Patterned printhead and resistive anode for electrodeposition thickness distribution control

Abstract

In a plating chamber, a metal may be plated on a semiconductor substrate, the plating chamber being provided with an array of micro inert anodes proximate to the semiconductor substrate having one or more chips. The micro inert anode array comprises a plurality of independently controllable micro inert anode elements. The current applied to the micro inert anode elements may form a current distribution in an array, which may be based at least in part on chip layout in the semiconductor substrate, or at least in part on global correction within the wafer. This current distribution can achieve a uniform plating thickness even if the feature distribution in the semiconductor substrate chip is not uniform. In some implementations, the current distribution in the array may be adjusted according to a rotation path of the semiconductor substrate during rotation of the substrate.

Description

[0001] Incorporated by Reference The specification of the PCT Application Table, filed concurrently herewith, is hereby incorporated by reference in its entirety and made part of this specification for all purposes. Each of the applications listed in the concurrently filed PCT Application Table from which this application claims benefit of or priority is hereby incorporated by reference in its entirety and for all purposes. TECHNICAL FIELD

[0002] The implementations herein relate to methods and apparatus for electroplating metal on a semiconductor wafer. More specifically, the methods and apparatus described herein relate to electroplating metal on a chip layout of a semiconductor wafer. BACKGROUND

[0003] In semiconductor device fabrication, a conductive material (e.g., copper) is often deposited by electroplating onto a metal seed layer to fill one or more recessed features on a semiconductor wafer. Electroplating is a common method for depositing metal into vias and trenches of a wafer in a damascene process, and is also used for through-resist plating in wafer-level packaging (WLP) applications to form metal pillars and metal lines. Another application of electroplating is to fill through-silicon vias (TSVs), which are relatively large vertical electrical connections used in 3D integrated circuits and 3D packaging.

[0004] In certain electroplating processes, prior to electroplating (typically in damascene and TSV processes), a conductive seed layer covers the entire substrate surface, and electroplating of the metal occurs across the entire substrate. The electroplating can be performed in a manner that facilitates deposition of the entire seed metallized surface into the recess. This is sometimes referred to as fill from the bottom up. In other electroplating processes, a portion of the seed layer is covered by a non-conductive masking material (e.g., photoresist), and another portion of the seed layer is exposed. For a substrate with a partially masked seed layer, electroplating occurs only on the exposed portion of the seed layer, while the covered portion of the seed layer is protected from electroplating. Electroplating on a substrate with a seed layer coated with a patterned masking material (e.g., photoresist) is referred to as masked electroplating, and is typically used in wafer-level packaging (WLP) applications.

[0005] Manufacturing of semiconductor devices often involves a series of steps to form fine line interconnects and other metal features. For example, in 3D packaging, a WLP application can involve forming a conductive seed layer on a semiconductor substrate, forming a photoresist layer on the conductive seed layer, and exposing and developing the photoresist layer to define a pattern therein, where the pattern is typically repeated in size and shape, which can be referred to as a "die." After the metallization operation, the semiconductor wafer is typically sliced ("diced") into functionally identical entities (referred to as "dies"), which are then subjected to further packaging operations involving other semiconductor wafers and dies.

[0006] Typically, lines, pads, and pillars are electroplated to establish bonds between substrates and to establish electrical connections for interconnections within and between chips of different functionality. It is generally desirable for electroplating to produce acceptable within-die (WID), within-wafer (WIW), and within-feature (WIF) electroplating non-uniformity.

[0007] The background description provided herein is for the purpose of generally presenting the context of the disclosure. The work of the presently named inventors in this regard, as described in this Background section, as well as aspects of the description that can not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. SUMMARY

[0008] Aspects of the present disclosure relate to a print head that can be characterized by: (a) a template layer comprising a non-conductive material having recesses or openings that define a pattern of conductive material to be printed on a substrate; (b) a conductive layer that covers the pattern of conductive material; and (c) a resistive intermediate layer disposed between the template layer and the conductive layer. In certain embodiments, the template layer contacts the resistive intermediate layer, which contacts the conductive layer.

[0009] In certain embodiments, the resistive layer has an electrical conductivity of about 10 -5 to 10 -7 S / cm. In certain embodiments, the resistive layer has a thickness that is no greater than about 0.1 times a minimum pitch of the pattern of conductive material to be printed on a substrate. In certain embodiments, the resistive layer has a thickness of about 0.1 microns to 10 microns. In certain embodiments, the resistive layer comprises a carbon film.

[0010] In certain embodiments, the conductive layer has a sheet resistance of at most about 0.1 ohm / square. In certain embodiments, the conductive layer has a thickness of about 0.01 microns to 10 microns. In certain embodiments, the conductive layer comprises copper, nickel, cobalt, titanium, or any combination thereof.

[0011] In certain embodiments, the non-conductive material of the template layer comprises glass, a polymer, a ceramic, or any combination thereof.

[0012] In certain embodiments, the recesses or openings in the template layer have a thickness of about 5 microns to 300 microns. In certain embodiments, the pattern of conductive material to be printed on the substrate comprises a WLP pattern. In certain cases, the WLP pattern is an RDL pattern. In certain cases, the WLP pattern is a pillar pattern.

[0013] In certain embodiments, the print head further comprises a conductive contact connected with the conductive layer to apply a power potential to the conductive layer. In certain cases, the conductive contact is in contact with a peripheral portion of the conductive layer. For example, the conductive contact can be in contact with a peripheral portion of the conductive layer at multiple points and is configured to provide a substantially uniform current distribution around the peripheral portion of the conductive layer.

[0014] Aspects of the present disclosure relate to methods of printing features on a substrate. Such methods can be characterized by: (I) electroplating metal into a recess of a print head, wherein the print head comprises: (a) a template layer comprising a non-conductive material having a recess or opening that defines a pattern of features to be printed on a substrate; (b) a conductive layer that substantially covers an entire area of the recess or opening; and (c) a resistive intermediate layer disposed between the template layer and the conductive layer; and (II) electroplating the metal in the recess of the print head template onto the substrate to print the features on the substrate.

[0015] In certain embodiments, electroplating the metal into the recess of the print head comprises applying a cathodic potential to the conductive layer relative to a counter electrode. In certain embodiments, electroplating the metal into the recess of the print head comprises electroplating the metal from a secondary electrode used as the counter electrode. In certain embodiments, electroplating the metal into the recess of the print head comprises electroplating the metal onto an exposed portion of the resistive intermediate layer.

[0016] In certain embodiments, electroplating the metal into the recess of the print head comprises flowing an electrolyte over a surface of the template layer.

[0017] In certain embodiments, electroplating the metal in the recess of the print head template onto the substrate comprises applying an anodic potential to the conductive layer relative to the substrate.

[0018] In certain embodiments, electroplating the metal in the recess of the print head template onto the substrate comprises contacting the template layer with the substrate without contacting the metal electroplated into the recess of the print head template with the substrate.

[0019] In certain embodiments, the method further comprises electroplating a second metal into the recesses of the print head, thereby forming a layer of the metal and a layer of the second metal within the recesses of the print head. In certain implementations, electroplating the metal in the recesses of the print head stencil onto the substrate is performed after electroplating the second metal into the recesses of the print head. In certain embodiments, electroplating the metal in the recesses of the print head stencil onto the substrate results in printing a stack of the metal and the second metal on the substrate.

[0020] Certain aspects of the present disclosure relate to an electroplating platform, which can be characterized by: (I) a print head comprising recess features defining a pattern to be printed on a substrate; (II) a chamber comprising: (i) a support configured to hold the substrate; and (ii) a support configured to hold a secondary anode; and (III) a controller configured to: (i) electroplate a metal from the secondary anode into the recess features of the print head; and (ii) electroplate the metal in the recess features of the print head onto the substrate.

[0021] In certain embodiments, the print head comprises: (a) a stencil layer comprising a non-conductive material having recesses or openings defining the pattern of the conductive material to be printed on a substrate; (b) a conductive layer substantially covering the entire pattern of the conductive material; and (c) a resistive intermediate layer disposed between the stencil layer and the conductive layer.

[0022] In certain embodiments, the resistive layer has an electrical conductivity of about 10 -5 to 10 -7 S / cm. In certain embodiments, the resistive layer has a thickness no greater than about 0.1 times a smallest pitch of the pattern of the conductive material to be printed on a substrate.

[0023] In certain embodiments, the conductive layer comprises copper, nickel, cobalt, titanium, or any combination thereof.

[0024] In certain embodiments, the non-conductive material of the stencil layer comprises glass, polymer, ceramic, or any combination thereof.

[0025] In certain embodiments, the pattern of the conductive material to be printed on the substrate comprises a WLP pattern.

[0026] In certain embodiments, the secondary anode is disposed about a perimeter of the print head while metal is electroplated from the secondary anode into the recessed features of the print head. In certain embodiments, the secondary anode is substantially planar and is aligned substantially parallel to and facing the recessed features of the print head during electroplating of metal from the secondary anode into the recessed features of the print head.

[0027] In certain embodiments, the controller is further configured to cause: (i) a first gap between the print head and the substrate while metal is electroplated from the secondary anode into the recessed features of the print head; and (ii) a second gap between the print head and the substrate while the metal in the recessed features of the print head is electroplated onto the substrate, wherein the second gap is less than the first gap. In certain embodiments, the print head contacts the substrate while the metal in the recessed features of the print head is electroplated onto the substrate.

[0028] In certain embodiments, the chamber is configured to induce convection above the recessed features of the print head while metal is electroplated from the secondary anode into the recessed features of the print head. In certain embodiments, the chamber is configured to flow electrolyte substantially parallel to a surface of the print head while metal is electroplated from the secondary anode into the recessed features of the print head. In certain embodiments, the chamber is configured to rotate the print head while metal is electroplated from the secondary anode into the recessed features of the print head.

[0029] Certain aspects of the present disclosure relate to methods of fabricating a print head. Such methods can be characterized by: (I) forming a conductive layer of conductive material having a substantially uniform thickness; (II) forming a resistive intermediate layer on the conductive layer, wherein the resistive intermediate layer has a substantially uniform thickness of resistive material; and (III) forming a template layer on the resistive intermediate layer, wherein the template layer comprises a non-conductive material having recesses or openings that define a pattern of conductive material to be printed on a substrate.

[0030] In certain embodiments, forming the template layer comprises: (a) electroplating a metal pattern into recesses of a patterned photoresist; (b) removing the photoresist from about the metal pattern; (c) coating a dielectric layer on the metal pattern; and (d) removing raised metal features to form the template layer.

[0031] In certain embodiments, the resistive layer has an electrical conductivity of about 10 -5 to 10 -7S / cm. In certain embodiments, the thickness of the resistive layer is no greater than about 0.1 times the smallest pitch of the pattern of electrically conductive material to be printed on the substrate. In certain embodiments, the resistive layer comprises a carbon film.

[0032] In certain embodiments, the electrically conductive layer comprises copper, nickel, cobalt, titanium, or any combination thereof.

[0033] In certain embodiments, the non-conductive material of the template layer comprises glass, polymer, ceramic, or any combination thereof.

[0034] In certain embodiments, the pattern of electrically conductive material to be printed on the substrate comprises a WLP pattern.

[0035] In certain embodiments, forming the template layer comprises: (a) depositing an electrically conductive seed layer on the resistive intermediate layer; (b) applying and patterning a photoresist on the seed layer; (c) electroplating a metal into recesses of the photoresist; (d) removing the photoresist from the seed layer; (e) etching away the electrically conductive seed layer in areas not electroplated with the metal, thereby creating isolated raised metal features; (f) coating the raised metal features with a dielectric layer; (g) planarizing the dielectric layer to expose the raised metal features; and (h) removing the raised metal features to form the template layer.

[0036] Certain aspects of the present disclosure relate to a patterned resistive anode, which can be characterized by: (a) a template layer comprising recesses or openings having a non-conductive material, the recesses or openings defining a pattern of electrically conductive material to be printed on a substrate; (b) a plurality of micro-anodes located in the recesses or openings of the template layer; (c) an electrically conductive layer covering the pattern of electrically conductive material; and (d) a resistive intermediate layer disposed between the template layer and the electrically conductive layer.

[0037] In certain embodiments, the micro-anodes have a maximum width or diameter of about 5 to 200 pm. In certain embodiments, the micro-anodes comprise titanium, tantalum, tungsten, niobium, platinum, gold, iridium, or any combination thereof.

[0038] In certain embodiments, the template layer has a thickness of about 5 microns or less.

[0039] In certain embodiments, the thickness of the resistive layer is no greater than about 0.1 times the smallest pitch of the pattern of electrically conductive material to be printed on the substrate. In certain embodiments, the thickness of the resistive layer is about 0.1 microns to 10 microns.

[0040] In certain embodiments, the electrically conductive layer has a sheet resistance of at most about 0.1 ohm / square. In certain embodiments, the pattern of electrically conductive material to be printed on the substrate comprises a WLP pattern.

[0041] Certain aspects of the present disclosure relate to methods of depositing features on a substrate. Such methods are characterized by: (I) receiving, in an electroplating cell, the substrate having a mask layer on a surface, wherein the mask layer comprises recesses corresponding to a pattern of features to be electrodeposited on the substrate; and (II) electroplating metal into the recesses of the mask layer by controlling a patterned resistive anode, the patterned resistive anode comprising: (a) a template layer comprising a non-conductive material and micro-anodes corresponding to the pattern of features to be electrodeposited on the substrate; (b) an electrically conductive layer covering the template layer; and (c) a resistive layer disposed between the template layer and the electrically conductive layer.

[0042] In certain embodiments, electroplating the metal into the recesses of the mask layer comprises applying an anodic current and / or an anodic potential to the patterned resistive anode in the electroplating cell relative to the substrate.

[0043] In certain embodiments, a gap between the patterned resistive anode and the substrate is about 0.1 millimeter to 2 millimeters while electroplating the metal into the recesses of the mask layer.

[0044] In certain embodiments, the template layer has a thickness of about 5 micrometers or less.

[0045] In certain embodiments, the micro-anodes comprise titanium, tantalum, tungsten, niobium, platinum, gold, iridium, or any combination thereof.

