WO2024081507A1

WO2024081507A1 - Electrodeposition system with ion-exchange membrane irrigation

Info

Publication number: WO2024081507A1
Application number: PCT/US2023/075229
Authority: WO
Inventors: Frederick Dean Wilmot; Nirmal Shankar SIGAMANI; Jingbin Feng
Original assignee: Lam Research Corporation
Priority date: 2022-10-11
Filing date: 2023-09-27
Publication date: 2024-04-18

Abstract

Examples are disclosed that relate to irrigating an ion exchange membrane in an electrodeposition system. In one example, the electrodeposition system comprises a fluid distribution system comprising a membrane assembly that comprises a membrane frame configured to support an ion exchange membrane that defines a boundary of a cathode chamber. The fluid distribution system further comprises a high resistance virtual anode (HRVA) positioned between the membrane frame and a substrate holder, a catholyte circulation loop operable to flow catholyte in a first direction across a surface of the HRVA facing the substrate holder and a plurality of flow barriers extending between the membrane frame and the HRVA along a second direction, transverse to the first direction. Irrigation conduits are positioned between adjacent flow barriers, each irrigation conduit configured to receive catholyte from the catholyte circulation loop and to direct catholyte towards the membrane assembly via a plurality of emitters.

Description

ELECTRODEPOSITION SYSTEM WITH ION-EXCHANGE MEMBRANE

IRRIGATION

BACKGROUND

[0001] Electroplating can be used in integrated circuit manufacturing processes to deposit electrically conductive films onto substrates. Electroplating involves the electrochemical reduction of dissolved ions of a selected metal to an elemental state on a substrate to form a film of the selected metal. Electroplating systems comprise a cathode chamber through which a catholyte solution circulates, and an anode chamber through which an anolyte solution circulates. An ion exchange membrane is positioned between the cathode chamber and anode chamber. The ion exchange membrane selectively allows some ions to pass from the anolyte to the catholyte while preventing the passage of other ions and organic additives.

SUMMARY

[0002] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0003] Examples are disclosed that relate to actively irrigating an ion exchange membrane in an electrodeposition system. In one example system, the electrodeposition system comprises a fluid distribution system. The fluid distribution system comprises a membrane assembly comprising a membrane frame configured to support an ion exchange membrane, the ion exchange membrane defining a boundary of a cathode chamber. The fluid distribution system further comprises a high resistance virtual anode (HRVA) positioned between the membrane frame and a substrate holder, a catholyte circulation loop operable to flow catholyte in a first direction across a surface of the HRVA facing the substrate holder and a plurality of flow barriers extending between the membrane frame and the HRVA along a second direction, transverse to the first direction. Irrigation conduits are positioned between adjacent flow barriers. Each irrigation conduit is configured to receive catholyte from the catholyte circulation loop and to direct catholyte towards the membrane assembly via a plurality of emitters.

[0004] In some such examples, the flow barriers alternatively or additionally are integrated with the membrane frame.

[0005] In some such examples, adjacent flow barriers alternatively or additionally define opposing walls of a segmented volume, and wherein the flow barriers alternatively or additionally comprise apertures proximal to the membrane frame, the apertures fluidly coupling adjacent segmented volumes.

[0006] In some such examples, the irrigation conduits alternatively or additionally are formed in a distribution manifold fluidly coupled to the catholyte circulation loop.

[0007] In some such examples, the distribution manifold alternatively or additionally is fluidly coupled to the catholyte circulation loop via an inlet manifold of the membrane frame.

[0008] In some such examples, the distribution manifold alternatively or additionally is fluidly coupled to the inlet manifold of the membrane frame via two or more inlet ports.

[0009] In some such examples, the distribution manifold alternatively or additionally comprises one or more outlet ports opposite the two or more inlet ports.

[0010] In some such examples, the membrane frame alternatively or additionally comprises a grid structure comprising a plurality of openings that expose the ion-exchange membrane.

[0011] In some such examples, the emitters alternatively or additionally are positioned to expel catholyte towards intersections of the grid structure.

[0012] In some such examples, the emitters alternatively or additionally are positioned to expel catholyte towards alternating intersections of the grid structure.

[0013] Another example provides a fluid distribution system for an electrodeposition system. The fluid distribution system comprises a membrane frame configured to support an ion exchange membrane, the membrane frame comprising a grid structure and a plurality of flow barriers extending from the grid structure. The fluid distribution system further comprises a plurality of irrigation conduits, each irrigation conduit of the plurality of irrigation conduits being configured to be positioned between adjacent flow barriers, to receive catholyte from a catholyte circulation loop and to direct the catholyte towards a membrane assembly via a plurality of emitters.

[0014] In some such examples, the flow barriers alternatively or additionally are integrated with the membrane frame.

[0015] In some such examples, the irrigation conduits alternatively or additionally are formed in a distribution manifold fluidly coupled to an inlet manifold of the membrane frame via two or more inlet ports.

[0016] In some such examples, the distribution manifold alternatively or additionally comprises one or more outlet ports opposite the two or more inlet ports.

