tungsten oxide electrochromic layer
(NiWO1) and second portion of the nickel tungsten oxide (NiWO2) are
as follows:
[0080] NiWO1
[0081] 1 mTorr<Pressure<50 mTorr
[0082] 60%<O2%<100% (volume or molar)
[0083] 0C<Deposition Temperature<150 C
[0084] NiWO2
[0085] 1 mTorr<Pressure<50 mTorr
[0086] 40%<O2%<70%
[0087] 25 C<Deposition Temperature<200 C
[0088] In other examples, process conditions used to form each of
NiWO1 and NiWO2 are as follows:
[0089] NiWO1
[0090] 5 mTorr<Pressure<15 mTorr (or 7-12 mTorr)
[0091] 70%<O2%<90% (volume) (or 70-80%)
[0092] 20 C<Deposition Temperature<60 C
[0093] NiWO2
[0094] 1 mTorr<Pressure<10 mTorr (or 3-7 mTorr)
[0095] 40%<O2%<60% (or 45-55%)
[0096] 25 C<Deposition Temperature<60 C
[0097] FIG. 5D presents a process flow, 525, for an embodiment
employing particle removal at a point in the process intermediate
between deposition of two portions of the same electrochromic or
counter electrode layer. The process begins at an operation 531,
where a substrate is received having a first transparent conducting
layer. In certain embodiments, the transparent conducting layer is
a fluorinated tin oxide layer that is optionally covered by an
insulating layer of TiO.sub.2. Glass substrates having such
properties are provided by Pilkington of St. Helens, United Kingdom
under the brand name Eclipse Advantage.TM. for example. The
substrate received in operation 531 may be washed and prepared as
described above. See operation 533. Next the process employs an
optional particle removal operation as indicated at operation
535.
[0098] After the first particle removal operation is performed, the
process may continue essentially as described with reference to
FIGS. 5B and/or 5C. A first electrochromic layer is deposited in an
operation 537, followed by an optional lithiation operation 539.
Thereafter, an ion conducting layer or intermediate layer (e.g., a
high oxygen content layer of the first electrochromic material) is
optionally deposited or formed in situ. Regardless of whether such
material is deposited, the process next involves depositing a first
portion of a second electrochromic or other counter electrode
layer. See operation 541. The device fabricated to this point is
then processed by a particle removal device as indicated in
operation 543. A second portion of the second electrochromic our
counter electrode layer is formed in an operation 545. The material
used to form this second portion may be the same or different from
that used to form the first portion layer in operation 541. After
the second portion of the second electrochromic layer has been
formed, the process deposits a second transparent conductive layer.
See operation 547. Thereafter an optional post treatment is
performed as described above. See operation 549.
[0099] FIG. 5E presents a process flow, 527, of forming a
low-defectivity electrochromic device. The process begins as shown
at a block 551 with the receipt of a substrate having one or more
layers pre-formed thereon. These layers may include one or more
diffusion barrier layers such as a tin oxide and a silicon oxide
layer, a first transparent conductive layer such as a fluorinated
tin oxide layer, and a defect-mitigating insulating layer. In
certain embodiments, the defect-mitigating insulating layer may
include or be titanium oxide, tin oxide, silicon oxide, silicon
aluminum oxide, tantalum oxide nickel tungsten oxide, various
nitrides, carbides, oxycarbides, oxynitrides, and variants of any
of these, etc.
[0100] Upon receiving the substrate, it may be washed and otherwise
prepared for device fabrication as indicated in block 553. The
preparation may include cutting cleaning tempering, etc.
Thereafter, as indicated at block 555, the substrate surface is
optionally treated to remove particles. After the optional particle
removal, the first and second electrochromic layers are deposited
as described above and as indicated in blocks 557 and 561 of FIG.
5E. Thereafter, a particle removal operation is performed as
indicated at block 563. Then, an optional lithiation operation is
performed. See block 565. After the particle removal and optional
lithiation operations are performed, a second transparent
conductive layer is deposited as indicated by block 567.
Thereafter, a post-treatment such as a thermal conditioning or
thermal chemical conditioning is performed as described above. See
block 569. The process is thus complete for purposes of this
illustration.
[0101] The particle removal operation may be performed at various
stages in the electrochromic device fabrication sequence. While the
above description has focused on removal from a partially
fabricated electrochromic device, it should be understood that any
of the removal techniques can also be performed on a fully
fabricated electrochromic device.
