U.S. patent application number 12/620788 was filed with the patent office on 2010-05-27 for apparatus and method for forming 3d nanostructure electrode for electrochemical battery and capacitor.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Robert Z. Bachrach, SERGEY D. LOPATIN.
Application Number | 20100126849 12/620788 |
Document ID | / |
Family ID | 42195224 |
Filed Date | 2010-05-27 |
United States Patent
Application |
20100126849 |
Kind Code |
A1 |
LOPATIN; SERGEY D. ; et
al. |
May 27, 2010 |
APPARATUS AND METHOD FOR FORMING 3D NANOSTRUCTURE ELECTRODE FOR
ELECTROCHEMICAL BATTERY AND CAPACITOR
Abstract
Embodiments described herein generally relate to an electrode
structure for an electrochemical battery or capacitor,
particularly, apparatus and methods of creating a reliable and cost
efficient 3D electrode nano structure for an electrochemical
battery or capacitor that has an improved lifetime, lower
production costs, and improved process performance.
Inventors: |
LOPATIN; SERGEY D.; (Santa
Clara, CA) ; Bachrach; Robert Z.; (Burlingame,
CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP - - APPM/TX
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
42195224 |
Appl. No.: |
12/620788 |
Filed: |
November 18, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61117535 |
Nov 24, 2008 |
|
|
|
Current U.S.
Class: |
204/275.1 |
Current CPC
Class: |
C25D 5/022 20130101;
C25D 1/003 20130101; C25D 5/08 20130101; H01M 4/0438 20130101; C25D
7/00 20130101; Y02E 60/10 20130101; Y02E 60/13 20130101; C25D 17/10
20130101; C25D 17/00 20130101 |
Class at
Publication: |
204/275.1 |
International
Class: |
C25D 5/02 20060101
C25D005/02; C25D 5/08 20060101 C25D005/08 |
Claims
1. An apparatus for plating a metal on a large area substrate,
comprising: a chamber body defining a processing volume, wherein
the processing volume is configured to retain a plating bath
therein, and the chamber body has an upper opening; a plurality of
jet sprays configured to dispend a plating solution to form the
plating bath in the processing volume, wherein the plurality of jet
sprays open to a side wall of the chamber body; a draining system
configured to drain the plating bath from the processing volume; an
anode assembly disposed in the processing volume, wherein the anode
assembly comprises an anode emerged in the plating bath in a
substantially vertical position; and a cathode assembly disposed in
the processing volume, and the cathode assembly comprises: a
substrate handler configured to position one or more large area
substrates substantially parallel to the anode in the processing
volume; and a contacting mechanism configured to couple an electric
bias to the one or more large area substrates.
2. The apparatus of claim 1, wherein the cathode assembly is
configured to be lowered into the processing volume to emerge the
one or more large area substrates in the plating bath and lifted
out the processing volume to retrieve the one or more large area
substrates from the plating bath.
3. The apparatus of claim 2, wherein the contacting mechanism
comprises a masking plate positioned against a plating surface of
the one or more large area substrates, wherein the masking plate is
configured to expose portions of the one or more large areas
substrates to be plated.
4. The apparatus of claim 3, wherein the masking plate comprises: a
dielectric plate body having a plurality of through holes
configured to define areas to be plated; and a plurality of
electrical contacts embedded in the dielectric plate body, wherein
the plurality of electrical contacts are in electrical connection
with a power source, and the plurality of electrical contacts are
configured to be in contact with the surface of the one or more
large area substrates and not exposed to the plating bath.
5. The apparatus of claim 4, wherein the substrate holder further
comprises: a thrust plate configured to press the one or more large
area substrates against the masking plate, wherein the masking
plate and the thrust plate are positioned on opposite sides of the
one or more large area substrates.
6. The apparatus of claim 1, wherein the cathode assembly further
comprises: a feed roll disposed out side the processing volume and
configured to retain a portion of a flexible base, wherein the one
or more large area substrates are formed on the flexible base; a
bottom roll disposed near a bottom portion of the processing volume
and configured to retain a portion of the flexible base; and a take
up roll disposed out side the processing volume and configured to
retain a portion of the flexible base, wherein the feed roll,
bottom roll and take up roll are configured to transfer the one or
more large area substrates in and out the processing volume, and
hold the one or more large area substrates in the processing volume
by handling the flexible base.
7. The apparatus of claim 6, further comprising: a thrust plate
movably disposed in the processing volume, wherein the thrust plate
is configured to push against a portion of the flexible base.
8. The apparatus of claim 7, further comprising: a masking plate
positioned against a plating surface of the one or more large area
substrates, wherein the masking plate is configured to expose
portions of the one or more large areas substrates to be
plated.
9. The apparatus of claim 8, wherein the masking plate comprises: a
dielectric plate body having a plurality of through holes
configured to define areas to be plated; and a plurality of
electrical contacts embedded in the dielectric plate body, wherein
the plurality of electrical contacts are in electrical connection
with a power source, and the plurality of electrical contacts are
configured to be in contact with the surface of the one or more
large area substrates and not exposed to the plating bath.
10. The apparatus of claim 6, further comprising: a power source
connected between the anode and a conductive layer formed on the
surface of one or more large area substrates, wherein the power
source is connected to the conductive layer directly or via the
feed roll.
11. A substrate processing system, comprising: a pre-wetting
chamber configured to clean a seed layer of a large area substrate;
a first plating chamber configured to form a columnar layer of a
first metal on the seed layer of the large area substrate; a second
plating chamber configured to form a porous layer over the columnar
layer; a rinse dry chamber configured to clean and dry the large
area substrate; and a substrate transfer mechanism configured to
transfer the large area substrate among the chambers, wherein each
of the first and second plating chamber comprises: a chamber body
defining a processing volume, wherein the processing volume is
configured to retain a plating bath therein, and the chamber body
has an upper opening; a draining system configured to drain the
plating bath from the processing volume; an anode assembly disposed
in the processing volume, wherein the anode assembly comprises an
anode emerged in the plating bath; and a cathode assembly disposed
in the processing volume, and the cathode assembly comprises: a
substrate handler configured position one or more large area
substrates substantially parallel to the anode in the processing
volume; and a contacting mechanism configured to couple an electric
bias to the one or more large area substrates.
12. The substrate processing system of claim 11, wherein the large
area substrates are formed on a continuous flexible base, and each
chamber comprises: a feed roll disposed out side the processing
volume and configured to retain a portion of the flexible base; a
bottom roll disposed near a bottom portion of the processing volume
and configured to retain a portion of the flexible base; and a take
up roll disposed out side the processing volume and configured to
retain a portion of the flexible base, wherein the substrate
transfer mechanism is configured to activate the feed rolls and the
take up rolls to move the flexible base to transfer the one or more
large area substrates in and out each chambers, and hold the one or
more large area substrates in the processing volume of each
chamber.
13. The substrate processing system of claim 12, wherein the large
area substrates are positioned substantially vertical in each
chamber during processing, and each plating chamber further
comprises a thrust plate movably disposed in the processing volume,
wherein the thrust plate is configured to push against a portion of
the flexible base so that the one or more large area substrates are
proximate to and substantially parallel to the anode.
14. The substrate processing system of claim 13, wherein each
plating chamber further comprises: a masking plate positioned
against a plating surface of the one or more large area substrates,
wherein the masking plate is configured to expose portions of the
one or more large areas substrates to be plated.
15. The substrate processing system of claim 11, wherein the
substrate handler comprises a substrate frame configured to hold
the one or more large area substrates in the plating bath, and the
substrate handler is configured to be transferred among the
chambers.
16. The substrate processing system of claim 15, wherein the
substrate transfer mechanism is configured to simultaneously lift
the substrate frame from each chamber, transfer the substrate
frames over the chambers, and lower each substrate frame to a
different chamber so that the one or more substrates are positioned
for a subsequent processing step.
17. The substrate processing system of claim 15, wherein the
contacting mechanism of each plating chamber comprises a masking
plate positioned against a plating surface of the one or more large
area substrates, wherein the masking plate is configured to expose
portions of the one or more large areas substrates to be
plated.
18. The substrate processing system of claim 12, wherein the second
plating chamber is configured to form the porous layer of the first
metal, and the porous layer comprises at least one of macro
porosity, micro-porousity, and meso-porousity.
19. The substrate processing system of claim 18, further
comprising: a rinsing chamber configured to rinse the large area
substrate after formation of the porous layer in the second plating
chamber; and a third plating chamber configured to plate a layer of
a second metal over the porous layer, wherein the first metal is
different from the second metal.