[0017] In some such examples, the grid structure alternatively or additionally comprises a plurality of openings that expose the ion-exchange membrane, and wherein the emitters are positioned to expel catholyte towards intersections of the grid structure [0018] In some such examples, the emitters alternatively or additionally are positioned to expel catholyte towards alternating intersections of the grid structure.

[0019] Another example provides a method of irrigating an ion-exchange membrane in an electrodeposition system. The method comprises flowing catholyte across a HRVA in a first direction, the HRVA separated from the ion-exchange membrane by a membrane frame, the membrane frame including a plurality of flow barriers that extend from the membrane frame to the HRVA in a second direction, transverse to the first direction. The method further comprises diverting some catholyte to a distribution manifold comprising irrigation conduits positioned between adjacent flow barriers, each irrigation conduit configured to direct catholyte towards the membrane frame via a plurality of emitters.

[0020] In some such examples, diverting catholyte to the distribution manifold alternatively or additionally comprises diverting catholyte via two or more inlet ports fluidly coupled to an inlet manifold of the membrane frame, and the method alternatively or additionally comprises diverting catholyte to one or more outlet ports of the distribution manifold, the one or more outlet ports located opposite the inlet ports. [0021] In some such examples, directing catholyte towards the membrane frame via a plurality of emitters alternatively or additionally comprises expelling catholyte towards intersections of a grid structure of the membrane frame, the grid structure comprising a plurality of openings that expose the ion-exchange membrane. [0022] In some such examples, expelling catholyte towards intersections of the grid structure alternatively or additionally comprises expelling catholyte towards alternating intersections of the grid structure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0001] FIG. 1 shows a block diagram of an example electrodeposition tool.

[0002] FIG. 2 schematically shows an example electrodeposition cell comprising a fluid distribution system.

[0003] FIG. 3 illustrates an example fluid distribution system for an electrodeposition cell.

[0004] FIG. 4 illustrates an example membrane assembly for an electrodeposition cell comprising a fluid distribution system.

[0005] FIG. 5 illustrates an example distribution manifold and gasket for the membrane assembly of FIG. 4.

[0006] FIGS. 6A and 6B illustrate example constructions of a distribution manifold and gasket assembly.

[0007] FIG. 7 schematically illustrates an example flow-focusing manifold for a membrane assembly.

[0008] FIG. 8 schematically illustrates an example irrigation scheme for a flowfocusing manifold using a distribution manifold.

[0009] FIG. 9 shows example plots for inlet pressure within a flow-focused membrane assembly.

[0010] FIG. 10 shows a flow diagram depicting an example method of irrigating an ion-exchange membrane in an electrodeposition system.

DETAILED DESCRIPTION

[0011] The term “anode” may generally represent an electrically conductive structure at which electrochemical oxidation occurs during an electroplating process.

[0012] The term “anode chamber” may generally represent a physical structure configured to hold at least an anode and anolyte and that provides selective separation from a cathode chamber.

[0013] The term “anolyte” may generally represent a solution used in an anode chamber during an electroplating process. [0014] The term “aperture” may generally represent an opening that allows for flow of a solution between adjacent volumes.

[0015] The term “cathode” may generally represent a conductive layer on a substrate that is grown during electroplating by the electrochemical reduction of ions.

[0016] The term “cathode chamber” may generally represent a physical structure configured to hold at least a cathode and catholyte and that provides selective separation from an anode chamber.

[0017] The term “catholyte” may generally represent a solution used in a cathode chamber during an electroplating process.

[0018] The term “circulation loop” may generally represent a path along which a liquid is recirculated over time. The term circulation loop may generally represent a catholyte circulation loop and also may generally represent an anolyte circulation loop. [0019] The term “distribution manifold” may generally represent a structure that allows for a solution to be diverted from one conduit into multiple conduits.

[0020] The terms “electroplating”, “plating”, “deposition”, and variants thereof may generally represent a process in which dissolved ions of one or more metals are reduced on a substrate surface to form a film of the one or more metals.

[0021] The term “electrodeposition system” may generally represent a machine configured to perform electrodeposition.

[0022] The term “emitter” may generally represent a structure that directs flow of a solution out of a conduit.

[0023] The term “flow barrier” may generally represent a structure that impedes flow of a liquid or solution in a given direction.

[0024] The term “fluid distribution system” may generally represent a series of conduits, tubes, manifolds, pumps, inlets, and outlets configured to distribute fluid for an electrodeposition system.

[0025] The term “grid structure” may generally represent an array of component structures that meet at intersections to form a two-dimensional network with openings between the component structures.

[0026] The term “high resistance virtual anode” (HRVA) may generally represent an ionically resistive structure positioned between a substrate holder and an anode of an electroplating tool through which ions flow from the anode to a cathode during electroplating. A HRVA approximates a suitably constant and uniform current source in proximity to the cathode. [0027] The term “inlet manifold” may generally represent a set of chambers or conduits that intake a fluid from fluid source and distribute the fluid to one or more locations.