[0102] The standard device fabrication sequence may be interrupted
at any point after depositing the first TC layer to perform
particle removal, so long as the removal operation is eventually
followed by the deposition or partial deposition of an insulating
layer, i.e. either EC or CE. And, multiple particle removal
operations may be appropriate, depending on the embodiment. A
number of process examples are presented below. Each is a variation
on the following base process:
[0103] Base Device Fabrication Process [0104] Form first TC layer
[0105] Form EC layer [0106] Form IC layer (optional) [0107] Form CE
layer [0108] Form second TC layer
[0109] Processes in which an Ion Conducting Layer is not Deposited
in a Separate Operation
[0110] Option 1 [0111] Form first TC layer [0112] Particle removal
[0113] Form EC layer [0114] Form CE layer [0115] Form second TC
layer
[0116] Option 2 [0117] Form first TC layer [0118] Form EC layer
[0119] Particle removal [0120] Form CE layer [0121] Form second TC
layer
[0122] Option 3 [0123] Form first TC layer [0124] Form EC layer
[0125] Form CE layer [0126] Particle removal [0127] Form second TC
layer
[0128] Option 4 [0129] Form first TC layer [0130] Form EC layer
[0131] Particle removal [0132] Form CE layer [0133] Particle
removal [0134] Form second TC layer
[0135] Option 5 [0136] Form first TC layer [0137] Particle removal
[0138] Form EC layer [0139] Form CE layer [0140] Particle removal
[0141] Form second TC layer
[0142] Option 6 [0143] Form first TC layer [0144] Form EC layer
[0145] Form partial CE layer [0146] Particle removal [0147] Form
remainder of CE layer [0148] Form second TC layer
[0149] Option 7 [0150] Form first TC layer [0151] Particle removal
[0152] Form EC layer [0153] Form partial CE layer [0154] Particle
removal [0155] Form remainder of CE layer [0156] Form second TC
layer
[0157] Option 8 [0158] Form first TC layer [0159] Form EC layer
[0160] Particle removal [0161] Form partial CE layer [0162]
Particle removal [0163] Form remainder of CE layer [0164] Form
second TC layer
[0165] Option 9 [0166] Form first TC layer [0167] Particle removal
[0168] Form EC layer [0169] Particle removal [0170] Form CE layer
[0171] Form second TC layer
[0172] Option 10 [0173] Form first TC layer [0174] Form partial EC
layer [0175] Particle removal [0176] Form remainder of EC layer
[0177] Form CE layer [0178] Form second TC layer
[0179] Option 11 [0180] Form first TC layer [0181] Form partial EC
layer [0182] Particle removal [0183] Form remainder of EC layer
[0184] Particle removal [0185] Form CE layer [0186] Form second TC
layer
[0187] Option 12 [0188] Form first TC layer [0189] Form partial EC
layer [0190] Particle removal [0191] Form remainder of EC layer
[0192] Form partial CE layer [0193] Particle removal [0194] Form
remainder of CE layer [0195] Form second TC layer
[0196] Option 13 [0197] Form first TC layer [0198] Form partial EC
layer [0199] Particle removal [0200] Form remainder of EC layer
[0201] Particle removal [0202] Form partial CE layer [0203]
Particle removal [0204] Form remainder of CE layer [0205] Form
second TC layer
[0206] Option 14 [0207] Form first TC layer [0208] Particle removal
[0209] Form partial EC layer [0210] Particle removal [0211] Form
remainder of EC layer [0212] Particle removal [0213] Form partial
CE layer [0214] Particle removal [0215] Form remainder of CE layer
[0216] Form second TC layer [0217] Processes in which an ion
conducting layer is deposited in a separate operation:
[0218] Option 1 [0219] Form first TC layer [0220] Particle removal
[0221] Form EC layer [0222] Form IC layer [0223] Form CE layer
[0224] Form second TC layer
[0225] Option 2 [0226] Form first TC layer [0227] Form EC layer
[0228] Particle removal [0229] Form IC layer [0230] Form CE layer
[0231] Form second TC layer
[0232] Option 3 [0233] Form first TC layer [0234] Form EC layer
[0235] Form IC layer [0236] Particle removal [0237] Form CE layer
[0238] Form second TC layer
[0239] Option 4 [0240] Form first TC layer [0241] Form EC layer
[0242] Form IC layer [0243] Form CE layer [0244] Particle removal
[0245] Form second TC layer
[0246] Option 5 [0247] Form first TC layer [0248] Form EC layer
[0249] Particle removal [0250] Form IC layer [0251] Form CE layer
[0252] Particle removal [0253] Form second TC layer
[0254] Option 6 [0255] Form first TC layer [0256] Particle removal
[0257] Form EC layer [0258] Form IC layer [0259] Form CE layer
[0260] Particle removal [0261] Form second TC layer