20. The substrate processing system of claim 19, wherein the first
metal is copper and the second metal is tin.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional patent
application Ser. No. 61/117,535 (Attorney Docket No. 12922L), filed
Nov. 24, 2008, which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention generally relate to
apparatus and methods of forming an electrochemical battery or
capacitor. Particularly, embodiments of the present invention
relates to apparatus and methods for forming electrochemical
batteries or capacitors having electrodes with 3D
nanostructure.
[0004] 2. Description of the Related Art
[0005] Electrical energy can generally be stored in two
fundamentally different ways: 1) indirectly in batteries as
potential energy available as chemical energy that requires
oxidation and reduction of active species, or 2) directly, using
electrostatic charge formed on the plates of a capacitor.
Typically, ordinary capacitors store a small amount of charge due
to their size and thus only store a small amount of electrical
energy. Energy storage in conventional capacitors is generally
non-Faradaic, meaning that no electron transfer takes place across
an electrode interface, and the storage of electric charge and
energy is electrostatic.
[0006] In an effort to form an effective electrical energy storage
device that can store sufficient charge to be useful as independent
power sources, or supplemental power source for a broad spectrum of
portable electronic equipment and electric vehicles, devices known
as electrochemical capacitors have been created. Electrochemical
capacitors are energy storage devices which combine some aspects of
the high energy storage potential of batteries with the high energy
transfer rate and high recharging capabilities of capacitors.
[0007] The term electrochemical capacitor is sometimes described in
the art as a super-capacitor, electrical double-layer capacitors,
or ultra-capacitor. Electrochemical capacitors can have hundreds of
times more energy density than conventional capacitors and
thousands of times higher power density than batteries. It should
be noted that energy storage in electrochemical capacitors can be
both Faradaic or non-Faradaic.
[0008] In both the Faradaic electrochemical capacitors and
non-Faradaic electrochemical capacitors, capacitance is highly
dependent on the characteristics of the electrode and electrode
material. Ideally, the electrode material should be electrically
conducting and have a large surface area. Typically, the electrode
material will be formed from porous structures to enable the
formation of a large surface area that can be used either for the
development of the electrical double layer for static charge
storage to provide non-Faradaic capacitance or for the reversible
chemical redox reaction sites to provide Faradaic capacitance.
[0009] An electrochemical battery is a device that converts
chemical energy into electrical energy. An electrochemical battery
typically consists of a group of electric cells that are connected
to act as a source of direct current.
[0010] Generally, an electric cell consists of two dissimilar
substances, a positive electrode and a negative electrode, and a
third substance, an electrolyte. The positive and negative
electrodes conduct electricity. The electrolyte acts chemically on
the electrodes. The two electrodes are connected by an external
circuit, such as a piece of copper wire.
[0011] The electrolyte functions as an ionic conductor for the
transfer of the electrons between the electrodes. The voltage, or
electromotive force, depends on the chemical properties of the
substances used, but is not affected by the size of the electrodes
or the amount of electrolyte.
[0012] Electrochemical batteries are classed as either dry cell or
wet cell. In a dry cell, the electrolyte is absorbed in a porous
medium, or is otherwise restrained from flowing. In a wet cell, the
electrolyte is in liquid form and free to flow and move. Batteries
also can be generally divided into two main types--rechargeable and
nonrechargeable, or disposable.
[0013] Disposable batteries, also called primary cells, can be used
until the chemical changes that induce the electrical current
supply are complete, at which point the battery is discarded.
Disposable batteries are most commonly used in smaller, portable
devices that are only used intermittently or at a large distance
from an alternative power source or have a low current drain.
[0014] Rechargeable batteries, also called secondary cells, can be
reused after being drained. This is done by applying an external
electrical current, which causes the chemical changes that occur in
use to be reversed. The external devices that supply the
appropriate current are called chargers or rechargers.
[0015] Rechargeable batteries are sometimes known as storage
batteries. A storage battery is generally of the wet-cell type
using a liquid electrolyte and can be recharged many times. The
storage battery consists of several cells connected in series. Each
cell contains a number of alternately positive and negative plates
separated by the liquid electrolyte. The positive plates of the
cell are connected to form the positive electrode and the negative
plates form the negative electrode.
[0016] In the process of charging, each cell is made to operate in
reverse of its discharging operation. During charging, current is
forced through the cell in the opposite direction as during
discharging, causing the reverse of the chemical reaction that
ordinarily takes place during discharge. Electrical energy is
converted into stored chemical energy during charging.
[0017] The storage battery's greatest use has been in the
automobile where it was used to start the internal-combustion
engine. Improvements in battery technology have resulted in
vehicles in which the battery system supplies power to electric
drive motors instead.
[0018] To make electrochemical batteries or capacitors more of a
viable product, it is important to reduce the costs to produce the
electrochemical batteries or capacitors, and improve the efficiency
of the formed electrochemical battery or capacitor device.
[0019] Therefore, there is a need for method and apparatus for
forming electrodes of electrochemical batteries or capacitors that
have an improved lifetime, improved deposited film properties, and
reduced production cost.
SUMMARY OF THE INVENTION
[0020] Embodiments described herein generally relate to an
electrochemical battery and capacitor electrode structure,
particularly, apparatus and methods of creating a reliable and cost
efficient electrochemical battery and capacitor electrode structure
that has an improved lifetime, lower production costs, and improved
process performance.
[0021] One embodiment of the present invention provides an
apparatus for plating a metal on a large area substrate comprising
a chamber body defining a processing volume, wherein the processing
volume is configured to retain a plating bath therein, and the
chamber body has an upper opening, a plurality of jet sprays
configured to dispend a plating solution to form the plating bath
in the processing volume, wherein the plurality of jet sprays open
to a side wall of the chamber body, a draining system configured to
drain the plating bath from the processing volume, an anode
assembly disposed in the processing volume, wherein the anode
assembly comprises an anode emerged in the plating bath in a
substantially vertical position, and a cathode assembly disposed in
the processing volume, and the cathode assembly comprises a
substrate handler configured position one or more large area
substrates in a substantially vertical position and substantially
parallel to the anode the processing volume, and a contacting
mechanism configured to couple an electric bias to the one or more
large area substrates.
[0022] Another embodiment of the present invention provides a
substrate processing system comprising a pre-wetting chamber
configured to clean a seed layer of a large area substrate, a first
plating chamber configured to form a columnar layer of a first
metal on the seed layer of the large area substrate, a second
plating chamber configured to form a porous layer over the columnar
layer, a rinse dry chamber configured to clean and dry the large
are substrate, and a substrate transfer mechanism configured to
transfer the large area substrate among the chambers, wherein each
of the first and second plating chamber comprises a chamber body
defining a processing volume, wherein the processing volume is
configured to retain a plating bath therein, and the chamber body
has an upper opening, a draining system configured to drain the
plating bath from the processing volume, an anode assembly disposed
in the processing volume, wherein the anode assembly comprises an
anode emerged in the plating bath, and a cathode assembly disposed
in the processing volume, and the cathode assembly comprises, a
substrate handler configured position one or more large area
substrates substantially parallel to the anode the processing
volume, and a contacting mechanism configured to couple an electric
bias to the one or more large area substrates.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0024] FIG. 1A is a simplified schematic view of an active region
of an electrochemical capacitor unit.
[0025] FIG. 1B is a simplified schematic view a lithium-ion battery
cell.
[0026] FIG. 2 is a flow diagram of a method for forming an
electrode in accordance with embodiments described herein.
[0027] FIG. 3 is a schematic cross-sectional view showing formation
an anode according to embodiments of the present invention.
[0028] FIG. 4 is a flow diagram of a method for forming a porous
electrode in accordance with embodiments described herein.
[0029] FIG. 5A is a schematic sectional side view of a plating
chamber in accordance with one embodiment of the present
invention.
[0030] FIG. 5B is a schematic sectional side view of the plating
chamber of FIG. 5A in a substrate transferring position.
[0031] FIG. 5C schematically illustrates a plating system using one
or more plating chambers of FIG. 5A.
[0032] FIG. 6A is a schematic sectional side view of a plating
chamber in accordance with one embodiment of the present
invention.
[0033] FIG. 6B a schematic sectional side view of a plating chamber
in accordance with one embodiment of the present invention
[0034] FIG. 6C schematically illustrates a plating system using one
or more plating chambers of FIG. 6A.
[0035] FIG. 7A is a schematic perspective view of a plating chamber
in accordance with one embodiment of the present invention.
[0036] FIG. 7B is a schematic sectional side view of the plating
chamber of FIG. 7A in plating position.
[0037] FIG. 7C is a schematic view of a substrate holder in
accordance with one embodiment of the present invention.
