WO2010059865A2

WO2010059865A2 - Apparatus and method for forming 3d nanostructure electrode for electrochemical battery or capacitor

Info

Publication number: WO2010059865A2
Application number: PCT/US2009/065205
Authority: WO
Inventors: Sergey Lopatin; Robert Z. Bachrach
Original assignee: Applied Materials, Inc.
Priority date: 2008-11-24
Filing date: 2009-11-19
Publication date: 2010-05-27
Also published as: KR20110097898A; WO2010059865A3; EP2351138A2; TW201030190A; CN102224628A; JP2012510163A; US20100126849A1

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.

Description

APPARATUS AND METHOD FOR FORMING 3D NANOSTRUCTURE ELECTRODE FOR ELECTROCHEMICAL BATTERY AND CAPACITOR

BACKGROUND OF THE INVENTION Field of the Invention

[0001] 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.

Description of the Related Art

[0002] 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.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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. [0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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. [0016] 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

[0017] 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.

[0018] 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.

[0019] 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

[0020] 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.

[0021] Figure 1A is a simplified schematic view of an active region of an electrochemical capacitor unit.

[0022] Figure 1 B is a simplified schematic view a lithium-ion battery cell.

[0023] Figure 2 is a flow diagram of a method for forming an electrode in accordance with embodiments described herein.

[0024] Figure 3 is a schematic cross-sectional view showing formation an anode according to embodiments of the present invention. [0025] Figure 4 is a flow diagram of a method for forming a porous electrode in accordance with embodiments described herein.

[0026] Figure 5A is a schematic sectional side view of a plating chamber in accordance with one embodiment of the present invention.

[0027] Figure 5B is a schematic sectional side view of the plating chamber of Figure 5A in a substrate transferring position.

[0028] Figure 5C schematically illustrates a plating system using one or more plating chambers of Figure 5A.

[0029] Figure 6A is a schematic sectional side view of a plating chamber in accordance with one embodiment of the present invention.

[0030] Figure 6B a schematic sectional side view of a plating chamber in accordance with one embodiment of the present invention

[0031] Figure 6C schematically illustrates a plating system using one or more plating chambers of Figures 6A.

[0032] Figure 7A is a schematic perspective view of a plating chamber in accordance with one embodiment of the present invention.

[0033] Figure 7B is a schematic sectional side view of the plating chamber of Figure 7A in plating position.

[0034] Figure 7C is a schematic view of a substrate holder in accordance with one embodiment of the present invention.

[0035] Figures 8A-8B schematically illustrate a processing system in accordance with one embodiment of the present invention.

[0036] 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

[0037] 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.

[0038] 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_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.

[0039] Figure 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.

[0040] 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.

[0041] 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™, available from the E.I. DuPont de Nemeours & Co. Other suitable membrane materials include Gore Select™, sulphonated fluorocarbon polymers, the polybenzimidazole (PBI) membrane (available from Celanese Chemicals, Dallas, Texas), polyether ether ketone (PEEK) membranes and other materials.

[0042] 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.

[0043] 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.

[0044] 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_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. [0045] Figure 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 ceil 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.

[0046] 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.

[0047] 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.

[0048] 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 TiS₂ (titanium disulfide). Exemplary oxides may be layered lithium cobalt oxide, or mixed metal oxide, such as LiNi_xCo-_I-2X MnO₂, LiMn₂O₄. Li It is desirable that the anode 151 has a large surface area. Exemplary phosphates may be iron olivine (LiFePO₄) and it is variants (such as LiFeI -_xMgPO₄), LiMoPO4, LiCoPO₄, Li₃V₂(PO₄)₃, LiVOPO₄, LiMP₂O₇, or LiFeL₅P₂O₇. Exemplary fluorophosphates may be LiVPO₄F, LiAIPO₄F, Li₅V(PO₄)₂F_2, Li₅Cr(PO₄)₂F_2, Li₂CoPO₄F, Li₂NiPO₄F, or Na₅V₂(PO₄)₂F_3. Exemplary silicates may be Li₂FeSiO₄, Li₂MnSiO₄, or Li₂VOSiO_4.

[0049] 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).