[0262] Option 7 [0263] Form first TC layer [0264] Form EC layer
[0265] Form IC layer [0266] Form partial CE layer [0267] Particle
removal [0268] Form remainder of CE layer [0269] Form second TC
layer
[0270] Option 8 [0271] Form first TC layer [0272] Form EC layer
[0273] Particle removal [0274] Form IC layer [0275] Form partial CE
layer [0276] Particle removal [0277] Form remainder of CE layer
[0278] Form second TC layer
[0279] Option 9 [0280] Form first TC layer [0281] Particle removal
[0282] Form EC layer [0283] Form IC layer [0284] Form partial CE
layer [0285] Particle removal [0286] Form remainder of CE layer
[0287] Form second TC layer
[0288] In general, depending on the embodiment, a particle removal
operation may be inserted anywhere in the sequence after deposition
of the first TC layer, including interrupting deposition of a CE or
EC layer, so long as the particle removal operation is not inserted
immediately preceding deposition of the second TC layer.
[0289] While each of the above options show the electrochromic
layer deposited before the counter electrode layer, the deposition
order could be reversed in any of the options. Additionally, while
the above embodiments indicate that the processes form a first TC
layer, it is often the case that the first TC layer in the depicted
embodiments is pre-formed on the substrate provided to the device
fabrication process.
[0290] In various embodiments, the particle removal operation can
be coupled with an operation of forming a defect mitigating
insulating layer. Such layers generally have an electronic
resistivity level that is substantially greater than that of the
transparent conductive layer, often orders of magnitude greater. In
some embodiments, the insulating layer has an electronic
resistivity that is intermediate between that of a conventional ion
conducting layer and that of a transparent conductive layer (e.g.,
indium doped tin oxide). Thus, the electronic resistivity should be
greater than about 10.sup.-4 .OMEGA.-cm (approximate resistivity of
indium tin oxide) or greater than about 10.sup.-6 .OMEGA.-cm. In
some cases, it has an electronic resistivity between about
10.sup.-4 .OMEGA.-cm and 10.sup.14 .OMEGA.-cm (approximate
resistivity of a typical ion conductor for electrochromic devices)
or between about 10.sup.-5 .OMEGA.-cm and 10.sup.12 .OMEGA.-cm. In
certain embodiments, the electronic resistivity of the material in
the insulating layer is between about 1 and 5.times.10.sup.13
.OMEGA.-cm or between about 10.sup.2 and 10.sup.12 .OMEGA.-cm or
between about 10.sup.6 and 5.times.10.sup.12 .OMEGA.-cm, or between
about 10.sup.7 and 5.times.10.sup.9 .OMEGA.-cm. In some
embodiments, the defect mitigating insulating layer material will
have a resistivity that is comparable (e.g., within an order of
magnitude) of that of the electrochromic layer of counter electrode
material. In various embodiments, the defect mitigating insulating
layer is deposited immediately after the particle removal operation
takes place; i.e., before any other layer or portion of a device
layer is deposited. Defect mitigating insulating layers, devices
incorporating them, and methods of forming devices incorporating
them are described in U.S. patent application Ser. No. 13/763,505,
filed Feb. 8, 2013, which is incorporated herein by reference in
its entirety.
[0291] In various embodiments, the particle removal happens within
a high resistivity layer of the electrochromic device. In a
traditional five layer EC device (the base structure
above--TC1/EC/IC/CE/TC2), the particle removal may occur (a) at or
after 5% of IC has been deposited but (b) before or when 95% of the
IC has been deposited, and/or (c) at or after 5% of the CE has been
deposited, but (d) before or when 95% of the CE has been deposited.
In certain embodiments, particles are removed after a portion of a
resistive constituent material (and one that stays resistive even
in the presence of lithium) but before the remainder of the
resistive material is deposited. The particles that are removed
will leave a hole, potentially down to the TC1 layer that will then
be filled with the insulating material. Any particles that are
added in the process of particle removal will already reside on top
of the first portion of the resistive component of the device and
therefore will not pose a threat for short circuits. Note that
tungsten oxide may become conductive in the presence of lithium.