[0038] FIGS. 8A-8B schematically illustrate a processing system in
accordance with one embodiment of the present invention.
[0039] To facilitate understanding, identical reference numerals
have been used, wherever possible, to designate identical elements
that are common to the figures. It is contemplated that elements
and/or process steps of one embodiment may be beneficially
incorporated in other embodiments without additional recitation
DETAILED DESCRIPTION
[0040] Embodiments described herein generally relate to an
electrode structure, particularly for an electrochemical battery or
capacitor, apparatus and methods of creating a reliable and cost
efficient electrochemical battery or capacitor electrode structure
that has an improved lifetime, lower production costs, and improved
process performance. One embodiment provides a substrate plating
system comprising a first plating chamber configure to form a
columnar structure on a seed layer of a substrate, and a second
plating chamber configured to form a porous layer on the columnar
structure. One embodiment provides a plating chamber configured to
plate one or more large area substrate. In one embodiment, the
plating chamber comprises a feed roll, a bottom roll and a take up
roll configured to position large area substrates formed in a
continuous flexible base in a processing volume, and to transfer
the large area substrates in and out the processing volume. In
another embodiment, the plating chamber comprises a substrate
holder movably disposed in a processing volume and configured to
hold one or more large area substrate, and to transfer the one or
more large area substrates in and out the processing volume.
[0041] In an effort to achieve high plating rates and achieve
desirable plated film properties, it is often desirable to increase
the concentration of metal ions near the cathode (e.g., seed layer
surface) by reducing the diffusion boundary layer or by increasing
the metal ion concentration in the electrolyte bath. It should be
noted that the diffusion boundary layer is strongly related to the
hydrodynamic boundary layer. If the metal ion concentration is too
low and/or the diffusion boundary layer is too large at a desired
plating rate the limiting current (i.sub.L) will be reached. The
diffusion limited plating process created when the limiting current
is reached, prevents the increase in plating rate by the
application of more power (e.g., voltage) to the cathode (e.g.,
metallized substrate surface). When the limiting current is reached
a low density columnar film is produced due to the evolution of gas
and resulting dendritic type film growth that occurs due to the
mass transport limited process.
[0042] FIG. 1A illustrates a simplified schematic view of an active
region 140 of an electrochemical capacitor unit 100 that can be
powered by use of a power source 160. An electrochemical capacitor
unit 100 can be of any shape, e.g., circular, square, rectangle,
polygonal, and size. The active region 140 generally contains a
membrane 110, porous electrodes 120 formed according to embodiments
described herein, charge collector plates 150 and an electrolyte
130 that is in contact with the porous electrodes 120, charge
collector plates 150 and membrane 110. The electrically conductive
charge collector plates 150 sandwich the porous electrodes 120 and
membrane 110.
[0043] The electrolyte 130 that is contained between the charge
collector plates 150 generally provides a charge reservoir for the
electrochemical capacitor unit 100. The electrolyte 130 can be a
solid or a fluid material that has a desirable electrical
resistance and properties to achieve desirable charge or discharge
properties of the formed device. If the electrolyte is a fluid, the
electrolyte enters the pores of the electrode material and provides
the ionic charge carriers for charge storage. A fluid electrolyte
requires that a membrane 110 be non-conducting to prevent shorting
of the charge collected on either of the charge collector plates
150.
[0044] The membrane 110 is typically permeable to allow ion flow
between the electrodes and is fluid permeable. Examples of
non-conducting permeable separator material are porous hydrophilic
polyethylene, polypropylene, fiberglass mats, and porous glass
paper. The membrane 110 can be made from an ion exchange resin
material, polymeric material, or a porous inorganic support. For
example, three layers of polyolefin, three layers of polyolefin
with ceramic particles, an ionic perfluoronated sulfonic acid
polymer membrane, such as Nafion.TM., available from the E.I.
DuPont de Nemeours & Co. Other suitable membrane materials
include Gore Select.TM., sulphonated fluorocarbon polymers, the
polybenzimidazole (PBI) membrane (available from Celanese
Chemicals, Dallas, Tex.), polyether ether ketone (PEEK) membranes
and other materials.
[0045] The porous electrodes 120 generally contain a conductive
material that has a large surface area and has a desirable pore
distribution to allow the electrolyte 130 to permeate the
structure. The porous electrodes 120 generally require a large
surface area to provide an area to form a double-layer and/or an
area to allow a reaction between the solid porous electrode
material and the electrolyte components, such as pseudo-capacitance
type capacitors. The porous electrodes 120 can be formed from
various metals, plastics, glass materials, graphites, or other
suitable materials. In one embodiment, the porous electrode 120 is
made of any conductive material, such as a metal, plastic,
graphite, polymers, carbon-containing polymer, composite, or other
suitable materials. More specifically, the porous electrode 120 may
comprise copper, aluminum, zinc, nickel, cobalt, palladium,
platinum, tin, ruthenium, stainless steel, titanium, lithium,
alloys thereof, and combinations thereof.
[0046] Embodiments described herein, generally contain various
apparatus and methods for increasing the surface area of an
electrode by three-dimensional growth of electrode material.
Advantageously, the increased surface area of the porous
three-dimensional electrode provides increased capacitance with
improved cycling, rapid charging using the high conductivity
three-dimensional nanomaterial, and large energy and power
densities.
[0047] In one embodiment, three dimensional growth of electrode
material is performed using a high plating rate electroplating
process performed at current densities above the limiting current
(i.sub.L). In one embodiment, a columnar metal layer is formed at a
first current density by a diffusion limited deposition process
followed by the three dimensional growth of electrode material at a
second current density greater than the first current density. The
resulting electrode structure has an improved lifetime, lower
production cost, and improved process performance.
[0048] FIG. 2B is a simplified schematic view of a lithium-ion
battery cell 158. Lithium-ion batteries are a type of
electrochemical batteries. A plurality of lithium-ion battery cells
150 can be assembled together when in use. The lithium-ion battery
cell 150 comprises an anode 151, and a cathode 152, a separator
153, and an electrolyte 154 that is in contact with the anode 151,
the cathode 152, the separator 153, and an electrolyte 154 disposed
between the anode 151 and the cathode 152.
[0049] Both the anode 151 and the cathode 152 comprise materials
into which and from which lithium can migrate. The process of
lithium moving into the anode 151 or cathode 152 is referred to as
insertion or intercalation. The reverse process, in which lithium
moves out of the anode 151 or cathode 152 is referred to as
extraction or deintercalation. When the lithium-ion battery cell
150 is discharging, lithium is extracted from the anode 151 and
inserted into the cathode 152. When the lithium-ion battery cell
150 is charging, lithium is extracted from the cathode 152 and
inserted into the anode 151.
[0050] The anode 151 is configured to store lithium ions 155. The
anode 151 may be formed from carbon containing material or metallic
material. The anode 151 may comprise oxides, phosphates,
fluorophosphates, or silicates.
[0051] The cathode 152 may be made from a layered oxide, such as
lithium cobalt oxide, a polyanion, such as lithium iron phosphate,
a spinel, such as lithium manganese oxide, or TiS.sub.2 (titanium
disulfide). Exemplary oxides may be layered lithium cobalt oxide,
or mixed metal oxide, such as LiNi.sub.xCo.sub.1-2xMnO.sub.2,
LiMn.sub.2O.sub.4. Li It is desirable that the anode 151 has a
large surface area. Exemplary phosphates may be iron olivine
(LiFePO.sub.4) and it is variants (such as LiFe1-.sub.xMgPO.sub.4),
LiMoPO4, LiCoPO.sub.4, Li.sub.3V.sub.2(PO.sub.4).sub.3,
LiVOPO.sub.4, LiMP.sub.2O.sub.7, or LiFe.sub.1.5P.sub.2O.sub.7.
Exemplary fluorophosphates may be LiVPO.sub.4F, LiAlPO.sub.4F,
Li.sub.5V(PO.sub.4).sub.2F.sub.2,
Li.sub.5Cr(PO.sub.4).sub.2F.sub.2, Li.sub.2CoPO.sub.4F,
Li.sub.2NiPO.sub.4F, or Na.sub.5V.sub.2(PO.sub.4).sub.2F.sub.3.
Exemplary silicates may be Li.sub.2FeSiO.sub.4,
Li.sub.2MnSiO.sub.4, or Li.sub.2VOSiO.sub.4.
[0052] The separator 153 is configured to supply ion channels for
in movement between the anode 151 and the cathode 152 while keeping
the anode 151 and the cathode 152 physically separated to avoid a
short. The separator 153 may be solid polymer, such as
polyethyleneoxide (PEO).