[0046] Certain aspects of the present disclosure relate to an electroplating platform, which can be characterized by: (I) an electroplating cell comprising a support configured to hold a substrate; and (II) a patterned resistive anode comprising micro-anodes corresponding to a pattern of features to be deposited on the substrate; and (III) a controller configured to: (i) receive, in the electroplating cell, the substrate having a mask layer on a surface, wherein the mask layer comprises recesses corresponding to the pattern of features to be deposited on the substrate; and (ii) electroplate metal into the recesses of the mask layer by controlling a patterned resistive anode.

[0047] In certain embodiments, the patterned resistive anode comprises: (a) a template layer comprising a non-conductive material and micro-anodes corresponding to the pattern of features to be deposited on a substrate; (b) a conductive layer covering the template layer; and (c) a resistive layer disposed between the template layer and the conductive layer.

[0048] In certain embodiments, the resistive layer has an electrical conductivity of about 10 -5 to 10 -7 S / cm. In certain embodiments, the resistive layer has a thickness no greater than about 0.1 times the smallest pitch of the pattern of conductive material to be deposited on a substrate.

[0049] In certain embodiments, the micro-anodes comprise titanium, tantalum, tungsten, niobium, platinum, gold, iridium, or any combination of these metals.

[0050] In certain embodiments, the non-conductive material of the template layer comprises glass, polymer, ceramic, or any combination thereof. In certain embodiments, the template layer has a thickness of about 5 microns or less.

[0051] In certain embodiments, the pattern of conductive material to be deposited on the substrate comprises a WLP pattern.

[0052] In certain embodiments, electroplating the metal into the recesses of the mask layer comprises applying an anodic current and / or an anodic potential to the patterned resistive anode in the plating cell relative to the substrate. In certain embodiments, the controller is further configured to cause a gap of about 0.1 mm to 2 mm to be provided between the patterned resistive anode and the substrate while electroplating the metal into the recesses of the mask layer.

[0053] In certain embodiments, the plating cell is configured to flow electrolyte substantially parallel to a surface of the patterned resistive anode while electroplating the metal into the recesses of the mask layer.

[0054] These and other features of the present disclosure will be more fully understood in the following detailed description, sometimes with reference to the related drawings. BRIEF DESCRIPTION OF DRAWINGS

[0055] FIG. 1A is a flowchart of an exemplary method of electroplating patterned metal features on a substrate.

[0056] FIG. 1B schematically illustrates a cross-section of a template feature in a two-stage metal pattern printing process.

[0057] FIG. 2A is a flowchart of a two-stage procedure for printing a multi-layer metal stack, according to a first embodiment.

[0058] Figure 2B is a cross-sectional schematic of a stencil feature used in printing a multi-layer metal stack, according to a first embodiment.

[0059] Figure 3 is a flowchart of a two-stage procedure for printing a multi-layer metal stack, according to a second embodiment.

[0060] Figure 4A schematically illustrates a cross-section of a print head, according to certain embodiments.

[0061] Figure 4B schematically illustrates a print head having an electrical bus in contact with the periphery of a conductive layer in the print head.

[0062] Figure 5 schematically illustrates a series of operations for fabricating a print head, according to certain embodiments.

[0063] Figures 6A and 6B illustrate schematics of electrolyte flow and its effect on electroplating within patterned features.

[0064] Figures 7A and 7B illustrate two embodiments of a patterned resistive anode configured for electroplating through features in a mask on a substrate.

[0065] Figure 7C illustrates a patterned resistive anode used in electroplating through features in a mask on a substrate.

[0066] Figure 8A illustrates a schematic of an example of a print head electroplating cell in conjunction with a general electroplating cell fluid and electroplating control, according to certain embodiments.

[0067] Figure 8B illustrates a simplified view of a multi-tool electroplating apparatus, according to certain embodiments.

[0068] Figure 9 illustrates a simplified view of an exemplary electroplating apparatus having different electroplating cells and modules, according to certain embodiments. DETAILED DESCRIPTION

[0069] In the present disclosure, the terms "semiconductor wafer," "wafer," "substrate," "wafer substrate," and "partially fabricated integrated circuit" are used interchangeably. Those skilled in the art will appreciate that the term "partially fabricated integrated circuit" can refer to a silicon wafer at any of a number of stages of integrated circuit fabrication thereon. Wafers or substrates used in the semiconductor device industry are typically 200 mm, 300 mm, or 450 mm in diameter. The following detailed description assumes that the embodiments are implemented on wafers. However, the embodiments are not so limited. The workpiece can have various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that can utilize the disclosed embodiments include various articles such as glass panels, printed circuit boards, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micro-mechanical devices, partially fabricated display devices, and the like. The workpiece in the disclosed embodiments can include a substrate having a seed layer and a masked surface, which can include a semiconductor wafer, a printed circuit board, a panel, and the like.

[0070] In the present disclosure, the terms "electrolyte," "plating bath," "bath," and "electroplating solution" are used interchangeably.

[0071] In the present disclosure, the term "printing" refers to a process of forming raised features on a nominally planar substrate. The printed features can form a pattern of raised features on the substrate. The printed features can occupy a relatively small portion of the substrate surface area (e.g., about 50% or about 20% or less). In certain embodiments, printing is performed by electroplating metal from recesses in a stencil onto a substrate.

[0072] In the present disclosure, the term "print head" refers to a device that can provide metal or other printable material on a substrate. In some embodiments, the print head temporarily holds the printable material and releases the material in a subsequent operation to deposit a pattern of material on a substrate; the print head can have a stencil that contains a pattern of recesses corresponding to the pattern to be printed on the substrate.

[0073] When referring to a pattern or other physical property of a substrate, print head, resistive anode, or similar structure, the term "corresponding to" includes both structures that are identical to the pattern or other physical property and related variants of such structures. For example, a physical process such as electroplating can employ a stencil pattern that is related to but different from the pattern to be electroplated onto a substrate using the stencil. This is because the physical properties of electroplating (e.g., current distribution, mass transport, and kinetics) can cause some changes in the process of transferring the pattern on the stencil to the deposited pattern on the substrate.

[0074] In the following description, for purposes of providing a complete understanding of the present disclosure, numerous specific details are set forth. The present embodiments of the disclosure can be practiced without some or all of these specific details. In other instances, well known process operations have not been described in particular detail so as not to unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0075] Brief Introduction and Overview Aspects of the present disclosure relate to forming raised features on a substrate. Such features can be electrically conductive, such as metal features for integrated circuit packaging. In some implementations, these features are formed through photoresist-free patterning using electrochemical deposition in a manner that prints the features on the substrate.

[0076] Conventionally, at the integrated package scale (i.e., features on the order of 1 to 100 microns), patterning of copper interconnects is performed using a through-resist electroplating process. Conventional patterning requires a series of complex process flows to create and pattern photoresist, electrodeposit metal in the features of the photoresist, and finally remove the photoresist. These unit operations can include spin coating, baking, photopatterning, scumming / ashing, and photoresist stripping. Each of these operations can require dedicated tooling or hardware. Certain embodiments of the present disclosure omit portions or all of these operations. Further, due to differences in feature density and related differences in electrolytic resistivity between various regions on the substrate, conventional through-resist electroplating processes inherently cannot uniformly electroplate across a chip, and also cannot uniformly electroplate across a wafer due to the large electrical resistance of the seed layer on the substrate from the edge to the center.

[0077] Various electroplating techniques (e.g., high-resistance virtual anodes and organic electroplating additives) are used to compensate for these effects, but increasingly complex patterns and specifications sometimes result in these existing techniques not meeting the requirements.

[0078] In various embodiments, a two-operation process is used to print a pattern of electrically conductive features. In a first step operation, a print head containing a pattern of features (which can match the physical layout of the integrated circuit wiring) is electroplated to fill a recessed feature or “recess” with an electrically conductive material (e.g., a metal or alloy). A second step operation is then performed to transfer the electrically conductive material to the substrate. In the second step operation, the print head can contact or be close to the surface of the substrate being printed on. In this second step operation, the electrically conductive material previously electroplated into the recesses in the print head will serve as an anode. The second step operation can be performed in a manner such that the electrically conductive material is electroplated directly from the print head to the substrate to produce a printed pattern determined by the pattern of recesses (stencil) in the print head.

[0079] The first step operation can be performed in such a way that substantially the same amount of conductive material is electroplated in each recess or area of the print head. Thus, the first operation can address the problem of potential non-uniformity due to loading effects (variation in feature density) and / or termination effects (decrease in potential in the center region of the substrate due to ohmic losses as current flows from the edge of the substrate in electrical contact with the power supply to the center of the substrate with no external electrical contact).

[0080] The desired electroplating uniformity can be achieved by using a print head with a layered structure having a film located below the patterned recess template. In some embodiments, the layered structure can comprise, in the following order: (a) a conductive metal bottom layer, (b) a resistive middle layer, and (c) a template comprising recesses defining the pattern to be printed. See, e.g., FIG. 4A. In some embodiments, the conductive layer is thick enough and has a large enough specific conductance so that powering the conductive layer at the edge of the print head (through electrical leads) results in only a small lateral voltage drop and minimal termination effects. In some embodiments, the conductive layer is in contact with the backplate at multiple points (or covers a large surface), thereby exhibiting at most minimal termination effects. In some embodiments, the thickness of the middle layer is at most about 0.1 times the minimum pitch or critical dimension of the pattern to be printed. During the first operation, the resistive middle layer can "swamp" the resistive distribution of the electroplating solution and variations caused by feature loading and / or termination effects.

[0081] After filling the recesses of the print head in the first operation, the print head can be brought close to, or even in contact with, the substrate. During this operation, the conductive electrolyte present in the recesses is in contact with the metal electroplated in the first operation and the substrate. After the print head and substrate are properly aligned, the substrate is negatively polarized (as a cathode), and subsequently the conductive material in the features of the print head is transferred to the substrate (printing).

[0082] In certain embodiments, the entire template of the print head is in an electric field powered by a single conductive surface or electrode, which can be the conductive metal bottom layer (a). This conductive surface / electrode can cover the entire area occupied by the template. This design is different from a print head design that employs individually addressable electrodes, which are configured to selectively power discrete areas or features of the print head, such that in any printing operation certain features are on while others are off. In embodiments that employ only a single conductive surface / electrode, the template pattern can be customized according to the particular application, such as a particular RDL pattern or a columnar pattern.

[0083] It is important to note that these two operations imply that the printing operation (second operation) is performed using a consumable anode (metal or other conductive material that fills the print head recesses during the first operation). This metal is "consumed" in the operation of transferring it to the product substrate. This approach is different from approaches that use one or more inert anodes in the print head during the printing operation.

[0084] The methods disclosed herein can be part of a pattern forming process, thereby eliminating repetitive photoresist processing sequences. In addition, the print head and associated hardware can be scaled to large sizes (e.g., 500 x 500 mm and larger panels), while it is increasingly difficult to uniformly process these large size panels using prior art, patterning, and electroplating methods.

[0085] Substrate printing process As noted above, printing on a substrate can include a recess filling stage and a printing stage. In the recess filling stage, metal is electroplated into the recesses of a print head, the recesses containing a pattern of features therein. In the printing stage, the metal previously electroplated into the recesses is electroplated onto a substrate. The metal now printed on the substrate has a pattern that is a mirror image or otherwise related to the pattern of features in the recesses of the print head. These two stages can have a variety of variations, some of which will be explained herein.

[0086] Certain two-stage printing processes can generally be characterized by the following operations: (I) electroplating metal into recesses of a print head; and (II) electroplating the metal in the recesses of the print head stencil onto a substrate to print features on the substrate. The print head includes (a) a stencil layer comprising a non-conductive material having recesses or openings defining a pattern of features to be printed on the substrate; (b) a conductive layer that substantially covers the entire area of the recesses or openings; and (c) a resistive intermediate layer disposed between the stencil layer and the conductive layer. In some embodiments, the print head substrate and the conductive layer are bonded together (forming a solid working component that is operable and transfers current to the resistive layer during operation). The area of the resistive intermediate layer of the print head can be exposed at the bottom of the recesses. Thus, the metal electroplated in operation (I) can be electroplated directly onto the exposed area of the resistive layer.

[0087] The first operation (electroplating metal into recesses of a print head) can involve applying a cathodic potential to the conductive layer relative to a counter electrode, while the second operation (electroplating the metal in the print head stencil recesses onto a substrate) can involve applying an anodic potential to the conductive layer relative to the product substrate. In certain embodiments, the counter electrode in the first operation can be a consumable anode (e.g., made of the metal being electroplated) or an inert anode. In certain embodiments, the second operation (electroplating the metal in the print head stencil recesses onto a substrate) can involve contacting the stencil layer with the product substrate without contacting the metal electroplated into the print head stencil recesses with the substrate.

[0088] The metal can be any metal that can be printed onto a substrate by electroplating. Examples include those commonly used to fabricate electrically conductive lines, pillars, pads, contacts, and other structures in electronic devices. Such metals can include materials that can be electroplated in aqueous media, such as copper, nickel, tin, silver, cobalt, gold, cadmium, iron, palladium, indium, lead, and materials that can only be electroplated in other solvents, media, or molten salts, as well as alloys or mixtures of these materials.

[0089] Electroplating in the first operation (trench filling) can involve positioning the print head in an electroplating apparatus so as to make electrical contact with the conductive layer on the periphery and / or backside of the print head. In the first stage, the electroplating apparatus houses a secondary anode and an electrolyte solution that contains metal ions for electroplating. The print head is cathodically biased and immersed in the electrolyte solution, which produces metal ions that are reduced in the trenches of the print head, as shown in the following equation, where M is the metal (e.g., copper), n is the number of electrons transferred during reduction: Because the electrolyte solution only experiences the highest cathodic potential at the exposed bottom of the features of the stencil layer (other portions of the electrode are masked by the insulator and do not have a physical or electrical connection between the conductive layer and the resistive layer), electrochemical deposition (e.g., deposition achieved through a through-mask electroplating process) only occurs within the trench features and not in the field regions of the stencil (e.g., the top surface of the stencil). Thus, electroplating can be used to at least partially fill the trenches in the stencil with metal.

[0090] The first operation can be performed in a manner that electroplates substantially the same amount of electrically conductive material in each feature of the print head. Thus, the first operation can address issues of potential non-uniformity due to loading effects (variations in feature density within a chip) and / or termination effects (Ohmic losses that result in a decrease in potential in the center region of a substrate as current flows from the edges of the substrate that are in electrical contact with a power source to the center of the substrate that is not in external electrical contact).