Therefore, in certain embodiments employing tungsten oxide as the
electrochromic material, particle removal and deposition of the
insulating layer occur in a layer other than the tungsten oxide
layer.
[0292] Particle Removal Examples
[0293] Various techniques may serve to promote particle removal.
One of these is "contact cleaning," a process that involves
contacting a layer of a partially fabricated electrochromic device
with a contact roller, strip, or brush, which sticks to or attracts
particles and then removes them from the device. Typically, contact
cleaning employs static attraction and/or adhesion to attract
remove particles. Some contact cleaning products are commercially
available, being marketed to the contact sheet cleaning and web
cleaning industries. In various embodiments, a roller mechanism is
used. In some cases, two rollers are used: the first one for
contacting and removing particles from the device surface and a
second roller for contacting the first roller to remove the
particles that were picked up by the first roller in its most
recent rotation. Examples of contact cleaning products sold for
cleaning bare glass are manufactured by Teknek.TM. of Renfrewshire,
Scotland, UK and Technica.
[0294] In some implementations, a contact cleaner is integrated
with an electrochromic device fabrication system. Typically, though
not always, the contact cleaner is deployed outside the vacuum
environment of the system for depositing layers of the
electrochromic device. In "cut and coat" fabrication process flows,
a contact cleaner of a single size may be used. In other
fabrication flows, contact cleaners of different size are employed
for cleaning devices fabricated on glass of different sizes.
[0295] Another category of particle removal techniques rely on
differences in the thermal expansion of particles and the substrate
layers in which they are embedded. When the particle volume expands
or contracts relative to the surrounding layers, the particles may
eject, particularly when the relative volume change is rapid. In
some embodiments, a mechanism driving the volume change is
irradiation of the substrate at wavelength that is selectively
absorbed by the particles but not the surrounding layer(s), or vice
versa. In some embodiments, a mechanism driving a relative volume
change is a different coefficient of thermal expansion of the
particles and the surrounding layer(s).
[0296] Thermal energy may be delivered in various ways. For
example, as mentioned, the particles and or the substrate layer(s)
may be heated by irradiation. The irradiation may be provided at a
wavelength or spectrum of wavelengths from the infrared through
ultraviolet ranges. The irradiation may be provided by one or more
lamp, lasers, etc. In one approach, a collimated laser beam is
passed over a surface of the partially fabricated electrochromic
device. For example, the beam grazes the surface of the device over
the width of the device. The beam may propagate in a direction
perpendicular or substantially perpendicular to the direction of
travel of the substrate carrying the electrochromic device. In
another approach, a laser beam is focused on the device and moved
in a raster scan over the surface.
[0297] In some embodiments, thermal energy is provided by heating
the substrate by a non-radiative mechanism such as passing heated
gas over the surface of the substrate/device and/or passing the
substrate/device over a heated element such as a roller. In one
implementation, the heated element is heated by resistive
heating.
[0298] In another approach to particle removal, electrostatic force
is applied to the partially fabricated electrochromic device. This
may be accomplished by, e.g., contacting the device with a plasma
or applying a charge to the substrate containing the device. In one
embodiment, a two stage process is employed. In the first stage,
the particles are charged by exposure to a plasma. Then, in the
second stage, the substrate with charged particles receives an
electrical charge, which causes the charged particles to eject. For
example, an electrical contact is made to a conductive or partially
conductive layer of the substrate and charge is applied to the
device through the contact. In some implementations, the substrate
is contacted with a charge of the same sign as the charge applied
to the particles by contact with the plasma.
[0299] In a further approach, the partially fabricated
electrochromic device is exposed to a supercritical fluid such as
supercritical carbon dioxide. Supercritical fluids are quite
effective at dislodging and removing particles. The fluid may
include a supercritical solvent such as supercritical carbon
dioxide with one or more additives contained therein to improve the
cleaning power or other property of the fluid. The supercritical
fluid may be brought into contact with the partially fabricated
electrochromic device using any of a number of processes. For
example, the device may be immersed or passed through the
supercritical fluid. The fluid itself may be provided in a
quiescent or flowing state. In various embodiments, some convection
will be employed. For example, the supercritical fluid may flow
through a substrate contact chamber driven by a pump in a
recirculation loop. In certain embodiments, the supercritical fluid
is provided as a cryogenic aerosol. The fluid may be sprayed on the
device as the device or a spray nozzle (or spray gun) moves with
respect to the other.