[0053] The electrolyte 154 is generally a solution of lithium salts
such as LiPF.sub.6, LiBF.sub.4, or LiClO.sub.4, in an organic
solvents.
[0054] When the lithium-ion battery cell 150 discharges, lithium
ions 155 moves from the anode 151 to the cathode 152 providing a
current to power a load 156 connected between the anode 151 and the
cathode 152. When the lithium-ion battery cell 150 is depleted, a
charger 157 may be connected between the anode 151 and the cathode
152 providing a current to drive the lithium ions 155 to the anode
151. Since the amount of energy stored in the lithium-ion battery
cell 150 defends on the amount of lithium ion 155 stored in the
anode 151, it is desirable to have as large a surface area on the
anode 151 as possible. Embodiments of the present invention
described below provide methods and apparatus for producing
electrodes with increased surface area.
[0055] FIG. 2 is a flow diagram according to one embodiment
described herein of a process 200 for forming an electrode in
accordance with embodiments described herein. FIG. 3 is a schematic
cross-sectional view of an electrode formed according to
embodiments described herein. The process 200 includes process
steps 202-212, wherein an electrode is formed on a substrate 220.
The process 200 may be performed with systems in accordance to
embodiments of the present invention.
[0056] The first process step 202 includes providing the substrate
220. The substrate 220 may comprise a material selected from the
group comprising copper, aluminum, nickel, zinc, tin, flexible
materials, stainless steel, and combinations thereof. Flexible
substrates can be constructed from polymeric materials, such as a
polyimide (e.g., KAPTON.TM. by DuPont Corporation),
polyethyleneterephthalate (PET), polyacrylates, polycarbonate,
silicone, epoxy resins, silicone-functionalized epoxy resins,
polyester (e.g., MYLAR.TM. by E.I. du Pont de Nemours & Co.),
APICAL AV manufactured by Kanegaftigi Chemical Industry Company,
UPILEX manufactured by UBE Industries, Ltd.; polyethersulfones
(PES) manufactured by Sumitomo, a polyetherimide (e.g., ULTEM by
General Electric Company), and polyethylenenaphthalene (PEN). In
some cases the substrate can be constructed from a metal foil, such
as stainless steel that has an insulating coating disposed thereon.
Alternately, flexible substrate can be constructed from a
relatively thin glass that is reinforced with a polymeric
coating.
[0057] The second process step 204 includes optionally depositing a
barrier layer over the substrate. The barrier layer 222 may be
deposited to prevent or inhibit diffusion of subsequently deposited
materials over the barrier layer into the underlying substrate.
Examples of barrier layer materials include refractory metals and
refractory metal nitrides such as tantalum (Ta), tantalum nitride
(TaN.sub.x), titanium (Ti), titanium nitride (TiN.sub.x), tungsten
(W), tungsten nitride (WN.sub.x), and combinations thereof. Other
examples of barrier layer materials include PVD titanium stuffed
with nitrogen, doped silicon, aluminum, aluminum oxides, titanium
silicon nitride, tungsten silicon nitride, and combinations
thereof. Exemplary barrier layers and barrier layer deposition
techniques are further described in U.S. Patent Application
Publication 2003/0143837 entitled "Method of Depositing A Catalytic
Seed Layer," filed on Jan. 28, 2002, which is incorporated herein
by reference to the extent not inconsistent with the embodiments
described herein.
[0058] The barrier layer may be deposited by CVD, PVD, electroless
deposition techniques, evaporation, or molecular beam epitaxy. The
barrier layer may also be a multi-layered film deposited
individually or sequentially by the same or by a combination of
techniques.
[0059] The third process step 206 includes optionally depositing a
seed layer 224 over the substrate 220. The seed layer 224 comprises
a conductive metal that aids in subsequent deposition of materials
thereover. The seed layer 224 preferably comprises a copper seed
layer or alloys thereof. Other metals, particularly noble metals,
may also be used for the seed layer. The seed layer 224 may be
deposited over the barrier layer by techniques conventionally known
in the art including physical vapor deposition techniques, chemical
vapor deposition techniques, evaporation, and electroless
deposition techniques.
[0060] The fourth process step 208 includes forming a columnar
metal layer 226 over the seed layer 224. Formation of the columnar
metal layer 226 includes establishing process conditions under
which evolution of hydrogen results in the formation of a porous
metal film. Formation of the columnar metal layer 226 generally
takes place in a plating chamber using a suitable plating solution.
Suitable plating solutions that may be used with the processes
described herein to plate copper may include at least one copper
source compound, at least one acid based electrolyte, and optional
additives.
[0061] The plating solution contains at least one copper source
compound complexed or chelated with at least one of a variety of
ligands. Complexed copper includes a copper atom in the nucleus and
surrounded by ligands, functional groups, molecules or ions with a
strong finite to the copper, as opposed to free copper ions with
very low finite, if any, to a ligand, such as water. Complexed
copper sources are either chelated before being added to the
plating solution, such as copper citrate, or are formed in situ by
combining a free copper ion source such as copper sulfate with a
complexing agent, such as citric acid or sodium citrate. The copper
atom may be in any oxidation state, such as 0, 1 or 2, before,
during or after complexing with a ligand. Therefore, throughout the
disclosure, the use of the word copper or elemental symbol Cu
includes the use of copper metal (Cu.sup.0), cupric (Cu.sup.+1) or
cuprous (Cu.sup.+2), unless otherwise distinguished or noted.
[0062] Examples of suitable copper source compounds include copper
sulfate, copper phosphate, copper nitrate, copper citrate, copper
tartrate, copper oxalate, copper EDTA, copper acetate, copper
pyrophosphorate and combinations thereof, preferably copper sulfate
and/or copper citrate. A particular copper source compound may have
ligated varieties. For example, copper citrate may include at least
one cupric atom, cuprous atom or combinations thereof and at least
one citrate ligand and include Cu(C.sub.6H.sub.7O.sub.7),
Cu.sub.2(C.sub.6H.sub.4O.sub.7), Cu.sub.3(C.sub.6H.sub.5O.sub.7) or
Cu(C.sub.6H.sub.7O.sub.7).sub.2. In another example, copper EDTA
may include at least one cupric atom, cuprous atom or combinations
thereof and at least one EDTA ligand and include
Cu(C.sub.10H.sub.15O.sub.8N.sub.2),
Cu.sub.2(C.sub.10H.sub.14O.sub.8N.sub.2),
Cu.sub.3(C.sub.10H.sub.13O.sub.8N.sub.2),
Cu.sub.4(C.sub.10H.sub.12O.sub.8N.sub.2),
Cu(C.sub.10H.sub.14O.sub.8N.sub.2) or
Cu.sub.2(C.sub.10H.sub.12O.sub.8N.sub.2). The plating solution may
include one or more copper source compounds or complexed metal
compounds at a concentration in the range from about 0.02 M to
about 0.8 M, preferably in the range from about 0.1 M to about 0.5
M. For example, about 0.25 M of copper sulfate may be used as a
copper source compound.
[0063] Examples of suitable tin source may be soluble tin compound.
A soluble tin compound can be a stannic or stannous salt. The
stannic or stannous salt can be a sulfate, an alkane sulfonate, or
an alkanol sulfonate. For example, the bath soluble tin compound
can be one or more stannous alkane sulfonates of the formula:
(RSO.sub.3).sub.2Sn
where R is an alkyl group that includes from one to twelve carbon
atoms. The stannous alkane sulfonate can be stannous methane
sulfonate with the formula:
##STR00001##
The bath soluble tin compound can also be stannous sulfate of the
formula: SnSO.sub.4
[0064] Examples of the soluble tin compound can also include
tin(II) salts of organic sulfonic acid such as methanesulfonic
acid, ethanesulfonic acid, 2-propanolsulfonic acid,
p-phenolsulfonic acid and like, tin(II) borofluoride, tin(II)
sulfosuccinate, tin(II) sulfate, tin(II) oxide, tin(II) chloride
and the like. These soluble tin(II) compounds may be used alone or
in combination of two or more kinds.
[0065] Example of suitable cobalt source may include cobalt salt
selected from cobalt sulfate, cobalt nitrate, cobalt chloride,
cobalt bromide, cobalt carbonate, cobalt acetate, ethylene diamine
tetraacetic acid cobalt, cobalt (II) acetyl acetonate, cobalt (III)
acetyl acetonate, glycine cobalt (III), and cobalt pyrophosphate,
or combinations thereof.
[0066] In one embodiment, the plating solution contains free copper
ions in place of copper source compounds and complexed copper
ions.