[0050] The electrolyte 154 is generally a solution of lithium salts, such as LiPF₆, LiBF₄, or LiCIO₄, in an organic solvents.

[0051] 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.

[0052] Figure 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. Figure 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.

[0053] 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™ by DuPont Corporation), polyethyleneterephthalate (PET), polyacrylates, polycarbonate, silicone, epoxy resins, silicone-functionalized epoxy resins, polyester (e.g., MYLAR™ 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.

[0054] 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_x), titanium (Ti), titanium nitride (TiN_x), tungsten (W), tungsten nitride (WN_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 January 28, 2002, which is incorporated herein by reference to the extent not inconsistent with the embodiments described herein.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 (Cu⁰), cupric (Cu⁺¹) or cuprous (Cu⁺²), unless otherwise distinguished or noted.

[0059] 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(C₆H₇O₇), Cu₂(C₆H₄O₇), Cu₃(C₆H₅O₇) or Cu(C₆H₇O₇)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-_IoHi₅O₈N₂), Cu₂(C₁₀H₁₄O₈N₂), Cu₃(C₁₀H₁₃O₈N₂), Cu₄(C₁₀H₁₂O₈N₂), Cu(C₁₀H₁₄O₈N₂) or Cu₂(C₁₀H₁₂O₈N₂). 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.

[0060] 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:

(RSO₃)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:

O O

CH₃ -S - O - Sn - O -S-CH₃

O O

The bath soluble tin compound can also be stannous sulfate of the formula: SnSO₄

[0061] Examples of the soluble tin compound can also include tin(ll) salts of organic sulfonic acid such as methanesulfonic acid, ethanesulfonic acid, 2- propanolsulfonic acid, p-phenolsulfonic acid and like, tin(ll) borofluoride, tin(ll) sulfosuccinate, tin(ll) sulfate, tin(ll) oxide, tin(ll) chloride and the like. These soluble tin(ll) compounds may be used alone or in combination of two or more kinds. [0062] 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.

[0063] In one embodiment, the plating solution contains free copper ions in place of copper source compounds and complexed copper ions.

[0064] 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.

[0065] 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.

[0066] 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_x(C₆H_8-XO₇) or Na_xEDTA, whereas X=1-4. Such salt combines with a copper source to produce NaCu(C₆H₅O₇). 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).

[0067] 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.

[0068] Optinoally, 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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_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/cm² or less, preferably about 5 A/cm² or less, more preferably at about 3 A/cm² or less. In one embodiment, the deposition bias has a current density in the range from about 0.5 A/cm² to about 3.0 A/cm², for example, about 2.0 A/cm².

[0074] 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/cm² or less, preferably about 5 A/cm² or less, more preferably at about 3 A/cm² or less. In one embodiment, the deposition bias has a current density in the range from about 0.5 A/cm² to about 3.0 A/cm², for example, about 2.0 A/cm².

[0075] 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 2nm to about 50nm 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.

[0076] 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.

[0077] Optionally, a sixth processing step 212 can be performed to form a passivation layer 230 on the porous structure 228, as shown in Figure 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.

[0078] Embodiments of the present invention provide a processing system for continuously perform steps 208, 210, 212 of the process 200. Figure 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.

[0079] 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.

[0080] In block 254, the pre-wetted substrate is emerged in a plating bath of a first plating chamber to form a columnar metal layer. [0081] 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.

[0082] 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.

[0083] In block 258, the substrate is rinsed in a rinsing chamber to remove any residual plating path on the substrate.

[0084] 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.

[0085] In block 262, the substrate is rinsed and dried in a rinse-dry chamber for subsequent processing.

[0086] Figures 5-8 describe chambers and systems configured to perform formation of an electrode for an electrochemical battery or capacitor using the method 250.

[0087] Figure 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. Figure 5B is a schematic sectional side view of the plating chamber 400 in a substrate transferring position.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] In one embodiment, as shown in Figure 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).

[0096] 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.

[0097] 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.

[0098] Figure 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.

[0099] Figure 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.

[0100] 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.

[0101] 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 Figure 5A without the electrodes 420, the masking plate 410, and the power supply 450 required for plating process.

[0102] 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 Figure 4A described above. [0103] 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 Figure 4A described above.

[0104] 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 Figure 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 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 Figure 4A described above.