[0091] Electroplating uniformity can be achieved by using a print head that has a resistive layer between the stencil trenches (or openings) and the conductive layer that applies a cathodic potential to the print head. The resistive middle layer can “suppress” the resistance variations caused by feature loading and / or termination effects during the first operation. This approach can enable metal to be deposited into the print head trenches in a highly uniform pattern (e.g., nearly the same thickness for each individual plated feature) whether on a short distance “chip” scale or on a long distance full product substrate global (e.g., panel or wafer) scale. This resistive suppression effect and its control over current distribution will be further explained elsewhere herein.

[0092] During the first operation, the print head, the secondary electrode, and the electrolyte located therebetween define an electroplating cell. The print head serves as a cathode, and the secondary electrode serves as an anode. The metal that is electroplated into the print head recess comes directly from the electrolyte. In some embodiments, the secondary electrode comprises the same metal as the metal to be electroplated. In other embodiments, the secondary electrode does not comprise that metal. For example, the secondary electrode can be an inert electrode that facilitates oxidation reactions of electrolyte constituents (e.g., water or ferrous ions, if present).

[0093] The secondary electrode is typically not the substrate onto which the metal is printed in the second operation, but in some cases the two can be the same. If present in the first operation, the metal will be removed from the substrate substantially uniformly in the first operation, but not completely (as a metal film on the substrate is needed to enable deposition on the substrate in the second operation), or more commonly, the substrate can not participate in the electrochemical reaction (e.g., be in the electrolyte but not electrically powered).

[0094] In certain embodiments, the electrolyte used in the first operation has components with the following characteristics: copper ions from, e.g., a sulfate salt (a source of metal ions) at a concentration of about 10 to 80 g / L or about 20 to 65 g / L, and sulfuric acid at a concentration of about 5 to 120 g / L or about 20 to 100 g / L. The electrolyte optionally comprises one or more additives, e.g., accelerators, suppressors, and optionally levelers, to promote bottom-up filling. For example, such additives can include 50 ppm chloride ions (a suppressor adsorption bond), 10 ppm 2,3-dimercapto-l-propanesulfonic acid (a surface brightener and an accelerator), 1000 ppm of 10,000 MW polyethylene glycol (a suppressor). In some embodiments, the three common classes of commercial copper electroplating organic additives (accelerators, suppressors / carriers, and levelers) can be used to their full extent and functionality. However, when printing using a print head according to the present disclosure, a leveler can not be used as it can compensate for spatial plating non-uniformity and loading effects related to feature density non-uniformity. In certain embodiments, the resistive layer of the print head achieves the same purpose in a different way (i.e., through electrical compensation rather than electrochemical surface reaction kinetics).

[0095] From a process design perspective, a high-resistance electrolyte results in a large dimensionless ratio of the resistive film resistance to the electrolyte resistance in the gap between the print head and the workpiece (Rf / Rg) and a large ratio of the surface kinetic resistance to the electrolyte resistance in the gap between the anode and the workpiece (Rs / Rg). The higher the values of Rf / Rg and Rs / Rg, the better the uniformity of the feature distribution. From an electrochemical perspective, Rs / Rg can be understood as the Wagner number, i.e., it is desirable to obtain a high surface resistance so that the influence of the electrolyte distribution resistance can be overcome. Similarly, for a fixed Rf, a higher bath conductivity will have a more significant impact on the resistive film resistance, resulting in a more constant current between isolated and dense areas of anode features. But from a practical deposition rate, production efficiency, and feature morphology perspective, there is a balance and limit to selecting the highest conductivity electrolyte composition. Typically, the hydrogen ion mobility is higher than the copper ion mobility, so the conductivity of an acid / copper solution is highest at very high acid concentrations and very low copper concentrations. However, if the copper concentration is too low, the rate of the copper plating process will be limited by mass transport. Therefore, there is a balance between having sufficient copper content in the solution to meet process rate and feature morphology requirements and desiring a high conductivity solution to meet feature thickness distribution requirements. Thus, various solution compositions can be selected based on the balance of these needs. These concentrations are limited by the solution solubility limits, which are typically predicted by the chemical solubility product rule for two cations in a common anion solution.

[0096] Typically, for copper electroplating applications, the electrolyte contains copper ions from a copper salt (e.g., copper sulfate, copper methane sulfonate, copper pyrophosphate, copper propane sulfonate, etc.). The electrolyte can contain an acid to increase the electrolyte conductivity. Exemplary acids include, but are not limited to, sulfuric acid, phosphoric acid, and methane sulfonic acid. In some embodiments, the electrolyte contains electroplating additives. Electroplating additives change the surface reaction kinetics and generally help improve the current distribution (feature shape and thickness distribution) relative to the case where the additives are not present (improvement relative to the initial current distribution or electrolyte resistance driven current distribution).

[0097] With respect to electroplating additives, accelerators can include alkane chains with at least one sulfhydryl group and one sulfonic acid group or acid salt. For example, accelerators can include mercaptopropanesulfonic acid or mercaptoethanesulfonic acid. In some embodiments, suppressors can include derivatives of polyethylene glycol and polypropylene glycol and oxides thereof. In these or other cases, suppressors can include at least one material selected from the group of polyethylene oxide, polypropylene oxide, polyethylene glycol, polypropylene glycol, polyethylene with at least one S and / or N containing functional group, and polypropylene oxide with at least one S and / or N containing functional group. Other electroplating additives can include carriers and / or extenders. The composition of additives in the electrolyte can be optimized for the use of the print head in the electroplating process.

[0098] In certain embodiments, the temperature of the electrolyte is maintained at about 15 to 45 °C during the first operation.

[0099] In certain embodiments, the gap between the template surface and a substantially parallel surface of another element in the electroplating cell is about 100 to 100 microns. The volume defined by the gap contains electrolyte during the first operation. In some embodiments, the other element (opposite the template surface) is a substrate on which metal is printed in a second operation. In some embodiments, the other element is an inert element, such as a high resistance dummy anode or a solid inert material. The other element can be disconnected from a power source or load during the first operation. The other element can not participate in the ionic production in the electrochemical reaction during the first operation. In certain embodiments, the other element is a secondary electrode that participates in the electrochemical reaction that electroplates metal into the template recesses.

[0100] In certain embodiments, the electrolyte exhibits convection during the first operation. This can promote uniform plating rates across the template surface and / or promote smooth or regular plating into the recess features of the template. The convection can have any of a variety of possible patterns. For example, the convection can be achieved by (a) rotating the template in the electroplating cell, (b) using a reciprocating paddle in front of the template, (c) flowing across or against the template surface (in a direction substantially parallel to the template surface), or (d) any combination of these effects. In some embodiments, the electrolyte flows across the template surface in a direction substantially perpendicular to the direction of the recesses of the template layer. This flow is sometimes referred to herein as shearing or “cross-flow,” and devices for producing cross-flow are described elsewhere herein. In general, devices and methods that deliver cross-flow to the surface of a print head having recessed features can produce a spatially uniform flow shear time-averaged intensity over all of the features. This enables convective vortices and ionic plating within the features to equally access the features, with more uniform plating of the feature surfaces and shapes, and / or composition (e.g., when electroplating an alloy).

[0101] In certain embodiments, the secondary electrode used in the first operation is disposed around the perimeter of the print head. In certain embodiments, the secondary electrode used in the first operation is substantially planar, and the secondary anode is substantially parallel to and facing the recessed features of the print head when electroplating metal from the secondary anode into the recessed features of the print head.

[0102] As previously described, the second operation (printing) electroplates metal from the recesses of the print head onto the substrate surface. During this operation, the print head can be close to the substrate, or even uniformly contact the substrate. In certain embodiments, the print head contacts and conforms to the substrate surface. However, to avoid shorting, the metal within the print head recesses does not contact the substrate surface.

[0103] An electrically conductive electrolyte is present within the recesses, which is in contact with both the metal electroplated in the first operation and the substrate. Thus, an electroplating cell is formed by the print head (or more accurately, the metal in the recesses, which acts as an anode), the substrate (which acts as a cathode), and the electrolyte between the two.

[0104] After the print head and substrate are properly aligned, the substrate is negatively polarized (as a cathode), whereby the metal in the print head features is transferred to the substrate (i.e., printing).

[0105] In certain embodiments, both operations (recess filling and printing to the substrate) are performed in the same electroplating chamber. In some examples, the substrate is in the electroplating chamber during both operations. The substrate can be mounted on a chuck. In certain embodiments, a first gap is left between the print head and the substrate when the first operation is performed, and a second gap is left between the print head and the substrate when the second operation is performed, the second gap being smaller than the first gap. For example, the first gap can be about 200 microns or more, and the second gap can be about 1 micron or less (e.g., the substrate and print head can actually contact each other). In other embodiments, the two operations are performed in different electroplating chambers.

[0106] In certain embodiments, the gap between the print head and the substrate during the second operation is no more than about 1 micron. In certain embodiments, the print head and the substrate contact each other during the second operation. During the contact, the un-recessed areas of the stencil layer can be in contact with the substrate surface, and the electrolyte is substantially confined within the recessed areas.

[0107] In certain embodiments, the print head and product substrate can be aligned with each other prior to or during the second operation. In some embodiments, the alignment is achieved by configuring at least one of the print head or substrate elements to flex and move, for example by actuators and piezoelectric devices capable of actively moving the two components relative to each other in three or more axes; alternatively or in combination, a set of self-aligning elements can be provided, including gimbals and / or elastomeric underlayer material elements (e.g. rubber membranes, allowing the components to flex and conform to another surface). Free motion in global and local ranges can be achieved by only one or both of the print head and substrate.

[0108] In certain embodiments, during the second operation, the electrolyte is at rest or flows at a rate that is very low compared to the flow rate employed during the first operation.

[0109] In certain embodiments, the electrolyte used during the second operation has a composition that includes an acid and metal ions of the metal to be deposited. The composition can be based in part on the considerations described above for the electrolyte used in the first operation. However, in embodiments where the substrate does not have a mask, the electrolyte need not include some or any additives that promote bottom-up filling. In certain embodiments, the second operation includes 70 g / L copper sulfate and 5 g / L sulfuric acid. For example, the electrolyte can include copper ions from a copper salt (e.g. copper sulfate, copper methane sulfonate, copper pyrophosphate, copper propane sulfonate, etc.). The electrolyte can include an acid to increase the electrolyte conductivity. Exemplary acids include, but are not limited to, sulfuric acid, phosphoric acid, and methanesulfonic acid. In some embodiments, the electrolyte includes electroplating additives. Unlike conventional electroplating processes, the electroplating performed according to this operation does not require electroplating additives to modify and control the thickness profile of the printed bumps or lines. They can be added, however, to control the surface finish (if desired, a smooth, shiny film can be obtained) and / or to control the designed grain structure or chemical impurities of the deposit.

[0110] In certain embodiments, during the second operation, the temperature of the electrolyte is maintained at about 15 to 45 °C.

[0111] For ease of understanding, the two-stage printing process can be part of an integrated electronic device manufacturing process. An example of such a manufacturing process is shown in FIG. 1A. The operations in the process shown in FIG. 1A can be performed in a different order, and / or include different, fewer, or additional operations.

[0112] As shown, the two-stage printing process 100 can begin at block 102, where a print head is loaded. In some implementations, a semiconductor substrate can also be loaded. For example, the print head and / or semiconductor substrate can be loaded into a print head or substrate load / unload station. The loading operation can place the print head and multiple substrates in an electroplating apparatus having one or more electroplating stations. For example, multiple substrates can be provided to a FOUP.

[0113] In block 104, the print head and, in some implementations, the semiconductor substrate, are optionally pre-treated. The pre-treatment of the print head can remove contaminants. The pre-treatment of the semiconductor substrate can reduce oxides and / or remove contaminants (e.g., organic contaminants). In addition, the pre-treatment can involve vacuum surface pre-wetting. For example, the print head and / or semiconductor substrate can be transferred from the load / unload station to a print head and / or substrate pre-treatment station by a robot. In some cases, the pre-treatment station is configured as a vacuum backfill station. In some cases, the pre-treatment station is configured as an acid pre-wetting station.

[0114] In some implementations, the print head is loaded at a particular time and then remains associated with a particular electroplating station for a longer period of time during which multiple substrates are processed at the electroplating station by operations 102 and 104.

[0115] In preparation for electroplating, in block 106, the print head and optionally the semiconductor substrate are immersed in an electrolyte of an electroplating station. The electroplating station can also be referred to as an electroplating vessel, an electroplating cell, an electroplating chamber, etc. The electroplating chamber is configured to contain an electrolyte and one or more secondary anodes while electroplating metal into the recesses of the print head. For example, the print head can be transferred from the pre-treatment station to the electroplating station by a robot. The electroplating operation can be performed in one or more electroplating stations.

[0116] The print head template layer is immersed in an electrolyte containing metal ions to be electroplated, and the print head is cathodically biased by electrical contact with its conductive layer. In some examples, the electrolyte contains copper ions, acid, electroplating additives, etc., as described elsewhere herein. In the presence of the template layer, the intermediate resistive layer, and the conductive layer (all present in the print head), the distribution of ionic current is relatively uniform across the template layer.

[0117] In some embodiments, electrolyte convection is provided to achieve a particular spatial and / or temporal deposition pattern in the print head. See block 108. Convection can increase the rate at which plating occurs in particular areas, and can promote uniform plating. In addition, a bias in the flow conditions can create distorted deposition features in the print head, which can cause subsequently deposited features to grow irregularly on the substrate. For example, in FIGS. 6A and 6B, if the flow field occurs in one direction, then an uneven feature profile can be created in the recessed features. Thus, in the step of filling the print head with metal, convection (e.g., "cross flow" or "shear flow") not only helps to increase the process rate, but also provides for uniform feature shape deposition. In this regard, the convection can be uniform in direction and strength when averaged over the time scale of the feature filling step. Some options for convection that meet these criteria include rotating the print head and providing a reciprocating paddle in the plating station.

[0118] In some embodiments, the electrolyte flows laterally across the stencil layer of the print head. In such embodiments, the electrolyte flows substantially in one direction and enters and exits the plating chamber at opposite azimuthal locations near the periphery of the plating chamber. The print head can optionally be rotated while the electrolyte flows laterally. However, it should be understood that alternative techniques can be employed to increase uniformity within the features, such as having the flow beneath the print head come from a set of different directions or continuously varying directions.