[0067] The plating solution may contain at least one or more acid
based electrolytes. Suitable acid based electrolyte systems
include, for example, sulfuric acid based electrolytes, phosphoric
acid based electrolytes, perchloric acid based electrolytes, acetic
acid based electrolytes, and combinations thereof. Suitable acid
based electrolyte systems include an acid electrolyte, such as
phosphoric acid and sulfuric acid, as well as acid electrolyte
derivatives, including ammonium and potassium salts thereof. The
acid based electrolyte system may also buffer the composition to
maintain a desired pH level for processing a substrate.
[0068] Optionally, the plating solution may contain one or more
chelating or complexing compounds and include compounds having one
or more functional groups selected from the group of carboxylate
groups, hydroxyl groups, alkoxyl, oxo acids groups, mixture of
hydroxyl and carboxylate groups and combinations thereof. Examples
of suitable chelating compounds having one or more carboxylate
groups include citric acid, tartaric acid, pyrophosphoric acid,
succinic acid, oxalic acid, and combinations thereof. Other
suitable acids having one or more carboxylate groups include acetic
acid, adipic acid, butyric acid, capric acid, caproic acid,
caprylic acid, glutaric acid, glycolic acid, formic acid, fumaric
acid, lactic acid, lauric acid, malic acid, maleic acid, malonic
acid, myristic acid, plamitic acid, phthalic acid, propionic acid,
pyruvic acid, stearic acid, valeric acid, quinaldine acid, glycine,
anthranilic acid, phenylalanine and combinations thereof. Further
examples of suitable chelating compounds include compounds having
one or more amine and amide functional groups, such as
ethylenediamine, diethylenetriamine, diethylenetriamine
derivatives, hexadiamine, amino acids, ethylenediaminetetraacetic
acid, methylformamide or combinations thereof. The plating solution
may include one or more chelating agents at a concentration in the
range from about 0.02 M to about 1.6 M, preferably in the range
from about 0.2 M to about 1.0 M. For example, about 0.5 M of citric
acid may be used as a chelating agent.
[0069] The one or more chelating compounds may also include salts
of the chelating compounds described herein, such as lithium,
sodium, potassium, cesium, calcium, magnesium, ammonium and
combinations thereof. The salts of chelating compounds may
completely or only partially contain the aforementioned cations
(e.g., sodium) as well as acidic protons, such as
Na.sub.x(C.sub.6H.sub.8-xO.sub.7) or Na.sub.xEDTA, whereas X=1-4.
Such salt combines with a copper source to produce
NaCu(C.sub.6H.sub.5O.sub.7). Examples of suitable inorganic or
organic acid salts include ammonium and potassium salts or organic
acids, such as ammonium oxalate, ammonium citrate, ammonium
succinate, monobasic potassium citrate, dibasic potassium citrate,
tribasic potassium citrate, potassium tartrate, ammonium tartrate,
potassium succinate, potassium oxalate, and combinations thereof.
The one or more chelating compounds may also include complexed
salts, such as hydrates (e.g., sodium citrate dihydrate).
[0070] Although the plating solutions are particularly useful for
plating copper, it is believed that the solutions also may be used
for depositing other conductive materials, such as platinum,
tungsten, titanium, cobalt, gold, silver, ruthenium, tin, alloys
thereof, and combinations thereof. A copper precursor is
substituted by a precursor containing the aforementioned metal and
at least one ligand, such as cobalt citrate, cobalt sulfate or
cobalt phosphate.
[0071] Optionally, wetting agents or suppressors, such as
electrically resistive additives that reduce the conductivity of
the plating solution may be added to the solution in a range from
about 10 ppm to about 2,000 ppm, preferably in a range from about
50 ppm to about 1,000 ppm. Suppressors include polyacrylamide,
polyacrylic acid polymers, polycarboxylate copolymers, polyethers
or polyesters of ethylene oxide and/or propylene oxide (EO/PO),
coconut diethanolamide, oleic diethanolamide, ethanolamide
derivatives or combinations thereof.
[0072] One or more pH-adjusting agents are optionally added to the
plating solution to achieve a pH less than 7, preferably between
about 3 and about 7, more preferably between about 4.5 and about
6.5. The amount of pH adjusting agent can vary as the concentration
of the other components is varied in different formulations.
Different compounds may provide different pH levels for a given
concentration, for example, the composition may include between
about 0.1% and about 10% by volume of a base, such as potassium
hydroxide, ammonium hydroxide or combinations thereof, to provide
the desired pH level. The one or more pH adjusting agents can be
chosen from a class of acids including, carboxylic acids, such as
acetic acid, citric acid, oxalic acid, phosphate-containing
components including phosphoric acid, ammonium phosphates,
potassium phosphates, inorganic acids, such as sulfuric acid,
nitric acid, hydrochloric acid and combinations thereof.
[0073] The balance or remainder of the plating solution described
herein is a solvent, such as a polar solvent. Water is a preferred
solvent, preferably deionized water. Organic solvents, for example,
alcohols or glycols, may also be used, but are generally included
in an aqueous solution.
[0074] Optionally, the plating solution may include one or more
additive compounds. Additive compounds include electrolyte
additives including, but not limited to, suppressors, enhancers,
levelers, brighteners and stabilizers to improve the effectiveness
of the plating solution for depositing metal, namely copper to the
substrate surface. For example, certain additives may decrease the
ionization rate of the metal atoms, thereby inhibiting the
dissolution process, whereas other additives may provide a
finished, shiny substrate surface. The additives may be present in
the plating solution in concentrations up to about 15% by weight or
volume, and may vary based upon the desired result after
plating.
[0075] In one embodiment, the plating solution includes at least
one copper source compound, at least one acid based electrolyte,
and at least one additive, such as a chelating agent. In one
embodiment, the at least one copper source compound includes copper
sulfate, the at least one acid based electrolyte includes sulfuric
acid, and the chelating compound includes citrate salt.
[0076] The columnar metal layer 226 is formed using a high plating
rate deposition process. The current densities of the deposition
bias are selected such that the current densities are above the
limiting current (i.sub.L). When the limiting current is reached
the columnar metal film is formed due to the evolution of hydrogen
gas and resulting dendritic type film growth that occurs due to the
mass transport limited process. During formation of the columnar
metal layer, the deposition bias generally has a current density of
about 10 A/cm.sup.2 or less, preferably about 5 A/cm.sup.2 or less,
more preferably at about 3 A/cm.sup.2 or less. In one embodiment,
the deposition bias has a current density in the range from about
0.5 A/cm.sup.2 to about 3.0 A/cm.sup.2, for example, about 2.0
A/cm.sup.2.
[0077] The fifth process step 210 includes forming porous structure
228 on the columnar metal layer 226. The porous structure 228 may
be formed on the columnar metal layer 226 by increasing the voltage
and corresponding current density from the deposition of the
columnar metal layer. The deposition bias generally has a current
density of about 10 A/cm.sup.2 or less, preferably about 5
A/cm.sup.2 or less, more preferably at about 3 A/cm.sup.2 or less.
In one embodiment, the deposition bias has a current density in the
range from about 0.5 A/cm.sup.2 to about 3.0 A/cm.sup.2, for
example, about 2.0 A/cm.sup.2.
[0078] In one embodiment, the porous structure 228 may comprise one
or more of various forms of porosities. In one embodiment, the
porous structure 228 comprises macro porosity structure having
pores of about 100 microns or less, wherein the non-porous portion
of the macro porosity structure having pores of between about 2 nm
to about 50 nm in diameter (meso porosity). In another embodiment,
the porous structure 228 comprises macro porosity structure having
pores of about 30 microns. Additionally, surface of the porous
structure 228 may comprise nano structures. The combination of
micro porosity, meso porosity, and nano structure increases surface
area of the porous structure 408 tremendously.
[0079] In one embodiment, the porous structure 228 may be formed
from a single material, such as copper, zinc, nickel, cobalt,
palladium, platinum, tin, ruthenium, and other suitable material.
In another embodiment, the porous structure 228 may comprises alloy
of copper, zinc, nickel, cobalt, palladium, platinum, tin,
ruthenium, or other suitable material.
[0080] Optionally, a sixth processing step 212 can be performed to
form a passivation layer 230 on the porous structure 228, as shown
in FIG. 3F. The passivation layer 230 can be formed by an
electrochemical plating process. The passiviation layer 230
provides high capacity and long cycle life for the electrode to be
formed. In one embodiment, the porous structure 228 comprises
copper and tin alloy and the passivation layer 230 comprises a tin
film. In another embodiment, the porous structure 228 comprises
cobalt and tin alloy. In one embodiment, the passivation layer 230
may be formed by emerging the substrate 220 in a new plating bath
configured to plating the passivation layer 230 after a rinsing
step.