[0028] The term “inlet port” may generally represent a structure that acts as an entry way for fluid to ingress to a channel.

[0029] The term “intersection of the grid structure” may generally represent a point or region wherein component structures of a grid structure meet at an angle.

[0030] The term “ion exchange membrane” may generally represent a semi- permeable membrane that allows the transport of certain dissolved ions, but not other dissolved ions or neutrally charged molecules.

[0031] The term “irrigation conduits” may generally represent a set of tubes configured to receive catholyte at an inlet and to expel catholyte towards an ion exchange membrane via one or more emitters.

[0032] The term “membrane assembly” may generally represent a set of components that includes at least an ion exchange membrane, a membrane frame, and a portion of a catholyte circulation loop.

[0033] The term “membrane frame” may generally represent a device that supports an ion exchange membrane.

[0034] The term “outlet port” may generally represent a structure that acts as an exit way for fluid to egress from a channel.

[0035] The term “segmented volume” may generally represent a volume between flow barriers.

[0036] The term “substrate” represents any object on which a film can be deposited.

[0037] The term “substrate holder” may generally any structure for supporting a substrate during an electrodeposition process.

[0038] In the semiconductor processing industry, there is increasing demand to electrodeposit metals onto substrates rapidly while maintaining high uniformity. To meet this demand, electroplating technologies are tending toward higher plating currents, cooler plating bath temperatures, and chemistries that can support increased plating rates. For example, catholyte and anolyte solutions may comprise nearsaturation concentrations of metal salts. However, such conditions may lead to deposits of metal salt precipitates forming in an electroplating tool over time. [0039] As a more specific example, to achieve relatively higher copper electroplating growth rates, plating currents may exceed 10 Amperes. Further, catholytes and anolytes may contain nearly-saturated solutions of copper sulfate (CuSC ), sulfuric acid (H2SO4), and potentially other supporting additives. Copper electroplating may utilize a cation exchange membrane to separate anolyte and catholyte chambers to prevent the oxidation of organic additives at the anode. Example cation exchange membranes may comprise sulfonated tetrafluoroethylenebased fluoropolymer-copolymer. Metal ions passing through the cation exchange membranes from an anolyte to a catholyte add to the concentration of metal ions in the catholyte adjacent to the cation exchange membrane. This localized increase in concentration may lead to supersaturation of the catholyte solution at the cation exchange membrane under some conditions. Supersaturation may be a particular problem when the catholyte stagnates at the membrane surface. This may cause metal salt precipitates to form on the cation exchange membrane and/or adjacent structures. Low convection of the catholyte at this membrane also may lead to precipitate formation and crystal growth. Over time, precipitate buildup may passivate portions of the cation exchange membrane. This may negatively impact a uniformity of an electroplated film on a substrate.

[0040] Currently, a strategy for recovering the target substrate deposition profile for tools that suffer from precipitate accumulation is manual intervention. Manual intervention may involve removing/replacing the affected membranes and parts. Such intervention may be time consuming and relatively expensive due at least to the cost of parts and impact to tool uptime. Other strategies, such as reducing metal ion concentrations and/or electric currents used for electroplating, may reduce tool utility. Plating bath temperatures may be increased, but this may necessitate the introduction of additives. Such additives may impact a plating process.

[0041] Accordingly, examples are disclosed that relate to irrigating an ion exchange membrane in order to reduce catholyte stagnation at the membrane. Reducing catholyte stagnation may help to reduce the buildup of metal salt precipitates. The disclosed examples use a fluid distribution system to increase flow at the ion exchange membrane. Further, the disclosed examples may directly focus flow on the membrane itself. The disclosed examples may help to avoid part replacement due to precipitate buildup. This may decrease the overall impact of precipitate removal on tool uptime. Further, reducing buildup may result in more consistent and uniform plating over time. The disclosed examples are described primarily in the context of copper electrodeposition tools and copper sulfate crystal buildup at an ion exchange membrane. However, the disclosed examples may be used with any suitable chemistry on any suitable electrodeposition tool. The disclosed processes are non-invasive. Thus, the disclosed processes may be performed without breaking the plane of an electrodeposition tool.

[0042] As an example, a membrane frame configured to support an ion exchange membrane may be configured to divert some of the catholyte solution to a distribution manifold which directs flow across the ion exchange membrane surface. This flow helps to reduce a risk of stagnant fluid, particularly near corner and outlet regions of the membrane frame. The flow thus may help to prevent crystal formation. [0043] FIG. 1 schematically shows a block diagram of an example electrodeposition tool 100. Electrodeposition tool 100 comprises an electrodeposition cell 102 comprising an anode chamber 104 and a cathode chamber 106. Electrodeposition tool 100 further comprises an ion exchange membrane 108 separating the anode chamber 104 and the cathode chamber 106, and a HRVA 109 within cathode chamber 106. Anode chamber 104 comprises an anode 110. Anode chamber 104 further comprises an anolyte. Cathode chamber 106 comprises a catholyte. The catholyte comprises an ionic species to be deposited on a cathode layer of a substrate 111 as a metal by electrochemical reduction. In some examples, anode 110 may comprise a consumable anode formed from the metal being deposited. In other examples, anode 110 may comprise an inert anode. Where anode 110 comprises the metal being deposited, electrochemical oxidation of anode 110 at least partially replenishes the ionic species consumed by the electroplating process. Bulk anolyte and/or catholyte solutions may be added at times to replenish the ionic species.

