Electrodeposition system for sequential plating operations

Abstract

Sequential electroplating methods and apparatus electroplate copper or other metal into features in two or more sequential operations, with each operation performed under different conditions and optionally in different electroplating cells. In one example, a first electroplating operation completely fills small features and partially fills larger features on the same wafer, while a subsequent electroplating step finishes filling the larger features and forms overburden on all features.

Description

Attorney Docket No. LAM1P093WO-12158-1WO ELECTRODEPOSITION SYSTEM FOR SEQUENTIAL PLATING OPERATIONSINCORPORATION BY REFERENCE

[0000] A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in their entireties and for all purposes.BACKGROUND

[0001] In semiconductor device manufacturing, a conductive material, such as copper, is often deposited by electroplating onto a seed layer of metal to fill one or more recessed features on a semiconductor wafer. Electroplating is a method of choice for depositing metal into the vias and trenches of the wafer during Damascene processing and is also used in through-mask plating in wafer level packaging (WLP) applications to form pillars and lines of metal. Another application of electroplating is filling through-silicon vias (TSVs). which are relatively large vertical electrical connections used in 3D integrated circuits and 3D packages.

[0002] The background provided herein is for the purposes of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent that it is described in this background, as well as aspects of the description that may 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

[0003] Some aspects of this disclosure pertain to methods of electroplating a metal, which methods may be characterized by the following operations: receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, where the substrate surface has a conductive layer disposed thereon; performing a first electroplating operation under first electroplating conditions to deposit metal that at least partially fills the one or more recessed features; and performing a second electroplating operation under second electroplating conditions, which are different than the first electroplating conditions, to deposit additional metal over the metal deposited in the first electroplating operation.

[0004] In certain embodiments, the one or more recessed features comprise Damascene features including vias and interconnect paths. In some embodiments, the one or more recessed features comprise a first feature having a first size and a second feature having a second size, where the first size is greater than the second size. In some cases, the first electroplating operation fully fills the second feature but does not fully fill the first feature. Further, in some cases, the additionalAttorney Docket No. LAM1P093WO-12158-1WO metal deposited by the second or a later electroplating operation completes filling the first feature. In some embodiments, the additional metal deposited by the second electroplating operation comprises at least a portion of an overburden layer.

[0005] In certain embodiments, at least some of the one or more recessed features have a critical dimension of at most about 30 nm. In certain embodiments, the conductive layer comprises a copper seed layer. In certain embodiments, the substrate surface has a diffusion barrier layer disposed thereon. In certain embodiments, the substrate surface has a cobalt layer disposed thereon.

[0006] In some process schemes, the first electroplating operation deposits the metal in a substantially conformal manner in the one or more recessed features. In such schemes, the second electroplating operation may deposit the additional metal in a bottom-up fill manner. In some examples, the conformal deposition is performed using an alkaline electroplating bath and / or the bottom-up fill is performed using an acidic electroplating bath. The acidic electroplating bath may include one or more organic additives that promote bottom-up fill.

[0007] The disclosed method aspects may additionally include, prior to performing the first electroplating operation, an operation of pretreating the substrate surface. In certain embodiments, the pretreating comprises subjecting the conductive layer to a chemically reducing environment and removing a native oxide and / or removing an impurity. In certain embodiments, the pretreating comprises a plurality of operations, all performed in a vacuum environment.

[0008] The disclosed method aspects may additionally include, between performing the first electroplating operation and performing the second electroplating operation, an operation of reflowing the metal. The disclosed method aspects may additionally include, after the first electroplating operation and / or the second electroplating operation, an operation of annealing the metal and / or the additional metal.

[0009] In certain embodiments, the first electroplating operation is performed in a first electroplating cell and the second electroplating operation is performed in a second electroplating cell. In such embodiments, a method may additionally include performing a third electroplating operation in third electroplating cell.

[0010] In certain embodiments, the first electroplating cell comprises first electrical contacts defining a first perimeter where the first electrical contacts electrically contact the substrate during the first electroplating operation; and the second electroplating cell comprises second electrical contacts defining a second perimeter where the second electrical contacts electrically contact the substrate during the second electroplating operation. The second perimeter is smaller than the first perimeter.Attorney Docket No. LAM1P093WO-12158-1WO

[0011] Some aspects of this disclosure pertain to electroplating systems that may be characterized by the following elements: a first electroplating cell configured to electroplate metal under first electroplating conditions that at least partially fill one or more recessed features on a surface of a substrate having a conductive layer disposed thereon; a second electroplating cell configured to electroplate additional metal under second electroplating conditions, which are different than the first electroplating conditions and electroplate the additional metal over the metal that at least partially fills one or more recessed features; and a controller. The controller may be configured to cause, sequentially:receiving the substrate to be electroplated under the first electroplating conditions in the first electroplating cell,thereafter, transferring the substrate to the second electroplating cell, and electroplating the substrate under the second electroplating conditions in the second electroplating cell.

[0012] In some embodiments, an electroplating system additionally includes a substrate handler configured to act under control of the controller and to (a) transfer the substrate into and out of the first and second electroplating cells, and (b) transfer the substrate between the first and second electroplating cells.

[0013] In some embodiments, an electroplating system additionally includes a pre-processing module configured to expose the substrate to conditions that improve the quality of the conductive layer prior the first electroplating operation. The pre-processing module may be disposed within a vacuum region, and where the first and second electroplating cells are in a tool that is outside the vacuum region. In certain embodiments, the pre-processing module comprises multiple substrate processing stations within the vacuum region.

[0014] In some embodiments, an electroplating system additionally includes an anneal module configured to heat the substrate in a manner that changes the crystal structure of the metal and / or the additional metal. In some embodiments, an electroplating system additionally includes a reflow module configured to heat the substrate in a manner that changes the position of the metal and / or the additional metal within the one or more recessed features.

[0015] In some embodiments, an electroplating system additionally includes a tool comprising multiple stations in a vacuum environment, where at least one of the stations is configured to (a) anneal the substrate or (b) re-flow the metal and / or the additional metal. Such tool may additionally include a station for pre-processing the substrate in a manner that improves the quality of the conductive layer prior to the first electroplating operation.

[0016] In certain embodiments, the first electroplating cell comprises first electrical contacts defining a first perimeter where the first electrical contacts electrically contact the substrate duringAttorney Docket No. LAM1P093WO-12158-1WO the first electroplating operation; and the second electroplating cell comprises second electrical contacts defining a second perimeter where the second electrical contacts electrically contact the substrate during the second electroplating operation. The second perimeter is smaller than the first perimeter.

[0017] In some embodiments, an electroplating system additionally includes a third electroplating cell configured to electroplate still more metal over the additional metal electroplated in the second electroplating operation.

[0018] In certain embodiments, the one or more recessed features comprise a first feature having a first size and a second feature having a second size, where the first size is greater than the second size. In some such embodiments, the first electroplating conditions fully fill the second feature but do not fully fill the first feature. Then, the additional metal deposited under the second electroplating conditions may complete the filling of the first feature. In certain embodiments, the additional metal deposited under the second electroplating cell conditions forms at least a portion of an overburden layer.

[0019] In certain embodiments, the first electroplating conditions deposit the metal in a substantially conformal manner in the one or more recessed features, and the second electroplating conditions deposit the additional metal in a bottom-up fill manner.

[0020] In some embodiments, an electroplating system additionally includes a vacuum environment enclosing a plurality of modules or stations configured to (a) pre-treat the substrate, (b) re-flow the metal and / or the additional metal electrodeposited in the recessed features, and / or (c) anneal the metal and / or the additional metal electrodeposited in the recessed features. In some implementations, the vacuum environment is a quad-station tool.

[0021] In some embodiments, an electroplating system additionally includes a vacuum environment enclosing: (i) a first module or station configured to pre-treat the substrate; and (ii) a second module or station configured to re-flow the metal and / or the additional metal electrodeposited in the recessed features, and / or anneal the metal and / or the additional metal electrodeposited in the recessed features.

[0022] Some aspects of this disclosure pertain to electroplating systems that may be characterized by the following elements:a first electroplating cell configured to electroplate metal under first electroplating conditions that at least partially fill one or more recessed features on a surface of a substrate having a conductive seed layer disposed thereon, where the first electroplating cell comprises first electrical contacts defining a first perimeter where the first electrical contacts electrically contact the substrate during the first electroplating operation; andAttorney Docket No. LAM1P093WO-12158-1WO a second electroplating cell configured to electroplate additional metal under second electroplating conditions, which are different than the first electroplating conditions and electroplate the additional metal over the metal that at least partially fill one or more recessed features, where the second electroplating cell comprises second electrical contacts defining a second perimeter where the second electrical contacts electrically contact the substrate during the second electroplating operation, and where the second perimeter is smaller than the first perimeter.

[0023] In certain embodiments, such systems additionally include a controller configured to cause, sequentially: (i) the substrate to be electroplated under the first electroplating conditions in the first electroplating cell, (ii) thereafter, the substrate to be transferred from the first electroplating cell to the second electroplating cell; and (iii) the substrate to be electroplated under the second electroplating conditions in the second electroplating cell.

[0024] Some aspects of this disclosure pertain to methods of electroplating a metal, which methods may be characterized by the following operations: (a) receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, where the substrate surface has a conductive seed layer disposed thereon; (b) performing a first electroplating operation under first electroplating conditions to deposit metal that at least partially fills the one or more recessed features; (c) re-flowing or annealing the metal deposited in the first electroplating operation; and (d) after the re-flowing or annealing, performing a second electroplating operation under second electroplating conditions, which are different than the first electroplating conditions, to deposit additional metal over the metal deposited in the first electroplating operation.

[0025] In certain embodiments, the first electroplating operation is performed in a first electroplating cell, and the second electroplating operation is performed in a second electroplating cell.

[0026] In some aspects, the techniques described herein relate to an electroplating system including: a first electroplating cell configured to perform a first operation that electroplates metal that at least partially fills one or more recessed features on a surface of a substrate, wherein the first electroplating cell includes first electrical contacts defining a first arrangement of contact points where the first electrical contacts electrically contact the substrate during the first electroplating operation; a second electroplating cell configured to perform a second operation that electroplates electroplate additional metal over the metal that at least partially fills one or more recessed features, wherein the second electroplating cell includes second electrical contacts defining a second arrangement of contact points where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second arrangement is different than the first arrangement.Attorney Docket No. LAM1P093WO-12158-1WO

[0027] In some aspects, the techniques described herein relate to a method of electroplating a metal including: receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated; performing a first electroplating operation that deposits metal that at least partially fills the one or more recessed features, wherein the first electroplating operation is performed in first electroplating cell including first electrical contacts defining a first arrangement of contact points where the first electrical contacts electrically contact the substrate during the first electroplating operation; performing a second electroplating operation that deposits additional metal over the metal deposited in the first electroplating operation, wherein the second electroplating operation is performed in a second electroplating cell including second electrical contacts defining a second arrangement of contact points where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second arrangement is different than the first arrangement.

[0028] In some aspects, the techniques described herein relate to a method of electroplating a metal including: receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, wherein the substrate surface does not have a copper seed layer disposed thereon; performing a first electroplating operation that deposits a copper seed layer onto the substrate; and performing a second electroplating operation under second electroplating conditions that deposit copper onto the copper seed layer, wherein the second electroplating operation at least partially fills the one or more recessed features.

[0029] In some aspects, the techniques described herein relate to a method, wherein the second electroplating operation deposits the copper substantially conformally onto the copper seed layer.

[0030] In some aspects, the techniques described herein relate to a method, wherein the second electroplating operation deposits the copper via a bottom up fill mechanism onto the copper seed layer.

[0031] In some aspects, the techniques described herein relate to a method, wherein the substrate includes a layer including ruthenium, cobalt, nickel, or any combination, and wherein the first electroplating operation deposits the copper seed layer directly onto the layer.

[0032] In some aspects, the techniques described herein relate to a method, further including: performing a third electroplating operation under third electroplating conditions, which are different than the second electroplating conditions, to deposit additional metal over the metal deposited in the second electroplating operation.

[0033] These and other features of the disclosure will be presented in more detail below, sometimes with references to the associated drawings.Attorney Docket No. LAM1P093WO-12158-1WO BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 illustrates one example of a traditional Damascene process flow for electroplating metal into recessed features.

[0035] Figure 2A depicts an example two-phase, sequential electroplating process in accordance with some embodiments.

[0036] Figure 2B presents a flowchart that generally follows the sequence of operations of the sequential electroplating process depicted in Figure 2A.

[0037] Figure 3A depicts another example of a sequential electroplating process.