[0106] 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 Figure 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.

[0107] 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-_I-₆ and take up rolls 508i_-6 of each chamber. In one embodiment, the feed rolls 507-I_-6 and take up rolls 508i-₆ may be activated simultaneously during substrate transferring step to move each substrate 511 one chamber forward.

[0108] 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.

[0109] Figure 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 Figure 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.

[0110] 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.

[0111] 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. [0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] In one embodiment, a power source 617i 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 617i 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).

[0119] In another embodiment, a power source 611₂ , instead of the power source 617^ 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.

[0120] In yet another embodiment, a power source 617₃ , instead of the power source 617i, 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.

[0121] Figure 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 Figure 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.

[0122] Figure 6C schematically illustrates a plating system 700 using one or more plating chambers of Figures 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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_1-6 and take up rolls 708i_-6 of each chamber. In one embodiment, the feed rolls 707i_-6 and take up rolls 708_1-6 may be activated simultaneously during substrate transferring step to move each portion of the flexible base 710 one chamber forward.

[0131] Figure 7A is a schematic perspective view of a plating chamber 800 in accordance with one embodiment of the present invention. Figure 7B is a schematic sectional side view of the plating chamber 800 of Figure 7A in plating position.

[0132] 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.

[0133] 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 Figure 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.

[0134] 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. [0135] 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,

[0136] 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 Figure 7B. As illustrated in Figure 7A, the cathode assembly 806 can be lowered into the processing volume 802 via the top opening 802a.

[0137] 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.

[0138] 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.

[0139] 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. [0140] 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.

[0141] 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).

[0142] The cathode assembly 806 may be configured to support a single substrate or multiple substrates. Figure 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 Figure 7C is configured to support 4 substrates 808. The cathode assembly 806 comprises a supporting frame 815 on which substrates 808 may be mounted.

[0143] Figures 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 Figure 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.

[0144] 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 907i-907₆. The substrate holders 907_r907₆ may be transferred by a substrate transferring mechanism 910 among the processing chambers 901-906. [0145] In one embodiment, the substrate holders 907r907₆ are similar to the cathode assembly 806 of the plating chamber 800 described above.

[0146] In one embodiment, the processing chamber 901 may be a pre-wetting chamber configured to pre-wet a substrate disposed therein.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] The processing chamber 906 may be a rinse-dry station configured to rinse and dry the substrate after the third plating process.

[0152] Figures 8A-8B illustrate a substrate transferring sequence during processing. As shown in Figure 8A, the substrate holder 907₆ 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_r907₅ in the processing chambers 901-905 simultaneously after processes are complete in each chamber. [0153] In Figure 8B, the substrate transferring mechanism 910 picks up the substrate holders 907r907₅ from the processing chambers 901-905 and moves the substrate holders 907i-907₅ down the line to the next chambers. The processing chamber 901 is ready for new substrates being secured in a new substrate holder 907₇.

[0154] The substrate transferring mechanism 910 drops the substrate holders 907i-907₅ to the processing chambers 902-906 respectively. The processing chamber 901 processing the substrates secured in the substrate holder 907₇.

[0155] The substrate transferring mechanism 910 moves backward to pick up the substrate holders 907₇, and 907_r907₄ to the processing chambers 901-905 respectively. The substrates in the substrate holder 907₅ are ready to exit the plating system 900. These moving steps are repeated for a streamline process.

[0156] 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.

Claims

What is Claimed is:

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, 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.

4. The apparatus of claim 3, 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.

5. 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.

6. The apparatus of claim 5, 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; and 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, 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.

7. The apparatus of claim 5, 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.

8. 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.

9. The substrate processing system of claim 8, 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.

10. The substrate processing system of claim 9, 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.

11. The substrate processing system of claim 10, 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.

12. The substrate processing system of claim 8, 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.

13. The substrate processing system of claim 12, 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.

14. The substrate processing system of claim 12, 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.

15. The substrate processing system of claim 9, further comprising: a rinsing chamber configured to rinse the large area substrate after formation of a porous layer of the first metal in the second plating chamber, wherein the porous layer comprises at least one of macro porosity, micro-porosity; and a third plating chamber configured to plate a layer of a second metal over the porous layer.