[0119] With the stencil layer of the print head immersed in the electrolyte, which is optionally flowing relative to the stencil layer, a cathodic current or voltage is applied to the conductive layer of the print head to cause metal to be electroplated from the secondary anode into the stencil features of the print head. See block 110. As described above, the electroplated metal is deposited on the intermediate insulating layer of the print head, rather than on the conductive layer of the print head. This process is schematically illustrated in the upper panel 152 of FIG. IB. Note that during this plating operation, there is a gap between the print head and the secondary anode. If there is a semiconductor substrate in the plating station, then this substrate can be positioned beneath the print head, so there is a gap between the substrate and the print head.

[0120] After the metal is completely electroplated into the recesses of the stencil layer, the print head will be moved into position proximate to or in contact with the substrate on which printing is to be performed. See block 112. This prepares the print head and the substrate for the printing operation.

[0121] During the printing process, metal is electroplated from the recesses of the print head onto the substrate. See block 114. This printing operation is schematically illustrated in the middle panel 154 of FIG. IB. In the illustrated embodiment, the surface of the stencil layer contacts the substrate, but the electroplated metal in the print head does not contact the substrate. Rather, the electrolyte separates the metal from the substrate. The electrolyte is in a small gap between the electroplated metal and the substrate.

[0122] During printing, the print head serves as the anode and the substrate serves as the cathode. After the printing operation is complete, the stencil and the substrate are separated from each other. This is depicted in the lower portion of Figure IB, legend 156.

[0123] In some embodiments, the semiconductor substrate can have a conductive seed layer, such as a copper seed layer. The conductive seed layer can be disposed on a material layer, such as a dielectric layer. The semiconductor substrate can be a partially or fully fabricated semiconductor substrate that contains one or more dies having a distribution of features.

[0124] In block 116, the semiconductor substrate can be subjected to a post-substrate treatment. In some embodiments, the post-substrate treatment can include a rinsing, drying, and / or cleaning operation in a rinse / dry / clean station. In some embodiments, the post-substrate treatment can include an etching in an etching module. The etching can be performed to selectively remove patterned features or non-patterned features. Removing the patterned features can remove only a portion of the patterned features to achieve coplanarity. Thus, the process can include both a plating operation and an etching operation.

[0125] As shown in Figure IB, the print head can include a resistive layer 162 and a stencil layer 160. It typically also includes a conductive layer, but is not shown in Figure IB. The stencil layer 160 contains a plurality of recessed features, one of which is indicated by the numeral 164 in the figure. In a first operation (as shown in legend 152), cathodic current flows into the recess 164 and anodic current flows into the secondary electrode 166. As a result, metal (in this example, copper) is plated in the recessed feature 164. The plated copper is indicated by the numeral 170 in the second legend 154 of Figure IB.

[0126] In a second stage, the print head is brought close to or into contact with the substrate 168, and an anodic potential is applied to the print head while a cathodic potential is applied to the substrate 168. This results in electroplating (printing) of the metal 170 in the recessed feature 164 onto the substrate 168, but only in the area of the recessed feature 164. See legend 154.

[0127] After the metal 170 in the recessed feature 164 is fully electroplated onto the substrate 168, the print head is separated from the substrate, revealing the newly printed metal feature 172. See legend 156.

[0128] It is generally desirable for the deposition rate to be uniform within the recessed feature, i.e., at the end of the process, the metal deposition height is similar for each feature, and thus coplanar. This can be achieved by careful control of the deposition conditions, including electrolyte composition and convection. The concentration of plating additives can be controlled to improve coplanarity and reduce the height variation of the metal features within a die or wafer.

[0129] Within-wafer (WIW) uniformity is an important industry metric that measures the difference in features across a wafer. WIW uniformity compares the average thickness distribution of multiple dies on a substrate and can indicate the difference in process performance of different dies at different locations in a set of wafers from that wafer. WIW distribution can be non-uniform due to a variety of factors including, but not limited to, flow variations, edge field non-uniformity, feature layout discontinuities (e.g., missing die areas), and wafer edge contact uncompensated seed layer resistance termination effects. The methods and apparatus of the present disclosure are not affected by the underlying physical-chemical reasons for these effects and, therefore, can improve WIW uniformity (in operation 1 or operation 2) relative to conventionally used plating apparatus and methods.

[0130] Within-die (WID) uniformity is a metric that measures the thickness variation of all features within a die and can be compared to the total feature thickness distribution of a wafer and other dies. For example, a smaller WID variability makes the formation of a blanket film of a subsequent layer more challenging and more reliable, or makes the pillar and pad bonding of multiple features on a chip between two different dies easier and more reliable. WID plating non-uniformity can occur even if the electric and flow fields on a chip are uniform. The thickness distribution of various features within a die is primarily driven by the exposure variation of various features and feature areas. This is sometimes referred to as “feature density distribution” or “loading effect” that occurs because the electric and mass transfer field resistance around low density features and low density feature areas is less than high density feature areas. The apparatus and methods of the present disclosure can improve WID uniformity (in operation 1 or operation 2) relative to conventionally used apparatus and methods, in part because the variability of the electric and mass transfer field resistance caused by loading that conventionally exists does not play a role when using a plating apparatus that electrolytically isolates each feature from each other.

[0131] Within-feature (WIF) uniformity is a metric that measures the flatness of a feature top surface shape relative to a base plane and other features. For example, a smaller WIF uniformity makes the formation of a blanket film of a subsequent layer easier or more reliable, or makes the single pillar and pad bonding of two different dies easier and more reliable. The apparatus and methods of the present disclosure can improve WIF uniformity (in operation 1 or operation 2) relative to conventionally used apparatus and methods.

[0132] As described above, the first operation can be performed in a manner that uniformly plates metal in the print head template recesses without being affected by feature loading differences and / or termination effects. This is because the print head design shifts the control resistance to a so-called “suppression resistor” that can be implemented as the thin resistance layer described herein. Depending on the specific implementation details, the suppression resistor is able to achieve substantially uniform metal electrodeposition across the features and across the print head layer.

[0133] When filling electrode features with metal on any patterned surface, the electrical resistance varies primarily between features according to their relative exposure to the electrolyte solution. Isolated features have a relatively straight path from the electrolyte to their surface compared to features with many neighbors. As a result, isolated features tend to plate faster. If not compensated, this phenomenon leads to non-uniform metal thickness between different features. Thin layers of resistive material introduce more resistance in the plating process than the electrolyte resistance inherent to the patterned print head, thereby dampening the otherwise varying electrical resistance between features, leading to a near constant plating current density and deposition rate for all plated features on the print head.

[0134] After the patterned print head is uniformly filled with metal, the metal will be transferred to a substrate in substantially the same shape as the target pattern formed on the print head (second operation), thereby obtaining a printed pattern with very uniform thickness.

[0135] In certain embodiments, the two-stage process of the present disclosure prints a multi-layer structure on a substrate. The individual layers of such a structure can have different compositions. For example, the printed structure can have a first layer of a first metal and a second layer of a second metal. Exemplary combinations of metal layers can include any two or more of the following: a copper layer, a nickel layer, and a tin layer. In some embodiments, three or more layers make up the multi-layer printed structure. In some embodiments, multiple alternating layers of two or more metals make up the multi-layer printed structure.

[0136] There are several possible process sequences. Some of them involve depositing a multi-layer metal into the grooves of the print head before printing the metal layers onto a substrate. Other sequences deposit and print each layer separately, respectively.

[0137] In certain embodiments, as shown in FIGS. 2A and 2B, the process sequence 201 includes: (a) electroplating a first metal (metal 1) into the template layer of the print head, thereby forming a layer of metal 1 in contact with the surface of the inert anode (metal 1, operation 1, block 203); (b) electroplating a second metal (metal 2) from a different electrolyte composition containing the second metal into the template layer, thereby forming a layer in contact with the surface of metal 1 (metal 2, operation 1, block 205); optionally (c) electroplating one or more additional metal layers into the grooves of the template layer (operation 205); and (d) electroplating (printing) the entire stack of metal 1, metal 2,... onto a substrate (stack, operation 207).

[0138] Figure 2A schematically illustrates operation 2 of the stacked printing process. The print head has a resistive layer 260 and a stencil layer 262 with recesses in which metal stacks 274 (two or more layers of metal) have been loaded. The print head with stacks 274 contacts a substrate 268. See upper legend. Upon contact, an anodic potential is applied to the print head and a cathodic potential is applied to the substrate 268. This causes the stacks 274 to transfer to the substrate 268 and form printed features 276 comprising multiple layers on the substrate 268. See lower legend.

[0139] In certain embodiments, as shown in Figure 3, the process sequence 301 includes: (a) electroplating a first metal (Metal 1) into the stencil features and forming a layer in contact with the surface of the resistive layer (Metal 1, operation 1, block 303); (b) electroplating (printing) Metal 1 onto the substrate (Metal 1, operation 2, block 305); (c) electroplating a second metal (Metal 2) into the stencil features and forming a layer in contact with the surface of the resistive layer (Metal 2, operation 1, block 307); (d) electroplating (printing) Metal 2 onto the substrate to form a printed stack (Metal 1 and Metal 2, operation 2, block 309); and (e) optionally, electroplating one or more additional metal layers into the stencil features and onto the substrate (operations 1 and 2, block 311).

[0140] The electrolyte used to transfer the multi-metal stack from the print head to the substrate can be free of any electroplatable metal, can contain a metal included in the stack, or can contain only the first metal to be transferred to the substrate (i.e., the metal that bonds with the product substrate metal seed layer). Examples include a solution containing only acid (e.g., 180 g / L sulfuric acid), or a solution containing 80 g / L copper sulfate and 5 g / L sulfuric acid (when depositing the first layer of copper).

[0141] Print head design The print head can have a stencil layer and two or more additional layers. As described above, the stencil layer can include recessed features that define a pattern to be printed on the substrate. The additional layers can provide a conductive surface to deliver an electrical potential over the area occupied by the stencil features. These layers can be configured to provide this electrical potential substantially uniformly over the area of the stencil features, independent of local feature density and distance of the bus or contact from the power source. In certain embodiments, the additional layers include a highly conductive metal layer overlaid with a thin resistive film. During a first operation (as described above), a printable pattern is formed on the resistive film within the recesses of the stencil layer. During a second operation, the metal from the printable pattern is electroplated to the surface of the substrate.

[0142] In certain embodiments, the print head is characterized by the following elements: (a) a template layer comprising a non-conductive material having recesses or openings defining a pattern of conductive material to be printed on a substrate; (b) a conductive layer covering the pattern of conductive material; and (c) a resistive intermediate layer disposed between the template layer and the conductive layer.

[0143] Figure 4A is a cross-sectional view of a print head 401 that includes a substrate 403, a conductive layer 405, a resistive layer 407, and a template layer (also referred to as a mask) 409. The template layer 409 includes a plurality of recessed features 411 that extend from an exposed face or surface of the template layer 409 to the resistive layer 407. The recessed features 411 define at least a portion of a pattern to be printed onto a workpiece (e.g., a semiconductor wafer).

[0144] The substrate 403 supports the conductive layer 405, the resistive layer 407, and the template layer 409. It can be made of any mechanically stable material that does not negatively affect the transmission of an electric field to the template layer. For example, it can be made of glass, plastic, ceramic, or a semiconductor material (e.g., silicon), or any combination of these materials. It should be distinguished from the "substrate" onto which metal is electroplated in the second operation of the printing process.

[0145] Template layer The template layer has recessed features that collectively map to a layout or pattern of a structure to be printed onto a substrate (e.g., a semiconductor wafer). In certain embodiments, the pattern of conductive material to be printed onto the substrate includes a wafer-level packaging (WLP) pattern. For example, the WLP pattern is an RDL pattern and / or a pillar pattern.

[0146] In various implementations, different template layers are needed for each application. That is, a template layer for a given application has a fixed pattern. A single template layer (typically on a single print head) with a fixed pattern is used to print a pattern on multiple substrates. Different template layers with different fixed patterns are used to print different patterns on multiple substrates.

[0147] In certain embodiments, the template layer comprises a non-conductive material, such as glass, a polymer (e.g., photoresist or other polymer, such as an epoxy), an oxide (e.g., silicon oxide), and the like. In certain embodiments, the recesses or openings in the template layer have a thickness of about 5 to 300 microns.

[0148] Conductive layer As noted above, in the electroplating process, the conductive layer provides the electric field in the recesses of the template layer. In some embodiments, the conductive layer has a sheet resistance of at most about 0.1 ohm / square. In some embodiments, the conductive layer has a thickness of about 0.01 to 10 microns. In some implementations, the conductive layer comprises a conductive metal, such as copper, nickel, cobalt, titanium, or any combination thereof. In one example, the conductive layer is a 6000 A thick copper layer deposited by, for example, PVD.

[0149] Resistive layer As noted above, a resistive layer can be interposed between the template layer and the conductive layer. Its role is to dampen local electrolyte resistance variations caused by, for example, feature loading and / or to dampen the ohmic potential drop from edge to center in the conductive layer. Thus, the resistive layer helps to produce a substantially uniform electric field across the printing area of the print head.

[0150] In some embodiments, the resistive layer has an electrical conductivity of about 10 -5 to 10 -7 S / cm.

[0151] In some embodiments, the resistive layer has a porosity of less than about 5%. In some embodiments, the thickness of such a resistive layer is no greater than about 0.2 times or about 0.1 times the smallest pitch or critical dimension of the pattern of conductive material to be printed on the substrate. In some embodiments, the resistive layer has a thickness of about 0.05 to 10 microns. In some embodiments, the resistive layer comprises a carbon film, such as a hydrogenated amorphous carbon film, optionally deposited by sputtering, or deposited by decomposition of an organic compound (e.g., a polymer), and / or by conversion to a carbon film via heat treatment (e.g., about 400-600 °C) in an inert atmosphere. The resistive layer can be made of other materials, such as a polymer, a semiconductor, a ceramic, a glass, etc.

[0152] In some embodiments, the resistive layer provides a continuous layer that is substantially coextensive with the pattern of the template layer. In some embodiments, the resistive layer comprises two or more discrete portions that cover at least all or substantially all of the openings through the template layer.

[0153] In some embodiments, the template layer and the resistive layer are combined. That is, a single component (optionally a monolithic component) of the print head comprises both the template layer and the resistive layer. In some implementations, the combined component comprises a single material, such as silicon oxide or a polymer.