[0038] Figure 3B depicts a variation of the sequential electroplating process depicted in Figure 3A.

[0039] Figures 4A-4C present flow charts of process flows in a sequential electroplating process includes an operation of electrochemically depositing a metal seed layer such as a copper seed layer on a substrate prior to successive electroplating operations that provide bulk fill, overburden deposition, etc.

[0040] Figure 5 illustrates a sequential electroplating process flow that employs electroplating cells, oxide reduction modules, cooling modules, a reflow module, and substrate transfer components.

[0041] Figure 6 illustrates a sequential electroplating system having two separate vacuum tools for performing non-electroplating operations.

[0042] Figure 7A illustrates a sequential electroplating system having only one vacuum platform for performing non-electroplating operations.

[0043] Figure 7B presents a scaled back variant of the electroplating system of Figure 7A.

[0044] Figure 8 schematically illustrates a single electrical contact in a lip seal engaging with a perimeter position of a substrate.

[0045] Figure 9 provides additional details of certain wafer holder configurations.

[0046] Figure 10 schematically illustrates a progression of electroplating cells for a first, second, and third electroplating operation, in which each successive operation employs electrical contacts defining a smaller footprint (e.g., perimeter).

[0047] Figure 11 illustrates an example sequence of operations in a sequential electroplating scheme that employs electroplating cells with successively smaller electrical contact footprints.DETAILED DESCRIPTIONIntroduction and Context

[0048] A traditional approach to creating interconnects by electroplating involves filling features and forming overburden in a single step plating operation. Such step often employs an acidic electrolyte with additives that promote bottom-up fill.Attorney Docket No. LAM1P093WO-12158-1WO

[0049] While the methods and apparatus described herein have many applications, some of which are described below, one example application pertains to filling features on dies of a substrate. In general, when discussing methods and apparatus in the context of this example, the inventors intend that such methods and apparatus extend to other applications.

[0050] Note that in Figures 1. 2 A, 3 A, and 3B, the features illustrated in cross-section may be Damascene features such as recesses for forming conductive vias and / or interconnect lines. However, the depicted embodiments should be understood to represent any arbitrary recessed feature, which need not have the shapes or arrangements shown in the figures.

[0051] In some of the depicted embodiments, a bottom rectangular portion of the depicted feature represents of via which may be filled with a conductive material to electrically connect an interconnect line with an underlying contact or another interconnect line. An upper rectangular portion represents a region where an interconnect line is formed. The upper horizontal surfaces to the left and right represent portions of a field region that extends across the substrate surface.

[0052] Figure 1 illustrates one example of a traditional Damascene process flow for electroplating metal into recessed features. An incoming substrate to be electroplated includes a recessed feature 101 below field regions 103. In some embodiments, a feature such as feature 101 includes a via portion 105 and interconnect portion 107.

[0053] In a typical electroplating process flow, the substrate surface, which includes the surfaces of feature 101, is coated with one or more thin conductive seed layers, such as one including a cobalt seed layer 109 and an overlying copper seed layer 111. More generally, any substrate to be electroplated may arrive in an electroplating system with a thin diffusion barrier layer and a thin conductive seed layer or combination of layers as is the case for the cobalt and copper layers in the illustrated embodiment. A diffusion barrier, which is not shown, may include titanium / titanium nitride, tantalum / tantalum nitride or other suitable material(s).

[0054] In the depicted process flow, the electroplating system receives a substrate to be electroplated. Upon receiving the substrate, including feature 101, the electroplating system may pretreat the substrate to improve the quality of the copper and / or cobalt seed layers 111 and 109. See operation 104. In some embodiments, the pretreatment includes exposure to a reducing atmosphere that chemically reduces native oxide and possibly removes other impurities that have formed on one or both seed layers through, e.g., exposure to the atmosphere.

[0055] After the optional pretreatment, the substrate including feature 101 is subjected to an electroplating operation 106 that completely fills feature 101 with a conductive metal 113 within the feature and additionally forms an overburden layer 115 on top of feature 101 and field regions 103. Of interest, this process depicted in Figure 1 employs a single electroplating step, typically with a single electroplating bath to both fill feature 101 and form overburden layer 115.Attorney Docket No. LAM1P093WO-12158-1WO

[0056] In some embodiments, after electroplating operation 106 is complete, the substrate is subjected to a post-electroplating operation 108, which may include, for example, an anneal such as a thermal anneal. In a typical process flow, after electroplating operation 106 is completed, overburden layer 115 is removed by a planarization process such as chemical mechanical polishing.

[0057] As device technology continues to advance and feature sizes become increasingly small, a single electroplating operation is sometimes inadequate to completely fill features and also form overburden. The challenge is due, in part, to interconnect and via structures in Damascene and other processes having very small sizes: e.g., critical dimensions on the order of 30 nanometers. To accommodate such small features, metal seed layers and diffusion barrier layers must be so thin that they' may contain gaps and / or are easily damaged by conventional electrolytes, which are often acidic. Further, an unplated bevel region at the perimeter of a substrate, which resides at the point of electrical contact (under the lipseal) may be attacked by moisture in the substrate holder, rinse water in the electroplating cell and / or a post-electrofill module, and by thermal treatments needed to reflow or move the metal deposition to fill features.

[0058] In some cases, an electroplating process uses alkaline electroly tes to minimize damage to thin metal seed layers, but. when filling large features and / or forming overburden, alkaline electrolytes may deposit metal too slowly. In alkaline electrolytes, electroplating 20-50 nm of metal can be completed in a reasonable time frame, but forming overburden, which requires electroplating hundreds of nanometers of metal, may require too much time.

[0059] Some aspects of this disclosure pertain to sequential electroplating operations that electroplate copper or other metal into features in two or more sequential operations, with each operation performed under different conditions and optionally in different electroplating cells. In a simple example, electroplating metal on a substrate takes place in two operations. A first electroplating operation completely fills small features and partially fills larger features on the same wafer, while a subsequent electroplating step finishes filling the larger features and forms overburden on all features.

[0060] Figure 2A depicts an example two-phase, sequential electroplating process in accordance with some embodiments. The process begins in the same manner as the process of Figure 1, with an electroplating system receiving a substrate having a feature 201 disposed below the surface of field regions 203, where substrate surface including feature 201 is coated with thin seed layers, including a cobalt seed layer 209 and a copper seed layer 211. Also, as illustrated with respect to the process of Figure 1, the incoming substrate feature 201 may be a Damascene feature having a via portion 205, and an interconnect portion 207.

[0061] Note that while Figure 2A and other process sequence figures show a copper seed layerAttorney Docket No. LAM1P093WO-12158-1WO having continuous coverage, this need not be the case. In many advanced processes, the copper seed layer does not provide complete coverage, but rather has multiple gaps. This is one reason why some embodiments employ a cobalt seed layer under the copper seed layer. As explained, alkaline electrolytes can electroplate directly on cobalt surfaces.

[0062] Still further, as depicted in the traditional process flow of Figure 1, the two-phase process of Figure 2A optionally includes a pre-treatment operation 204 that may improve the quality of one or both seed layers 209 and 211.

[0063] After this point, the process flow deviates from the one depicted in Figure 1 in that two separate electroplating operations are performed. In the depicted process flow, a first electroplating operation 206 electrodeposits some metal in feature 201 but does not form a complete electroplated structure that includes both a fully electrofilled feature and a complete overburden layer. Rather, the initial electroplating operation 206 may only partially fill some features, particularly larger features. Also, operation 206 may not form an overburden layer, or at least not form a complete overburden layer.

[0064] Note that a given substrate may have different types of features, which may have different sizes and / or shapes. Hence some smaller features may be completely filled in the first electroplating operation, while other larger features may be only partially filled in the first electroplating operation.

[0065] As illustrated, the first electroplating operation 206 partial fills feature 201 with metal fill 219. Additionally, first electroplating operation 206 deposits some additional material on field regions 203. However, as illustrated, this first phase of electroplating does not form overburden, at least not over feature 201.

[0066] As depicted in Figure 2A, after first electroplating operation 206 is complete, the substrate is optionally exposed to an annealing or reflowing operation that subjects the substrate to increased temperature in order to change the crystal structure of deposited metal 219 and / or reflow deposited material 219. See operation 208.

[0067] Thereafter, the substrate is subjected to a second electroplating operation 210 that deposits additional metal 225, including an overburden layer on top of feature 201 as well as on field regions 203. Thus, the process flow disclosed in Figure 2A has two sequential electroplating operations.

[0068] After second electroplating operation 210 is complete, the substrate is optionally annealed via an operation 212.

[0069] Figure 2B presents a flowchart that generally follows the sequence of operations of the sequential electroplating process depicted in Figure 2A. As depicted in Figure 2B, a process flow begins at operation 251 with an electroplating system receiving a substrate having recessed features and a conductive seed layer.Attorney Docket No. LAM1P093WO-12158-1WO

[0070] Thereafter, as illustrated in an operation 253, the substrate is optionally pretreated to, e.g., improve the conductive seed layer. Such pretreatment may include, for example, exposure to a chemically reducing environment that chemically reduces oxides and / or otherwise removes impurities and / or makes the conductive seed layer more continuous over the surface of the substrate. Other pretreatment operations may include pre-wetting, degassing, etc.

[0071] Next, at an operation 255, the electroplating system performs a first electroplating operation, which electroplates metal into the features, and fully and / or partially fills some of those features. However, the first electroplating operation does not complete the electroplating process in that it leaves some or all an overburden layer unformed.

[0072] Next, at an operation 257, the electroplating system optionally, anneals and / or reflows metal that was electroplated into the features in first electroplating operation 255.

[0073] After the optional anneal and / or reflow operation, the electroplating system performs a second electroplating operation which electroplates metal on the metal that was previous electroplated in the first electroplating operation. As an example, the second electroplating operation can complete the fill the previously unfilled features, as well as form an overburden layer over the entire substrate surface.

[0074] Finally, at in operation 261, the wafer or the substrate is optionally annealed to change the crystallinity’ or morphology of the electroplated metal. In some embodiments, one or more additional operations is performed such as a third electroplating operation that, e.g., completes the formation of an overburden layer.Terminology

[0075] In this disclosure, the terms "‘semiconductor wafer,” “wafer,” “substrate,” “panel,” and "partially fabricated integrated circuit” may be used interchangeably. One of ordinary skill in the art would understand that the term “partially fabricated integrated circuit” can refer to a semiconductor or dielectric substrate during any of many stages of integrated circuit fabrication thereon. A wafer used in the semiconductor device industry may have a diameter of 200 mm, or 300 mm. or 450 mm. The following detailed description assumes the embodiments are implemented on a wafer, a panel, or other commonly used structure in the electronic device field. However, the embodiments are not so limited. The substrate may be of various shapes, sizes, and materials. In addition to semiconductor wafers or packaging panels, other work pieces that may take advantage of 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. Substrates in the disclosed embodiments may include substrates with seed layers and masked surfaces, which can include semiconductor wafers, printed circuit boards, panels, and the like.Attorney Docket No. LAM1P093WO-12158-1WO

[0076] In various embodiments, the substrate is patterned. A patterned substrate may have ■‘features” such as pillars, poles, trenches, via or contact holes, which may be characterized by one or more critical dimensions, shapes, aspect ratios, etc. The features of a substrate may be formed in one or more dielectric layers. In some embodiments, the feature may have a dimension such as a diameter or line width of less than about 100 nm, or less than about 50 nm, or about 5 nm to 30 nm. Disclosed methods may be performed on substrates with features having opening dimensions of about 150 nm or less. A via, trench or other recessed feature may be referred to as an unfilled feature or a feature.

[0077] In the context of electroplating operations disclosed herein, the terms ‘■electrolyte,” “electroplating solution,” “electroplating bath,” “plating solution” and the like may be used interchangeably. An electrolyte may comprise ions of a metal to be electroplated and additional ions to increase the conductivity of an aqueous medium. An electrolyte may be acidic or basic. In some sequential electroplating embodiments described herein, a first electroplating operation employs a basic electrolyte, whereas a second or later electroplating operation employs an acidic electrolyte.

[0078] As an example, an alkaline electrolyte may contain an aqueous solution of pH greater than 7 having a copper salt present in, e.g., a concentration of about 0.1 to 60 g / L. Examples of copper salts include copper(II) sulfate. In some cases, an alkaline electrolyte contains a copper(II) complexing agent such as aliphatic amines, e.g., ethylene diamine. In some cases, an alkaline electrolyte has one or more additives that promote bottom up fill. For example, the additives may include a combination of a suppressor and accelerator. Examples of accelerators include a thiocyanate salt and thiourea. Examples of suppressors include polyallylamine, saccharin.