[0300] In still another approach, particles are dislodged and/or
removed by applying acoustic energy to the partially fabricated
electrochromic device. The acoustic energy may be provided at any
of a number of frequencies, including megasonic, supersonic,
ultrasonic, etc. In certain embodiments, a vibration source is
directly coupled to the substrate. In certain embodiments, a
vibration source is directly coupled to a fluid in contact with the
substrate/device.
[0301] Another removal technique involves ionized air blow off,
optionally with an air knife.
[0302] Yet another technique involves etch-back of a layer of the
device containing particles. The etch-back may be accomplished with
a plasma (e.g., a fluorine or oxygen containing plasma), by using
ion milling, etc. The particles may be removed by the etch-back
process or merely dislodged. In one embodiment, the etch-back is
performed at a sufficient depth to remove any roll off areas on the
device. In the latter case, a separate particle removal operation
may be applied after etch-back. Such process may include one or
more other process described above such as applying a charge to the
substrate, contacting the substrate with a supercritical fluid, or
selectively heating the particles.
[0303] When lithiation is employed as a particle removal technique,
it may be implemented in various formats. For example, the lithium
may be delivered in a single dose or in multiple doses, sometimes
to different layers of the device, such as to the electrochromic
and counter electrode layers. In some embodiments, all the lithium
needed for the device is delivered in a single operation. For
example, the lithium may be delivered to the counter electrode
layer and allowed to diffuse or migrate into the remainder of the
device. When all lithium is provided in one operation, the
incorporation provides maximal volumetric stress on the device and
likely provides the most effective way to remove particles via
lithiation. However, the lithiation options are not limited to a
single dose.
[0304] Apparatus
[0305] In certain embodiments, some or all of the device
fabrication operations are performed under vacuum or other
controlled environmental conditions. For example, an in line
fabrication process may involve passing the substrate through a
series of interconnected chambers or stations, each associated with
a particular process operation and each integrated with a vacuum
system or other pressure control system. In some embodiments, the
integrated deposition system includes a substrate holder and
transport mechanism operable to hold the architectural glass or
other substrate in a vertical or horizontal orientation while in
the plurality of deposition stations. In some cases, the integrated
deposition system includes one or more load locks for passing the
substrate between an external environment and the integrated
deposition system. In another embodiment, the plurality of
deposition stations include one or more stations for depositing any
one or more of the electrochromic layer, the ion conducting layer,
and the counter electrode layer. Sputtering or other physical vapor
deposition systems may be used for depositing any one or more of
the individual layers making up the electrochromic device. A
sputtering system may also be used to deposit lithium on the
device. One or more stations are provided for particle removal.
Such stations may optionally be included within the controlled
environment of the sputtering stations.
[0306] Many types of apparatus may be employed to deposit
electrochromic materials and electrochromic devices in accordance
with the embodiments disclosed herein. Frequently one or more
controllers are employed in the apparatus to control the
fabrication process. Those of ordinary skill in the art will
appreciate that processes disclosed herein may employ various
processes involving data stored in or transferred through one or
more computer systems and/or controllers. Certain embodiments
relate to the apparatus, including associated computers and
microcontrollers, for performing these operations. A control
apparatus may be specially constructed for the required purposes,
or it may be a general-purpose computer selectively activated or
reconfigured by a computer program and/or data structure stored in
the computer. The processes presented herein are not inherently
related to any particular computer or other apparatus. In various
embodiments, a controller executes system control software
including sets of instructions for controlling the timing and
sequence of the processing steps, processing conditions as
described herein, and the like.
[0307] In certain embodiments, the controller contains or executes
instructions for directing a substrate through a series of
deposition stations for depositing the layers of the electrochromic
stack. The controller may specify, inter al/a, the rate and
direction of substrate transfer, the sputter conditions in any
station (e.g., pressure, temperature, sputtering power, and gas
flow rates), and the pre- and post-treatment of a substrate. The
controller may include specific instructions for polishing and
otherwise pretreating the substrate prior to deposition. The
controller may include specific instructions for substrate
post-treatments such as thermal or chemical conditioning. The
controller may specify the timing and conditions under which the
particle removal device operates. Other computer programs, scripts,
or routines stored on memory devices associated with the controller
may be employed in some embodiments.