[0081] Embodiments of the present invention provide a processing
system for continuously perform steps 208, 210, 212 of the process
200. FIG. 4 is a flow diagram of a method 250 for forming a porous
electrode in accordance with embodiments described herein. Each
block in method 250 is generally performed in a separated
processing chamber. A substrate being processed is generally
streamlined from one chamber to the next to complete the
process.
[0082] In block 252, a substrate deposited with a seed layer, by a
PVD process or an evaporation process, is positioned in a
pre-wetting chamber to remove oxides, carbon, or other
contaminations before plating. Compared to PVD process, evaporation
process is generally at a lower cost.
[0083] In block 254, the pre-wetted substrate is emerged in a
plating bath of a first plating chamber to form a columnar metal
layer.
[0084] In block 256, the substrate having the columnar metal layer
formed thereon is removed from the first plating chamber and
emerged in a plating bath of a second plating chamber to form a
porous layer over the columnar metal layer.
[0085] In one embodiment, the columnar metal layer and the porous
layer may comprise the same metal, such as copper, and the plating
baths in the first and second chambers may similar or compatible in
chemistry. In another embodiment, the porous layer may comprise tin
and copper alloy. In another embodiment, the porous layer may
comprise cobalt and tin alloy. In another embodiment, the porous
layer may comprise alloy of cobalt, tin and copper.
[0086] In block 258, the substrate is rinsed in a rinsing chamber
to remove any residual plating path on the substrate.
[0087] In block 260, the substrate is emerged in a plating bath in
a third plating chamber to form a passivation thin film. In one
embodiment, the passivation thin film may comprise a thin film of
tin.
[0088] In block 262, the substrate is rinsed and dried in a
rinse-dry chamber for subsequent processing.
[0089] FIGS. 5-8 describe chambers and systems configured to
perform formation of an electrode for an electrochemical battery or
capacitor using the method 250.
[0090] FIG. 5A is a schematic sectional side view of a plating
chamber 400 in accordance with one embodiment of the present
invention. The plating chamber 400 is in a plating position. FIG.
5B is a schematic sectional side view of the plating chamber 400 in
a substrate transferring position.
[0091] The plating chamber 400 is configured to form a metal layer
306 over a seed layer 305, or a conductive layer, formed on a
flexible base 301. In one embodiment, the flexible base 301 is
supplied to the plating chamber 400 by portion by portion. Each
portion may be considered a substrate. Each substrate is generally
cut from the rest of the flexible base 301 after processing.
[0092] In one embodiment, the plating chamber 400 is configured to
deposit the metal layer 306 selectively over desired regions of the
seed layer 305 using a masking plate 410. The masking plate 410 has
a plurality of apertures 413 that preferentially allow the
electrochemically deposited material to form therein. In one
embodiment, the masking plate 410 may define a pattern configured
for a light-receiving side of the flexible solar cell.
[0093] The plating chamber 400 generally contains a head assembly
405, flexible substrate assembly, an electrode 420, a power supply
450, a system controller 251, and a plating cell assembly 430.
[0094] The plating cell assembly 430 generally contains a cell body
431 defining a plating region 435 and an electrolyte collection
region 436. In operation it is generally desirable to pump an
electrolyte "A" from the electrolyte collection region 436 through
a plenum 437 formed between the electrode 420 and the support
features 434 past the apertures 413 formed in the masking plate 410
and then over a weir 432 separating the plating region 435 and to
the electrolyte collection region 436, by use of a pump 440.
[0095] In one embodiment, the electrode 420 may be supported on one
or more support features 434 formed in the cell body 431. In one
embodiment, the electrode 420 contains a plurality of holes 421
that allow the electrolyte "A" passing from the plenum 437 to the
plating region 435 to have a uniform flow distributed across
masking plate 410 and contact at least one surface on the flexible
base 301. The fluid motion created by the pump 440 allows the
replenishment of the electrolyte components at the exposed region
404 that is exposed at one ends of the apertures 413.
[0096] The electrode 420 may be formed from material that is
consumable during the electroplating reaction, but is more
preferably formed from a non-consumable material. A non-consumable
electrode may be made of a conductive material that is not etched
during the formation the metal layer 306, such as platinum or
ruthenium coated titanium.
[0097] The head assembly 405 generally contains a thrust plate 414
and a masking plate 410 that is adapted to hold a portion of the
flexible base 301 in a position relative to the electrode 420
during the electrochemical deposition process. In one aspect, a
mechanical actuator 415 is used to urge the thrust plate 414 and
the flexible base 301 against electrical contacts 412 formed on a
top surface 418 of the masking plate 410 so that an electrical
connection can be formed between the seed layer 305 formed on the
surface of the flexible base 301 and the power supply 450 through
the lead 451.
[0098] In one embodiment, as shown in FIG. 5A, the electrical
contacts 412 are formed on a surface of the masking plate 410. In
another embodiment, the electrical contacts 412 may be formed from
separate and discrete conductive contacts that are nested within a
recess formed in the masking plate 410 when the flexible base 301
is being urged against the masking plate 410. The electrical
contacts 412 may be formed from a metal, such as platinum, gold, or
nickel, or another conductive material, such as graphite, copper
Cu, phosphorous doped copper (CuP), and platinum coated titanium
(Pt/Ti).
[0099] The flexible substrate assembly 460 comprises a feed roll
461 coupled to a feed actuator, and a take-up roll 462 coupled to a
take-up actuator. The flexible substrate assembly 460 is configured
to feed, position portions of the flexible base 301 within the
plating chamber 400 during processing.
[0100] In one aspect, the feed roll 461 contains an amount of the
flexible base 301 on which a seed layer 305 has been formed. The
take-up roll 462 generally contains an amount of the flexible base
301 after the metal layer 306. The feed actuator and take-up
actuator are used to position and apply a desired tension to the
flexible base 301 so that the electrochemical processes can be
performed on thereon. The feed actuator and take-up actuator may be
DC servo motor, stepper motor, mechanical spring and brake, or
other device that can be used to position and hold the flexible
substrate in a desired position with the plating chamber 400.
[0101] FIG. 5B is a side cross-sectional view that illustrates the
plating chamber 400 in transferring position to allow positioning a
desired portion of the flexible base 301 containing the seed layer
305 into a desired position relative to masking plate 410 and the
electrode 420 so that a metal layer 306 will be formed thereon. In
on aspect, various convention encoders or other devices are used in
conjunction with the feed actuator and/or take-up actuator to
control and position a desired portion of the flexible base 301
containing the seed layer 305 within the head assembly 405.
[0102] FIG. 5C schematically illustrates a plating system 500
configured for plating an electrode of an electrochemical battery
or capacitor using a method similar to the method 250 described
above.
[0103] The plating system 500 generally comprises a plurality of
processing chambers arranged in a line, each configured to perform
one processing step to a substrate 511 formed on one portion of a
continuous flexible base.
[0104] The plating system 500 comprises a pre-wetting chamber 501
configured to pre-wet a substrate 511 formed on a portion of the
flexible base. The pre-wetting chamber 501 may be similar in
structure to the plating chamber 400 of FIG. 5A without the
electrodes 420, the masking plate 410, and the power supply 450
required for plating process.
[0105] The plating system 500 further comprises a first plating
chamber 502 configured to perform a first plating process on the
substrate 511 after being pre-wetted. The first plating chamber 502
is generally disposed next to the cleaning pre-wetting station. In
one embodiment, the first plating process may be plating a columnar
copper layer on a seed layer of formed on the substrate 511. The
first plating chamber 502 may be similar to the plating chamber 400
of FIG. 4A described above.
[0106] The plating system 500 further comprises a second plating
chamber 503 disposed next to the first plating chamber 502. The
second plating chamber 503 is configured to perform a second
plating process. In one embodiment, the second plating process is
forming a porous layer of copper or alloys on the columnar copper
layer. The second plating chamber 503 may be similar to the plating
chamber 400 of FIG. 4A described above.
[0107] The plating system 500 further comprises a rinsing station
504 disposed next to the second plating chamber 503 and configured
to rinse and remove any residual plating solution from the
substrate 511. The rinsing station 504 may be similar in structure
to the plating chamber 400 of FIG. 5A without the electrodes 420,
the masking plate 410, and the power supply 450 required for
plating process.
[0108] The plating system 500 further comprises a third plating
chamber 505 disposed next to the rinsing station 504. The third
plating chamber 505 is configured to perform a third plating
process. In one embodiment, the third plating process is forming a
thin film over the porous layer. The third plating chamber 505 may
be similar to the plating chamber 400 of FIG. 4A described
above.