[0154] Consumable anode In use, the second operation electroplates the metal in the printhead stencil recesses onto the substrate. Thus, the metal in the printhead (electroplated there after the first operation) acts as a consumable anode, rather than an inert anode. In theory, inert electrodes could be used as anodes during printing, but these inert electrodes can require special treatment to suppress oxygen evolution, which can introduce defects into the devices fabricated on the substrate.

[0155] Addressable electrode In certain embodiments, the conductive layer is a continuous sheet of conductive material that can cover all or most of the area occupied by the pattern in the stencil layer. In such embodiments, the printhead requires only a single connection or circuit. In alternative embodiments, the conductive layer is not continuous, but rather is composed of two or more discrete or separate portions that can be addressed independently. Such embodiments can employ a thin-film transistor-based array of patterned feature micro-anodes (the features having various lengths, sizes, and shapes to match the desired wiring pattern). In this approach, each feature can require a separate and unique wiring control circuit.

[0156] Contact with conductive layer In certain embodiments, the electrical connection to the printhead is established between the periphery of the printhead and the conductive layer. In some cases, the electrical connection is established in a manner at the periphery of the printhead so that current is fed uniformly across the peripheral area. This can employ multiple parallel feed lines and contact points across some or all of the peripheral area of the conductive layer. Alternatively, a large current carrying bus connected to a main power line can be employed. Such a bus can make continuous contact with the conductive layer.

[0157] Figure 4B is a schematic illustration of one embodiment of a printhead 421 having a peripheral bus 435 electrically connected to the peripheral area 428 of the conductive layer 425. Figure 4B includes a plan view (left) and a cross-sectional view (right) of the printhead 421. The printhead itself includes an interposer substrate 423, on which the conductive layer 425 and the stencil layer 429 are formed. The intervening resistive layer is not shown, nor are the recesses in the stencil.

[0158] Method of manufacturing a printhead The printheads described herein can be manufactured by a variety of techniques. In some embodiments, the manufacturing process of the printhead is manufactured using the following operations: (a) forming a conductive layer; (b) forming a resistive intervening layer on the conductive layer; and (c) forming a stencil layer on the resistive intervening layer, wherein the stencil layer is made of a non-conductive material having recesses or openings for defining a pattern of conductive material to be printed on a substrate. In some embodiments, the pattern of conductive material to be printed on a substrate includes a WLP pattern.

[0159] In some cases, the conductive layer has a substantially uniform thickness of conductive material. In some cases, the resistive intermediate layer has a substantially uniform thickness of resistive material. In general, the properties of the conductive layer, resistive layer, and / or template layer can be as described elsewhere herein.

[0160] In some embodiments, forming the template layer includes the following operations: (i) electroplating a metal pattern into recesses of a patterned photoresist or other material that can be selectively removed, e.g., by ashing, dissolving in a solvent, etc., while leaving behind the metal features; (ii) removing the photoresist or other material from around the metal pattern; (iii) coating the metal pattern with a dielectric material, thereby filling the recesses around the pattern metal features; and (iv) removing the raised metal features of the metal pattern to form the template layer. The dielectric remaining of the template layer can have a “negative” image of the metal pattern, while the metal pattern can have a “positive” image of the pattern that will be formed on the substrate during the second step operation of the two-phase process described herein.

[0161] In some examples, forming the template layer includes the following operations: (i) depositing a conductive seed layer on the partially fabricated printhead, which includes the resistive intermediate layer on the conductive layer; (ii) applying and patterning a photoresist on the seed layer; (iii) electroplating a metal into recesses of the photoresist; (iv) removing the photoresist from the seed layer; (v) etching away the conductive seed layer in areas where no metal was electroplated (this will result in raised metal features); (vi) coating the raised metal features with a dielectric layer; (vii) planarizing the dielectric layer to expose the raised metal features; and (viii) removing the raised metal features to form the template layer.

[0162] FIG. 5 illustrates a series of operations 501, where some or all of the operations can be used to fabricate a printhead. First, as shown in the upper left legend of FIG. 5, the fabrication process can start with a partially fabricated printhead that has a substrate 503 and a conductive layer 505. These elements remain unchanged throughout the remainder of the illustrated process. Next, as shown in the upper center legend of FIG. 5, an intermediate resistive layer 507 is formed over / on the conductive layer 505. The resistive layer 507 remains unchanged throughout the remainder of the fabrication process. Next, as shown in the upper right legend of FIG. 5, the process deposits a conductive seed layer 509 on the intermediate resistive layer 507. The seed layer 509 can be formed of a metal that will be subsequently electroplated. One example is copper. The seed layer 509 can be deposited substantially uniformly by a process such as physical vapor deposition.

[0163] Next, as shown in the middle left legend, the manufacturing process forms a patterned sacrificial layer 511 that defines a template for the pattern to be electroplated (which can represent the final pattern, such as a WLP pattern to be placed on a semiconductor device or wafer). In some embodiments, the sacrificial layer 511 is a photoresist layer that is coated and then patterned using, for example, a photolithography process. As shown, the layer 511 has recesses that define the pattern for a subsequent electroplating process, as shown in the middle legend. As shown in this legend, metal 513 is electroplated into the recesses of the patterned layer 511. The electroplating takes advantage of the exposed surface of the seed layer 509. After the electroplating is complete, as shown in the middle right legend, the photoresist or other sacrificial material of the layer 511 is removed. In addition, the remaining seed layer material (from layer 509) that is located beneath the layer 511 material is etched away or otherwise removed, leaving behind the protruding electroplated features 513 that are electrically isolated. Next, as shown in the lower left legend, a layered dielectric 515, such as a polymer (e.g., epoxy), is coated over the semi-finished print head having the protruding metal features 513. This dielectric serves as the material for the template layer of the final finished print head. Since the dielectric completely encases the metal features 513 (which must ultimately be selectively removed), the semi-finished print head can be subjected to a planarization process, as shown in the lower middle legend, to expose the top surfaces of the features 513. The resulting dielectric material can define a template 517. Thereafter, the manufacturing process is completed by removing the electroplated metal features 513 via, for example, a selective metal etching process (wet or dry). The final template layer 517 is left on the middle resist layer 507 and over the conductive layer 505. See the lower left legend.

[0164] Platform for electroplating directly on a substrate The platform and associated electroplating chamber for two-stage printing using a print head can have a variety of different configurations. Examples of such platforms and chambers are shown in FIGS. 7-9. It is noted that some embodiments use the same electroplating chamber for both stages of the printing process. However, the following discussion will separately describe key features and examples of equipment for each stage.

[0165] In certain embodiments, the first operation employs an electroplating system having: (a) a print head as described herein (e.g., having recessed features that define a pattern to be printed on a substrate); (b) an electroplating chamber containing a support configured to support a secondary anode; and (c) a controller configured to electroplate metal into the recessed features of the print head. The secondary anode can consist of the metal to be electroplated onto the print head or can have a suitable metal surface to act as an inert anode (e.g., a platinum film).

[0166] The secondary anode is located in the chamber in many different positions, as long as it is in contact with the electrolyte while the metal is being plated to the print head. When the resistivity of the template is high enough, the current distribution over the features and locations of the template will be uniform enough that the position of the secondary anode relative to the print head is not important to provide uniform plating. For example, the secondary anode can be located to the side of the print head, as a concentric ring around the perimeter of the print head or as a polygon around the print head, as a flat plate under the print head (substantially coplanar with the template). The secondary electrode can be of the inert or active metal type known in the art, and can include support hardware to make it have a separate anode compartment to avoid various deleterious reactions that occur when exposed to the catholyte (see Mayer et al., USP 6,527,920, issued March 18, 2003). In one embodiment, the secondary electrode used to fill the print head with metal is substantially the same shape and / or size as the substrate on which the metal is subsequently printed. For example, if the substrate is a 300 mm wafer, the secondary electrode can be a disc-shaped wafer of about 300 mm in diameter.

[0167] In some embodiments, the plating chamber used to plate metal onto the print head is configured to provide electrolyte convection during this step. This convection can increase the rate of uniform plating in the template grooves.

[0168] Furthermore, the convection can be implemented in a way that improves the uniformity or flatness of the internal shape of the features. Any directional and / or temporal bias in the flow can cause the feature shape to be deformed, which can cause irregular growth of the features in subsequent depositions. In certain embodiments, the plating chamber is configured to provide convection in a way that increases the plating rate while providing uniform deposition in terms of direction and intensity over the course of the average process time for groove filling. Some examples of convection that meet these criteria include: (1) rotating the print head during the plating process; (2) pushing the electrolyte back and forth over the surface of the print head (e.g., by a reciprocating paddle in the plating chamber); (3) flowing the electrolyte substantially perpendicular to the surface of the print head template by a showerhead or related structure that optionally provides electrolyte jets that impact the surface of the print head; and (4) flowing the electrolyte substantially parallel to the surface of the print head at high velocity, where the electrolyte flow is confined in a channel between a high ionic resistance plate and the print head. Examples 2, 3, and 4 are optionally implemented with the print head rotating during the plating process.

[0169] In certain embodiments, the plating chamber includes an electrolyte injection flow system designed to produce flow parallel to the semiconductor substrate. The electrolyte can flow over the surface of the semiconductor substrate at high velocity. Furthermore, the electrolyte injection flow system is designed such that the flow of electrolyte is parallel to the print head. The print head can be placed within the plating chamber such that a thin gap is left between the print head and the semiconductor substrate.

[0170] The plating chamber can include a cross flow manifold to facilitate lateral flow of electrolyte across the substrate surface. The cross flow manifold can be configured to contain electrolyte flowing across the surface of the print head. The cross flow manifold can also be referred to as a flow injection manifold. The flow injection manifold can be a cavity with a series of exit holes around its perimeter and below a cross flow confinement ring. The flow injection manifold can be used to inject fluid into the cross flow gap in an azimuthally uniform manner. In alternative embodiments, spatially distributed electrolyte vias can be provided in the print head so that fresh electrolyte can enter the gap from the space and holes between the print head and the opposite side of the gap defined by the secondary anode and flow out of the gap from the approximate edge.

[0171] FIGS. 6A and 6B show a schematic of the flow direction of electrolyte within the template grooves and its effect on electroplating. If the flow is uniform over time, then the convection within the groove features defined by the template layer will exhibit a unidirectional bias. In FIGS. 6A and 6B, a cross-sectional schematic of a groove feature within a template layer is shown, where the bottom of the groove feature includes an exposed portion of the resistive layer adjacent to the conductive layer. The arrows represent the flow field and direction of flow of the electrolyte. When the electrolyte flows from left to right, the flow field creates a clockwise rotating flow (vortex) within the groove feature, as shown in FIG. 6A. When the electrolyte flows from right to left, the flow field creates a counterclockwise rotating flow within the groove feature, as shown in FIG. 6B. Since metal deposition can occur under mass transfer limitations of the metal ions in the electrolyte, the downstream position of the vortex bottom receives a more replenished, higher concentration stream of metal ions than the upstream position of the vortex bottom. This is because the electrolyte metal ions are first depleted more at the downstream position, thus depleting before the position in the upstream direction. As shown in FIG. 6A, the deposition rate at position 2 (downstream position) is faster than position 1, and the thickness at position 2 is greater, resulting in non-uniform feature profile. As shown in FIG. 6B, the deposition rate at position 1 (downstream position) is faster than position 2, and the thickness at position 1 is greater, resulting in non-uniform feature profile, opposite to FIG. 6A. If the duration of flow from left to right and right to left is equal during the electroplating operation, then the above mass transfer bias and undesirable non-uniform feature profile can be avoided. This applies not only to two dimensions, but also to three dimensions. Thus, applying bidirectional flow (e.g., from left to right and right to left) only in two dimensions leaves a bias in the third dimension. By implementing flow directions into and out of the page, some of the bias in the third dimension can be eliminated, but not necessarily all. By continuously changing the flow direction over time to equalize the flow rate in all directions, uniform mass transfer exposure can be achieved. One way to achieve angularly uniform mass transfer exposure is to rotate the print head around the linear flow field in the plating gap at a fixed rotation rate during the electroplating process. Alternatively, the rotation rate and / or direction can be varied during the electroplating process. In some embodiments, the rotation rate can be varied rapidly, e.g., over a short time relative to the duration of the electroplating process, or the rotation rate can be varied continuously (e.g., a slowly ramped rotation rate) over the entire duration of the electroplating process.

[0172] As shown, in certain embodiments, both the first and second operations are performed in the same chamber. In other embodiments, they are performed in different chambers. Typically, the electroplating system used for the second operation employs the following elements: (a) a print head comprising groove features defining a pattern to be printed on a substrate; (b) a chamber containing a support configured to support the substrate when electroplating on the substrate; and (c) a controller configured to electroplate metal at the print head groove features onto the substrate.

[0173] In certain embodiments, if the first and second operations use the same chamber or station, during the first operation, the print head is loaded and supported in the electroplating station in the same manner and position as the substrate in a conventional electrofill cell. In addition, during the first operation, a secondary electrode element is loaded into the electroplating station and used as an anode to electroplate into the print head. After the first operation is complete (i.e., metal is electroplated into the recesses of the print head), the secondary electrode is removed from the station in order to load the substrate (e.g., a semiconductor substrate) into the station in the appropriate position and transfer / print the metal previously plated onto the print head onto the substrate (i.e., the substrate is held at a cathodic potential and the print head is held at an anodic potential). In some embodiments that employ the same station for both operations, the secondary electrode is shaped substantially the same as the substrate (e.g., if the substrate is a 300 mm wafer, the secondary anode can be a disc shaped structure with a diameter of approximately 300 mm).

[0174] In certain embodiments, the platform optionally includes an automated robotic device configured for moving the print head and substrate between various processing stations, which can include one or more of the following: 1) a front end FOUP station for housing / storing one or more print heads or one or more defined patterns; 2) a print head electroplating station containing a counter electrode that is not a substrate; 3) a substrate electroplating station having a print head used as a counter electrode (anode); and any of the stations mentioned below. In certain embodiments, the substrate electroplating station includes a robotic automation device configured for inserting / removing the print head into / from the substrate electroplating station and establishing the appropriate electrical contact with the print head. Some embodiments include a positioning and sealing device configured for using the print head as an anode in close proximity to the substrate. In certain embodiments, the platform includes one or more wafer / substrate and pre-treatment stations configured for processing one or both of the substrate and print head, for example, by chemical exposure and spraying, immersion or vacuum wetting. In certain embodiments, the platform includes one or more post- electroplating processing chambers configured for performing post-process treatments, for example, chemical treatment and spin-rinse-drying of one or both of the substrate or print head.