[0079] Alkaline electrolytes may have the ability to electroplate directly on cobalt or ruthenium, not just copper. So, for example, when copper or other seed layer is very thin (e.g., in narrow features) and has gaps, an alkaline electrolyte can electroplate copper both in the gaps where, e.g., cobalt is now exposed and also on the intact copper seed layer.

[0080] As an example, an acidic electrolyte may contain copper ions from a copper salt such as copper sulfate, copper methane sulfonate, copper pyrophosphate, copper propane sulfonate, etc. The electrolyte may include an acid increasing the electrolyte conductivity. Example acids include but are not limited to sulfuric acid and methane sulfonic acid. In some embodiments, the electrolyte includes electroplating additives. Electroplating additives modify surface reaction kinetics and may be useful in improving the current distribution (feature shape and thickness distribution) relative to that which occurs in their absence (improved relative to the primary or electrolyte-resistance-driven current distribution).

[0081] In some implementations, the electrolyte includes plating additives such as accelerators,Attorney Docket No. LAM1P093WO-12158-1WO suppressors, levelers, or any combination thereof. Other plating additives may include carriers and / or ductilizers. In some embodiments, an accelerator may include an alkane chain with at least one mercapto- and one sulfonic acid group or acid-salt. For example, the accelerator may include mercaptopropane sulfonic acid or mercaptoethane sulfonic acid. In some embodiments, the suppressor may include derivatives of polyethylene- and polypropylene-glycols and oxides. In these or other cases, the suppressor may include at least one material selected from the group consisting 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.

[0082] A seed layer is a thin layer conductive material that coats a substrate surface where electroplating is to occur. For substrates having features, the seed layer may conformally coat the surface, providing a comparably thick / thin layer on the field regions and feature surfaces. Examples of materials used in seed layers include copper, cobalt, ruthenium, and any alloy or combination of any two or more of these. In some embodiments, a seed layer is deposited by physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), electroless deposition, or any combination of these. In some embodiments, a deposited seed layer is subsequently treated to improve its quality or accomplish a necessary condition of the substrate. In one example, after depositing a seed layer by PVD or CVD, it is subjected to etching and / or reflowing. In certain embodiments herein, the seed layer is quite thin, e.g., on the order of about 10 nm or less or about 0.5 to 3 nm on average. Note that such thin seed layers may provide only partial coverage. For example, a copper seed layer of 1 nm or less (on average) may not make a full continuous layer. In other words, its thickness might be 0 nm in some locations and 0.75 nm in some other locations. In some implementations, exposed material in gaps may be cobalt or a mixture of cobalt and another material.

[0083] In some implementations, the conductive seed layer does not substantially comprise copper. For example, the seed layer may be limited to cobalt and / or ruthenium. In other words, metal may be electroplated directly on cobalt or ruthenium.

[0084] In some embodiments, a conductive seed layer comprises two or more layers. For example, a conductive seed may comprise an outer copper layer and an underlying cobalt or ruthenium layer.

[0085] Many different metals may be electroplated using methods described herein. Examples include copper, cobalt, nickel, silver-tin, gold, rhodium, rhenium, platinum, palladium, copperzinc, iron, cadmium, chromium, lead, and all alloys and other combinations thereof.

[0086] Overburden refers to a layer of electroplated metal that covers not only a substrate’s features but its field regions as well. It may be a few hundred nanometers to micrometers thick.Attorney Docket No. LAM1P093WO-12158-1WO Its top surface may be substantially planar compared to the topology of the substrate before electroplating.

[0087] Annealing is a process in which heat is applied to a substrate to change crystal structure, typically without exposing previously covered features or otherwise substantially changing the position of deposited metal such as a seed layer or an electroplated deposit. In some embodiments, annealing is applied to substrates on which the overburden has been formed. Examples of process conditions that may be employed during anneal are:Temperature: 100 -■ 400°CPressure: high vacuum, low vacuum, or atmospheric pressureGas: forming gas (H2 / He, H2 / N2). Argon, nitrogen, hydrogen (substantially pure), or plasmas formed from these gases.

[0088] Reflowing is another process in which heat is applied to a substrate. Unlike annealing, reflow typically causes a deposited metal to change its position, sometimes exposing regions that were previously covered by the deposited metal. See e.g.. reflow operation 306 in Figures 3 A and 3B, where field regions that were previously covered become exposed

[0089] Examples of process conditions suitable for reflow operations may be simi lar to the anneal conditions above. However, the temperature and / or plasma condition may be slightly more aggressive (higher) so the metal adhesion to the substrate is disrupted, and the metal can move due to capillary actions into the features. As an example, if copper is annealed at a temperature under 200°C in forming gas, copper may be reflowed at a temperature above 200°C in forming gas. As another example, if copper is annealed or subjected to native oxide reduction at a temperature under 100°C in a hydrogen plasma, copper may be reflowed at a temperature above 100°C m hydrogen plasma.

[0090] As used herein, the terms “top,” “botom,” “upper,” “lower,” “above,” and “below” are used to provide a relative relationship between structures. The use of these terms does not indicate or require that a particular structure must be located at a particular location in the apparatus.

[0091] It should be understood that the ranges of the properties and descriptions of operations described in this section and elsewhere herein may apply to any of the process and system embodiments disclosed herein. For example, any process disclosed herein that recites use of a seed layer may employ any of the seed layer materials encompassed in the discussion here. For a further example, any process disclosed herein that recites use of an acidic or basic electrolyte may employ any of the acidic or basic electrolytes, respectively, encompassed in the discussion herein Sequential Electroplating Process Examples

[0092] Figure 3A depicts another example of a sequential electroplating process. In this example, a substrate to be electroplated includes a recessed feature 301 surrounded by a field regionAttorney Docket No. LAM1P093WO-12158-1WO including regions 303. The entire surface of the substrate is coated with a thin cobalt seed layer 309 and a thin copper seed layer 311. Initially, the substrate is optionally pretreated in a process 302 to improve the quality of one or both seed layers.

[0093] Next, a first electroplating operation 304 is performed in which a relatively small amount of metal is electroplated within feature 301 to form a thin conformal layer 316. In certain embodiments, first electroplating operation 304 is performed in an alkaline electrolyte. Regardless, first electroplating operation 304 electro-deposits metal in a more conformal manner than in a typical bottom-up fill process.

[0094] While electroplating operation 304 may be good at filling small features without compromising seed layer 311, it is essentially a conformal process, so it may form a void or seam 318 within feature 301. This may be unacceptable for subsequent processing, so a separate operation may be employed to remove void 318. In the depicted embodiment, a reflow operation 306, with an optional anneal, is performed on the substrate after first electroplating operation 304. As a result of reflowing, the electro-deposited material 316 flows into void 318 and removes it to create a re-flowed fill material 316’.

[0095] Note that due to reflowing and / or an associated process such as rinsing after operation 304, conductive material may be substantially removed from field region 303. In some cases, without further improvement, the conductance of the field region 303 may be insufficient for subsequent electroplating to produce, e.g., overburden. Therefore, the depicted electroplating process employs a second electroplating operation 308 in which a thin layer of electro-deposited metal 319 covers the substrate, optionally in a conformal manner as illustrated with respect to operation 304.

[0096] Note that electroplating operation 308 may be successfully completed even’ though the copper seed layer is no longer present in the field regions. This is particularly true when the electroplating is performed using an alkaline electrolyte, which can electroplate directly on cobalt as well as copper. A benefit of alkaline electrolytes is that they can electroplate on thin copper and thin cobalt layers because they can be used in process regimes that reduce oxide and also do not rapidly dissolve away the surfaces.

[0097] Next, a third electroplating operation 310 deposits an overburden layer 320 on the substrate, including over electro-filled metal 316’ and layer 319. In certain embodiments, third electroplating operation 310 is performed with an acidic electrolyte having additives to promote bottom-up fill.

[0098] Finally, the entire structure produced after electroplating operation 310 is subject to an anneal operation 312.

[0099] Figure 3B depicts a variation of the sequential electroplating process depicted in Figure 3A. In the process of Figure 3B, the initial substrate with feature 301, cobalt layer 309 and copperAttorney Docket No. LAM1P093WO-12158-1WO seed layer 311 is subjected to the same initial operations as the substrate in Figure 3 A. That is, the substrate is first pretreated in operation 302, then subjected to a first electrochemical deposition operation 304, then the electrodeposited metal is reflowed in operation 306, and subsequently subjected to a second electrodeposition operation 308.

[0100] However, after second electroplating operation 308, the process diverges from that of Figure 3 A. In the embodiment of Figure 3B, the second electroplated metal 319 is subject to reflow and an optional anneal in an operation 350 to produce a re-flowed metal plug 352 that effectively completes the filling of feature 301 before the overburden is formed. Thereafter, the substrate is subjected to a third electroplating operation 353 that deposits a partial overburden layer 354 on the entire substrate surface including the field regions and reflowed metal plug 352 within feature 301. Subsequently, an optional operation 355 is performed to anneal partial overburden layer 354.

[0101] Thereafter, in an operation 357, a second overburden layer 356 is electroplated directly on overburden layer 354. The resulting structure comprises two metal components that fill feature 301 and two separate overburden layers (lower layer 354 and upper layer 356) covering the entire substrate surface.

[0102] Thus, the process depicted in Figure 3B employs four separate electroplating operations, operations 304 and 308 deposit metal that fills feature 301 and operations 353 and 357 deposit metal that forms the overburden bilayer.

[0103] Note that the overburden is formed in two separate electroplating operations. This is because the third electroplating operation 353 may employ an alkaline electroplating environment to deposit copper directly on the now exposed cobalt in the field regions. Acidic electroplating may not work in operation 353. The fourth electroplating operation 357 may employ an acidic electrolyte because it electroplates on the copper coverage provided by an alkaline electrolyte in operation 353. The acidic electrolyte may provide a faster deposition rate of the copper overburden.

[0104] In sequential electroplating embodiments of this disclosure, such as those presented in Figures 2A, 2B, 3A. and 3B, any two of the electroplating operations may employ the same or different electroplating baths Further, in some sequential electroplating embodiments, any two of the electroplating operations may electroplate the same metal or two different metals.

[0105] In some sequential electroplating embodiments, a first electroplating operation and a second electroplating operation may be performed under different electroplating conditions such as using different electrolytes, different current densities, different current pulsing regimes, and the like. In some sequential electroplating embodiments, a first electroplating operation is performed in a first electroplating cell and a second electroplating operation is performed in aAttorney Docket No. LAM1P093WO-12158-1WO second electroplating cell. Further, in some cases, the process includes performing a third electroplating operation in third electroplating cell.

[0106] If different electroplating baths are employed between two electroplating operations, the difference may reside in the composition and / or physical property(ies) of the baths. For example, the different baths may have different pHs, metal ions, anions, organic additives, or inorganic additives. In some embodiments, an earlier of two electroplating operations employs an alkaline electroplating bath while the later of the two electroplating operations employs a more acidic electroplating bath. In some embodiments, one electroplating bath has a composition suitable for conformal deposition and a different electroplating bath has a composition suitable for bottom-up fill In some implementations, an electroplating bath used in an earlier operation is suitable for conformal deposition while a different electroplating bath used in a subsequent operation is suitable for bottom-up fill.

[0107] In some sequential electroplating embodiments, a given type of electroplating bath may be employed in only one electroplating tool or in multiple different electroplating tools.

[0108] While this disclosure focuses on pretreatment and post treatment for electroplating, the conformal deposition operations (e.g., operation 304 of Figures 3A and 3B) could be done with electroless deposition of some or all the operation.

[0109] In various embodiments, a method of sequentially electroplating a metal involves (a) performing a first electroplating operation under first electroplating conditions to deposit metal that at least partially fills one or more recessed features on a substrate; and (b) performing a second electroplating operation under second electroplating conditions, which are different than the first electroplating conditions, to deposit additional metal over the metal deposited in the first electroplating operation. In some cases, the one or more recessed features comprise Damascene features such as vias and / or interconnect paths.

[0110] In various embodiments of interest, at least some of the one or more recessed features have a critical dimension of at most about 30 nm. This is the dimension of the feature after the seed layer and diffusion barrier have been formed. In some embodiments, at least some of the one or more recessed features have a critical dimension of at most about 25nm. An example of this is found with dual Damascene processes, as the via below the trench will be smaller. In some embodiments, at least some of the one or more recessed features have a critical dimension of at most about 20 nm. An example of this is for single Damascene trenches.