[0109] The plating system 500 further comprises a rinse-dry station
506 disposed next to the third plating chamber 505 and configured
to rinse and dry the substrate 511 after the plating processes and
to get the substrate 511 ready for subsequent processing. The
rinse-dry station 506 may be similar in structure to the plating
chamber 400 of FIG. 5A without the electrodes 420, the masking
plate 410, and the power supply 450 required for plating process.
In one embodiment, the rinse-dry station 506 may comprise one or
more vapor jets 506a configured to direct a drying vapor toward the
substrate 511 as the substrate 511 exits the rinse-dry chamber
506.
[0110] The processing chambers 501-506 are generally arranged along
a line so that the substrates 511 can be streamlined through each
chamber through feed rolls 507.sub.1-6 and take up rolls
508.sub.1-6 of each chamber. In one embodiment, the feed rolls
507.sub.1-6 and take up rolls 508.sub.1-6 may be activated
simultaneously during substrate transferring step to move each
substrate 511 one chamber forward.
[0111] Substrates are positioned in a substantially horizontal
position in the description of the plating system 500 above.
However, other substrate orientations, such as vertical or tilted
can be used in accordance with embodiments of the present
invention.
[0112] FIG. 6A is a schematic sectional side view of a plating
chamber 600 in accordance with one embodiment of the present
invention. The plating chamber 600 is configured to form a metal
layer over a seed layer 602, or a conductive layer, formed on a
flexible base 601. Similar to the plating chamber 400 of FIG. 5A,
the flexible base 601 is supplied to the plating chamber 600 by
portion by portion. Each portion may be considered a substrate.
Each substrate is generally cut from the rest of the flexible base
601 after processing.
[0113] The plating chamber 600 generally comprises a chamber body
603 defining a processing volume 604. The processing volume 604 is
in fluid communication with one or more inlet jet 605 configured to
dispense a plating solution in the processing volume 604. The
processing volume 604 is also in fluid communication with a drain
606 configured to remove the plating solution from the processing
volume 604.
[0114] The plating chamber 600 comprises a flexible substrate
assembly 608 configured to move the flexible base 601 and to
position a particular portion the flexible base 601 in the
processing volume 604 to processing. The flexible substrate
assembly 608 comprises a feed roll 609 disposed above the
processing volume 604, a bottom roll 610 disposed near a bottom
portion of the processing volume 604, a take-up roll 611 disposed
above the processing volume 604. Each of the feed roll 609, the
bottom roll 610, and the take up roll 611 is configured to retain a
portion of the flexible base 601. The flexible substrate assembly
608 is configured to feed, position portions of the flexible base
601 within the plating chamber 600 during processing.
[0115] In one embodiment, at least the feed roll 609 and the take
up roll 611 are coupled to actuators. The feed actuator and take-up
actuator are used to position and apply a desired tension to the
flexible base 601 so that the electrochemical processes can be
performed on thereon. The feed actuator and take-up actuator may be
DC servo motor, stepper motor, mechanical spring and brake, or
other device that can be used to position and hold the flexible
substrate in a desired position with the plating chamber 600.
[0116] The plating chamber 600 also comprises an anode assembly 607
disposed in the processing volume 604. In one embodiment, the anode
assembly 607 is disposed in a substantially vertical orientation.
In one embodiment, the anode assembly 607 may contains a plurality
of holes that allow the plating bath passing from the inlet jets
605 to have a uniform flow distributed across a plating surface of
the flexible base 601.
[0117] The anode assembly 607 may be formed from material that is
consumable during the electroplating reaction, but is more
preferably formed from a non-consumable material. A non-consumable
electrode may be made of a conductive material that is not etched
during the formation a metal layer over the flexible base 601, such
as platinum or ruthenium coated titanium.
[0118] In one embodiment, the plating chamber 600 comprises a
masking plate 613 configured to selectively expose regions of the
seed layer 602 during processing. The masking plate 613 has a
plurality of apertures 614 that preferentially allow the
electrochemically deposited material to form therein. In one
embodiment, the masking plate 613 may define a pattern configured
for a light-receiving side of the flexible solar cell.
[0119] In one embodiment, the plating chamber 600 comprises a
thrust plate 616 disposed in the processing volume 604,
substantially parallel to the anode assembly 607. The thrust plate
616 is configured to hold a portion of the flexible base 601 in a
position relative to the anode assembly 607 during the
electrochemical deposition process. The thrust plate 616 is
positioned on a backside of the flexible base 601 and the anode
assembly 607 and masking plate 613 are positioned on a front side
of the flexible base 601.
[0120] In one embodiment, the thrust plate 616 is horizontally
movable. During transferring stage, the thrust plate 616 is moved
away from the flexible base 601 and neither the masking plate 613
nor the thrust plate 616 is in contact with the flexible base 601.
Before processing, at least one of the thrust plate 616 and the
masking plate 613 is moved towards the other sandwiching the
flexible base 601 in between. The thrust plate 616 ensures that the
flexible base 601 is substantially parallel to the anode assembly
607 and in a desired distance from the anode assembly 607.
[0121] In one embodiment, a power source 617.sub.1 is coupled
between the anode assembly 607 and the masking plate 613 to provide
electric bias for a plating process. In one embodiment, a plurality
of electrical contacts 615 is formed on a surface of the masking
plate 613. The power source 617.sub.1 is coupled to the plurality
of electrical contacts 615 which then provides electrical bias to
the seed layer 602 when the masking plate 613 contacts the flexible
base 601. The plurality of electrical contacts 615 may be formed
from separate and discrete conductive contacts that are nested
within a recess formed in the masking plate 613 when the flexible
base 601 is being urged against the masking plate 613. The
electrical contacts 615 may be formed from a metal, such as
platinum, gold, or nickel, or another conductive material, such as
graphite, copper Cu, phosphorous doped copper (CuP), and platinum
coated titanium (Pt/Ti).
[0122] In another embodiment, a power source 617.sub.2, instead of
the power source 617.sub.1, is coupled between the anode assembly
607 and the seed layer 602 directly. This is configuration is
usually applicable when the seed layer 602 is continuous within
each portion (substrate) and isolated from portion to portion.
[0123] In yet another embodiment, a power source 617.sub.3, instead
of the power source 617.sub.1, is coupled between the anode
assembly 607 and the feed roll 609, which is in electrical contact
with the flexible base 601. This is configuration is usually
applicable when the flexible base 601 is conductive.
[0124] FIG. 6B is a schematic sectional side view of a plating
chamber 600c in accordance with one embodiment of the present
invention. The plating chamber 600c is similar to the plating
chamber 600 of FIG. 6A except that the plating chamber 600c is
configured to processing two portions of the flexible base 601
simultaneously. This is configuration can nearly double the system
throughput.
[0125] FIG. 6C schematically illustrates a plating system 700 using
one or more plating chambers of FIGS. 6A-6B. The plating system 700
configured for plating an electrode of an electrochemical battery
or capacitor using a method similar to the method 250 described
above.
[0126] The plating system 700 generally comprises a plurality of
processing chambers arranged in a line, each configured to perform
one processing step to a substrate formed on one portion of a
continuous flexible base 710.
[0127] The plating system 700 comprises a pre-wetting chamber 701
configured to pre-wet a portion of the flexible base 710. The
pre-wetting chamber 701 may be similar in structure to the plating
chambers 600, 600c described above without the anode assembly 607,
the masking plate 613, the thrust plate 616, and the power source
617 required for plating process.
[0128] The plating system 700 further comprises a first plating
chamber 702 configured to perform a first plating process the
portion of the flexible base 710 after being pre-wetted. The first
plating chamber 702 is generally disposed next to the cleaning
pre-wetting station. In one embodiment, the first plating process
may be plating a columnar copper layer on a seed layer of formed on
a seed layer formed on the portion of the flexible base 710. The
first plating chamber 702 may be similar to the plating chambers
600, 600c described above.
[0129] The plating system 700 further comprises a second plating
chamber 703 disposed next to the first plating chamber 702. The
second plating chamber 703 is configured to perform a second
plating process. In one embodiment, the second plating process is
forming a porous layer of copper or alloys on the columnar copper
layer. The second plating chamber 703 may be similar to the plating
chambers 600, 600c described above.
[0130] The plating system 700 further comprises a rinsing station
704 disposed next to the second plating chamber 703 and configured
to rinse and remove any residual plating solution from the portion
of flexible base 710 processed by the second plating chamber 703.
The rinsing station 704 may be similar in structure to the plating
chambers 600, 600c described above without the anode assembly 607,
the masking plate 613, the thrust plate 615, and the power source
617 required for plating process.
[0131] The plating system 700 further comprises a third plating
chamber 705 disposed next to the rinsing station 704. The third
plating chamber 705 is configured to perform a third plating
process. In one embodiment, the third plating process is forming a
thin film over the porous layer. The third plating chamber 705 may
be similar to the plating chambers 600, 600c described above.