[0175] In certain embodiments, the electroplating system has an actuator or other control device configured to control the gap between the print head surface and the substrate. Operation 1 and operation 2 can use different gaps. The controller and the actuator can be configured to: (i) provide a first gap between the print head and the substrate while electroplating metal from the secondary anode into the recess features of the print head (operation 1); and (ii) provide a second gap between the print head and the substrate while electroplating metal from the print head recess features onto the substrate (operation 2). In many embodiments, the second gap is smaller than the first gap. For example, the first gap can be about 200 microns or more, while the second gap can be about 1 micron or less. In certain embodiments, the print head contacts the substrate while electroplating metal from the print head recess features onto the substrate (operation 2). See, e.g., FIG. IB (154).

[0176] In embodiments where the electroplating system prints a stack comprising two or more printed layers (e.g., a stack comprising some layers with two or more of Cu, Ni, Sn), the electroplating system can use separate chambers for each of the multiple versions of operation 1. For example, in the case of a three-layer stack, metal 1 is electroplated in the upper position of the print head features (deepest within the template recess), metal 2 is electroplated in the middle position of the print head features (in contact with metal 1), and metal 3 is electroplated in the lower position (in contact with metal 2 but exposed to the electrolyte). Each of these three electroplating operations can be performed in its dedicated electroplating chamber, using electrolyte and / or anodes optimized for electroplating the respective metal. In alternative embodiments, operation 1 uses a single chamber, and the electroplating chemistry is changed to electroplate each metal layer separately.

[0177] In some embodiments, after electroplating the metal stack into the recesses of the print head, operation 2 is performed in a single chamber in which the entire stack is printed onto the substrate.

[0178] Patterned resistive anode In certain embodiments, a patterned resistive anode similar to the print heads described herein is used to electroplate features onto a substrate through a patterned mask on the substrate. Such a mask can be, for example, a patterned photoresist on the substrate, such as a patterned silicon wafer, which is commonly used to electroplate through the resist to create connection bumps between substrates, or current carrying lines on or inside a substrate. In this embodiment, the electroplated features are defined by the photoresist pattern on the substrate, which ensures that the metal is electroplated only into the areas defined by the mask features. A patterned resistive anode is an example of a type of anode that directs current in a specific pattern to minimize differences in electroplated metal thickness between different patterned features.

[0179] In some such embodiments, the patterned resistive anode employs two or more small size (e.g., diameter or largest dimension of about 5 to 200 pm) inert anodes, as opposed to a single inert or active anode commonly used in the art. Typically, the small anodes can comprise a dimensionally stable inert metal or alloy, or an active metal (e.g., copper), or other material to be electroplated onto the substrate. The individual anodes of the patterned resistive anode can be exposed surfaces separated by insulating masking material (also referred to elsewhere herein as a template layer, e.g., photoresist, epoxy, silicon dioxide) distributed in a targeted manner across the anode surface, thereby spatially matching and correlating with a particular belt masked through resist substrate, and ultimately improving its feature plating uniformity. The anode surface exposed to the electrolyte can catalyze electrooxidation reactions (e.g., water hydrolysis or ferrous ion oxidation) and is essentially non-corrodible in the electroplating process. Each anode is substantially coplanar with the patterned resistive anode surface. The template layer (sometimes also referred to as a masking layer) of the patterned resistive anode can be relatively thin, e.g., less than about 5 pm. The surface of the anode exposed to the electroplating electrolyte can be comprised of a material that is resistant to electrolytic oxidation and is capable of facilitating redox reactions in addition to corroding the exposed material. Examples of suitable materials for the surface film of each anode are dimensionally stable inert electrode materials (e.g., Ti, Ta, W, and Nb) and noble metals (e.g., Pt, Au, and Ir), or alloys comprising any of these materials.

[0180] In some through resist electroplating embodiments, the system is not configured to pre-load the patterned resistive anode with copper or other metal to be deposited. This is because the electrolyte provides the source of metal to be deposited. Thus, unlike using a two-stage electroplating operation, these embodiments employ only a single electroplating operation (to feature plate into resist features and to plate onto the workpiece surface) without the need to deposit copper into the template features on the print head. Such embodiments do not require contact to the workpiece surface and do not require metal transfer to the workpiece while in contact with the surface.

[0181] FIGS. 7A and 7B illustrate an example of a patterned resistive anode 701 that includes a conductive layer 703 that can be used as a bus layer to distribute current uniformly across the surface of the patterned resistive anode. Adjacent to the conductive layer 703 is a resistive layer 705 that can be structured and function similarly to the intermediate resistive layer in the print head embodiments described above. Finally, the patterned resistive anode 701 includes a template layer 707 in contact with the resistive layer 705 and a conductive layer 703 opposite. In the embodiment of FIG. 7A, the template layer 707 comprises a patterned dielectric structure 709 with small anodes 711 embedded therein. In the embodiment of FIG. 7B, the template layer does not comprise a patterned dielectric substrate.

[0182] For applications where the template layer is used as an anode source (as opposed to the two-step electroplating and transfer process of contact printing), the resistive portion of the template layer is not always necessary, but can be used to prevent corrosion of the resistive film. The resistive portion does not serve to define the storage location of the electroplated metal prior to transfer to the substrate as in the two-step printing embodiment. Thus, if the resistive film is not oxidized or corroded during deposition, the embodiment of FIG. 7B is sufficient.

[0183] A patterned resistive anode for through-resist electroplating can be fabricated by a method similar to that shown and described in FIG. 5. In addition, a patterned resistive anode for through-resist electroplating can have a similar structure as that shown and described in relation to FIG. 4A. However, there are differences in certain implementations. Notably, a dimensionally stable inert material, such as a catalytic material (e.g., platinum), is typically provided in the areas of the template layer exposed, rather than a resistive material as in the embodiment shown in FIG. 4A.

[0184] By using a resistive underlayer film to create a uniform current density anode surface, and then patterning the film to create a plurality of micro anode sources distributed based on the layout of the pattern to be deposited, the electrochemical deposition system can achieve an improved current distribution for a particular pattern layout. In certain embodiments, the individual anodes cannot act independently (i.e., the current of each micro anode cannot be set individually). An inert anode metal surface (e.g., a Pt metal surface) is exposed to the electrolyte. However, if the noble metal surface is uniformly distributed on the resistive film, and the substrate surface is covered with a patterned mask, the conductive Pt anode layer will not serve the intended purpose of the resistive film (e.g., the current can flow through the resistive film, but is easily diverted to the isolation features that favor the resistivity of the electrolyte, resulting in an undesirable current distribution). Thus, each micro anode of the patterned resistive anode has an inert anode metal region that is isolated from one another.

[0185] Conductive layer The conductive layer of the patterned resistive anode can comprise any conductive material, such as those described above in the print head embodiment. The conductive layer can act as a bus to uniformly deliver the electrical potential to the areas of the patterned resistive anode.

[0186] As with the print head embodiment described above, the conductive layer of the patterned resistive anode can be a continuous sheet of conductive material that can cover all or most of the area of the template layer occupied by the pattern. Such a conductive layer can be electrically connected to a bus (e.g., at its periphery or at its back surface). In alternative embodiments, the conductive layer is not continuous, but is comprised of two or more discrete or separate portions that can be addressed independently. For example, such an embodiment can employ thin film transistors to control each electrode portion separately. In such an approach, each portion of the conductive layer can require a separate and unique wiring control circuit.

[0187] Resistive layer As with the printing head embodiments described above, the resistive layer of the patterned resistive anode can be a continuous sheet of insulating material that can cover all or most of the area of the template layer occupied by the pattern. The resistive layer is interposed between the template layer and the conductive layer. It serves to suppress local changes in electrolyte resistance caused by, for example, feature loading and / or to suppress the ohmic potential drop from edge to center in the conductive layer. Thus, the resistive layer helps to produce a substantially uniform electric field across the printed area of the patterned resistive anode. The resistive layer can have the composition and other characteristics described above with respect to the printing head embodiments.

[0188] In many embodiments, the resistive layer is thin relative to the spacing between the individual features, e.g., about 0.2 times or less the minimum distance between adjacent feature edges, or about 0.1 times or less the minimum distance between adjacent feature edges. This restriction stems from the desire to have the same anode current between individual anodes, and not be affected by variable resistance in the electrolyte. If the film were the same size as the feature spacing, the edges of the array features could draw current from more interior features. As a result of these two requirements, the specific resistivity of the film falls in a target range, which is introduced elsewhere herein.

[0189] Template structure The patterned resistive anode for through-resist electroplating can employ a dielectric template portion comprising a dielectric material that defines a pattern corresponding to the features to be electrodeposited on the surface of the substrate. Where the dielectric material is absent in the pattern of the template layer, the template structure comprises a chemically inert, conductive electrode material. Examples of such conductive materials include platinum, iridium, gold, titanium, tantalum, tungsten, or niobium. The areas of the template occupied by the conductive material serve as small anodes, sometimes also referred to as micro-anodes.

[0190] The dielectric portion of the template layer can be relatively thin and is generally coplanar with the micro-anodes. In other words, the patterned resistive anode can be free of recesses. As shown in FIG. 4A, the micro-anodes can be embedded in the dielectric layer and have surfaces that are coplanar with the dielectric layer. In some cases, the portions of the template layer occupied by the micro-anodes are relatively shallow recesses. This is because the patterned resistive anode need not serve as a receptacle to hold copper or other metal that serves as an active anode and is thus consumed in electroplating features onto a substrate. Moreover, if the anode reaction includes hydrolysis and generation of dissolved oxygen, any gas bubbles that can be generated in the process are not trapped or clogged in the anode recesses.

[0191] In certain embodiments, the template layer has a thickness of no more than about 5 microns, or a thickness between about 0.1 and 2 microns.

[0192] While the design criteria for the layers of the print head and the layers of the patterned resistive anode can be similar, the reasons for these criteria can be different. In the case of printing, the properties of the resistive film ensure that the plating proceeds at the same rate on the print head for different loads and between features on the print head by making the resistive film uniform in resistance across the surface and between features and the dominant resistance in a series of resistances from the counter electrode to the surface of the anode. For the patterned resistive anode, the resistance is uniform in space and is a resistive resistance relative to the variable resistance between features on the substrate, including the variable resistance of the local electrolyte environment (i.e., the distribution of primary current) and the resistance of the seed layer from center to edge. In other words, the total resistance of the layer must be greater than the resistance of the electrolyte in the gap between the micro-anode and the workpiece, as well as the resistance of the workpiece seed layer from center to edge.

[0193] Electrolyte chemistry (inert anode) In certain embodiments, the composition of the electrolyte used when plating through the patterned resistive anode is similar to the composition of the electrolyte used when the print head embodiments described herein are first operated. For example, the electrolyte can have a composition with a concentration of copper ions (e.g., from a sulfate salt (a source of metal ions)) of about 10 to 80 g / L or about 20 to 65 g / L, and a concentration of sulfuric acid of about 5 to 120 g / L or about 20 to 100 g / L. The electrolyte can optionally include one or more additives, such as accelerators, inhibitors, and optionally levelers, to promote bottom-up filling.

[0194] When using an inert anode, such as when used during plating through the patterned resistive anode, one or more modifications to the process can be made to address the generation of acid and / or oxygen bubbles in the electrolyte in the plating process. This is because the oxidation electrochemical half-reaction at the inert anode can cause a drop in pH and an increase in oxygen generation (2H2O O2+4H + +4e - ) due to water decomposition. At the same time, metal ions (e.g., copper ions) on the workpiece are depleted through the reduction electrochemical half-reaction (2Cu +2 +4e - 2Cu).

[0195] The acidification and depletion of copper can be mitigated by adding a known concentration and volume of electrolyte, such as a solution that can have a higher concentration of copper than the plating electrolyte and a lower concentration of acid than the plating electrolyte. In addition, the process can periodically remove excess plating solution to maintain consistency in the total volume of the system. Such a process can be implemented as a “bleed and feed” operation.

[0196] In some embodiments, a material is added that will react with the excess acid generated and release copper ions during the process. For example, a solid metal oxide such as copper oxide or copper hydroxide is added. This can be implemented as part of the overall plating system bath composition control. A metal oxide dosing control unit can be fluidly coupled to the plating solution reservoir. Using the stoichiometric ratio associated with the reaction, the metal oxide can be used to balance the bath composition. For example, adding copper oxide reacts with hydrogen ions to generate copper ions and water (4H + + 2CuO → 2Cu +2 + 2H2O). This compensates for copper loss and acidification in the plating solution. More generally, a reaction with an oxide or hydroxide of the same oxidation state as the metal being plated (e.g., Cu +2 / CuO, Ni +2 / NiO, or Sn +2 / SnO) will replace the generated acid with metal ions and water and remove oxygen.

[0197] In some embodiments, a soluble positive ion with multiple oxidation states is employed as the anode to reduce the generation of hydrogen ions. Any number or possible soluble ion redox couples can be used. For example, ferrous ions (Fe +2 ) can be used. During operation, the ferrous ions are oxidized to ferric ions (Fe +3 ) at the inert anode surface. In such embodiments, no gas is generated and the pH of the electrolyte remains relatively stable since no oxygen or hydrogen ions are generated. However, the concentration of Fe +3 ions will increase over time if no mitigation is taken. There are two approaches to address this problem: as described above, dosing a solution with a known concentration of ferrous ions (e.g., a bleed and feed); or driving a reverse electrochemical reaction in an electrochemical cell containing the main plating electrolyte 1375 (2Fe +3 + Cu → 2Fe +2 +Cu +2 ). This can be implemented as part of a recirculation loop or by moving the electrolyte to a separate device and returning the electrolyte to the main reservoir periodically or continuously.

[0198] Bubbling caused by generated oxygen can be mitigated by using a non-oxygen saturated electrolyte. Such an electrolyte can be flowed near the inert anode. Dissolved oxygen can be removed from the electrolyte by, for example, using a contactor / membrane degasser in the flow loop that is connected to a vacuum device and removes dissolved gases from the solution.