[0044] Ion exchange membrane 108 prevents organic species and some ionic species from crossing between cathode chamber 106 and anode chamber 104, while allowing selected ions to cross from anode chamber 104 to cathode chamber 106. As an example, ion exchange membrane 108 may allow metal ions to cross from anode chamber 104 to cathode chamber 106 for plating. As mentioned above, HRVA 109 comprises an ionically resistive element that approximates a suitably constant and uniform current source in proximity to a substrate cathode.

[0045] Substrate holder 112 is coupled to a substrate holder movement system 113 comprising a lift 114 that is configured to adjust a spacing between substrate holder 112 and HRVA 109. For example, lift 114 may lower substrate holder 112 to position substrate 111 within the catholyte for electroplating. Lift 114 further may raise substrate holder 112 from the catholyte after electroplating. Substrate holder movement system 113 further may comprise components to control the opening and closing of substrate holder 112.

[0046] The catholyte may be circulated between cathode chamber 106 and a catholyte reservoir 120 via a combination of gravity and one or more pumps 122. Likewise, the anolyte may be circulated through anolyte reservoir 124 and anode chamber 104 via a combination of gravity and one or more pumps 126.

[0047] FIG. 2 schematically shows an example electrodeposition system 200 comprising an electroplating cell 202. Electroplating cell 202 is an example of electrodeposition cell 102 of FIG. 1. Electroplating cell 202 comprises an anode chamber 204 and a cathode chamber 206. Electroplating cell 202 further comprises a cation exchange membrane 208 defining a boundary between anode chamber 204 and cathode chamber 206. Cation exchange membrane 208 is an example of ion exchange membrane 108. A substrate holder 210 is configured to hold and position a substrate 212 such that a deposition surface of substrate 212 is positioned within cathode chamber 206.

[0048] Anode chamber 204 comprises an anolyte bath 216 in which anode 218 is disposed. In this example, anode 218 comprises a copper metal anode. In other examples, anode 218 may comprise another consumable anode, or an inert anode. A voltage source 219 applies a voltage across substrate 212 and anode 218 to drive flow of metal ions for deposition on substrate 212.

[0049] Anolyte bath 216 is located within an anolyte circulating loop 220. Anolyte enters anode chamber 204 at inlet 222 and exits at outlet 224. Anolyte circulating loop 220 comprises a heater 226 (e.g. a heater/chiller) configured to adjust and/or maintain a temperature of anolyte flowing through anolyte circulating loop 220. Electroplating cell 202 further comprises a fluid distribution system 230. Fluid distribution system 230 comprises a membrane assembly 232 comprising a membrane frame 234 configure to support ion exchange membrane 208. Fluid distribution system 230 further comprises HRVA 236 positioned between membrane frame 234 and substrate holder 210.

[0050] Fluid distribution system 230 supplies cathode chamber 206 with a catholyte bath 238 that comprises ionic copper (Cu²⁺) to be deposited onto substrate 212 that acts as a cathode. Catholyte bath 238 is located within a catholyte circulating loop 240. Catholyte enters cathode chamber 206 at inlet 242 and exits at outlet 244. Catholyte circulating loop 240 comprises a heater 246 (e.g. a heater/chiller) configured to adjust and/or maintain a temperature of catholyte flowing through catholyte circulating loop 240.

[0051] For copper electroplating, in some examples, anode 218 may comprise copper pieces (e.g. balls) or a copper slab, as examples. As mentioned above, in other examples, anode 218 may comprise an inert anode. In the depicted example, the applied voltage causes oxidation of copper metal to Cu²⁺ at anode 218. Cation exchange membrane 208 passes Cu²⁺ ions from anolyte bath 216 to catholyte bath 238. The Cu²⁺ ions crossing cation exchange membrane 208 replace at least some copper ions in catholyte bath 238 that are reduced onto substrate 212.

[0052] Heater 246 may be controlled to maintain catholyte bath 238 at a predetermined process temperature during an electroplating process. Heater 226 similarly may be controlled maintain anolyte bath 216 at a predetermined process temperature during an electroplating process. The process temperature may comprise a relatively low temperature in some processes. For example, a process temperature in a range of 22-26 °C may be used in some copper deposition processes.

[0053] As mentioned above, some electroplating conditions may increase a concentration of dissolved copper ions in a catholyte near the cation exchange membrane surface. The resulting concentration may exceed the solubility limit of the catholyte solvent (e.g. water) at the process temperature. This may result in the formation of crystals at the cation exchange membrane. In the example of FIG. 2, Cu²⁺ ions in anolyte bath 216 pass through cation exchange membrane 208 and into catholyte bath 238. Thus, the catholyte just above cation exchange membrane 208 contains ions both from the catholyte in catholyte bath 238 and the additional Cu²⁺ from anolyte bath 216. The additional Cu²⁺ concentration increases as plating current increases.