[0308] FIG. 6A depicts a simplified representation of an integrated
deposition system 600 in a perspective view and with more detail
including a cutaway view of the interior. In this example, system
600 is modular, where entry load lock 602 and exit load lock 604
are connected to deposition module 606. There is an entry port,
610, for loading, for example, architectural glass substrate 625
(load lock 604 has a corresponding exit port). Substrate 625 is
supported by a substrate holder, pallet 620 in this example, which
travels along a track, 615. In this example, pallet 620 is
supported by track 615 via hanging but pallet 620 could also be
supported atop a track located near the bottom of apparatus 600 or
a track, for example mid-way between top and bottom of apparatus
600. Pallet 620 can translate (as indicated by the double headed
arrow) forward and/or backward through system 600. For example
during lithium deposition, the substrate may be moved forward and
backward in front of a lithium target, 630, making multiple passes
in order to achieve a desired lithiation. This function is not
limited to lithium targets, however, for example a tungsten target
may pass multiple times past a substrate, or the substrate may pass
by via forward/backward motion path in front of the tungsten target
to deposit, for example, an electrochromic layer. Pallet 620 and
substrate 625 are in a substantially vertical orientation.
[0309] Target 630, in this case a cylindrical target, is oriented
substantially parallel to and in front of the substrate surface
where deposition is to take place (for convenience, other sputter
means are not depicted here). Substrate 625 can translate past
target 630 during deposition and/or target 630 can move in front of
substrate 625. The movement path of target 630 is not limited to
translation along the path of substrate 625. Target 630 may rotate
along an axis through its length, translate along the path of the
substrate (forward and/or backward), translate along a path
perpendicular to the path of the substrate, move in a circular path
in a plane parallel to substrate 625, etc. Target 630 need not be
cylindrical, it can be planar or any shape necessary for deposition
of the desired layer with the desired properties. Also, there may
be more than one target in each deposition station and/or targets
may move from station to station depending on the desired process.
The various stations of an integrated deposition system of the
invention may be modular, but once connected, form a continuous
system where a controlled ambient environment is established and
maintained in order to process substrates at the various stations
within the system.
[0310] Integrated deposition system 600 also has various vacuum
pumps, gas inlets, pressure sensors and the like that establish and
maintain a controlled ambient environment within the system. These
components are not shown, but rather would be appreciated by one of
ordinary skill in the art. The operation of system 600 is
controlled by, for example, a computer system or other controller.
A user interface for such controller is represented in FIG. 6A by
an LCD and a keyboard 635.
[0311] FIG. 6B illustrates a variation of the apparatus shown in
FIG. 6A. While the apparatus in 6A provides the substrate oriented
vertically, the apparatus of FIG. 6B provides the substrate in a
horizontal orientation. There are certain advantages to processing
large format glass, such as architectural glass (at least about
20''.times.20'') in a horizontal format. It can be difficult to
support vertically oriented substrates in a fixed position during
deposition. Horizontal substrates, however, can be fully supported
underneath and held in fixed position by gravity. However,
horizontal processing suffers from particle accumulation on the
substrate, which provides a large surface for falling particles.
However, with the integration of a particle removal station or
device in the apparatus, horizontal processing becomes
feasible.
[0312] FIG. 6B shows an electrochromic fabrication system 650
configured to process substrates 665 in a horizontal orientations.
A horizontally oriented track or conveyor 660 supports substrates
665 as they pass through an integrated deposition system 655. The
deposition system 655 may contain multiple sputter deposition
stations and optionally a particle removal station housing a
particle removal device for removing particles in accordance with
one or more the particle removal methods described herein. In other
embodiments, the particle removal device is located outside
integrated deposition system 655. In such cases, the apparatus may
include two separate integrated deposition systems separated by a
particle removal station. The first layer or layers are deposited
in a first system, then particle removal is performed after the
substrate leaves the first system. After particle removal is
completed, the substrate enters the second system, where the
remaining layers are deposited to complete the electrochromic
device. Some or all stations employed forming layers are sputter
deposition stations as described above.
[0313] Further examples of apparatus for fabricating electrochromic
devices are described in the following US patent applications, each
incorporated herein by reference in its entirety: Ser. Nos.
12/645,111, 12/645,159, 13/462,725, and 12/814,279.
CONCLUSION
[0314] Although the foregoing invention has been described in some
detail to facilitate understanding, the described embodiments are
to be considered illustrative and not limiting. It will be apparent
to one of ordinary skill in the art that certain changes and
modifications can be practiced within the scope of the appended
claims.
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