[0111] In some embodiments, the substrate has a conductive seed layer that may comprise copper, cobalt, ruthenium, or any alloys of these. A conductive seed layer may be used in a stack with or without a barrier material such as tantalum / TaN, titanium / TiN, or a tungsten nitride. Metal may beAttorney Docket No. LAM1P093WO-12158-1WO electroplating onto a conductive seed layer comprised of copper, cobalt, ruthenium, an alloy such as a manganese-zinc alloy, a combination of Ru / Co / Cu, etc.

[0112] In some embodiments, the substrate has different sized features that may require different electroplating considerations. For example, the one or more recessed features may comprise a first feature having a first size and a second feature having a second size, where the first size is greater than the second size. In this example, the first electroplating operation may fully fill the second feature but not the first feature. Then, the additional metal deposited by the second electroplating operation may complete the filling the first feature. It may also, optionally, form some or all overburden on the substrate.

[0113] In some cases, the first electroplating operation deposits the metal conformally or substantially conformally in the one or more recessed features. This may be accomplished by using an electrolyte without significant organic additives for promoting bottom up fill. In some cases, such electrolyte has an alkaline pH. In some cases, when the first electroplating operation deposits metal conformally or substantially conformally, the second electroplating operation deposits the additional metal in a bottom-up fill manner. This may be accomplished by using an electroplating bath comprising one or more organic additives that promote bottom-up fill. In some cases, such electrolyte has an acidic pH.

[0114] In some examples, an incoming substrate for sequential processing does not have a conductive copper seed layer formed thereon. In such cases, the substrate may merely have a thin conformal layer of a material that is perhaps not as electrically conductive as copper. Such thin layer may serve as diffusion barrier to copper atoms. Examples of materials suitable for such thin layers include cobalt, ruthenium, nickel, platinum, rhodium, and alloys or other compositions comprising any of these.

[0115] While substrates containing conformal layers of such materials may be inadequate to serve as typical conductive seed layer that support bulk electroplating, they may be sufficiently conductive to permit an initial electrochemical deposition operation that directly forms what amounts to a surrogate copper seed layer. Such electrochemical deposition of a seed layer may be integrated into a sequential deposition process flow as described herein. Any of the process flows presented above may be modified to include an additional initial electrofill operation that forms a layer that initially functions as a copper seed layer.

[0116] Examples of such process flows are depicted in the flowcharts of Figures 4A through 4C. In Figure 4A, the process begins with an operation 403 that receives a substrate having recessed features that are conformally covered with a non-copper layer that is at least partially electrically conductive. The substrate is optionally pre-treated with a process that improves the quality (e.g. the electrical conductivity and / or coverage) of the non-copper layer. Examples of such optionalAttorney Docket No. LAM1P093WO-12158-1WO treatments include annealing, thermal chemical reduction, and plasma-based chemical reduction. Ruthenium, as an example, can form a ruthenium oxide that adheres to the ruthenium surface and would, if not removed, degrade the ability of copper to be electroplated onto its surface.

[0117] After receiving the substrate and optionally pre-treating it, an operation 405 electroplates a thin conformal layer of copper on to the substrate surface. This layer may substantially cover the underlying non-copper layer of, e.g., cobalt, ruthenium, or nickel. The electroplated copper layer may serve as a seed layer for subsequent electrochemical deposition operations. In some embodiments, operation 405 is performed using an alkaline electrolyte. In some embodiments, operation 405 is performed using an electrolyte having few if any additives for promoting bottom up fill.

[0118] Next, in an optional operation 407, the now deposited copper seed layer is treated to improve its properties (e.g., its coverage). As examples, operation 407 may be an annealing or chemical reduction operation.

[0119] Next, at an operation 409, a second electroplating operation is performed. This operation deposits a conformal copper layer on the copper seed layer that was deposited in operation 405. The deposited conformal copper layer may be similar to layer 316 electrochemically deposited in operation 304 in Figure 3B. Operation 409 may be performed under electroplating conditions that are different in at least one regard from those employed to form the seed layer (operation 405). However, it may be similar in that few if any additives for promoting bottom up fill are present in the electrolyte.

[0120] The process continues with an optional anneal and / or reflow of the metal currently in the features (i.e., metal electrodeposited in operations 405 and 409). Thereafter, the process may continue with an optional third electroplating operation 413 and an optional anneal of the deposited metal operation 415.

[0121] Figure 4B illustrates a sequential electroplating process that is similar to the one depicted in Figure 4A in that it employs electrochemical deposition to form a copper seed layer. However, in the next electroplating operation, it deposits additional copper by a primarily bottom up fill mechanism, rather than conformally.

[0122] The depicted process in Figure 4B begins with an operation 423, where an electroplating system receives a substrate having features such as recessed features. The substrate is conformally covered with a non-copper layer that is at least partially electrically conductive. The substrate may be pre-treated with a process that improves the quality of the non-copper layer.

[0123] Then, in an operation 425, the electroplating system performs a first electroplating operation that electroplates a conformal copper seed layer on the substrate including in the recessedAttorney Docket No. LAM1P093WO-12158-1WO feature. This is analogous to operation 405 in Figure 4A. The seed layer may be treated to improve its properties (e.g., its coverage). See operation 427.

[0124] The electroplating system then performs second electroplating operation bottom up electroplating metal into features. See operation 429. Unlike parallel operation 409 in the Figure 4A process flow, operation 429 is performed under conditions that promote bottom up fill. For example, the electrolyte used in operation 429 may contain organic additives such as an accelerator and a suppressor. The electrolyte may be acidic or basic. The substrate may then be subjected to an optional anneal and / or reflow electroplated metal in features. See operation 431.

[0125] Thereafter, the electroplating system optionally performs a third electroplating operation (433) that electroplates metal on the metal previously electroplated in the second electroplating operation. Finally, in the depicted process, the substrate is optionally annealed. See operation 435.

[0126] In some examples, the sequential electroplating process employs an electrochemical deposition operation to deposit not only what functions as an electrically conductive seed layer but continues on in the same electroplating operation and deposits material that at least partially fills the features in a bottom up manner. At the conclusion of this operation, the electroplated metal in the feature may resemble that shown as metal 219 in the cross-section depicted for operation 206 in Figure 2 A.

[0127] Figure 4C illustrates an example of such a sequential electroplating process in which an initial electroplating operation on a non-copper coated substrate allows bulk fill to partially proceed at least partially. In other words, the initial electroplating operation serves the purpose of forming a copper seed layer and then continuing on to at least partially fill the features.

[0128] As depicted in Figure 4C, the sequential electroplating process begins with the electroplating system receiving a substrate having recessed features, and optionally a conformal layer of material that can serve as at least a modestly electrically conductive layer and / or a metal diffusion barrier. See operation 443. As mentioned, examples include thin layers of ruthenium, nickel, cobalt, etc.

[0129] Next, at an operation 445, the electroplating system performs a first electroplating operation, which is a hybrid electroplating of a conductive metal seed layer and a partial bulk fill of features on the substrate. The resulting partially filled features comprise conformal fill, bottom up fill, or a combination thereof. In some examples, the deposition conditions of operation 445 at least approximate those employed in bulk, bottom fill, with the electrolyte comprising organic additives such as one or more accelerators and / or suppressors. In some cases, bottom up fill proceeds in stages, with an initial stage in which the organic additives set up within the feature where bottom up fill occurs. During this set up stage, electroplating may briefly proceed in aAttorney Docket No. LAM1P093WO-12158-1WO manner that deposits metal conformally on the surface, in the manner of an electrically conductive seed layer. In some implementation, the electrolyte of operation 445 is an alkaline electrolyte comprising one or more accelerators and one or more suppressors.

[0130] Thereafter, the substrate may be subjected to an optional anneal and / or reflow electroplated metal in features. See operation 447.

[0131] Thereafter, the electroplating system optionally performs a second electroplating operation (449) that electroplates metal on the metal previously electroplated in the first electroplating operation. This operation may be conducted in a manner that performs additional bottom up electroplating metal into features. Operation 449 may fully fill at least some features on the substrate. However, it may leave others at least partially unfilled. Regardless, the process proceed with an optional anneal and / or reflow electroplated metal in features. See operation 451.

[0132] Next, in the depicted process, the substrate is optionally subjected to a third electroplating operation that electroplate additional metal on metal previously electroplated in the features. See operation 453. This operation may only be necessary if second electroplating operation 449 did not fully fill all the features of the substrate and / or overburden is needed.

[0133] The process depicted in Figure 4C concludes at an operation 455, where the electroplated metal deposited via the sequential electroplating is optionally annealed.Integration with Non-Electroplating Operations

[0134] The sequential electroplating operations disclosed herein may, depending on various considerations, incorporate one or more non-electroplating operations that involve pre-treating the incoming substrate or seed layer before electroplating and / or thermally modifying material deposited by the electroplating. Examples include metal seed pretreatment to reduce oxides on the seed layer prior to electroplating, and metal film post treatments prior to anneal operations or prior to reflow.

[0135] As indicated, prior to performing one of the electroplating operations, particularly the first electroplating operation, the process flow may include pretreating the substrate surface. In some embodiments, the pretreating comprises subjecting the conductive seed layer to a chemically reducing environment. In some cases, the pretreating at least partially removes a native oxide and / or one or more impurities.

[0136] In some cases, a pretreatment is performed after one electroplating operation but before a second one. For example, if an oxide forms on one electroplated layer, reduction of that oxide may be employed before reflow or other subsequent operation. Note that oxide and contaminates can be incorporated into a reflowing metal and lead to voids and / or higher resistance in features.

[0137] Examples of oxide removal pretreatment conditions for metal seed layers (e.g., about 2 to 50 Angstroms thickness) follow:Attorney Docket No. LAM1P093WO-12158-1WO Copper seed layer: reduction temperature 30°C to 200°C in an atmosphere of reducing gas (e.g., forming gas) and / or hydrogen radicals generated from a remote plasma.Cobalt seed layer: reduction temperature 30°C to 250°C in an atmosphere of reducing gas (e.g., forming gas) and / or hydrogen radicals generated from a remote plasma.Ruthenium seed layer: reduction temperature 250°C to 500°C in an atmosphere of reducing gas (e.g., forming gas) and / or hydrogen radicals generated from a remote plasma.

[0138] Examples of other types of pretreatment operations include cleaning the substrate with a liquid cleaner, contacting the substrate with a degassed electrolyte or other liquid, and other examples known in the art. In some cases where there are multiple pretreatment operations, they are all performed in a vacuum environment.

[0139] As indicated, examples of thermal treatments include metal annealing (modify metal grain structure) and metal reflow (modify position of metal). These may be performed on either seed layers or electrodeposited metals.

[0140] In some embodiments, a sequential electroplating process includes performing a first electroplating operation, reflowing metal deposited by the first electroplating operation, and thereafter performing a second electroplating operation on a substrate surface comprising the reflowed metal. In some embodiments, a sequential electroplating process includes annealing metal deposited in a first electroplating operation and / or in a second electroplating operation. The first and second electroplating operations may be performed under different electroplating conditions such as using different electrolytes, different current densities, different current pulsing regimes, and the like. In some embodiments, the first and second electroplating operations are performed in different electroplating cells.

[0141] In the context of metal oxide reduction and reflow of an electroplated film (e.g., about 10 to 1000 Angstroms thickness), example apparatus / process details follow:Oxide Reduction (Module 1): Temperature and reducing atmosphere, if employed, as above for seed layer types; optional plasma may be a plasma that directly contracts the substrate or is generated remotely, and radicals or other components are transported to the substrate.Metal Reflow (Module 2): Temperature of 100 to 400°C and optional reducing atmosphere (e.g., forming gas) and / or optional plasma that directly contracts the substrate or is generated remotely, and radicals or other components are transported to the substrate. Cooling (Module 3): Active or passive cooling

[0142] Examples of other non-electroplating operations in a sequential electroplating scheme include rinse operations optionally performed with degassed (low O2concentration) and / or alkaline pH adjusted water to minimize oxidation of bevel and / or electroplated films.Attorney Docket No. LAM1P093WO-12158-1WO Sequential Electroplating System Configurations

[0143] A system for sequential electroplating may include (a) a first electroplating cell configured to electroplate metal under first electroplating conditions that at least partially fill one or more recessed features on a surface of a substrate; (b) a second electroplating cell configured to electroplate additional metal under second electroplating conditions, which are different than the first electroplating conditions and electroplate the additional metal over the metal that at least partially fills one or more recessed features; and (c) a controller such as a component employing logic for causing various operations for executing sequential electroplating. In some embodiments, the controller is configured to cause, sequentially: receiving the substrate to be electroplated under the first electroplating conditions in the first electroplating cell; thereafter, transferring the substrate to the second electroplating cell; and electroplating the substrate under the second electroplating conditions in the second electroplating cell.