[0199] Isolation gap between plating head and substrate In certain embodiments, through-mask plating is performed with a patterned resist anode, such that the plating head does not contact the substrate surface while plating within the plating cell. More specifically, the anode does not contact the top of the mask on the substrate surface. In certain embodiments, the gap between the anode surface and the substantially parallel surface of the substrate is about 0.1 to 2 millimeters. Maintaining such a small and uniform gap mechanically across a 300 millimeter workpiece surface is challenging.

[0200] The higher electrolyte flow rate through the gap needed for good shear forces and high speed deposition is impeded by the smaller passage and rapidly increasing pressure. At smaller gaps, sealing components can be difficult to rotate. In contrast, for a patterned resist anode application, being closer to the surface provides better near field focusing and higher "throwing power" of the anode to the substrate features, resulting in better uniformity correction capability.

[0201] Through resist plating In embodiments employing through-mask plating, the process creates and patterns a mask material, electro-deposits metal in the photoresist features, and finally removes the mask material. Cell operations can include spin coating, baking, photolithographic patterning, scum removal / ashing, and mask stripping.

[0202] In some embodiments, the through-mask plating process first coats a thin layer of conductive seed layer material (e.g., Cu) on a substrate (e.g., a semiconductor substrate having a flat exposed surface). The substrate can be a partially fabricated semiconductor substrate having patterned features on one or more chips. Next, the process forms a non-conductive mask layer (e.g., photoresist) over the conductive seed layer. After that, the process patterns the mask layer to define recessed features (e.g., circular or polygonal holes), and then, if a photoresist mask is used, develops the mask layer. The recessed features define the selective space in which metal will be subsequently deposited.

[0203] Next, the process electroplates metal within the substrate area defined by the patterned photoresist. Finally, the process can strip the photoresist or other mask material from the substrate, and optionally remove portions of the conductive seed layer.

[0204] Both the template layer of the patterned resist anode and the mask layer on the substrate can have a pattern set by the metal pattern to be plated onto the substrate. Both layers can have features that collectively map to the layout or pattern of structures to be printed onto the substrate (e.g., a semiconductor wafer). Examples of structures that map to the pattern of conductive material to be deposited on the substrate include wafer level packaging (WLP) patterns.

[0205] In various implementations, different template layers and different substrate mask layer patterns are required for each application. That is, for a given application, the template layer and the substrate mask layer have a fixed pattern.

[0206] Figure 7C schematically illustrates a resistive anode electroplating cell 741 for through-mask electroplating. As shown, the cell 741 contains an electrolyte 743 containing dissolved metal ions (M) (e.g., copper ions). The cell 741 also includes a patterned resistive anode 747, which includes a conductive layer 748, a resistive layer 749, and a non-conductive template layer 751. Micro-anodes 461 are embedded in the recesses of the template layer 751. Electrical leads 753 are connected to the conductive layer 748. During the electroplating process, the leads 748 apply an anodic current and / or potential to the conductive layer 748.

[0207] The cell 741 also includes a substrate 755 having a patterned resist 757 disposed thereon. As shown, during the electroplating process, metal 759 is deposited within the recesses of the patterned resist 757. The metal 759 can be generated by oxidizing the metal ions M within the exposed portions of the substrate 755.

[0208] Platform Figure 8A illustrates a schematic diagram of an exemplary print head electroplating cell in conjunction with general electroplating cell fluid and electroplating control, according to certain implementations. The print head electroplating cell 811 optionally includes an assembly with an elastomeric seal and one or more electrical contact members. The assembly is used to hold the substrate at its periphery and to provide current to the substrate. The inert anode array electroplating cell 811 also includes a print head adjacent to the substrate with an adjustable small gap between the print head and the substrate. A plurality of straightening fins can be disposed around the substrate (as opposed to directly below the substrate), where the height of the plurality of straightening fins can be defined by the small gap. As the electrolyte fluid rises from the injection manifold, the electrolyte fluid is rotated 90 degrees to create a cross flow over the print head surface. This occurs with the help of the straightening fins.

[0209] In some embodiments, the print head plating cell 811 is fluidically coupled to the electroplating solution reservoir 891 by inlet and outlet conduits to form a recirculating flow loop. The electroplating system 801 includes the print head plating cell 811 and the electroplating solution reservoir 891. The electroplating system 801 can also include a recirculation pump 831, a flow meter 835, a degasser 837, cell and reservoir level monitors (e.g., level sensors 871), a heat exchanger and / or immersion heater 861, a thermocouple 851, a temperature controller 881 coupled to the thermocouple 851 and the heat exchanger and / or immersion heater 861, and one or more drain ports (e.g., side outlets). In some embodiments, the electroplating system 801 also includes a density, pH, and / or conductivity meter, which can be used for bath maintenance 841. In addition to the hardware components described above, the electroplating system 801 can also include a controller, such as a flow controller 833 for regulating and controlling the flow of electrolyte, the temperature of electrolyte, the dosing of additives to the electrolyte, the stoichiometry of acid, base, etc., and / or a controller 821. A power supply can be electrically connected to the controller 821 to power the print head, the secondary electrode, and / or the substrate. The controller can be configured with instructions or programmed to control one or more processes described herein. These processes can relate to flow rates, times, substrate rotation, substrate and chip layout recognition, and control of current distribution to the array of micro-inert anodes. In some embodiments, the electrochemical metal catalyst ion regeneration system is housed within or fluidically connected to the electroplating solution reservoir.

[0210] The two operational procedures described herein can be performed by any suitable system or platform, which can include one or more electroplating chambers. Suitable apparatuses include hardware for accomplishing the process operations and a system controller having instructions for controlling the process operations in accordance with embodiments of the present application. For example, in some embodiments, the hardware can include one or more processing stations included in a process tool.

[0211] FIG. 8B depicts a simplified view of a multi-tool plating apparatus, in accordance with some embodiments. In the illustrated embodiment, the electrodeposition apparatus 800 includes three separate electroplating modules 802, 804, and 806. The depicted apparatus 800 also includes three separate modules 812, 814, and 816 configured to perform various process operations. For example, in some embodiments, one or more of the modules 812, 814, and 816 can be a spin-rinse-dry (SRD) module. In other embodiments, one or more of the modules 812, 814, and 816 can be a post-electrofill module (PEM), each configured to perform functions such as backside etching and acid washing after a substrate is processed through one of the electroplating modules 802, 804, and 806.

[0212] The electroplating apparatus 800 includes a central electroplating chamber 824. The central electroplating chamber 824 is a chamber for holding chemical solutions used as plating solutions in the plating modules 802, 804, and 806. The electroplating apparatus 800 also includes a dosing system 826, which can store and deliver additives for the plating solutions. A chemical dilution module 822 can store and mix chemicals used as etchants. A filtration and pumping unit 828 can filter and pump the plating solutions of the central electroplating chamber 824 to the plating modules.

[0213] A system controller 830 provides electronic and interface control necessary to operate the electroplating apparatus 800. The system controller 830, which can include one or more physical or logical controllers, controls some or all of the attributes of the plating apparatus 800.

[0214] Signals for monitoring the process can be provided by analog and / or digital input connections of the system controller 830 from various process tool sensors. Signals for controlling the process can be output through analog and digital output connections of the process tool. Non-limiting examples of process tool sensors that can be monitored include mass flow controllers, pressure sensors (e.g., manometers), thermocouples, optical position sensors, etc. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain process conditions.

[0215] A transfer tool 840 can pick substrates from substrate cassettes (e.g., cassettes 842 or 844). The cassettes 842 or 844 can be front opening unified pods (FOUPs). A FOUP is a closed device configured to safely and reliably house substrates in a controlled environment and allow a tool equipped with appropriate load ports and robotic handling systems to access the substrates for processing or measurement. The transfer tool 840 can use vacuum suction devices or other suction mechanisms to hold the substrates. Another mechanism can be responsible for moving the print head into or out of one or more of the plating modules 802, 804, and 806.

[0216] The transfer tool 840 can interface with a wafer handling station 832, the cassettes 842 or 844, a transfer station 850, or an aligner 848. The transfer tool 846 can enable access to substrates from the transfer station 850. The transfer station 850 can be a slot or location from which the transfer tools 840 and 846 can transfer substrates to and from without passing through the aligner 848. However, in some embodiments, to ensure that the substrates are properly aligned on the transfer tool 846 for accurate transfer to the plating modules, the transfer tool 846 can align the substrates with the aligner 848. The transfer tool 846 can also transfer the substrates to one of the plating modules 802, 804, or 806, or to one of the three independent modules 812, 814, and 816 configured for various process operations.

[0217] One example of a process operation according to the above-described method can proceed as follows: (1) receiving a substrate in an electroplating module, wherein the substrate comprises one or more dies having a non-uniform distribution of features; (2) contacting the substrate with an electrolyte and a print head in the electroplating module; and (3) electroplating a metal on the substrate using the print head. In some embodiments, the print head contacts the substrate during printing onto the substrate. However, as explained, the print head is spaced apart from the substrate by a predetermined gap when electroplating is performed on the print head. In some embodiments, contacting the print head with the electrolyte during the first operation comprises flowing the electrolyte laterally across a surface of the substrate.

[0218] An apparatus configured to allow efficient cycling of substrates through sequential electroplating, rinsing, drying, and PEM process operations can be suitable for implementation for use in manufacturing environments. To achieve this, module 812 can be configured as a spin-rinse-dryer and edge-bevel-removal chamber. Using such a module 812, a substrate need only be transported between electroplating module 804 and module 812 to perform copper plating and EBR operations. In some embodiments, the methods described herein will be implemented in a system comprising an electroplating apparatus and a stepper.

[0219] FIG. 9 depicts a simplified view of an exemplary electroplating apparatus having different electroplating cells and modules, according to some embodiments. In the present embodiment, the electro-deposition apparatus 900 has a set of electroplating cells 907, each containing an electroplating bath, in pairs or multiple “dual” configurations. In addition to electroplating itself, the electro-deposition apparatus 900 can also perform various other electroplating-related processes and sub-steps, such as spin-rinsing, spin-drying, metal and silicon wet etching, chemical deposition, pre-wetting and pre-chemical treatment, reduction, annealing, electro-etching and / or electro-polishing, photoresist stripping, and surface pre-activation using a pre-accelerator solution. The electro-deposition apparatus 900 is schematically shown in plan view in FIG. 9, with only a single level or “floor” shown, but one skilled in the art will appreciate that such apparatuses (e.g., Lam Sabre TM 3D tools) can have two or more levels “stacked” on one another, each level potentially having the same or different types of processing stations.

[0220] Referring again to FIG. 9, substrates 906 to be electroplated are typically fed to the electro-deposition apparatus 900 through front opening unified pods (FOUPs) 901 and, in this example, brought to the main substrate processing area of the electro-deposition apparatus 900 via front end robots 902, which can retract and move substrates 906 driven in multiple dimensions by spindles 903 from one of the accessible stations to another, in this example, two front end accessible stations 904 and two front end accessible stations 908 are shown. The front end accessible stations 904 and 908 can include, for example, pre-treatment stations and spin rinse dry (SRD) stations. Lateral motion from one side of the front end robot 902 to the other is accomplished with a robot track 902a. Each of the substrates 906 can be held by a cup / cone assembly (not shown) driven by a spindle 903 connected to a motor (not shown), which can be affixed to a mounting bracket 909. Also shown in this example are four "dual" electroplating cells 907, for a total of eight electroplating cells 907. A system controller (not shown) can be coupled to the electro-deposition apparatus 900 to control some or all of the attributes of the electro-deposition apparatus 900. The system controller can be programmed or otherwise configured to execute instructions in accordance with the processes described previously herein.

[0221] In some implementations, a controller is part of a system, which can be part of the above-described examples. Such systems can include semiconductor processing equipment including one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, gas flow systems etc.). These systems can be integrated with electronics for controlling the operations of the semiconductor processing equipment before, during, and after processing of a semiconductor wafer or substrate. The electronics can be referred to as the “controller,” which can control various components of the system or subsystems thereof. The controller, depending on the processing requirements and / or system type, can be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., of heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfer into and out of a tool and other transfer tools, and load locks connected to or interfaced with a specific system.

[0222] Broadly speaking, the controller can be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits can include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions can be instructions (or sets of instructions) that are executed by the controller to implement one or more processes, algorithms, or other instructions (or sets of instructions) that are executable by the controller. The software can be stored in the memory. The memory can be embedded in the controller. The memory can be external to the controller and connected to the one or more microprocessors or microcontrollers via a memory port or a

[0223] In some implementations, the controller can be part of, or coupled to, a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller can be in "the cloud" or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer can enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, change parameters of current processing, set processing steps to follow in the current process, or start new processes. In some examples, a remote computer (e.g., a server) can provide process recipes to a system over a network, which can include a local network or the Internet. The remote computer can include a user interface that enables entry or programming of parameters and / or settings, which are then transmitted over the network to the system. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps during one or more operations. The parameters can be specific to the type of process being performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller can be distributed across all or a portion of the system. For example, one or more of the components of the controller, alone or in combination, can constitute a distributed controller. An example of a distributed controller for such purposes is one or more integrated circuits on a chamber in communication with one or more integrated circuits located off the chamber, e.g., in a platform level or as part of a remote computer, that work together to control a process on the chamber.

[0224] An exemplary system can include, but is not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor

[0225] Applications Applications of the methods, apparatuses, and systems herein include packaging technology. Wafer level packaging, bumps, redistribution layers, fan-out, and through-silicon vias (TSVs) are some advanced packaging types. In many cases, integrated circuit packaging involves wafer level packaging (WLP), which is an electrical connection technology that employs relatively large features, typically on the order of microns. Wafer level packaging, as generally understood by those skilled in the art, refers to the technology of packaging an integrated circuit (IC) while it is still part of a wafer, as opposed to the traditional method of cutting the wafer into individual circuits (chips) and then packaging. Examples of WLP features include redistribution wiring, bumps, and pillars. Such features in WLP applications can be generated using the two operating procedures and apparatuses described herein. Many of these applications are increasingly being performed on larger panel formats and substrates, and it should be understood that the above-described inventions are not in any way limited to the more prevalent high-density packaging wafer formats.

[0226] For certain applications, the printed features have a diameter of at least about 2 pm or at least about 20 pm. For certain applications, the printed features have a height of at least about 5 pm, or at least about 10 pm, or at least about 20 pm, or at least about 40 pm.