[0054] Without adequate convection of catholyte to remove excess Cu²⁺ ions, the solution above the cation exchange membrane may precipitate solid copper salts onto the cation exchange membrane. CuSC may be a primary component of the copper salt precipitates. Copper-containing catholytes also may comprise chloride and sulfonate anions. These anions also may form copper precipitates. Metal salt precipitates also may occur in other electroplating chemistries. Examples include tin and tin-silver alloys. For tin-silver, example counter anions comprise methylsulfonic acid and organic acids. Precipitates also may occur for other electroplating metals, including cobalt, indium, and nickel.

[0055] The presence of metal salt precipitates on cation exchange membrane 208 may block fluid transport and electrical current distribution. This condition may be referred to as passivation. If areas of the cation exchange membrane are partially or fully passivated, non-uniform current distribution may result. This may lead to nonuniform plating of metal onto a substrate. In some examples, one or more sensors may be positioned in and around electroplating cell 202 to monitor conditions and to provide indications of non-uniformity that may be indicative of metal salt precipitate accumulation. Example sensors include a cathode current sensor array and/or one or more optical sensors.

[0056] Passive irrigation may not be sufficient to reduce catholyte stagnation at cation exchange membrane 208. Thus, the disclosed examples utilize an active irrigation system to avoid stagnation and the resulting risk of metal salt precipitate formation.

[0057] Catholyte circulating loop 240 is operable to flow catholyte in a first direction across a surface of HRVA 236 . This direction is indicated by arrows between inlet 242 and outlet 244. As an example, some of the catholyte is ported through channels in membrane frame 234 leading to inlet holes in a plate supporting HRVA 236. This may be referred to as an under-flow HRVA. One or more outlet holes in such a plate may then couple the catholyte back to catholyte circulating loop 240 on the opposite side via outlet 244.

[0058] In this example, a plurality of flow barriers 248 extend between membrane frame 234 and HRVA 236 along a second direction, transverse to the first direction. This configuration may be referred to as a flow-focusing manifold. Flow barriers 248 may prevent flow from running under HRVA 236. This may reduce the fluid pressure needed to flow catholyte across HRVA 236. This may help to maintain or improve plating performance at substrate 212.

[0059] Additionally, membrane frame 234 includes an inlet manifold 250 to receive and distribute catholyte from catholyte circulating loop 240. Some of the received catholyte may be directed across HRVA 236 as described. At least some of the received catholyte may be diverted to a plurality of irrigation conduits 252 positioned between adjacent flow barriers 248. [0060] Irrigation conduits 252 are depicted as being positioned between adjacent flow barriers 248. Each irrigation conduit 252 may be configured to receive catholyte from catholyte circulating loop 240 and to direct catholyte towards membrane assembly via a plurality of emitters (e.g., as indicated by arrows). Irrigation conduits 252 may thus provide directed flow of catholyte towards the cation exchange membrane 208, thus irrigating the substrate-facing side of cation exchange membrane 208.

[0061] FIG. 3 shows a cross-section of an example membrane assembly 300. Membrane assembly 300 may be an example of membrane assembly 232. Membrane assembly 300 comprises membrane frame 302, ion exchange membrane 304 and HRVA 306. HRVA 306 may mount to a surface of membrane frame 302 (e.g., an upper surface). Ion exchange membrane 304 may be clamped or otherwise affixed to an opposite side (e.g., underside) of membrane frame 302 from HRVA 306. In this example, membrane frame 302 comprises a grid structure comprising a plurality of gaps openings 308 where ion exchange membrane 304 is exposed to fluid on either side.

[0062] Flow barriers 310 are integrated with membrane frame 302. Flow barriers 310 run transverse to the direction of fluid flow across HRVA 306. The flow barriers 310 extend across membrane frame 302. In this example, flow barriers 310 are integrally formed with portions of the grid structure. For example, every other cross bar of the grid may extend from membrane frame 302 towards HRVA 306 in order to prevent catholyte flow from running under HRVA 306. In some examples, a gasket is positioned in between flow barriers 310 and HRVA 306.

[0063] Adjacent flow barriers 310 thus define opposing walls of segmented volumes 312. Flow barriers 310 comprise apertures 314 proximal to membrane frame 302. The term “proximal to membrane frame” may generally represent a location closer to ion exchange membrane 304 than to HRVA 306 when membrane assembly 300 is assembled. Apertures 314 fluidly couple adjacent segmented volumes 312. Apertures 314 increase irrigation of increase irrigation of ion exchange membrane 304 by allowing some catholyte to transverse flow barriers 310 from high (e.g., inlet) to low (e.g., outlet) pressure and flowing between adjacent segmented volumes 312.

[0064] Irrigation conduits 316 extend centrally through each segmented volume 312 and operate to emit catholyte to irrigate the underlying exposed openings 308 of ion exchange membrane 304. Irrigation conduits 316 may be composed of a nonconducting material, such as a polymer or ceramic so as to reduce any electric fields that may interfere with the electrodeposition process. [0065] Each irrigation conduit 316 includes a plurality of emitters 318. In some examples, emitters 318 direct catholyte towards the grid structure of membrane frame 302. For example, emitters 318 may be designed to emit catholyte towards intersections of the grid structure. However, other configurations are contemplated. In some examples, emitters 318 direct catholyte flow normal to the surface of the respective irrigation conduit. However, some or all emitters may have directional output, such as a nozzle. This may allow advantageous placement of emitters 318, adjustable emission directions, and/or emissions targeted to regions likely to develop crystal growth.

[0066] FIG. 4 shows a cut-away exploded view of an example membrane assembly 400 for an electrodeposition cell comprising a fluid distribution system. Membrane assembly 400 may be an example of membrane assemblies 232 and 300. Membrane assembly 400 comprises a membrane frame 402 configured to support an ion exchange membrane 404. Membrane frame 402 comprises a plurality of flow barriers 406, and an inlet manifold 408 configured to receive catholyte from a catholyte circulation loop.

[0067] A distribution manifold 410 is configured to connect to membrane frame 402 for integration with membrane frame 402 via outer groove 411. Distribution manifold 410 comprises a plurality of irrigation conduits 412, each including a number of emitters 414. Distribution manifold 410 may be fluidly coupled to the catholyte circulation loop via inlet manifold 408. In some examples, membrane frame 402 may be routed to accommodate fluid inlets of distribution manifold 410.

[0068] When in position, distribution manifold 410 may be fluidly coupled to inlet manifold 408 of membrane frame 402 via two or more inlet ports. In this example, three inlet ports 415, 416, and 417 are shown arranged around the perimeter of membrane frame 402. Inlet ports 415, 416, and 417 extend from inlet manifold 408 to distribution manifold 410, delivering catholyte to distribution manifold 410.

[0069] In some examples, additional inlet ports may be included, though some or all of these ports may be capable of being plugged, e.g., via a threaded or press fit plug. In this way, the fluid pressure profile of membrane assembly 400 may be adjusted. Such adjustment may be performed dynamically by a controllable valve, during maintenance, or during installation. For example, different plating applications may demand different flow rates through the catholyte circulation loop. Different substrate positioning relative to the HRVA may also influence the flow and pressure through distribution manifold 410. [0070] The manifolding allows for approximately equal flow to be output from each emitter of irrigation conduits 412 in some examples, including the emitters located farthest from the inlet ports. The size of the emitters compared to the size of the channel for a given flow rate allows for the pressure drop between the inlets and the far side of the manifold to be suitably low. Such consistent pressure generates consistent flow through the emitters.

[0071] An electrical shield (not shown) may also be fitted into outer groove 411. The thickness of such an electrical shield influences plating on the substrate. By using a thinner distribution manifold, such as described further with regard to FIG. 6B, the backside insert can be made to be relatively thicker. In such a configuration, it may be advantageous to have a larger inlet flow volume. The depicted three inlet ports may provide a suitable flow volume.

[0072] FIG. 5 illustrates an exploded view 500 of distribution manifold 410 and an associated gasket 510 for the membrane assembly of FIG. 4. Distribution manifold 410 comprises a HRVA-facing piece 515 and a membrane-facing piece 517. Distribution manifold 410 is shown comprising a pair of outlet ports 522 and 523 opposite inlet ports 415, 416, and 417. Outlet ports 522 and 523 may include circular ports as shown, and/or elongated ports, such as an arc extending around a length of the distribution manifold.

[0073] In this example, outlet ports 522 and 523 are routed into membranefacing piece 517 and gasket 510. Emitters 525 are arrayed along cross pieces of membrane-facing piece 517.

[0074] Gasket 510 may be used to generate a seal when mounting distribution manifold 410 to membrane frame 402. While shown with a similar footprint to distribution manifold 410, gasket seals off inlet ports 415, 416, and 417, and outlet ports 522 and 523. Gasket 510 thus may be shaped differently in other examples while accommodating these ports. Gasket 510 may be made from an elastomeric material. Further, gasket 520 may be bonded to membrane-facing piece 517.

[0075] FIG. 6A and 6B show two example constructions for a distribution manifold and gasket assembly. In various examples, distribution manifold 410 may be routed or 3D printed as one piece or an assembly of interlocking pieces. In these examples, two parts with equivalent footprints are overlaid and joined to form a distribution manifold. For example, a HRVA-facing piece and a membrane-facing piece may be routed and then solvent bonded together. [0076] Distribution manifold and gasket assembly 600 includes a HRVA-facing piece 602, a membrane-facing piece 604, and a gasket 606. An inlet port 608 is shown in gasket 606. Portions of HRVA-facing piece 602 and membrane-facing piece 604 generate an irrigation conduit 610 with an emitter 612 formed in membrane-facing piece 604. In this example, both HRVA-facing piece 602 and membrane-facing piece 604 have depth, and may be routed to form a relatively thick construction for a distribution manifold.

[0077] Distribution manifold and gasket assembly 620 includes a HRVA-facing piece 622, a membrane-facing piece 624, and a gasket 626. An inlet port 628 is shown in gasket 626. Portions of HRVA-facing piece 622 and membrane-facing piece 624 generate an irrigation conduit 630 with an emitter 632 formed in membrane-facing piece 624. In this example, membrane-facing piece 624 is flat, with openings routed for emitters, inlet ports, and outlet ports.

[0078] FIGS. 7 and 8 illustrate an example membrane frame 700. Membrane frame 700 comprises a grid structure 702 comprising a plurality of openings 704 that expose an underlying cation exchange membrane. As such, membrane frame 700 may be an example of membrane frame 300.

[0079] Membrane frame 700 comprises a plurality of flow barriers 706, which extend from alternate grid lines in a direction transverse to flow of catholyte across the HRVA, as indicated by the arrow. The grid structure accommodates the positioning of the flow barriers in a way that may help to avoid disrupting conductivity through the cation exchange membrane. Membrane frame 700 comprises inlet ports 708. Inlet ports 708 receive catholyte from a catholyte circulating loop. Membrane frame 700 further comprises an outlet port 710. Outlet port 710 directs catholyte back into the catholyte circulating loop.

[0080] As shown in FIG. 3, irrigation conduits of a distribution manifold may be positioned within segmented volumes between adjacent flow barriers. This is schematically shown in FIG. 8 at 800. Irrigation conduits 802, 804, and 806 alternate with flow barriers 706. Each irrigation conduit includes a plurality of emitters 810, indicated by circles. In some examples, emission may be directed to adjacent portions of grid structure 702, thereby stirring up nearby catholyte without directing the flow directly against an ion exchange membrane.

[0081] Emitters 810 are positioned to expel catholyte towards intersections of grid structure 702. In this example, the emitters are positioned to expel catholyte towards alternating intersections of the grid structure. In this way, the irrigation conduits generate a collective uniform distribution of catholyte across membrane frame 700 between flow barriers 706.

[0082] As shown at 820, an emitter 810 expels catholyte as a jet of fluid which impinges an intersection 822 of grid structure 702, causing distribution of the emitted catholyte to the neighboring openings 704. Due to the presence of flow barriers 706, segregated volumes are formed in the membrane assembly. As such, fluid expelled from one emitter 810 does not impact the membrane irrigation in adjacent segregated volumes. The distribution manifold may thus be configured with multiple conduits, one or more per segregated volume, so that each segregated volume is irrigated. This ensures suitably even irrigation across whole membrane surface.

[0083] FIG. 9 shows example plots illustrating inlet pressure (e.g., pounds per square inch) over a range of plating pump total flow (e.g., liters per minute) for different plating gap distances. Plot 900 shows inlet pressure for scenarios where no distribution manifold is engaged, while plot 910 shows inlet pressure for a scenario where the distribution manifold is engaged. Each plot indicates pressure vs flow rate for plating gaps (e.g., between the top of a HRVA and the bottom of a substrate)ranging from a reference position and increased distances (arbitrary units +1.5, +2.5, +3.5 from reference) , and for a scenario where the substrate is not engaged (e.g., no plate).

[0084] For all plating gaps, the trends for inlet pressure are similar whether the distribution manifold is engaged (plot 910) or not engaged (plot 900). As such, a device with a distribution manifold engaged may perform similarly for electrodeposition scenarios over a range of pressures and a range of plating gaps that is similar to models without such a distribution manifold.

[0085] With such flow/pressure data it is also possible to model pressure of catholyte being expelled from the manifold emitters. In one example, emitter apertures on the order of 0.025-0.05 inches in diameter were simulated. At some flow rates, having apertures approximately 0.035 inches in diameter allowed for balanced flow across each emitter, while larger apertures generated unbalanced flow and smaller apertures caused choked flow. However, the performance may vary based on the dimensions of the distribution manifold among other factors.

[0086] FIG. 10 shows a flow diagram depicting an example method 1000 of irrigating an ion-exchange membrane in an electrodeposition system. Method 1000 may be performed by any suitable electrodeposition system comprising a fluid distribution system, such as electrodeposition system 200.

[0087] At 1010, method 1000 comprises flowing catholyte across a high resistance virtual anode (HRVA) in a first direction. The HRVA is separated from the ion-exchange membrane by a membrane frame Further, the membrane frame includes a plurality of flow barriers that extend from the membrane frame to the HRVA in a second direction, transverse to the first direction. The membrane frame may be routed to receive catholyte from a catholyte circulating loop into an inlet manifold. Further, the membrane frame is configured to direct the catholyte in the first direction.

[0088] At 1020, method 1000 comprises diverting some catholyte to a distribution manifold comprising irrigation conduits positioned between adjacent flow barriers. Each irrigation conduit is configured to direct catholyte towards the membrane frame via a plurality of emitters. In some such examples, diverting catholyte to the distribution manifold comprises diverting catholyte via two or more inlet ports fluidly coupled to an inlet manifold of the membrane frame. In such examples, method 1000 may further comprise diverting catholyte to one or more outlet ports of the distribution manifold. The one or more outlet ports are located opposite the inlet ports. In some such examples, directing catholyte towards the membrane frame via a plurality of emitters comprises expelling catholyte towards intersections of a grid structure of the membrane frame. The grid structure defines a plurality of openings that expose the ionexchange membrane. In some such examples, as shown in FIG. 8, expelling catholyte towards intersections of the grid structure comprises expelling catholyte towards alternating intersections of the grid structure.

[0089] It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and/or described may be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

[0090] The subject matter of the present disclosure includes all novel and non- obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.

Claims

CLAIMS:

1. An electrodeposition system, comprising: a fluid distribution system, comprising a membrane assembly comprising a membrane frame configured to support an ion exchange membrane, the ion exchange membrane defining a boundary of a cathode chamber; a high resistance virtual anode (HRVA) positioned between the membrane frame and a substrate holder; a catholyte circulation loop operable to flow catholyte in a first direction across a surface of the HRVA facing the substrate holder; a plurality of flow barriers extending between the membrane frame and the HRVA along a second direction, transverse to the first direction; and irrigation conduits positioned between adjacent flow barriers, each irrigation conduit configured to receive catholyte from the catholyte circulation loop and to direct catholyte towards the membrane assembly via a plurality of emitters.

2. The electrodeposition system of claim 1, wherein the flow barriers are integrated with the membrane frame.

3. The electrodeposition system of claim 1, wherein adjacent flow barriers define opposing walls of a segmented volume, and wherein the flow barriers comprise apertures proximal to the membrane frame, the apertures fluidly coupling adjacent segmented volumes.

4. The electrodeposition system of claim 1, wherein the irrigation conduits are formed in a distribution manifold fluidly coupled to the catholyte circulation loop.

5. The electrodeposition system of claim 4, wherein the distribution manifold is fluidly coupled to the catholyte circulation loop via an inlet manifold of the membrane frame. The electrodeposition system of claim 5, wherein the distribution manifold is fluidly coupled to the inlet manifold of the membrane frame via two or more inlet ports. The electrodeposition system of claim 6, wherein the distribution manifold comprises one or more outlet ports opposite the two or more inlet ports. The electrodeposition system of claim 1, wherein the membrane frame comprises a grid structure comprising a plurality of openings that expose the ion-exchange membrane. The electrodeposition system of claim 8, wherein the emitters are positioned to expel catholyte towards intersections of the grid structure. The electrodeposition system of claim 9, wherein the emitters are positioned to expel catholyte towards alternating intersections of the grid structure. A fluid distribution system for an electrodeposition system, the fluid distribution system comprising: a membrane frame configured to support an ion exchange membrane, the membrane frame comprising a grid structure and a plurality of flow barriers extending from the grid structure; and a plurality of irrigation conduits, each irrigation conduit of the plurality of irrigation conduits being configured to be positioned between adjacent flow barriers, to receive catholyte from a catholyte circulation loop and to direct the catholyte towards a membrane assembly via a plurality of emitters. The fluid distribution system of claim 11, wherein the flow barriers are integrated with the membrane frame. The fluid distribution system of claim 12, wherein the irrigation conduits are formed in a distribution manifold fluidly coupled to an inlet manifold of the membrane frame via two or more inlet ports, The fluid distribution system of claim 13, wherein the distribution manifold comprises one or more outlet ports opposite the two or more inlet ports. The fluid distribution system of claim 11, wherein the grid structure comprises a plurality of openings that expose the ion-exchange membrane, and wherein the emitters are positioned to expel catholyte towards intersections of the grid structure. The fluid distribution system of claim 15, wherein the emitters are positioned to expel catholyte towards alternating intersections of the grid structure. A method of irrigating an ion-exchange membrane in an electrodeposition system, comprising: flowing catholyte across a high resistance virtual anode (HRVA) in a first direction, the HRVA separated from the ion-exchange membrane by a membrane frame, the membrane frame including a plurality of flow barriers that extend from the membrane frame to the HRVA in a second direction, transverse to the first direction; and diverting some catholyte to a distribution manifold comprising irrigation conduits positioned between adjacent flow barriers, each irrigation conduit configured to direct catholyte towards the membrane frame via a plurality of emitters. The method of claim 17, wherein diverting catholyte to the distribution manifold comprises diverting catholyte via two or more inlet ports fluidly coupled to an inlet manifold of the membrane frame, and wherein the method further comprises diverting catholyte to one or more outlet ports of the distribution manifold, the one or more outlet ports located opposite the inlet ports. The method of claim 17, wherein directing catholyte towards the membrane frame via a plurality of emitters comprises expelling catholyte towards intersections of a grid structure of the membrane frame, the grid structure comprising a plurality of openings that expose the ion-exchange membrane. The method of claim 19, wherein expelling catholyte towards intersections of the grid structure comprises expelling catholyte towards alternating intersections of the grid structure.