[0144] In addition to the electroplating cells and controller, a system may include various tools or modules for substrate handling, preprocessing, and / or post-processing such as thermal treatments. In some embodiments, a sequential electroplating system includes a substrate handler configured to act under control of the controller and to (a) transfer the substrate into and out of the first and second electroplating cells, and (b) transfer the substrate between the first and second electroplating cells.

[0145] In some embodiments, a sequential electroplating system also includes a pre-processing module configured to expose the substrate to conditions that improve the quality of the conductive seed layer prior the first electroplating operation. In such embodiments, the system may be divided into vacuum and non-vacuum environments such that the pre-processing module is within a vacuum region, and the first and second electroplating cells are in a tool that is outside the vacuum region. In some cases, the pre-processing module comprises multiple substrate processing stations within the vacuum region. Such stations may include an oxide reduction station and a substrate cooling station.

[0146] In some embodiments, a sequential electroplating system includes a post-electrofill module such as an anneal module configured to heat the substrate in a manner that changes the crystal structure of the metal and / or the additional metal. In some embodiments, a post-electrofill module comprises a reflow module configured to heat the substrate in a manner that changes the position of the metal and / or the additional metal within the one or more recessed features. Post-electrofill modules such as an anneal module or a reflow module may be provided in a vacuum environment, separate from the electroplating cells in a non-vacuum environment. A sequential electroplating system may be configured to transfer a substrate that has been subjected to a post-electrofillAttorney Docket No. LAM1P093WO-12158-1WO thermal process (e.g., annealing and / or reflow) to a different electroplating cell for additional electroplating.

[0147] In some systems, a vacuum environment is provided for both a preprocessing station that improves the quality of a seed layer and a post-electrofill module that thermally treats (e.g., anneals or reflows) electroplated metal. For example, a sequential electroplating system may include a vacuum environment enclosing a plurality of modules or stations configured (a) pre-treat the substrate, (b) re-flow the metal and / or the additional metal electrodeposited in the recessed features, and / or (c) anneal the metal and / or the additional metal electrodeposited in the recessed features.

[0148] These and other systems for sequential electroplating sometimes require unique tool configurations and modules on a single platform or across two or more matched systems. Such configurations may enable the throughputs needed for high volume manufacturing. Examples of system configurations that can handle both oxide reduction operations and metal reflow operations along with sequential electroplating process flows include systems employing one or more pressure controlled quad stations and systems employing one multi-hub system. Examples of such systems are illustrated in Figures 5 and 6, respectively.

[0149] Among the considerations for such configurations are temperature management. For example, an operation that requires oxide reduction at a low temperature may be followed by a reflow operation at a much higher temperature followed by a cool down operation.

[0150] Further, oxide reduction operations may be required not only for pretreating substrates that have oxide formed on metal seed layers but for removing oxides that have formed on electroplated metal surfaces soon after electroplating has concluded.

[0151] Figure 5 illustrates a sequential electroplating process flow that employs electroplating cells, oxide reduction modules, cooling modules, a reflow module, and substrate transfer components. Similar to operations 302 to 308 in the sequential electroplating process of Figure 3A, the process of Figure 5 employs a substrate pretreatment operation, a first electroplating operation, a reflow operation, and a second electroplating operation. Figure 5 emphasizes how these various operations, as well as associated operations, may be handled in a system having electroplating elements and vacuum / dry processing elements.

[0152] In the depicted embodiment, an incoming substrate has a feature 501 with cobalt seed layer 509, an overlying copper seed layer 511, and an oxide / contaminant film 510. In an operation 502, the seed layer is pretreated to remove the oxide / contaminant film 510 by, e.g., subjecting the substrate to a chemically reducing environment, optionally in a vacuum or other controlled atmosphere environment. In conjunction with operation 502, the newly pretreated substrate is quickly transferred from the controlled environment to a first electroplating cell.Attorney Docket No. LAM1P093WO-12158-1WO

[0153] In the first electroplating cell, the substrate is subjected to a first electroplating operation (operation 504) in which a conformal metal 516 is deposited. Subsequently, the newly electroplated substrate is exposed to atmospheric conditions that form an oxide / contaminant layer 515 on the surface of newly electroplated conformal metal 516.

[0154] At this point, the substrate is transferred (operation 506) to a vacuum environment having stations and / or modules for operations such as oxide reduction, metal reflow, and substrate cooling. In the vacuum environment, the substrate enters a first module or station where it is exposed to a chemically reducing environment to remove oxide / contamination layer 515. See operation 508. Thereafter, the substrate is moved to a second module or station, while still in vacuum, where it is subjected to conditions that reflow conformal metal layer 516 to form a metal plug 516’ that substantially fills feature 501. See operation 510. Next, the substrate is transported to a third module or station, while still in vacuum, where the substrate is cooled. See operation 512. From there, the cooled substrate is quickly transported out of the vacuum environment to a second electroplating cell where the substrate is subjected to a second electroplating operation that deposits conformal layer 519. See operations 514 and 516. In certain embodiments, both the first electroplating operation 504 and the second electroplating operation 516 are performed in an alkaline electrolyte.

[0155] Figure 6 illustrates a sequential electroplating system having two separate vacuum tools for performing non-electroplating operations. In the depicted system, each of these vacuum tools is a “quad” station tool having four separate stations, indexable within a confined vacuum environment. It should be understood that either or both of these vacuum tools may have fewer or more than four stations: e.g., two stations, three stations, five stations, six stations, etc.

[0156] In Figure 6, the overall system 601 comprises four primary components: a seed treatment vacuum tool 603 configured to treat metal seed layers on substrates; a plurality of electroplating cells 605, optionally with post electrofill modules (PEMs) such as rinsing and / or drying modules; a post-electrofill vacuum tool 607 configured to treat substrates that have recently been electroplated; and one or more substrate storage units 609 for temporarily holding substrates before processing, between operations, and / or after processing in the sequential electroplating system. Such holding modules are sometimes referred to as FOUPs.

[0157] As an example, the electroplating cells 605 and associated PEMs may be embodied in an electroplating system available from Lam Research Corporation of Fremont, CA. Examples of such system include the Sabre™ tool and the Sabre 3D™ tool, each of which may be configured with multiple electroplating cells and / or PEMs and associated robotic schemes.

[0158] In an example sequence, a plurality of substrates is held in a FOUP 609 while they await initial processing. One by one the substrates are transferred to an inbound load lock 611 of seedAttorney Docket No. LAM1P093WO-12158-1WO treatment vacuum tool 603. Load lock 611 provides a transition between ambient pressure and the vacuum pressure of tool 603. Once in seed treatment vacuum tool 603, a single substrate occupies any of the stations labeled by numbers 1 through 4. Thus, at any one time, as many as four substrates may be present in the stations of seed treatment vacuum tool 603. Different stations within seed treatment vacuum tool 603 may perform the same or different operations. For example, some or all stations may be configured to reduce oxide on and / or decontaminate the seed layers on the substrates. In some cases, tool 603 applies a chemically reducing process gas and / or plasma to all stations of seed treatment vacuum tool 603. In some cases, one or more stations of seed treatment vacuum tool 603 apply a plasma treatment and one or more other stations do not apply a plasma treatment. Individual substrates within seed treatment vacuum tool 603 may move from station-to-station all the while being exposed to the same or different reducing environments. In some embodiments, one or more of the stations in tool 603 are used to cool substrates before exiting.

[0159] After seed treatment is complete for a wafer or group of wafers in seed treatment vacuum tool 603, the substrate or substrates are transferred out of seed treatment vacuum tool 603 via an outbound load lock 613. By the time a substrate reaches outbound load lock 613, its seed layer should be in good condition for electroplating.

[0160] From outbound load lock 613, substrates are rapidly transferred to electroplating cells 605, where they enter a first electroplating cell configured to perform the first electroplating operation on the substrates, which operation deposits metal directly onto the seed layer. After electroplating in the first electroplating cell, the substrate may be rinsed, spun, dried, or otherwise subjected a post-electrofill treatment in a post electrofill module. Note electroplating cells 605 and associated PEMs are typically not in a vacuum environment although they may be blanketed in a nonoxidizing gas such as nitrogen.

[0161] In some process flows, after a substrate is electroplated in a first electroplating cell, it is optionally electroplated in a second electroplating cell that deposits metal under different electroplating conditions than the first electroplating cell. In some cases, the substrate is even further electroplated in a third or other subsequent electroplating cell.

[0162] After electroplating in one or electroplating cells of the plurality of electroplating cells 605, and after one or more optional post-electrofill treatments, a substrate is transferred to an inbound load lock 615 on post-electrofill vacuum tool 607. Load lock 615 allows the substrate to transition from an ambient pressure to a vacuum pressure before entering post-electrofill vacuum tool 607 proper.

[0163] As illustrated, post-electrofill vacuum tool 607 comprises four stations numbered 1 through 4 in a vacuum environment. While the design of post-electrofill vacuum tool 607 may be similarAttorney Docket No. LAM1P093WO-12158-1WO to that of seed treatment vacuum tool 603, its functions may be different. The stations of postelectrofill vacuum tool 607 may be configured to perform a thermal treatment such as metal anneal or reflow or an oxide reduction treatment. The temperatures and environments of post-electrofill vacuum tool 607 are set to execute such operations. In one example, station 1 is configured to reduce oxide on a recently electroplated metal, while stations 2 and 3 are configured to perform reflow, and station 4 is configured to cool a substrate after being treated in stations 1 through 3. Note that each station or combination of stations in post-electrofill vacuum tool 607 may be separately configured operate at a different temperature and / or run a plasma.

[0164] As with seed treatment vacuum tool 603, the stations of post-electrofill vacuum tool 607 are configured to accommodate one substrate at a time, but there may be as many as four substrates in the tool at such time.

[0165] After receiving a vacuum-based treatment in post-electrofill vacuum tool 607, a substrate or substrates are transferred out of post-electrofill vacuum tool 607 via an outbound load lock 617. From there, depending on the process flow, the substrate or substrates will either return to substrate storage units 609 (FOUPs) or return to electroplating cells 605. If the substrate or substrates return to electroplating cells 605, the sequential electroplating process requires additional electroplating operations. See e.g., the process flow of Figure 3B (ECP Step 3). If the substrate or substrates return to substrate storage units 609, the overall sequential electroplating process may be complete.

[0166] An example process flow for two multi-station vacuum tools follows.1) A substrate arrives from a seed layer deposition module to a sequential electroplating system under exposure to the atmosphere. The seed layer oxidizes and contacts atmospheric contaminates.2) The substrate is loaded to load lock such as load lock 611, where the pressure is pumped down to vacuum.3) The substrate begins to move through a seed treatment vacuum tool (e.g., tool 603) as described. The seed treatment vacuum tool has four stations.4) The seed oxide is reduced and contamination is removed on stations 1 and 2 of the seed treatment vacuum tool.5) The substrate is moved to station 3 and / or 4 and an outbound load lock (e.g., load lock 613) for cooling6) The substrate is rapidly transferred from the load lock to a substrate holder of a first electroplating cell in module having multiple electroplating cells configured to perform different operations of a sequential electroplating scheme. The substrate is optionally held with electrical contacts 0.1mm from the perimeter. Electroplating is conducted under atmospheric conditions.Attorney Docket No. LAM1P093WO-12158-1WO 7) The electroplated substrate is rinsed in a first post-electrofill module in a platform comprising the multiple electroplating cells.8) The electroplated substrate is conveyed to a post-electrofill vacuum tool (e.g., tool 607). During conveyance, some oxide or contamination may form on the recently electroplated metal. The post-electrofill vacuum tool has four stations. Some of the stations have different temperatures and / or different plasma conditions. The substrate arrives via inbound load lock (e.g., load lock 615).9) In station 1 of the post-electrofill vacuum tool, the oxide formed on the recently electroplated is reduced at a relatively low temperature in plasma.10) The substrate moves to station 2 where the electroplated metal is reflowed. The temperature at station 2 may be higher than at station 1. A remotely -generated plasma may or may not be produced and delivered to station 2.11) The substrate is moved to stations 3 and 4, and ultimately to an outbound load lock (e.g., load lock 617) for cooling12) The substrate is transferred back to the electroplating cells for a second electroplating operation.13) Additional post-electrofill processing in a PEM and / or the post-electrofill vacuum tool is performed until the sequential electroplating process is completed.14) The substrate is transferred from electroplating cells platform or the post-electrofill vacuum tool to the FOUP.

[0167] While this process flow discusses a single substrate being subjected to a sequential electroplating scheme, the process flow naturally extends to cases in which multiple groups of substrates are processed together. For example, four substrates may be moved together in tandem.

[0168] As an alternative to a system employing two multi-station vacuum tools, a system may employ a single vacuum tool that, optionally, has a hub arrangement employing a robot that accesses standalone modular stations and contains a substrate holding station to hold substrates until a cell is available for electroplating. The holding station may maintain substrates at low temperature and in vacuum to preserve surfaces from oxidation while waiting for electroplating cells to open.

[0169] Figure 7A illustrates a sequential electroplating sy stem having only one vacuum platform for performing non-electroplating operations. A complete sequential electroplating system 701 comprises three primary components: (a) one or more substrate storage units 703 for temporarily holding substrates before and after processing in the sequential electroplating system, (b) a plurality of electroplating cells 705, optionally with post electrofill modules such as rinsing and / or drying modules, and (c) a vacuum environment platform 707 having stations configured to treatAttorney Docket No. LAM1P093WO-12158-1WO metal seed layers on incoming substrates and treat substrates that have recently been electroplated. The electroplating cells system 705 and substrate storage units 703 may be configured and operated in a manner similar to that of electroplating cells 605 and storage units 609, respectively, of system 601.

[0170] In the depicted embodiment, vacuum environment platform 707 has load locks for ingress and egress of substrates. The load locks include a FOUP-facing load lock 709 and an electroplating cell facing load lock 711. Vacuum environment platform 707 has multiple vacuum processing modules, which in this example are numbered 1 through 6. In some implementations, the process conditions in each of these processing modules is independently controllable in terms of, e.g., temperature, plasma conditions (frequency, power, pulse regime, etc.), process gases, pressure, processing time, etc. In some cases, certain ones of the processing modules are dedicated to specific unit operations such as seed layer reduction and / or decontamination, metal reflow, metal anneal, cooling, etc.

[0171] As illustrated, a vacuum environment platform may have a hub arrangement in which the vacuum processing modules straddle or partially straddle a robot.

[0172] In the depicted embodiment, vacuum environment platform 707 also has a substrate hold station 713, where substrates can temporarily rest while awaiting processing in one of the vacuum processing modules where the next vacuum operation is to take place. This configuration allows substrates to sit in vacuum before being reloaded back to electroplating cells and thereby minimize oxidation.

[0173] In the depicted embodiment, vacuum environment platform 707 also has a substrate handling robot 715 configured to grasp, transport, and unload substrates among the multiple vacuum processing modules as well as load locks 709 and 711. Substrate handling robot 715 resides and operates within the vacuum environment of platform 707.

[0174] An example process flow for a single hub-based vacuum environment platform follows.1) In an atmospheric ambient, a substrate arrives from a seed deposition module. Metal seed layers on substrates oxidize and / or get contaminated by the atmosphere.2) The substrate loaded to load lock of a vacuum environment. After receiving the substrate, the load lock is pumped down to vacuum. See e.g., load lock 709.3) A hub robot (e.g., robot 715) moves the substrate to a station 1 through a closable door. Station one is controllable for temperature, process time, pressure, plasma power, other plasma conditions, process gas composition and flow rate, and process time. Each of these conditions in station 1 may be controlled independently of the corresponding conditions in other stations of the vacuum environment.4) While in station 1, the seed oxide and / or contamination is reduced.Attorney Docket No. LAM1P093WO-12158-1WO 5) The substrate is moved to station 2 for cooling.6) The substrate is moved to a holding station (e.g., station 713), if needed, to maximize tool throughput.7) The substrate is rapidly transferred through the load lock to a first electroplating cell in a tool comprising a plurality of electroplating cells and associated PEMs (e.g.. tool 705). In the first electroplating cell, the substrate engages with electrical contacts at 0.1mm from the substrate perimeter. The substrate is electroplated in the first cell under an atmospheric ambient.8) The electroplated substrate is rinsed in a first PEM.9) The electroplated substrate is inserted into a load lock (e.g., load lock 711), which is then pumped to vacuum.10) The hub robot moves substrate to station 3 through a closable door. Station 3 is controllable for temperature, time, pressure, plasma power and other plasma conditions, process gas composition and flow rate, and process time. Each of these conditions may be controlled independently of corresponding conditions in other stations.11) While in station 3, oxide and / or contamination that formed on metal electroplated in the first electroplating cell is reduced.12) The substrate is moved to station 4, where the electroplated metal is reflowed. Station 4 is controllable for temperature, time, pressure, plasma power and other plasma conditions, process gas composition and flow rate, and process time. Each of these conditions may be controlled independently of corresponding conditions in other stations.13) The substrate is moved to station 5 for cooling.14) The substrate is moved to the holding station, if needed, for tool throughput.15) The substrate is rapidly transferred through the load lock to electroplating cell tool, where overburden is electroplated on the substrate in a third electroplating cell. In this electroplating cell, the substrate engages with 1mm inset electrical contacts. Electroplating takes place under atmospheric ambient conditions.16) The substrate is transferred back to the vacuum environment via a load lock, where it is inserted into station 6 for annealing to grow grains in electroplated metal.

[0175] While this process flow discusses a single substrate being subjected to a sequential electroplating scheme, the process flow naturally extends to cases in which multiple groups of substrates are processed together. For example, four substrates may be moved together in tandem.

[0176] Figure 7B presents a scaled back variant of the electroplating system of Figure 7A. Similar elements from Figure 7A are given the same reference numerals in Figure 7B. As depicted in Figure 7B, system 701 includes (a) one or more substrate storage units 703 for temporarily holdingAttorney Docket No. LAM1P093WO-12158-1WO substrates before and after processing in the sequential electroplating system, (b) a plurality of electroplating cells 705, optionally with one or more post electrofill modules such as rinsing and / or dry ing modules, and (c) a vacuum environment platform 707 having stations configured to treat metal seed layers on incoming substrates and treat substrates that have recently been electroplated. The electroplating cells tool 705 and substrate storage units 703 may be configured and operated in a manner similar to that of electroplating cells 605 and storage units 609, respectively, of system 601, and likewise in a manner similar to that of the electroplating cells depicted in Figure 7 A. Additionally, system 701 includes load locks 709, 711, wafer holding stations 713, and a robot 715, which may be configured and operated in a manner similar to that of load locks, stations, and robot, respectively, of the system in Figure 7A.

[0177] Unlike the system in Figure 7A, system 701 in Figure 7B has a scaled back set of vacuum processing modules, which in this example are numbered 1 through 3. A system with this limited set of vacuum processing modules may be appropriate for sequential electroplating schemes in which only limited post-electrofill processing is required. For example, system 701 of Figure 7B may be appropriate for sequential electroplating schemes in which no reflow is needed. As illustrated in this example, vacuum processing modules may be arranged in a linear configuration.Differences in Electroplating Cells’ Electrical Contacts

[0178] In some embodiments, a wafer holder configured for electroplating substrates has first element that engages a peripheral region of the side of the substrate being electroplated and second element that engages a center region of the other side of the substrate (the backside) and pushes the substrate against the first element. The opposing forces of the two elements on the substrate cause a lip seal on first element to engage w ith the peripheral regions of the side of the substrate to be electroplated. This pushing action closes a gap between the substrate and the lip seal to thereby form a lip seal cavity that may be defined by portions of the lip seal, the first element, and the substrate. In some implementations, the first element takes the form of a cup for holding the peripheral region of the substrate and the second element takes the form of a cone for pushing against the backside of the wafer. Wafer holders having this cup and cone arrangement are exemplified in the clam shell type wafer holders used in the Sabre™ and Sabre3D™ electroplating tools from Lam Research Corporation of Fremont, California.

[0179] Within the lip seal cavity' reside multiple electrical contacts (e.g., twenty or more such contacts) that engage with the perimeter of substrate, and particularly the thin metal seed layer to provide electrical potential to the entire surface of the substrate via the seed layer. As an example, the contacts may engage the substrate at contact points located about 0.1 mm from the outer edge of the substrate. The electrical contacts contact the substrate at plurality' of contact points that together define a geometric arrangement around the perimeter of the substrate.Attorney Docket No. LAM1P093WO-12158-1WO

[0180] Electrical contact positions have been developed and exist because of a desire to use as much of an electroplated substrate’s surface area as possible for integrated circuit production. Unfortunately, as explained below, this makes sequential electroplating challenging or impossible because a thin seed layer is often damaged by a previous electroplating operation or an associated prior operation.

[0181] Figure 8 schematically illustrates a single electrical contact 803 in a lip seal 805 engaging with a perimeter position of a substrate 807. The perimeter region of a substrate where electrical contact is made is sometimes referred to as a “bevel’' due to its shape. Electrical contact 803 is just one of a plurality of such contacts that, along with the lip seal 805 contact the outer perimeter of the substrate 807. The distal ends of the electrical contacts, including contact 803, contact a thin, and sometimes discontinuous, seed layer 809. Collectively, the electrical contacts provide the electrical current and / or potential needed to drive electroplating of a metal film 811.

[0182] Figure 9 provides additional details of certain wafer holder configurations. A first element 901 engages a bevel region of the side of a substrate 905 being electroplated, and a second element 903 engages a center region of the other side (the backside) of substrate 905 and pushes the substrate against first element 901. Associated with first element 901 is a lip seal 912 and an electrical contact 908.

[0183] A challenge with thin seed layers and sequential electroplating schemes is that if the same contact points are used for each of multiple electroplating operations, subsequent electroplating operations may fail. Unfortunately, after even one electroplating operation, the perimeter / bevel seed layer may be so compromised that it is incapable of providing useable electrical contact for a subsequent electroplating operation. Substrates may fail to electroplate in second and subsequent sequential electroplating operations because the first electroplating, rinsing, and / or annealing of the substrates damages the very thin incoming seed layers, and the damage does not allow the second electroplating operation to make adequate electrical contact.

[0184] In certain embodiments, sequential electroplating process flows employ different arrangements of electrical contacts in each of the electroplating cells or associated substrate holders employed for each of the sequential electroplating operations. In some cases, the different arrangements produce different diameters or perimeters of contact points where the electrical contacts touch the substrate perimeter. For example, a first electroplating cell may have first electrical contacts that define a first perimeter of contact points where the first electrical contacts electrically contact the substrate during the first electroplating operation, and a second electroplating cell may have second electrical contacts that define a second perimeter of contact points where the second electrical contacts electrically contact the substrate during the second electroplating operation. In some cases, the second perimeter is smaller than the first perimeter.Attorney Docket No. LAM1P093WO-12158-1WO For example, the contacts perimeter in a first electroplating cell may be inset from the outer edge of the substrate by about 0.1 mm and the contacts perimeter in a second electroplating cell may be inset from the outer edge of the substate by about 0.5 mm. If a third electroplating operation is employed, the cell for that operation may have electrical contacts that define a third perimeter of contact points that is smaller than the second perimeter, e.g., they are inset by about 1 mm etc. In another example, the electrical contacts’ perimeters for the first, second, and third electroplating cells are inset from the substrate edge by 0.4 mm, 1 mm, and 1.75 mm, respectively.

[0185] In certain embodiments, each electroplating cell in a sequential electroplating system has a unique electrical contact layout. In some cases, the contact fingers and lip seals of electroplating cells for second and subsequent electroplating operations are arranged to electrically contact the electrodeposited films from the prior operation. Such film(s) is / are thicker than the incoming and discontinuous seed at the substrate bevel region.

[0186] Figure 10 schematically illustrates a progression of electroplating cells for first, second, and third electroplating operations, in which each successive operation employs electrical contacts defining a smaller footprint (e.g., perimeter) of contact points on the substrate. As illustrated, a first electroplating cell 1001 has contacts that engage with an initial seed layer of the substrate. In the example, these contacts are inset from the substrate edge by only 0.1 mm. After the first electroplating operation is complete, an electroplated film 1003 is formed on the substrate.

[0187] A second electroplating cell 1005 has contacts that engage an outer edge of electroplated film 1003 and thereby provides good electrical contact with the substate. In the second electroplating cell 1005, the contacts are inset from the substrate edge by 0.5 mm. After the second electroplating operation is complete, a second electroplated film 1007 is formed on the substrate.

[0188] A third electroplating cell 1009 has contacts that engage an outer edge of electroplated film 1007 and thereby provides good electrical contact with the substate. In the third electroplating cell 1009, the contacts are inset from the substrate edge by 1 mm. After the third electroplating operation is complete, a second electroplated film 1011 is formed on the substrate.

[0189] The positions of the electrical contacts in the example of Figure 10 are only illustrative. Many other sequences of electrical contact positions, including inset distances, are possible and within the scope of this disclosure.

[0190] Figure 10 outlines the matching of contact fingers and lip seals to enable electrical contact onto the electrodeposited films from the electroplating operation before that are thicker than the incoming and discontinuous seed at bevels.

[0191] Figure 11 illustrates an example sequence of operations in a sequential electroplating scheme that employs electroplating cells with successively smaller electrical contact footprints. In the depicted example, the process begins with deposition of diffusion barrier and metal seed layersAttorney Docket No. LAM1P093WO-12158-1WO (operation 1103) to produce a thin conductive layer having a sheet resistance of, e.g., about 20-2000 Ohm / sq. Thereafter, the process optionally pretreats the deposited seed layer to reduce oxides and / or remove atmospheric contaminants. See operation 1105.

[0192] At this point, the process executes a first electroplating operation 1107. This operation optionally employs a complexed electrolyte with a pH that reduces certain metal oxides electrochemically. The first electroplating cell, which is employed in operation 1107, has an electrical contact footprint that contacts the substrate about 0.1 from the substrate edge. Associated with first electroplating operation 1107 is one or more post-electrofill operations such as rinsing, spinning, and drying the recently electroplated substrate.

[0193] After operation 1107, the process reflows the electroplated metal at elevated temperature and in the presence of a reducing gas. See operation 1109. First electroplating operation 1107, its post treatments such as rinsing, and / or reflow operation 1109 may degrade the quality of the seed layer.

[0194] Therefore, a second electroplating operation 1111 employs a second electroplating cell having an electrical contact footprint that contacts the substrate further inward compared to the first electroplating cell. In the illustrated example, the second electroplating cell has an electrical contact footprint that contacts the substrate about 0.5 mm inward of the substrate edge. This allows successful electroplating of additional metal on the substrate surface.

[0195] Next, in an operation 1113, a second reflow operation is performed. It has a similar effect as reflow operation 1109, but primarily reflows the metal deposited in second electroplating operation 1111.

[0196] Next, in an operation 1115, a third electroplating operation electroplates overburden over the entire substrate surface. Because prior operations may have further compromised the seed layer and possibly the peripheral regions of the metal deposited in second electroplating operation 1111, third electroplating operation 1115 employs a third electroplating cell having an electrical contact footprint that contacts the substrate even further inward compared to the second electroplating cell. In the illustrated example, the third electroplating cell has an electrical contact footprint that contacts the substrate about 1 mm inward of the substrate edge. This allows successful electroplating of the overburden on the substrate surface.

[0197] Finally, in an operation 1117, the substrate is subjected to a thermal or plasma annealing operation in the presence of a chemically reducing gas. Annealing operation 1117 grows grains of metal in the previously electroplated films.

[0198] In some examples, in a first electroplating operation, the inset distance of the electrical contact points is about 0.05 to 0.7 millimeters from the outer perimeter of the substrate. This firstAttorney Docket No. LAM1P093WO-12158-1WO electroplating operation may require that the electrical contact points be on an initial copper seed layer.

[0199] In some examples, a second electroplating operation, performed after the first electroplating operation employs a second arrangement of electrical contacts that utilizes contact points that have in inset distance of about 0.1 to 1.5 millimeters from the outer perimeter of the substrate. In some examples, a third electroplating operation, performed after the second electroplating operation employs a second arrangement of electrical contacts that utilizes contact points that have in inset distance of about 1 to 2.5 millimeters from the outer perimeter of the substrate.

[0200] While discussion herein has described various arrangements of electrical contacts that vary in the sizes of their perimeters (or substrate inset distances) from one electroplating operation to the next, this disclosure is not so limited. The different arrangements of electrical contacts between electroplating operations may be based on other geometric considerations such as in an angular offset between the contact point positions in the successive electroplating operations.

[0201] In some process flows in which three or more different electroplating operations are employed, not all of the electroplating operations use different electrical contact point arrangements such as arrangements having successively smaller diameters in successive electroplating operations. For example, in some cases, the last one or more electroplating operations may employ contact positions that are the same or substantially the same as those in an earlier electroplating operation. This may be suitable because, for example, an initially deposited copper layer, such as copper layer 316 in Figure 3A, is sufficiently robust that it can continue to provide good electrical contact in subsequent electroplating operations, even those that are performed after an intermediate operation such as cleaning or annealing. Thus, as an example, a sequential process that may employ three or more electroplating operations may employ (i) a first electroplating operation that has a wafer holder with electrical contact arrangement of the first perimeter, (ii) a second electroplating operation that has a different wafer holder with a different arrangement of a smaller perimeter than the first arrangement, and (iii) one or more subsequent electroplating operations that each have a wafer holder with an arrangement that is identical to, or equivalent to, that employed in second electroplating operation.

[0202] It should be understood that two different electroplating cells that employ wafer holders with different electrical contact arrangements may otherwise be equivalent or identical. In some embodiments, the only difference between the electroplating cells used in successive electroplating operations is the electrical contact arrangement in their substrate holders. The differences between the two cells may reside solely in their substrate holders or, more specifically, in their electrical contact patterns.Attorney Docket No. LAM1P093WO-12158-1WO Applications

[0203] Sequential electroplating may be employed for many different applications. For example, it may be employed to deposit metal into vias and / or trenches of a substrate during Damascene processing. It may also be used in through-mask plating in wafer level packaging (WLP) applications to form through via interconnects, redistribution lines, bumps, pillars, etc. Another application of sequential electroplating is filling through-silicon vias (TSVs), which are relatively large vertical electrical connections used in 3D integrated circuits and 3D packages.

[0204] In some embodiments, wafer holders and associated electroplating apparatus are configured to electroplate onto panels for integrated circuit packages. Such panels may be part of an integrated circuit structure used in, for example, panel level packaging or substrates that provide an interface between integrated circuits and printed circuit boards. Examples of electroplated features on or within a panel include contact bumps or pillars for wire bonding, signal redistribution lines, power lines, etc. In some embodiments, panels are generally rectangular structures that are about 5 to 100 cm in length or width.

[0205] In panel level packaging, typically multiple different integrated circuits are provided in a single package. These may be disposed on different levels of a multilevel package. For example, in certain graphical processing units, a logic chip is disposed on a lower level and one or more memory chips are disposed on an upper level. The overall packaging structure includes one or more panels for connecting to input / output ports of the chips and / or to contacts of a printed circuit board.

[0206] In some embodiments, panels have one or more levels of electroplated interconnects or redistribution lines within a dielectric structure. Panels for panel level packaging structures are sometimes electroplated on one side only. Substrates used in packaging are sometimes electroplated on both sides. Regardless, these and other panel-type substrates may be electroplated in substrate holders that have lip seal cavities as disclosed herein.Example ClausesFirst Method Clauses

[0207] Clause 1. A method of electroplating a metal comprising: receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, wherein the substrate surface has a conductive layer disposed thereon; performing a first electroplating operation under first electroplating conditions to deposit metal that at least partially fills the one or more recessed features; and performing a second electroplating operation under second electroplating conditions, which are different than the first electroplating conditions, to deposit additional metal over the metal deposited in the first electroplating operation.Attorney Docket No. LAM1P093WO-12158-1WO

[0208] Clause 2. The method of clause 1, wherein the one or more recessed features comprise Damascene features including vias and interconnect paths.

[0209] Clause 3. The method of clause 1, wherein the one or more recessed features comprise a first feature having a first size and a second feature having a second size, wherein the first size is greater than the second size.

[0210] Clause 4. The method of clause 3, wherein the first electroplating operation fully fills the second feature but does not fully fill the first feature.

[0211] Clause 5. The method of clause 4, wherein the additional metal deposited by the second electroplating operation completes filling the first feature.

[0212] Clause 6. The method of clause 1, wherein the additional metal deposited by the second electroplating operation comprises at least a portion of an overburden layer.

[0213] Clause 7. The method of clause 1, wherein the first electroplating operation deposits the metal in a substantially conformal manner in the one or more recessed features.

[0214] Clause 8. The method of clause 7, wherein the first electroplating operation is performed using an alkaline electroplating bath.

[0215] Clause 9. The method of clause 7, wherein the second electroplating operation deposits the additional metal in a bottom-up fill manner.

[0216] Clause 10. The method of clause 9, wherein the second electroplating operation is performed using an acidic electroplating bath.

[0217] Clause 11. The method of clause 10, wherein the acidic electroplating bath comprises one or more organic additives that promote bottom-up fill.

[0218] Clause 12. The method of clause 1, wherein at least some of the one or more recessed features have a critical dimension of at most about 30 nm.

[0219] Clause 13. The method of clause 1, wherein the conductive layer comprises a copper seed layer.

[0220] Clause 14. The method of clause 1, wherein the substrate surface has a diffusion barrier layer disposed thereon.

[0221] Clause 15. The method of clause 1, wherein the substrate surface has a cobalt layer disposed thereon.

[0222] Clause 16. The method of clause 1, further comprising, prior to performing the first electroplating operation, pretreating the substrate surface.

[0223] Clause 17. The method of clause 16, wherein the pretreating comprises subjecting the conductive layer to a chemically reducing environment and removing a native oxide and / or removing an impurity.Attorney Docket No. LAM1P093WO-12158-1WO

[0224] Clause 18. The method of clause 16, wherein the pretreating comprises a plurality of operations, all performed in a vacuum environment.

[0225] Clause 19. The method of clause 1, further comprising, between performing the first electroplating operation and performing the second electroplating operation, reflowing the metal.

[0226] Clause 20. The method of clause 1, further comprising, after the first electroplating operation and / or the second electroplating operation, annealing the metal and / or the additional metal.

[0227] Clause 21. The method of clause 1, wherein the first electroplating operation is performed in a first electroplating cell and the second electroplating operation is performed in a second electroplating cell.

[0228] Clause 22. The method of clause 21, further comprising performing a third electroplating operation in third electroplating cell.

[0229] Clause 23. The method of clause 21, wherein the first electroplating cell comprises first electrical contacts defining a first perimeter where the first electrical contacts electrically contact the substrate during the first electroplating operation.

[0230] Clause 24. The method of clause 23, wherein the second electroplating cell comprises second electrical contacts defining a second perimeter where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second perimeter is smaller than the first perimeter.First System Clauses

[0231] Clause 1. An electroplating system comprising: a first electroplating cell configured to electroplate metal under first electroplating conditions that at least partially fill one or more recessed features on a surface of a substrate having a conductive layer disposed thereon; a second electroplating cell configured to electroplate additional metal under second electroplating conditions, which are different than the first electroplating conditions and electroplate the additional metal over the metal that at least partially fills one or more recessed features; and a controller configured to cause, sequentially: receiving the substrate to be electroplated under the first electroplating conditions in the first electroplating cell, thereafter, transferring the substrate to the second electroplating cell, and electroplating the substrate under the second electroplating conditions in the second electroplating cell.

[0232] Clause 2. The electroplating system of clause 1, further comprising a substrate handler configured to act under control of the controller and to (a) transfer the substrate into and out of the first and second electroplating cells, and (b) transfer the substrate between the first and second electroplating cells.Attorney Docket No. LAM1P093WO-12158-1WO

[0233] Clause 3. The electroplating system of clause 1, further comprising a pre-processing module configured to expose the substrate to conditions that improve the quality of the conductive layer prior the first electroplating operation.

[0234] Clause 4. The electroplating system of clause 3, wherein the pre-processing module is within a vacuum region, and wherein the first and second electroplating cells are in a tool that is outside the vacuum region.

[0235] Clause 5. The electroplating system of clause 4, wherein the pre-processing module comprises multiple substrate processing stations within the vacuum region.

[0236] Clause 6. The electroplating system of clause 1, further comprising an anneal module configured to heat the substrate in a manner that changes the crystal structure of the metal and / or the additional metal.

[0237] Clause 7. The electroplating system of clause 1, further comprising a re-flow module configured to heat the substrate in a manner that changes the position of the metal and / or the additional metal within the one or more recessed features.

[0238] Clause 8. The electroplating system of clause 1, further comprising a tool comprising multiple stations in a vacuum environment, wherein at least one of the stations is configured to (a) anneal the substrate or (b) re-flow the metal and / or the additional metal.

[0239] Clause 9. The electroplating system of clause 8, wherein the tool further comprises a station for pre-processing the substrate in a manner that improves the quality of the conductive layer prior to the first electroplating operation.

[0240] Clause 10. The electroplating system of clause 1, wherein the first electroplating cell comprises first electrical contacts defining a first perimeter where the first electrical contacts electrically contact the substrate during the first electroplating operation.

[0241] Clause 11. The electroplating system of clause 10, wherein the second electroplating cell comprises second electrical contacts defining a second perimeter where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second perimeter is smaller than the first perimeter.

[0242] Clause 12. The electroplating system of clause 1, further comprising a third electroplating cell configured to electroplate still more metal over the additional metal electroplated in the second electroplating operation.

[0243] Clause 13. The electroplating system of clause 1, wherein the one or more recessed features comprise a first feature having a first size and a second feature having a second size, wherein the first size is greater than the second size.

[0244] Clause 14. The electroplating system of clause 13, wherein the first electroplating conditions fully fill the second feature but do not fully fill the first feature.Attorney Docket No. LAM1P093WO-12158-1WO

[0245] Clause 15. The electroplating system of clause 14, wherein the additional metal deposited under the second electroplating conditions completes filling the first feature.

[0246] Clause 16. The electroplating system of clause 1, wherein the additional metal deposited under the second electroplating cell conditions forms at least a portion of an overburden layer.

[0247] Clause 17. The electroplating system of clause 1, wherein the first electroplating conditions deposit the metal in a substantially conformal manner in the one or more recessed features.

[0248] Clause 18. The electroplating system of clause 17, wherein the second electroplating conditions deposit the additional metal in a bottom-up fill manner.

[0249] Clause 19. The electroplating system of clause 1, further comprising a vacuum environment enclosing a plurality of modules or stations configured to (a) pre-treat the substrate, (b) re-flow the metal and / or the additional metal electrodeposited in the recessed features, and / or (c) anneal the metal and / or the additional metal electrodeposited in the recessed features.

[0250] Clause 20. The electroplating system of clause 19. wherein the vacuum environment is a quad-station tool.

[0251] Clause 21. The electroplating system of clause 1, further comprising a vacuum environment enclosing a first module or station configured to pre-treat the substrate; and a second module or station configured to re-flow the metal and / or the additional metal electrodeposited in the recessed features, and / or anneal the metal and / or the additional metal electrodeposited in the recessed features.Second System Clauses

[0252] Clause 1. An electroplating system comprising: a first electroplating cell configured to perform a first operation that electroplates metal that at least partially fills one or more recessed features on a surface of a substrate, wherein the first electroplating cell comprises first electrical contacts defining a first arrangement of contact points where the first electrical contacts electrically contact the substrate during the first electroplating operation; a second electroplating cell configured to perform a second operation that electroplates electroplate additional metal over the metal that at least partially fills one or more recessed features, wherein the second electroplating cell comprises second electrical contacts defining a second arrangement of contact points where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second arrangement is different than the first arrangement.Second Method Clauses

[0253] Clause 1. A method of electroplating a metal comprising: receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated;Attorney Docket No. LAM1P093WO-12158-1WO performing a first electroplating operation that deposits metal that at least partially fills the one or more recessed features, wherein the first electroplating operation is performed in first electroplating cell comprising first electrical contacts defining a first arrangement of contact points where the first electrical contacts electrically contact the substrate during the first electroplating operation; performing a second electroplating operation that deposits additional metal over the metal deposited in the first electroplating operation, wherein the second electroplating operation is performed in a second electroplating cell comprising second electrical contacts defining a second arrangement of contact points where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second arrangement is different than the first arrangement.Third Method Clauses

[0254] Clause 1. A method of electroplating a metal comprising: receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, wherein the substrate surface does not have a copper seed layer disposed thereon; performing a first electroplating operation that deposits a copper seed layer onto the substrate; and performing a second electroplating operation under second electroplating conditions that deposit copper onto the copper seed layer, wherein the second electroplating operation at least partially fills the one or more recessed features.

[0255] Clause 2. The method of clause 1, wherein the second electroplating operation deposits the copper substantially conformally onto the copper seed layer.

[0256] Clause 3. The method of clause 1, wherein the second electroplating operation deposits the copper via a bottom up fill mechanism onto the copper seed layer.

[0257] Clause 4. The method of clause 1, wherein the substrate comprises a layer comprising ruthenium, cobalt, nickel, or any combination, and wherein the first electroplating operation deposits the copper seed layer directly onto the layer.

[0258] Clause 5. The method of clause 1, further comprising: performing a third electroplating operation under third electroplating conditions, which are different than the second electroplating conditions, to deposit additional metal over the metal deposited in the second electroplating operation.Conclusion

[0259] In the foregoing description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments are described in conjunction with the specific embodiments, it will beAttorney Docket No. LAM1P093WO-12158-1WO understood that it is not intended to limit the disclosed embodiments.

[0260] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

Attorney Docket No. LAM1P093WO-12158-1WOCLAIMSWhat is claimed is:

1. A method of electroplating a metal comprising:receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, wherein the substrate surface has a conductive layer disposed thereon;performing a first electroplating operation under first electroplating conditions to deposit metal that at least partially fills the one or more recessed features; andperforming a second electroplating operation under second electroplating conditions, which are different than the first electroplating conditions, to deposit additional metal over the metal deposited in the first electroplating operation.

2. The method of claim 1, wherein the one or more recessed features comprise Damascene features including vias and interconnect paths.

3. The method of claim 1, wherein the one or more recessed features comprise a first feature having a first size and a second feature having a second size, wherein the first size is greater than the second size.

4. The method of claim 3, wherein the first electroplating operation fully fills the second feature but does not fully fill the first feature.

5. The method of claim 4, wherein the additional metal deposited by the second electroplating operation completes filling the first feature.

6. The method of claim 1, wherein the first electroplating operation is performed using an alkaline electroplating bath.

7. The method of claim 1, wherein the second electroplating operation deposits the additional metal in a bottom-up fill manner.Attorney Docket No. LAM1P093WO-12158-1WO8. The method of claim 7, wherein the second electroplating operation is performed using an acidic electroplating bath.

9. The method of claim 8, wherein the acidic electroplating bath comprises one or more organic additives that promote bottom-up fill.

10. The method of claim 1, wherein the conductive layer comprises a copper seed layer.

11. The method of claim 1, wherein the substrate surface has a diffusion barrier layer disposed thereon.

12. The method of claim 1, further comprising, prior to performing the first electroplating operation, pretreating the substrate surface.

13. The method of claim 1, further comprising, between performing the first electroplating operation and performing the second electroplating operation, reflowing the metal.

14. The method of claim 1, further comprising, after the first electroplating operation and / or the second electroplating operation, annealing the metal and / or the additional metal.

15. The method of claim 1, wherein the first electroplating operation is performed in a first electroplating cell and the second electroplating operation is performed in a second electroplating cell.

16. The method of claim 15, further comprising performing a third electroplating operation in third electroplating cell.

17. The method of claim 15, wherein the first electroplating cell comprises first electrical contacts defining a first perimeter where the first electrical contacts electrically contact the substrate during the first electroplating operation.

18. The method of claim 17, wherein the second electroplating cell comprises second electrical contacts defining a second perimeter where the second electrical contacts electrically contact the substrate during the second electroplating operation, andAttorney Docket No. LAM1P093WO-12158-1WO wherein the second perimeter is smaller than the first perimeter.

19. An electroplating system comprising:a first electroplating cell configured to electroplate metal under first electroplating conditions that at least partially fill one or more recessed features on a surface of a substrate having a conductive layer disposed thereon;a second electroplating cell configured to electroplate additional metal under second electroplating conditions, which are different than the first electroplating conditions and electroplate the additional metal over the metal that at least partially fills one or more recessed features; andwherein the system is configured to cause, sequentially:receiving the substrate to be electroplated under the first electroplating conditions in the first electroplating cell,thereafter, transferring the substrate to the second electroplating cell, and electroplating the substrate under the second electroplating conditions in the second electroplating cell.

20. The electroplating system of claim 19, further comprising a substrate handler configured to (a) transfer the substrate into and out of the first and second electroplating cells, and (b) transfer the substrate between the first and second electroplating cells.

21. The electroplating system of claim 19, further comprising a pre-processing module configured to expose the substrate to conditions that improve the quality of the conductive layer prior to the first electroplating operation.

22. The electroplating system of claim 21, wherein the pre-processing module is within a vacuum region, and wherein the first and second electroplating cells are in a tool that is outside the vacuum region.Attorney Docket No. LAM1P093WO-12158-1WO 23. The electroplating system of claim 19, further comprising an anneal module configured to heat the substrate in a manner that changes the crystal structure of the metal and / or the additional metal.

24. The electroplating system of claim 19, further comprising a re-flow module configured to heat the substrate in a manner that changes the position of the metal and / or the additional metal within the one or more recessed features.

25. The electroplating system of claim 19, further comprising a tool comprising multiple stations in a vacuum environment, wherein at least one of the stations is configured to (a) anneal the substrate or (b) re-flow the metal and / or the additional metal.

26. The electroplating system of claim 19, wherein the first electroplating cell comprises first electrical contacts defining a first perimeter where the first electrical contacts electrically contact the substrate during the first electroplating operation.

27. The electroplating system of claim 26, wherein the second electroplating cell comprises second electrical contacts defining a second perimeter where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second perimeter is smaller than the first perimeter.

28. The electroplating system of claim 19, further comprising a third electroplating cell configured to electroplate still more metal over the additional metal electroplated in the second electroplating operation.

29. The electroplating system of claim 19, further comprising a vacuum environment enclosing a plurality of modules or stations configured to (a) pre-treat the substrate, (b) re-flow the metal and / or the additional metal electrodeposited in the recessed features, and / or (c) anneal the metal and / or the additional metal electrodeposited in the recessed features.

30. The electroplating system of claim 19, wherein the vacuum environment is a quad-station tool.Attorney Docket No. LAM1P093WO-12158-1WO 31. An electroplating system comprising:a first electroplating cell configured to perform a first operation that electroplates metal that at least partially fills one or more recessed features on a surface of a substrate, wherein the first electroplating cell comprises first electrical contacts defining a first arrangement of contact points where the first electrical contacts electrically contact the substrate during the first electroplating operation;a second electroplating cell configured to perform a second operation that electroplates electroplate additional metal over the metal that at least partially fills one or more recessed features, wherein the second electroplating cell comprises second electrical contacts defining a second arrangement of contact points where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second arrangement is different than the first arrangement.

32. A method of electroplating a metal comprising:receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated;performing a first electroplating operation that deposits metal that at least partially fills the one or more recessed features, wherein the first electroplating operation is performed in first electroplating cell comprising first electrical contacts defining a first arrangement of contact points where the first electrical contacts electrically contact the substrate during the first electroplating operation;performing a second electroplating operation that deposits additional metal over the metal deposited in the first electroplating operation, wherein the second electroplating operation is performed in a second electroplating cell comprising second electrical contacts defining a second arrangement of contact points where the second electrical contacts electrically contact the substrate during the second electroplating operation, and wherein the second arrangement is different than the first arrangement.

33. A method of electroplating a metal comprising:receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, wherein the substrate surface does not have a copper seed layer disposed thereon;Attorney Docket No. LAM1P093WO-12158-1WO performing a first electroplating operation that deposits a copper seed layer onto the substrate; andperforming a second electroplating operation under second electroplating conditions that deposit copper onto the copper seed layer, wherein the second electroplating operation at least partially fills the one or more recessed features.

34. The method of claim 33, wherein the second electroplating operation deposits the copper substantially conformally onto the copper seed layer.

35. The method of claim 33, wherein the second electroplating operation deposits the copper via a bottom up fill mechanism onto the copper seed layer.

36. The method of claim 33, wherein the substrate comprises a layer comprising ruthenium, cobalt, nickel, or any combination, and wherein the first electroplating operation deposits the copper seed layer directly onto the layer.

37. The method of claim 33, further comprising: performing a third electroplating operation under third electroplating conditions, which are different than the second electroplating conditions, to deposit additional metal over the metal deposited in the second electroplating operation.

38. A method of electroplating a metal comprising:receiving a substrate having one or more recessed features on a surface of the substrate on which metal is to be electroplated, wherein the substrate surface has a conductive seed layer disposed thereon;performing a first electroplating operation under first electroplating conditions to deposit metal that at least partially fills the one or more recessed features;re-flowing or annealing the metal deposited in the first electroplating operation; andAttorney Docket No. LAM1P093WO-12158-1WO after the re-flowing or annealing, performing a second electroplating operation under second electroplating conditions, which are different than the first electroplating conditions, to deposit additional metal over the metal deposited in the first electroplating operation.

39. The method of claim 38, wherein the first electroplating operation is performed in a first electroplating cell and the second electroplating operation is performed in a second electroplating cell.

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