[0227] While the present disclosure is primarily described in the context of WLP, it should be understood that the present disclosure is not limited to such applications. In some implementations, the present disclosure can be applied to non-WLP applications, such as damascene applications or TSV applications. Damascene and TSV processes involve electroplating over the entire seed layer and exposed surfaces of a substrate (no mask, but with a recessed metallization surface), and the feature density of the feature pattern can still vary, which can be addressed by the printing heads of the present disclosure.

[0228] Conclusion In the foregoing description, numerous specific details are set forth to provide a thorough understanding of the subject matter disclosed. However, it will be apparent that the disclosed implementations can be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the disclosed implementations. While the disclosed implementations are described in conjunction with particular implementations, it is to be understood that the disclosed implementations are not limited to those particular implementations.

[0229] While the forgoing implementations have been described in some detail for purposes of clarity and the specific embodiments described are shown by way of example, there are other ways to implement the claimed implementations. The disclosed implementations should not be limited by the described implementations, but rather should be given broad coverage.

Claims

1. A print head comprising: (a) a stencil layer comprising a non-conductive material having recesses or openings defining a pattern of conductive material to be printed on a substrate; (b) a conductive layer covering the pattern of conductive material; and (c) a resistive intermediate layer disposed between the stencil layer and the conductive layer.

3. The print head of claim 2, wherein the resistive layer has a thickness no greater than about 0.1 times a minimum pitch of the pattern of conductive material to be printed on a substrate.

2. The printhead of claim 1, wherein the electrical resistivity of the resistive layer is about 10 -5 to 10 -7 S / cm.

4. The print head of claim 2, wherein the resistive layer has a thickness of about 0.1 microns to 10 microns.

5. The print head of any of the preceding claims, wherein the resistive layer comprises a carbon film.

6. The print head of any of the preceding claims, wherein the conductive layer has a sheet resistance of at most about 0.1 ohm / square.

7. The print head of claim 6, wherein the conductive layer has a thickness of about 0.01 microns to 10 microns.

8. The print head of any of the preceding claims, wherein the conductive layer comprises copper, nickel, cobalt, titanium, or any combination thereof.

9. The print head of any of the preceding claims, wherein the recesses or openings in the stencil layer have a thickness of about 5 microns to 300 microns. the non-conductive material of the stencil layer comprises glass, a polymer, a ceramic, or any combination thereof.

10. A printing head according to any one of the preceding claims, wherein, the pattern of conductive material to be printed on the substrate comprises a WLP pattern.

11. A printing head according to any one of the preceding claims, wherein, the WLP pattern is an RDL pattern.

12. The printhead of claim 11, wherein, the WLP pattern is a columnar pattern.

13. The printhead of claim 11, wherein, 14. The print head of claim 1, further comprising a conductive contact connected with the conductive layer to apply a power supply potential to the conductive layer. the conductive contact is in contact with a peripheral portion of the conductive layer.

15. The printhead of claim 14, wherein, the conductive contact is in contact with a peripheral portion of the conductive layer at multiple points and is configured to provide a substantially uniform current distribution around the peripheral portion of the conductive layer.

16. The printhead of claim 15, wherein, the stencil layer is in contact with the resistive intermediate layer and the resistive intermediate layer is in contact with the conductive layer.

17. A printing head according to any one of the preceding claims, wherein, 18. A method of printing a feature on a substrate, the method comprising: electroplating a metal into recesses of a print head, wherein the print head comprises: (a) a stencil layer comprising a non-conductive material having recesses or openings defining a pattern of features to be printed on a substrate; (b) a conductive layer covering substantially an entire area of the recesses or openings; and (c) a resistive intermediate layer disposed between the stencil layer and the conductive layer; and electroplating the metal in the recesses of the print head stencil onto the substrate to print the feature on the substrate. electroplating the metal into the recesses of the print head comprises applying a cathodic potential to the conductive layer relative to a counter electrode.

19. The method of claim 18, wherein, 20. The method of claim 19, wherein electroplating the metal into the recesses of the print head comprises electroplating the metal from a secondary electrode used as the counter electrode. ​ 21. The method of claim 19, wherein electroplating the metal into the recesses of the print head comprises electroplating the metal onto exposed portions of the resistive interlayer.

22. The method of any one of claims 18-21, wherein electroplating the metal into the recesses of the print head comprises flowing an electrolyte over a surface of the stencil layer.

23. The method of any one of claims 18-22, wherein electroplating the metal in the recesses of the print head stencil onto the substrate comprises applying an anodic potential to the conductive layer relative to the substrate.

24. The method of any one of claims 18-23, wherein, electroplating the metal in the recesses of the print head stencil onto the substrate comprises contacting the stencil layer with the substrate without contacting the metal electroplated into the recesses of the print head stencil with the substrate.

25. The method of any one of claims 18-24, further comprising electroplating a second metal into the recesses of the print head, thereby forming a layer of the metal and a layer of the second metal within the recesses of the print head.

26. The method of claim 25, wherein electroplating the metal in the recesses of the print head stencil onto the substrate is performed after electroplating the second metal into the recesses of the print head, and wherein electroplating the metal in the recesses of the print head stencil onto the substrate results in printing a stack of the metal and the second metal on the substrate.

27. An electroplating platform comprising: a print head comprising recess features defining a pattern to be printed on a substrate; a chamber comprising: a support configured to hold the substrate; and a support configured to hold a secondary anode; and a controller configured to: electroplate a metal from the secondary anode into the recess features of the print head; and electroplate the metal in the recess features of the print head onto the substrate.

28. The electroplating platform of claim 27, wherein, the print head comprises: (a) a stencil layer comprising a non-conductive material having recesses or openings defining the pattern of the conductive material to be printed on a substrate; (b) a conductive layer covering substantially the entire pattern of the conductive material; and (c) a resistive interlayer disposed between the stencil layer and the conductive layer.

29. The electroplating platform of claim 28, wherein the electrical resistive layer has an electrical conductivity of about 10 -5 to 10 -7 S / cm.

30. The electroplating platform of claim 29, wherein a thickness of the resistive layer is no greater than about 0.1 times a minimum pitch of the pattern of the conductive material to be printed on a substrate.

31. The electroplating platform of claim 28, wherein, the conductive layer comprises copper, nickel, cobalt, titanium, or any combination thereof.

32. The electroplating platform of claim 28, wherein, the non-conductive material of the stencil layer comprises glass, a polymer, a ceramic, or any combination thereof.

33. The electroplating platform of claim 28, wherein, the pattern of the conductive material to be printed on the substrate comprises a WLP pattern.

34. The electroplating platform of any one of claims 27-33, wherein, the secondary anode is disposed about a perimeter of the print head when electroplating the metal from the secondary anode into the recess features of the print head.

35. The electroplating platform of any one of claims 27-33, wherein, The secondary anode is substantially planar and is aligned substantially parallel to and facing the recessed features of the print head during electroplating of metal from the secondary anode into the recessed features of the print head.

36. The electroplating platform of any one of claims 27-35, wherein, The controller is further configured to cause: (i) a first gap between the print head and the substrate while electroplating the metal from the secondary anode into the recessed features of the print head; and (ii) a second gap between the print head and the substrate while electroplating the metal in the recessed features of the print head onto the substrate, wherein the second gap is smaller than the first gap.

37. The electroplating platform of claim 36, wherein, The print head contacts the substrate while electroplating the metal in the recessed features of the print head onto the substrate.

38. The electroplating platform of any one of claims 27-37, wherein the chamber is configured to induce convection over the recessed features of the print head while electroplating the metal from the secondary anode into the recessed features of the print head.

39. The electroplating platform of any one of claims 27-38, wherein the chamber is configured to flow electrolyte substantially parallel to a surface of the print head while electroplating the metal from the secondary anode into the recessed features of the print head.

40. The electroplating platform of any one of claims 27-39, wherein the chamber is configured to rotate the print head while electroplating the metal from the secondary anode into the recessed features of the print head.

41. A method of manufacturing a print head, the method comprising: forming a conductive layer of conductive material having a substantially uniform thickness; forming a resistive intermediate layer over the conductive layer, wherein the resistive intermediate layer has a substantially uniform thickness of resistive material; and forming a template layer over the resistive intermediate layer, wherein the template layer comprises a non-conductive material having recesses or openings that define a pattern of conductive material to be printed on a substrate.

42. The method of claim 41, wherein, Forming the template layer comprises: electroplating a metal pattern into recesses of a patterned photoresist; removing the photoresist from around the metal pattern; applying a dielectric layer over the metal pattern; and removing the raised metal features to form the template layer.

43. The method of claim 41 or 42, wherein, The electrical conductivity of the resistive layer is about 10 -5 to 10 -7 S / cm.

44. The method of claim 43, wherein the thickness of the resistive layer is no greater than about 0.1 times a minimum pitch of the pattern of conductive material to be printed on a substrate.

45. The method of any one of claims 41-44, wherein, The resistive layer comprises a carbon film.

46. The method of any one of claims 41-45, wherein, The conductive layer comprises copper, nickel, cobalt, titanium, or any combination thereof.

47. The method of any one of claims 41-46, wherein, The non-conductive material of the template layer comprises glass, a polymer, a ceramic, or any combination thereof.

48. The method of any one of claims 41-47, wherein, The pattern of conductive material to be printed on the substrate comprises a WLP pattern.

49. The method of any one of claims 41-48, wherein, Forming the template layer comprises: depositing a conductive seed layer over the resistive intermediate layer; applying and patterning a photoresist over the seed layer; electroplating a metal into recesses of the photoresist; removing the photoresist from over the seed layer; etching away the conductive seed layer in areas not electroplated with the metal, thereby producing isolated raised metal features; coating the raised metal features with a dielectric layer; planarizing the dielectric layer to expose the raised metal features; and removing the raised metal features to form the template layer.

50. A patterned resistive anode comprising: (a) a template layer comprising recesses or openings of non-conductive material defining a pattern of conductive material to be printed on a substrate; (b) a plurality of micro-anodes located in the recesses or openings of the template layer; (c) a conductive layer covering the pattern of conductive material; and (d) a resistive intermediate layer disposed between the template layer and the conductive layer.

51. The patterned resistive anode of claim 50, wherein the micro-anodes have a maximum width or diameter of about 5 to 200 pm.

52. The patterned resistive anode of claim 50 or 51, wherein the micro-anodes comprise titanium, tantalum, tungsten, niobium, platinum, gold, iridium, or any combination thereof.

53. The patterned resistive anode of any one of claims 50-52, wherein the template layer has a thickness of about 5 micrometers or less.

54. The patterned resistive anode of any one of claims 50-53, wherein the resistive layer has a thickness no greater than about 0.1 times a minimum pitch of the pattern of conductive material to be printed on a substrate.

55. The patterned resistive anode of any one of claims 50-54, wherein the resistive layer has a thickness of about 0.1 micrometers to 10 micrometers.

56. The patterned resistive anode of any one of claims 50-55, wherein the conductive layer has a sheet resistance of at most about 0.1 ohm / square. the pattern of conductive material to be printed on the substrate comprises a WLP pattern.

57. The patterned resistive anode of any of claims 50-56, wherein, 58. A method of depositing features on a substrate, the method comprising: in an electroplating cell, receiving the substrate having a mask layer on a surface, wherein the mask layer comprises recesses corresponding to a pattern of features to be electrodeposited on the substrate; and electroplating metal into the recesses of the mask layer by controlling a patterned resistive anode, the patterned resistive anode comprising: (a) a template layer comprising non-conductive material and micro-anodes corresponding to the pattern of features to be electrodeposited on the substrate; (b) a conductive layer covering the template layer; and (c) a resistive layer disposed between the template layer and the conductive layer. electroplating the metal into the recesses of the mask layer includes applying an anodic current and / or an anodic potential to the patterned resistive anode in the electroplating cell relative to the substrate.

59. The method of claim 58, wherein, a gap between the patterned resistive anode and the substrate is about 0.1 millimeter to 2 millimeters while electroplating the metal into the recesses of the mask layer.

60. The method of claim 58 or 59, wherein, 61. The method of any one of claims 58-60, wherein the template layer has a thickness of about 5 micrometers or less.

62. The method of any one of claims 58-61, wherein the micro-anodes comprise titanium, tantalum, tungsten, niobium, platinum, gold, iridium, or any combination thereof.

63. An electroplating platform comprising: ​ an electroplating unit comprising a support configured to hold a substrate; and a patterned resistive anode comprising micro-anodes corresponding to a pattern of features to be deposited on the substrate; and a controller configured to: receive the substrate having a mask layer on a surface in the electroplating unit, wherein the mask layer comprises recesses corresponding to the pattern of features to be deposited on the substrate; and electroplate metal into the recesses of the mask layer by controlling a patterned resistive anode.

64. The electroplating platform of claim 63, wherein, The patterned resistive anode comprises: (a) a template layer comprising a non-conductive material and micro-anodes corresponding to the pattern of features to be deposited on a substrate; (b) a conductive layer covering the template layer; and (c) a resistive layer disposed between the template layer and the conductive layer.

65. The electroplating platform of claim 64, wherein, The electrical conductivity of the resistive layer is about 10 -5 to 10 -7 S / cm.

66. The electroplating platform of claim 65, wherein, The thickness of the resistive layer is not greater than about 0.1 times the minimum pitch of the pattern of conductive material to be deposited on a substrate.

67. The electroplating platform of claim 64, wherein, The micro-anodes comprise titanium, tantalum, tungsten, niobium, platinum, gold, iridium, or any combination of these metals.

68. The electroplating platform of claim 64, wherein, The non-conductive material of the template layer comprises glass, polymer, ceramic, or any combination thereof.

69. The electroplating platform of claim 64, wherein the pattern of conductive material to be deposited on the substrate comprises a WLP pattern.

70. The electroplating platform of claim 64, wherein the template layer has a thickness of about 5 microns or less.

71. The electroplating platform of any one of claims 63-70, wherein, Electroplating the metal into the recesses of the mask layer comprises applying an anodic current and / or an anodic potential to the patterned resistive anode in the electroplating unit relative to the substrate.

72. The electroplating platform of any one of claims 63-71, wherein, The controller is further configured to cause a gap to be provided between the patterned resistive anode and the substrate while electroplating the metal into the recesses of the mask layer, wherein the gap is about 0.1 mm to 2 mm.

73. The electroplating platform of any one of claims 63-72, wherein, The electroplating unit is configured to flow electrolyte substantially parallel to a surface of the patterned resistive anode while electroplating the metal into the recesses of the mask layer.

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