[0132] The plating system 700 further comprises a rinse-dry station
706 disposed next to the third plating chamber 705 and configured
to rinse and dry the portion of flexible base 710 after the plating
processes. The rinse-dry station 706 may be similar in structure to
the plating chambers 600, 600c described above without the anode
assembly 607, the masking plate 613, the thrust plate 615, and the
power source 617 required for plating process. In one embodiment,
the rinse-dry station 706 may comprise one or more vapor jets 706a
configured to direct a drying vapor toward the flexible base 710 as
the flexible base 710 exits the rinse-dry station 706.
[0133] The processing chambers 701-706 are generally arranged along
a line so that portions of the flexible base 710 can be streamlined
through each chamber through feed rolls 707.sub.1-6 and take up
rolls 708.sub.1-6 of each chamber. In one embodiment, the feed
rolls 707.sub.1-6 and take up rolls 708.sub.1-6 may be activated
simultaneously during substrate transferring step to move each
portion of the flexible base 710 one chamber forward.
[0134] FIG. 7A is a schematic perspective view of a plating chamber
800 in accordance with one embodiment of the present invention.
FIG. 7B is a schematic sectional side view of the plating chamber
800 of FIG. 7A in plating position.
[0135] The plating chamber 800 generally comprises a chamber body
801 defining a processing volume 802 configured retaining a plating
bath for processing one or more substrates in a substantially
vertical position. The processing volume 802 has a top opening 802a
configured to allow passage of substrates being processed. The
plating chamber comprises a plurality of inlet jets 803 disposed on
a sidewall of the chamber body 801. In one embodiment, the
plurality of inlet jets 803 may be distributed across the sidewall.
The plurality of inlet jets 803 may also be used to spray wetting
solution or cleaning solution towards a substrate being processed.
The plurality of inlet jets 803 are connected to a plating solution
source 804.
[0136] In one embodiment, the plating chamber 800 further comprises
a drain 812 configured to remove processing solution from the
processing volume 802. In another embodiment, as shown in FIG. 7B,
the plating chamber 800 may comprise a catch pen 825 configured to
retain plating solution overflowing from the top opening 802a of
the processing volume 802. In one embodiment, the plating solution
retained in the catch pen 825 may be filtered and flown back to the
plating solution source 804 for reuse.
[0137] The plating chamber 800 comprises an anode assembly 805
disposed in the processing volume 802 in a substantially vertical
orientation. In one embodiment, the anode assembly 805 may be
removable from the processing volume 802 for maintenance or
replacement. In one embodiment, the anode assembly 805 may contains
a plurality of holes that allow the plating bath passing from the
inlet jets 803 to have a uniform flow distributed across the
processing volume 802.
[0138] The anode assembly 805 may be formed from material that is
consumable during the electroplating reaction, but is more
preferably formed from a non-consumable material. A non-consumable
electrode may be made of a conductive material that is not etched
during plating, such as platinum or ruthenium coated titanium. The
advantages of non consumable anodes include low cost and
maintenance for being non-consumable, inert to chemical, good for
alloy combination, good for pulse condition,
[0139] The plating chamber 800 further comprises a cathode assembly
806 configured to transfer one or more substrates 808 and position
the one or more substrates 808 in a plating position as shown in
FIG. 7B. As illustrated in FIG. 7A, the cathode assembly 806 can be
lowered into the processing volume 802 via the top opening
802a.
[0140] Flexible substrates are commonly used in producing some
devices, such as solar battery cells. In one embodiment, the
cathode assembly 806 is configured to support one or more flexible
substrates for plating. In one embodiment, the cathode assembly 806
may comprise a back plate 810 configured to provide structural
support to the substrate 808.
[0141] As discussed above, a plating process is generally performed
to form a metal layer over a seed layer 809 formed on the substrate
808. The cathode assembly 806 is configured to support the
substrate 808 so that the seed layer 809 is facing the anode
assembly 805.
[0142] In one embodiment, the cathode assembly 806 comprises a
masking plate 807 configured to selectively expose regions of the
seed layer 809 during processing. The masking plate 807 has a
plurality of apertures 807a that preferentially allow the
electrochemically deposited material to form therein. In one
embodiment, the masking plate 807 may define a pattern configured
for a light-receiving side of the flexible solar cell.
[0143] In one embodiment, the anode assembly 805 and the cathode
assembly 806 may be moved relative to each other to achieve a
desired spacing between the substrate 808 and the anode assembly
805 for plating.
[0144] A power source 811 is coupled between the anode assembly 805
and the substrate 808 to provide a bias for electroplating. In one
embodiment, a plurality of electrical contacts 807b is formed on a
surface of the masking plate 807. In one embodiment, the power
source 811 may be connected to the substrate 808 via the electrical
contacts 807b of the masking plate 807. The electrical contacts
807b may be formed from a metal, such as platinum, gold, or nickel,
or another conductive material, such as graphite, copper Cu,
phosphorous doped copper (CuP), and platinum coated titanium
(Pt/Ti).
[0145] The cathode assembly 806 may be configured to support a
single substrate or multiple substrates. FIG. 7C is a schematic
view of the cathode assembly 806 in accordance with one embodiment
of the present invention. The cathode assembly 806 shown in FIG. 7C
is configured to support 4 substrates 808. The cathode assembly 806
comprises a supporting frame 815 on which substrates 808 may be
mounted.
[0146] FIGS. 8A-8B schematically illustrate a plating system 900 in
accordance with one embodiment of the present invention. The
plating system 900 comprises a plurality of processing chambers
similar in structure to the plating chamber 800 of FIG. 7A. The
plating system 900 configured for plating an electrode of an
electrochemical battery or capacitor using a method similar to the
method 250 described above.
[0147] The plating system 900 generally comprises a plurality of
processing chambers 901, 902, 903, 904, 905, 906 arranged in a
line, each configured to perform one processing step to substrates
secured on substrate holders 907.sub.1-907.sub.6. The substrate
holders 907.sub.1-907.sub.6 may be transferred by a substrate
transferring mechanism 910 among the processing chambers
901-906.
[0148] In one embodiment, the substrate holders 907.sub.1-907.sub.6
are similar to the cathode assembly 806 of the plating chamber 800
described above.
[0149] In one embodiment, the processing chamber 901 may be a
pre-wetting chamber configured to pre-wet a substrate disposed
therein.
[0150] The processing chamber 902 may be a plating chamber
configured to perform a first plating process the portion of the
substrate after being pre-wetted in the processing chamber 901. In
one embodiment, the first plating process may be configured to form
a columnar metal layer over a seed layer of the substrate.
[0151] The processing chamber 903 may be a plating chamber
configured to perform a second plating process the portion of the
substrate after the plating process in the processing chamber 902.
The second plating process may be configured to form a porous layer
over the columnar metal layer.
[0152] The processing chamber 904 may be a rinsing chamber
configured to rinse and remove any residual plating solution from
the substrate after the second plating process in the processing
chamber 903.
[0153] The processing chamber 905 may be a plating chamber
configured to perform a third plating process. In one embodiment,
the third plating process is configured to form a thin film over
the porous layer.
[0154] The processing chamber 906 may be a rinse-dry station
configured to rinse and dry the substrate after the third plating
process.
[0155] FIGS. 8A-8B illustrate a substrate transferring sequence
during processing. As shown in FIG. 8A, the substrate holder
907.sub.6 may be transferred out of the processing chamber 906
having vapor jets 907a after drying, while the substrate
transferring mechanism 910 is in position to pick up substrate
holders 907.sub.1-907.sub.5 in the processing chambers 901-905
simultaneously after processes are complete in each chamber.
[0156] In FIG. 8B, the substrate transferring mechanism 910 picks
up the substrate holders 907.sub.1-907.sub.5 from the processing
chambers 901-905 and moves the substrate holders
907.sub.1-907.sub.5 down the line to the next chambers. The
processing chamber 901 is ready for new substrates being secured in
a new substrate holder 907.sub.7.
[0157] The substrate transferring mechanism 910 drops the substrate
holders 907.sub.1-907.sub.5 to the processing chambers 902-906
respectively. The processing chamber 901 processing the substrates
secured in the substrate holder 907.sub.7.
[0158] The substrate transferring mechanism 910 moves backward to
pick up the substrate holders 907.sub.7, and 907.sub.1-907.sub.4 to
the processing chambers 901-905 respectively. The substrates in the
substrate holder 907.sub.5 are ready to exit the plating system
900. These moving steps are repeated for a streamline process.
[0159] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *