Wafer shielding to prevent lip seal plating out

Abstract

The undesirable deposition of metal on the lip seal during the electrodeposition of metal on the semiconductor substrate (lip seal plating out) is minimized or eliminated by minimizing or eliminating the ion current flowing to the lip seal. For example, electrodeposition can be performed to avoid contact between the lip seal and the cathode biased conductive material on the semiconductor substrate during the electroplating process. This can be achieved by shielding a small selected area near the lip seal to inhibit the electrodeposition of metal near the lip seal and avoid contact between the metal and the lip seal. In some embodiments, shielding is achieved by sequentially using lip seals of different inner diameters in the process of electroplating the metal into a through-resist feature, wherein a lip seal with a smaller diameter is used during the first electroplating step and used as a shield to block electrodeposition in the selected area. In the second electroplating step, a lip seal with a larger inner diameter is used.

Description

[0001] Incorporated by Reference

[0002] The PCT application form is filed concurrently with this specification as a part of this application. Each application to which this application claims the benefit or priority as identified in the concurrently filed PCT application form is incorporated herein by reference in its entirety and for all purposes. Technical Field

[0003] The present invention relates to methods and apparatus for fabricating semiconductor devices. In particular, embodiments of the present invention relate to electrodeposition of metals, particularly through-mask electroplating. Background Art

[0004] Through-mask electroplating in semiconductor device manufacturing involves electrodeposition of metal into recessed features (recessed features through the mask) having an exposed conductive layer at the bottom of the recessed features. The sidewalls and field regions of the recessed features in these substrates are made of a non-conductive mask material (e.g., photoresist). During electroplating, the semiconductor substrate is cathodically biased by making electrical contact with the conductive layer below the mask material and by applying a negative voltage from a power supply to the layer. This contact is typically made at the periphery of the semiconductor substrate in a substrate holder assembly.

[0005] The substrate holder also typically includes a cup that holds the semiconductor substrate and an elastomeric lip seal that seals the outer edge and backside of the wafer substrate from the electrolyte. During the electroplating process, the cathode-biased substrate is contacted with the electrolyte, causing the electrolyte to cause electrochemical reduction of ions contained in the electrolyte when in contact with the cathode-biased metal on the semiconductor substrate. In certain applications, such as in wafer-level packaging (WLP), two metals (e.g., tin and silver) are electroplated using an electrolyte containing tin and silver ions. The formed tin-silver (SnAg) bumps can then be used to solder multiple substrates together.

[0006] The background description provided here is for the purpose of generally presenting the context of the present disclosure. The work of the presently designated inventors is neither explicitly nor implicitly admitted to be prior art against the present disclosure to the extent that it is described in this background section and in aspects of the specification that were not determined to be prior art at the time the application was filed. Summary of the invention

[0007] In one aspect, a method is provided for electrodepositing a metal onto a semiconductor substrate having a plurality of recessed features through a mask while preventing or reducing deposition of the metal on a lip seal of an electroplating device (referred to as lip seal plate-out). In one embodiment, the method comprises: (a) electrodepositing a first metal into the recessed features through the mask of the semiconductor substrate in a first electroplating tank using a first lip seal; and (b) after electroplating the first metal, electrodepositing a second metal into the recessed features through the mask in a second electroplating tank using a second lip seal having an inner diameter greater than the first lip seal, wherein the semiconductor substrate comprises a selected area shielded from exposure to an electrolyte by the first lip seal but not by the second lip seal, so that the first metal is not electrodeposited in the selected area and the second metal is allowed to be electrodeposited in the selected area. The lip seal is typically made of an elastic material and seals the outer edge and back side of the semiconductor substrate. The inner diameter of the lip seal refers to the diameter of the opening portion of the lip seal. The width of the selected area is generally equal to the difference between the inner radius of the second lip seal and the inner radius of the first lip seal.

[0008] In some embodiments, electrodeposition of the second metal in the selected area does not result in electrodeposition above the plane of the mask. Preferably, electrodeposition of the second metal in the selected area does not result in the electrodeposited second metal contacting the second lip seal. In some implementations, electrodeposition of the second metal results in electrodeposition of the second metal above the plane of the mask outside the selected area. In one embodiment, electrodeposition of the second metal results in electrodeposition of the second metal above the plane of the mask outside the selected area, and electrodeposition below the plane of the mask in the selected area.

[0009] In some embodiments, the first metal and the second metal are different metals. For example, in one embodiment, the first metal is copper and the second metal is a combination of tin and silver. In other embodiments, the first metal and the second metal are the same metal (including a combination of metals). For example, in some embodiments, the first metal is a combination of tin and silver, and the second metal is a combination of tin and silver. In some embodiments, the width of the selected area is between about 0.05-1mm. In one implementation, the width of the selected area is about 0.25mm. In some embodiments, the mask is a photoresist, and the second lip seal is in direct contact with the photoresist during the electroplating process. The width of the recessed features of the through-mask can vary, and in some embodiments, the recessed features of the through-mask have a width between about 10-50μm. In some embodiments, the mask has a thickness between about 10-100μm.

[0010] In some embodiments, the first and second lip seals are made of an elastomeric material, the width of the selected area is equal to the difference between the inner radius of the second lip seal and the inner radius of the first lip seal, and the selected area has an annular shape.

[0011] On the other hand, a method for electroplating a metal onto a semiconductor substrate while preventing or reducing deposition of the metal on a lip seal of an electroplating device is provided, wherein, in one embodiment, the method comprises: (a) providing a semiconductor substrate into a substrate holder of the electroplating device, wherein the substrate holder comprises a lip seal, wherein the lip seal is positioned so that at least a portion of the lip seal contacts an electrolyte during electroplating; and (b) electroplating the metal onto the semiconductor substrate while preventing or reducing ionic current flowing to the lip seal.

[0012] In some embodiments, preventing or reducing the ionic current flowing to the lip seal includes electroplating the metal so that the lip seal does not contact the cathode-biased conductive material on the semiconductor substrate during the electroplating process. In some embodiments, the electroplating in (b) includes electrodepositing the metal into a recessed feature through a mask, while the lip seal contacts a non-conductive mask material and does not contact a conductive metal layer being electrodeposited onto the semiconductor substrate. In some embodiments, tin (Sn) and silver (Ag) are deposited simultaneously onto the semiconductor substrate (e.g., into a through-mask feature). In other embodiments, tin is electrodeposited as a single metal.

[0013] On the other hand, a method is provided, wherein the method includes: (a) using a first lip seal to electro-deposit a first metal into a recessed feature of a semiconductor substrate through a mask in a first electroplating tank, so that the metal is not electro-deposited in a selected area shielded by the first lip seal, wherein the selected area is located at the periphery of the substrate; (b) after (a), using a second lip seal having a larger diameter than the first lip seal and positioned near the selected area to electro-deposit a second metal into the recessed feature of the through mask in a second electroplating tank, wherein the electro-deposition in the selected area does not result in electro-deposition above the plane of the mask and does not result in contact between the electro-deposited second metal and the second lip seal, while the electro-deposition at other locations on the semiconductor substrate results in electro-deposition above the plane of the mask. In some embodiments, the first metal is copper and the second metal is a combination of tin and silver. In other embodiments, the first metal and the second metal are the same. For example, in one embodiment, the first metal is a combination of tin and silver, and the second metal is also a combination of tin and silver. In some embodiments, the width of the selected area is between about 0.05-1mm. For example, in one implementation, the width of the selected area is about 0.25 mm. In some embodiments, the recessed features through the mask have a width between about 10-50 μm. In some embodiments, the mask has a thickness between about 10-100 μm. The mask material can be a photoresist and the second lip seal is typically in direct contact with the photoresist during the electroplating process. On the other hand, on the other hand, a method for electrodepositing metal onto a semiconductor substrate having a plurality of recessed features through the mask while preventing or reducing the deposition of metal on the lip seal of an electroplating device is provided. In some embodiments, the method includes: (a) electrodepositing metal into the recessed features through the mask of the semiconductor substrate in an electroplating tank while shielding a selected area near the lip seal so that metal is not allowed to be deposited above the plane of the mask and contact the lip seal. In one embodiment, the selected area is shielded by a shield attached (e.g., releasably attached) to the lipseal, wherein the distance from the shield to the substrate is less than about 1 mm. In some embodiments, the selected area has a width of less than about 1 mm.

[0014] On the other hand, a method is provided, wherein the method includes: (a) using a flexible lip seal to electro-deposit metal into the recessed features of the through-mask of the semiconductor substrate in an electroplating bath, wherein the flexible lip seal is configured in a first position so that the metal is not electro-deposited in a selected area shielded by the seal in the first position, wherein the selected area is located at the periphery of the substrate; and (b) after (a), configuring the flexible lip seal to a second position to remove the shielding of the selected area, and while the lip seal is in the second position, electro-depositing the metal into the recessed features of the through-mask, wherein the electro-deposition in the selected area does not result in electro-deposition above the plane of the mask and does not contact the lip seal, while the electro-deposition at other locations on the semiconductor substrate results in electro-deposition above the plane of the mask. In some embodiments, the flexible lip seal changes from the first configuration to the second configuration using torque (including torque driven by a cup geometry). In some embodiments, the flexible lip seal changes from the first configuration to the second configuration using compression.

[0015] In some embodiments, the provided method further comprises the steps of: applying a photoresist to the semiconductor substrate; exposing the photoresist to light; patterning the photoresist and transferring the pattern to the semiconductor substrate; and selectively removing the photoresist from the semiconductor substrate.

[0016] On the other hand, a system for electroplating a metal onto a semiconductor substrate is provided, wherein the system comprises: (a) a first electroplating device configured to electrodeposit a first metal onto the semiconductor substrate, the first electroplating device comprising a substrate holder having a first lip seal; and (b) a second electroplating device configured to electrodeposit a second metal onto the semiconductor substrate, the second electroplating device comprising a substrate holder having a second lip seal, wherein the second lip seal has an inner diameter larger than that of the first lip seal. In some embodiments, the difference between the inner radius of the second lip seal and the inner radius of the first lip seal is less than about 1 mm. In some embodiments, the difference between the inner radius of the second lip seal and the inner radius of the first lip seal is between about 0.05-1 mm, for example, about 0.25 mm. In some embodiments, the first lip seal and the second lip seal comprise an elastomeric material. In one embodiment, the first metal and the second metal are different, and wherein the first electroplating device comprises a copper anode and the second electroplating device comprises a tin anode. In another embodiment, the first metal and the second metal are both a combination of tin and silver, and the first electroplating device and the second electroplating device both include a tin anode. In some embodiments, the system also includes a mechanism configured to transfer the semiconductor substrate from the first electroplating device to the second electroplating device. In some embodiments, at least one of the first electroplating device and the second electroplating device is configured to electrodeposit a combination of tin and silver, and includes a membrane separating an anode chamber and a cathode chamber, wherein the membrane substantially prevents silver ions from passing through the membrane. For example, in an implementation, the first electroplating device is configured to electrodeposit copper, and the second device is configured to electrodeposit a combination of tin and silver.

[0017] In some embodiments, the system also includes a controller having program instructions for causing: (i) electroplating a first metal in the first electroplating device to partially fill recessed features through the mask; (ii) transferring the semiconductor substrate to the second electroplating device; and (iii) electroplating a second metal on the first metal in the second electroplating device, such that the second lip seal does not contact the electrodeposited second metal during deposition and such that at least some of the recessed features through the mask are filled above the plane of the mask.

[0018] In another aspect, an electroplating apparatus for depositing a metal onto a semiconductor substrate is provided, wherein the apparatus comprises: (a) an electroplating vessel configured to contain an electrolyte and an anode; (b) a substrate holder configured to hold the semiconductor substrate and to cathodically bias the semiconductor substrate during electroplating, wherein the substrate holder comprises a lip seal having an attached shield extending inwardly from the inner surface of the lip seal. In some embodiments, the shield has a width of less than about 1 mm. In some embodiments, the shield is positioned such that a distance from the shield to the semiconductor substrate during electroplating is less than about 1 mm.

[0019] In another aspect, an electroplating apparatus for depositing metal onto a semiconductor substrate is provided, wherein the apparatus comprises: (a) a plating container configured to contain an electrolyte and an anode; and (b) a substrate holder configured to hold and cathodically bias the semiconductor substrate during electroplating, wherein the electroplating apparatus further comprises an annular shield having a width of less than about 1 mm positioned proximate a lip seal of the substrate holder.

[0020] In another aspect, an electroplating apparatus for depositing a metal onto a semiconductor substrate is provided, wherein the apparatus comprises: (a) a plating container configured to contain an electrolyte and an anode; and (b) a substrate holder configured to hold and cathodically bias the semiconductor substrate during electroplating, wherein the substrate holder comprises a flexible lip seal configured to change shape between a first position and a second position, wherein the first position and the second position shield the surface of the semiconductor substrate differently. In some embodiments, the flexible lip seal is configured to change shape between the first position and the second position using torque. In some embodiments, the flexible lip seal is configured to change shape between the first position and the second position using compression.

[0021] Any of the apparatus provided herein may include a controller having program instructions configured to cause any of the steps of the methods provided herein.

[0022] In another aspect, a non-transitory computer machine readable medium is provided, wherein the non-transitory computer machine readable medium includes code configured to cause the steps of any method provided herein.

[0023] These and other aspects of implementations of the subject matter described in this specification are set forth in the drawings and the description that follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of a portion of a plating cell showing the ion current flowing to the lip seal.

[0025] Figure 2A A schematic cross-sectional view of a portion of a semiconductor substrate in a substrate holder is provided, showing direct contact of a lip seal with the conductive material of the substrate.

[0026] Figure 2B A schematic cross-sectional view of a portion of a semiconductor substrate in a substrate holder is provided, illustrating the location of a lip seal without direct contact with the conductive material of the substrate.

[0027] Figure 3A A schematic cross-sectional view of a portion of a semiconductor substrate having a through-resist recessed feature showing a lip seal in contact with a raised metal is provided.

[0028] Figure 3B A schematic cross-sectional view of a portion of a semiconductor substrate having a through-resist recessed feature showing a lipseal without contact with raised metal according to embodiments provided herein is provided.

[0029] Figure 4 is a process flow diagram of an electrodeposition method according to embodiments provided herein.

[0030] Figure 5A-5B A schematic cross-sectional view of a portion of a semiconductor substrate having a through-resist recessed feature during an electroplating process is provided in accordance with embodiments provided herein.

[0031] Figure 6 A schematic cross-sectional view of a portion of a semiconductor substrate having a through-resist recessed feature that is electroplated using a lipseal with an attached shield is provided according to embodiments provided herein.

[0032] Figures 7A-7C A schematic cross-sectional view of a portion of a modifiable lipseal useful for electrodeposition is shown according to embodiments provided herein.

[0033] Figures 8A-8B Schematic cross-sectional views of different modifiable lipseals useful for electrodeposition are shown according to embodiments provided herein.

[0034] Fig. 9 is a simplified schematic cross-sectional illustration of a plating cell that may be used for electroplating according to embodiments provided herein.

[0035] Fig.10 is a schematic top view of a tool that can be used for electroplating according to embodiments provided herein. DETAILED DESCRIPTION

[0036] One of the problems encountered during electrodeposition of SnAg (a combination of tin and silver) metal in through-mask (e.g., through-resist) features is the unintentional formation of metal deposits on the lipseal. The formation mechanism of these deposits has not been fully understood before.

[0037] Provided herein are methods and apparatus for preventing or reducing metal deposition on lip seals. The methods provided have increased lip seal life by more than eight times. The methods and apparatus are particularly useful for electroplating on semiconductor substrates with recessed features that penetrate the mask (e.g., in WLP processing), but are not limited to these applications. The method can be used to minimize lip seal deposits during electroplating of multiple metals, but will be described primarily with reference to simultaneous electroplating of tin-silver (SnAg) on ​​substrates with through-mask features. The term "metal" used in the claims refers to one or more metals, and "electrodeposition of metal" is not limited to the electrodeposition of a single metal. For example, the metal may be a combination of two metals, one of which is more inert (having a higher electrode potential) than the other. For example, the "metal" may be a combination of tin and silver. In some embodiments, the method is used to electroplating tin (Sn) as a single metal. In other embodiments, the method is used to simultaneously electrodeposit tin (Sn) and another metal.

[0038] The term "semiconductor substrate" as used herein refers to a substrate at any stage of semiconductor device manufacturing, containing semiconductor material at any position in its structure. It should be understood that the semiconductor material in the semiconductor substrate does not need to be exposed. A semiconductor wafer having a plurality of other material (e.g., dielectric) layers covering the semiconductor material is an example of a semiconductor substrate. The following detailed description assumes that the disclosed embodiments are implemented on a semiconductor wafer, for example, on a 200mm, 300mm, or 450mm semiconductor wafer. However, the disclosed embodiments are not limited thereto. The workpiece can have various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that can utilize the disclosed embodiments include various articles, such as printed circuit boards, etc.

[0039] Unless otherwise indicated, the term "about" when used in reference to a numerical value includes a range of ±10% from the recited numerical value.

[0040] Metal deposition on the elastomeric seal (hereinafter referred to as lip seal) of the electrolytically processed wafer holding assembly is the main cause of wafer rejection in the SnAg electrodeposition process of wafer-level solder bumps. It was found that although the mechanism of lip seal plate-out involves an electroless and electrolytic components, the electrolytic component is the primary factor causing the plate-out, and the unwanted deposition of metal on the lip seal can be greatly reduced by preventing the lip seal from contacting the cathode biased conductive material on the semiconductor substrate. It was determined by calculation that electrolytic plating is more than 1,000 times faster than electroless plating on the lip seal, and that during plating on a wafer by the electroless plating mechanism, only a few angstroms of metal are typically deposited on the lip seal, while electrolytic plating on the lip seal can grow several microns of metal during each wafer processing process.

[0041] With repeated exposure to SnAg chemistry (tin and silver ions in an electrolyte), the lip seal and other hardware develop an atomic coating of metal atoms due to the self-reactive nature of the plating bath components (as opposed to, for example, a process driven by externally applied energy, such as an electrolytic process). This self-reactive process is referred to as the electroless portion of the lip seal plating-out mechanism. Contact between the surface-bound metal atoms on the lip seal and the cathodically biased metal layer on the substrate results in electroplating on the lip seal (referred to as the electrolytic portion of the mechanism). The metal on the lip seal (now also under cathodic bias) steals ionic current from the wafer substrate, resulting in incomplete solder bump deposition in the patterned features.

[0042] It is extremely difficult to prevent reactions in solution that cause metal atoms to bind to the surface of the lip seal (sensitization and activation in the electroless plating mechanism portion). This electroless plating portion is particularly suitable for tin-containing electrolytes due to the strong adsorption of tin to the elastic material of the lip seal. However, wafer scrapping can be avoided by ensuring that this reactive surface (formed after electroless deposition) does not contact the cathode biasing conductive layer on the wafer to diffuse the electrolytic metal deposition on the lip seal. If there is no contact between the lip seal and the cathode biasing metal on the substrate, an "open circuit" condition will be generated, so that the isolated metal atoms on the surface of the lip seal will never come into contact with the circuit driving the electrolytic deposition, which will form a thick metal plating layer on the metal atom nucleation sites.

[0043] The schematic diagram of electrical connections in the electroplating system is as follows Figure 1, which illustrates a lip seal 101 on a cathode biased conductive layer of a wafer substrate 103 in a container containing a positive biased anode 105 and an electrolyte 107, wherein both the lip seal 101 and the wafer substrate 104 are in contact with the electrolyte 107 containing metal ions. The ion current in the electrolyte 107 is represented by the arrows. An important parameter in this system is the resistance Rc between the lip seal 101 and the conductive layer on the wafer substrate. If Rc is small, such as if there is direct contact between the lip seal 101 and the cathode biased material of the substrate 103, the lip seal 101 will act as a secondary cathode and divert the ion current, resulting in a large amount of plating on the lip seal 101. If Rc is large, such as if the lip seal 101 is placed on a non-conductive mask material without contacting the cathode biased metal layer on the substrate 103, the ion current flowing to the lip seal 101 will be minimized. Other methods of reducing the ion current flowing to the lip seal include active shielding.

[0044] Therefore, in one embodiment, a method for electro-depositing a metal onto a semiconductor substrate while preventing or reducing metal deposition on a lip seal of an electroplating apparatus is provided. The method comprises: (a) providing a semiconductor substrate (e.g., a wafer having a plurality of recessed through-resist features) into a substrate holder of an electroplating apparatus, wherein the substrate holder comprises a lip seal at a peripheral portion of the substrate, wherein the lip seal is positioned such that at least a portion of the lip seal contacts an electrolyte during electroplating; (b) electroplating a metal onto the semiconductor substrate while preventing or reducing ionic current flowing to the lip seal.

[0045] The experiments demonstrated the importance of preventing contact between the lip seal and the cathode bias metal layer on the substrate. Figure 2A A cross-sectional view of the substrate periphery is schematically shown, which shows the contact between the lip seal 201 and the cathode biasing metal layer 205. The non-conductive material 203 (in some embodiments, photoresist) located on the cathode biasing metal layer 205 is offset from the edge of the wafer. The conductive area E not covered by the non-conductive material 203 is called a forbidden area. Figure 2B Another substrate is shown where the exclusion zone is smaller and the lip seal is not in direct contact with the conductive cathode bias metal layer 205 but is in direct contact with the non-conductive layer 203. In one specific example, Figure 2A The width of the exclusion zone E (starting from the edge of the wafer substrate) in the configuration shown is 3 mm, while Figure 2B The width of the exclusion zone E in the configuration shown is 0.75 mm. Figure 2A In the configuration shown, lip seal plating was detected after plating on 12 wafers. Figure 2BIn the configuration shown (no direct contact between the lip seal and the metal layer) no lip seal plating was detected after plating on the 384 wafer.

[0046] One of the configurations that should be avoided to prevent lip seal plateout is the contact of the lip seal with the metal layer on the substrate within the photoresist keep-out zone at the edge of the wafer. However, even if the diameter of the lip seal is chosen so that it contacts the non-conductive photoresist layer and not the metal at the very edge of the substrate, it is still possible to plate on the lip seal if the lip seal contacts the metal during the electroplating process. This occurs when the amount of electrodeposited metal is above the plane of the photoresist (also called "bumpout").

[0047] Figure 3A An example of a mushroom-shaped "bulge" that results in contact between the deposited metal and the lipseal is shown. A schematic cross-sectional view of the peripheral portion of the substrate / lipseal assembly is shown. Even though the lipseal layer 301 is initially located on the photoresist 303 without contacting the metal layer 305, during the deposition process, metal 307 is deposited so that the feature protrudes and the electrodeposited metal (which is cathodically biased during the deposition process) contacts the lipseal 301.

[0048] To prevent the protruding metal from contacting the lip seal, a selected area on the wafer substrate adjacent to the lip seal is treated to prevent protrusion in the selected area without preventing protrusion elsewhere on the wafer substrate. For example, the selected area can be shielded from electrodeposition during electroplating or in a previous step. Shielding can reduce or completely prevent electrodeposition in the selected area.

[0049] According to the embodiments provided herein, a schematic cross-sectional view of a peripheral portion of a substrate after electrodeposition is shown in Figure 3B In this embodiment, the lip seal 301 is directly above and in contact with the photoresist 303 without contacting the underlying metal layer 305, but with Figure 3A (Comparative example) The difference is that in Figure 3B In an embodiment of the present invention, the electrodeposited metal 309 is not allowed to protrude in the features adjacent to the lip seal 301 in the recessed features, while the electrodeposited metal 307 elsewhere on the wafer protrudes. The "selected area" adjacent to the lip seal that is treated (e.g., shielded) to prevent protrusion is typically an annular area with a width W. The width W should preferably be small, such as less than about 2 mm, more preferably less than about 1 mm, because features that are partially filled in the selected area are generally not used, and even the small width of the selected area can effectively prevent contact between the lip seal and the cathode bias metal. In some embodiments, the width of the selected area is between about 0.05-1 mm, such as between about 0.1-1 mm, such as about 0.25 mm.

[0050] In one embodiment, the selected area is treated to prevent protrusion by shielding the selected area in a previous electroplating operation. Shielding refers to blocking or reducing ion current by a dedicated shield or by a component with other functions of the electroplating device (e.g., by a lip seal). In some embodiments, the selected area is shielded so that all electrodeposition in the selected area is blocked in a previous electroplating operation. In some embodiments, shielding is used in a single-step deposition (e.g., using a dedicated shield). In other embodiments, shielding is used in one or both steps of a two-step deposition.

[0051] In one embodiment, a method for electrodepositing metal on a semiconductor substrate is provided, wherein the method includes at least two steps. The first step involves electrodepositing a first metal (e.g., copper) into a recessed through-mask feature of a semiconductor substrate in a first electroplating tank using a first lip seal, such that the metal is not electrodeposited in a selected area shielded by the first lip seal. The subsequent step involves electrodepositing a second metal (e.g., SnAg) into the recessed through-mask feature in a second electroplating tank using a second lip seal having an inner diameter greater than the first lip seal and positioned near the selected area, wherein the electrodeposition in the selected area does not result in electrodeposition (protrusion) above the mask plane and in contact with the second lip seal, while electrodeposition elsewhere on the semiconductor substrate results in electrodeposition (protrusion) above the mask plane. This Figure 4 , which shows a process flow chart for electrodepositing metal into a recessed feature that penetrates a mask while preventing or reducing electrodeposition on a lip seal. In step 401, a semiconductor substrate having a recessed feature that penetrates a mask is provided to an electroplating device. Next, in step 403, a first metal is electrodeposited into the recessed feature without completely filling the recessed feature using a first lip seal having a first inner diameter. After the first metal has been electrodeposited, in step 405, a second metal is electrodeposited into the recessed feature using a second lip seal, wherein the inner diameter of the second lip seal is greater than that of the first lip seal. In some embodiments, the first metal and the second metal are different metals (e.g., the first metal is copper and the second metal is a combination of tin and silver). In other embodiments, the first metal and the second metal are the same (e.g., the first metal and the second metal are both a combination of tin and silver).

[0052] Figure 5AAn example of a substrate obtained after a first electroplating step is shown. In the embodiment depicted in the first step, copper is electrodeposited into a recessed through-resist feature without completely filling the recessed feature in a copper electroplating bath using a lip seal 500. The lip seal 500 is located on the photoresist 503 without contacting the underlying copper layer 505 and serves as a shield to block ion current from flowing to a selected area. Copper 506 deposited in the recessed feature is shown. Next, the wafer substrate is transferred to a new electroplating bath configured to electroplate a SnAg cap on the copper in the feature. In the new electroplating bath, a lip seal 501 is used having an inner diameter larger than that of the lip seal 500. Due to this difference in diameter before SnAg is plated, the lip seal 501 is located near an unfilled recessed feature that forms a selected area with a width W. The width W of the selected area is equal to the difference between the inner radius of the second lip seal and the inner radius of the first lip seal. The numerical characteristics of the width of the selected area have been discussed. Because the recessed features adjacent to the lip seal 501 in the selected area are not filled at the start of the SnAg plating, while the other recessed features are partially filled with copper, the electroplating can be performed so that after the electroplating is completed, the recessed features outside the selected area have SnAg bumps 511 that are above the level of the photoresist 503, while the recessed features in the selected area have deposited SnAg 513, which remains below the level of the photoresist and has no risk of contacting the lip seal 301. The substrate obtained after the electrodeposition is as shown Figure 3B shown.

[0053] This method can be used to deposit a copper pillar with a SnAg cap. In the case of a multilayer stack (such as a copper pillar), different diameter lip seals are selected so that the bumps immediately adjacent to the lip seal will never protrude. This is achieved by selecting a smaller diameter lip seal for the Cu layer and a larger diameter lip seal for the SnAg layer. For example, a copper pillar can be composed of 20μm Cu and a 20μm SnAg cap. In this case, if the thickness of the photoresist is about 40μm or less, the SnAg cap may be plated out of the photoresist and in contact with the lip seal. However, if the diameter of the lip seal used to plate the copper is slightly smaller than the diameter of the lip seal used to plate the tin-silver (for example, the radius difference between the lip seals is 0.05–1 mm), then copper will not be plated directly adjacent to the lip seal. Therefore, the total thickness near the lip seal is only 20μm SnAg, and the metal will remain deep in the photoresist, so the lip seal will never contact the cathode. In this case, there is no copper plated next to the lip seal used in the tin-silver plating, so the SnAg layer will not protrude.

[0054] In some embodiments, additional electrodeposition steps may be added to the sequence. In one embodiment, a thin nickel layer is electroplated between the copper deposition step and the SnAg deposition step in a third electroplating tank configured for nickel deposition.

[0055] Note that although in the depicted example, the metal deposited in the first step is copper and the metal deposited in the second step is SnAg, the first metal and the second metal do not necessarily have to be different. For example, in some embodiments, the first metal and the second metal are both SnAg. The first portion of the SnAg is deposited using a lip seal that closes the selected area (without completely filling the feature), and then the substrate is transferred to another groove, which has a lip seal of a larger diameter, thereby opening the selected area with unfilled features. The remaining SnAg is then deposited so that the features outside the selected area can protrude. In the case of a single layer of SnAg deposition (such as a C4 bump), protrusion typically occurs in a single step. This method can be applied to C4 bumps, but the SnAg plating will be divided into two steps on two different electroplating devices. For example, the first step will plate 50% of the SnAg layer thickness using a lip seal of a smaller diameter, and then the second step will plate the remaining SnAg using a lip seal of a wider diameter.

[0056] In another aspect, a system for electroplating a metal onto a semiconductor substrate is provided, wherein the system comprises: (a) a first electroplating apparatus configured to electro-deposit a first metal onto the semiconductor substrate, the first electroplating apparatus having a substrate holder having a first lip seal; and (b) a second electroplating apparatus configured to electro-deposit a second metal onto the semiconductor substrate, the second electroplating apparatus having a substrate holder having a second lip seal, wherein the second lip seal has a larger diameter than the first lip seal. In some embodiments, the difference between the inner radius of the second lip seal and the inner radius of the first lip seal is less than about 1 mm. The apparatus may also include: a robot transport mechanism for transporting a substrate from the first electroplating apparatus to the second electroplating apparatus and a controller including program instructions for executing the method described herein.

[0057] In some embodiments, selected areas are shielded by using a shield, and the selected areas are treated to prevent protrusions while the electroplating is performed simultaneously. In some embodiments, a method of electroplating a metal (e.g., SnAg) onto a semiconductor substrate having a plurality of recessed features through a mask while preventing or reducing metal deposition on a lip seal of an electroplating apparatus is provided, wherein the method comprises: electroplating the metal into the recessed through-mask features of the semiconductor substrate in an electroplating tank while shielding selected areas near the lip seal so that the metal is not allowed to be deposited above the plane of the mask and contact the lip seal. In some embodiments, the selected area is shielded by a shield that is releasably attached to the lip seal. This configuration is Figure 6 , which illustrates a schematic cross-sectional view of the peripheral portion of a substrate having a filled through-resist recessed feature using a lip seal 601 with an additional shield 602. The shield is not in contact with the photoresist 603 (the gap between the shield and the substrate is filled with electrolyte), but is still effective in reducing the ion current in the selected area (and thus reducing the thickness of the plating). The ion current is illustrated by the arrow pointing to the cathode bias metal layer 605. It illustrates that the recessed features outside the selected area are allowed to protrude, as shown by the SnAg filler 611, while the recessed feature area in the selected area is fully shielded to keep the SnAg deposit 613 well within the feature. The shield may have a relatively small width W1 of less than about 2 mm (e.g., about 0.05-1 mm) or less than about 1 mm. In some embodiments, the shield is located near the substrate (e.g., within about 1 mm from the substrate, reference distance H1). In some embodiments, the shield is made of a non-elastic, non-conductive material compatible with the electrolyte chemistry. In some embodiments, the shield (the portion that protrudes inwardly from the lip seal) has a generally annular shape. More generally, any suitable shielding method will reduce the ion current in a very short range near the lip seal, and in most cases the shield will not contact the photoresist to ensure that the shield itself does not come into contact with the cathode and risk subsequent plating out. As mentioned above, the most effective shield will be an extension of the lip seal to achieve the most abrupt local cooling (ion current reduction), but in general the shield can be located anywhere between the substrate and the anode.

[0058] In another embodiment, the selected area can be treated to prevent bulging by using a flexible lip seal that is configured to change its form from a first configuration to a second configuration so that the selected area is shielded differently in the different configurations. The advantage of using such a modifiable lip seal is that electrodeposition in the selected area can be blocked and then the selected area can be opened for plating without changing the plating tank.

[0059] In one embodiment, the electrodeposition method includes: (a) electrodepositing metal into a recessed through-mask feature of a semiconductor substrate in a plating tank using a flexible lip seal, wherein the flexible lip seal is configured in a first position so that metal is not electrodeposited in a selected area shielded by the lip seal in the first position, wherein the selected area is located at the periphery of the substrate; and (b) configuring the flexible lip seal to a second position to remove the shielding of the selected area, and after (a), when the lip seal is in the second position, electrodepositing metal into the recessed through-mask feature, wherein the electrodeposition in the selected area does not result in electrodeposition above the plane of the mask and in contact with the lip seal, while the electrodeposition elsewhere on the semiconductor substrate results in electrodeposition above the plane of the mask.

[0060] In some embodiments, a torque is used to change the lipseal from a first configuration to a second configuration. In some embodiments, the torque is caused by the geometry of a cup that holds the substrate. Figures 7A-7C An example of such a lip seal is shown in FIG. Fig. 7A Configuration, Figure 7B Configuration and Figure 7C The torque on the cup 707 between the configurations changes the position of the lip seal-wafer contact 701. For example, when the lip seal 703 is located Fig. 7A 7B, the tin-silver plating can begin, with the point of contact 701 with the substrate 705 further inward. Next, before the feature is raised, the configuration of the lip seal 703 can be changed to the configuration shown in position 7B, so that the previously Fig. 7A The configuration shown in FIG. 1 is used to block selected areas that are opened for plating. Plating can then be performed so that features in the selected areas are not allowed to protrude, while features outside the selected areas protrude. Alternatively, plating can be performed in a manner that Figure 7C Start with the configuration shown, and then Fig. 7A or Figure 7B The configuration shown is complete. Different steps can have variations in the lip seal support hardware that drive different repulsions (shields) by twisting the same lip seal in different ways.

[0061] In some embodiments, compression is used to change the lipseal from the first configuration to the second configuration. Figures 8A-8B One example of such a lip seal is shown, where the size of the lip seal-wafer contact can be changed by using cup compression force or contact spring compression force. Fig. 8A A portion of the lip seal and substrate is shown, wherein the lip seal is in an uncompressed state and Figure 8BThe same portion of the lip seal and the substrate is shown, wherein the lip seal is in a compressed state. In some embodiments, when the lip seal is in Figure 8B When the lip seal 803 and the substrate 805 are in the position shown (compressed state), and before the features are protruded, the tin-silver plating can begin. In the compressed configuration, the innermost contact point 801 between the lip seal 803 and the substrate 805 is smaller than Fig. 8A The uncompressed state shown is closer to the center of the substrate. Figure 8B After the initial plating of the compression lip seal shown in the figure, the lip seal configuration can be changed to Fig. 8A The configuration shown in (uncompressed) will be Figure 8B The configuration shown in FIG. 1 opens the closed selected area for plating. Plating can then be performed so that features in the selected area are not allowed to protrude, while features outside the selected area protrude.

[0062] The methods and apparatus provided herein can reduce lip seal plating out and can be used alone or in combination with other methods that can reduce the effects of plating out. In some embodiments, the lip seal is made of an elastomeric non-conductive material, which in some embodiments can be hydrophobic or coated with a hydrophobic coating (e.g., a perfluorinated polymer). Using a hydrophobic surface for the lip seal material can reduce initial adsorption and chemical deposition of metal on the lip seal. In addition, in some embodiments, the lip seal can be used without periodic cleaning, while in other embodiments, cleaning of the lip seal can be performed periodically (e.g., after processing a defined number of wafers).

[0063] Device

[0064] Deposition method as described herein can be carried out in multiple electroplating devices. Suitable device comprises a plating chamber and a substrate holder configured to hold electrolyte and anode, and the substrate holder has contacts for cathode bias substrate, a cup and a lip seal for holding substrate. Deposition can be carried out in a face-up or face-down direction. Some plating tools can also be operated vertically. The example of suitable device is the SABER 3D tool available from Lam Research Corp. in Fremont, California. In some embodiments, the electroplating tool comprises a plurality of plating tanks (which are used for electro-depositing the same or different metals) and a manipulator tool for transferring substrates between each electroplating tank.

[0065] In some embodiments, electroplating of a first metal (e.g., copper) is performed in a first electroplating apparatus having a first plating chamber and a first substrate holder having a first lip seal, and electroplating of a second metal is performed in a second electroplating apparatus having a second plating chamber and a second substrate holder having a second lip seal (e.g., a lip seal having an inner diameter greater than the first lip seal).

[0066] Fig. 9 , a schematic cross-sectional view of an apparatus that can be used to electrodeposit a first or second metal in a face-down direction is shown. The apparatus includes an electroplating chamber 901 configured to contain an electrolyte 903 and an anode 905. A substrate holder 907 is configured to hold a semiconductor substrate 909 in a face-down direction and rotate the semiconductor substrate 909 during electroplating. The substrate holder 907 also includes an electrical contact that is configured to bias the substrate cathodically (negatively) during electroplating. In the illustrated embodiment, the apparatus also includes an ion-resistance ion-permeability element 911 proximate to the semiconductor substrate 909 (e.g., within a range of about 10 mm from the substrate). The ion-resistance ion-permeability element 911 is typically a plate made of a non-conductive material having multiple through-channels or a 3D porous network that allow electrolyte to flow. The ion-resistance ion-permeability element 911 is typically used to improve the uniformity of plating on the semiconductor substrate 909. The plating chamber 901 includes an opening 913 for introducing an electrolyte. In the depicted embodiment, the electrolyte can enter at the bottom of the plating chamber and then flow through the channels of the ion-resistive ion-permeable element 911 toward the semiconductor substrate 909 as indicated by arrows 915. In other embodiments, in addition to or in lieu of the electrolyte flow being substantially perpendicular to the working surface of the semiconductor substrate 909, the electrolyte can be injected laterally in a direction substantially parallel to the working surface of the semiconductor substrate 909.

[0067] In some embodiments, the apparatus further comprises an ion permeable membrane located between the anode and cathode bias substrates, which separates the plating chamber into an anolyte chamber and a cathode electrolyte chamber, wherein the electrolytes in the anolyte chamber and the cathode electrolyte chamber may have different compositions. For example, in the electrodeposition process of tin-silver, the cathode electrolyte includes tin and silver ions, while the anolyte may include only tin ions.

[0068] In some embodiments, the apparatus further comprises a controller having program instructions for causing performance of any of the method steps described herein.

[0069] Fig.10 An integrated apparatus configured for electrodeposition of a variety of metals is shown. In this embodiment, apparatus 1000 has a set of plating tanks 1007 in a pair or multiple "dual" configuration, each of which contains a bath containing an electrolyte. In addition to the electroplating itself, apparatus 1000 can also perform various other electroplating or electroplating related processes and sub-steps, such as spin rinse, spin dry, metal and silicon wet etching, electroless deposition, pre-wetting and pre-chemical treatment, reduction, annealing, photoresist stripping, and surface pre-activation. Apparatus 1000 is Fig.10Schematically viewed from top to bottom, only one layer or "floor" is shown in the figure, but it is easy for a person skilled in the art to understand that such a device, for example, Lam Research Sabre TM A 3D tool can "stack" two or more layers on top of each other, and each layer can have the same or different types of processing stations. In some embodiments, electroplating stations for different metals are arranged on different layers of the tool. In other embodiments, a single layer can include stations for electroplating a first metal and a second metal.

[0070] Reference again Fig.10 , the substrate 1006 to be plated is typically fed to the device 1000 via a front-end loading FOUP (front-end loading unified pod) 1001, and in this example, is brought from the FOUP to the main substrate processing area of ​​the device 1000 by a front-end robot 1002, which can retrieve and move the substrate 1006 driven from one station to another accessible station in multiple dimensions by a spindle 1003, in this example two front-end accessible stations 1004 and two front-end accessible stations 1008 are shown. The front-end accessible stations 1004 and 1008 may include, for example, a pre-treatment station and a spin rinse dry (SRD) station. The lateral movement of the front-end robot 1002 from one side to the other is accomplished using a robot track 1002a. Each substrate 1006 can be held by a cup / cone assembly (not shown) driven by a spindle connected to a motor (not shown), and the motor can be attached to a mounting bracket 1009. Also shown in this example are four "dual" plating tanks 1007, for a total of eight plating tanks 1007. The plating tanks 1007 can be used to plate a first metal and a second metal. After the first metal has been plated in one plating tank 1007, the substrate is transferred to a plating tank that is configured to plate a second metal on the same layer of the device 1000 or on a different layer of the device 1000. A system controller (not shown) can be coupled to the device 1000 to control some or all properties of the device 1000. The system controller can be programmed or otherwise configured to execute instructions according to the processes previously described herein.

[0071] The system controller will typically include one or more memory devices and one or more processors configured to execute instructions so that the apparatus will perform methods according to the invention.A machine-readable medium containing instructions for controlling processing operations according to the invention may be coupled to the system controller.

[0072] In some implementations, the controller is part of a system, which can be part of the above-described embodiments. Such a system can include a semiconductor processing device, which includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems can be integrated with electronic devices to control the operation of these systems before, during, or after the processing of semiconductor wafers or substrates. The electronic device can be referred to as a "controller" that can control various components or sub-parts of one or more systems. Depending on the processing requirements and / or the type of system, the controller can be programmed to control any of the processes disclosed herein, including controlling the delivery of electrolytes, temperature settings (e.g., heating and / or cooling), voltage delivered to the cathode, wafer entry and exit tools and other transfer tools, and / or the delivery of load locks connected to or interfaced with a specific system.

[0073] Broadly speaking, a controller can be defined as an electronic device with various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. The integrated circuit may include a chip storing program instructions in the form of firmware, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions delivered to a controller or system in the form of various different settings (or program files), and different settings (or program files) define operating parameters for performing specific processing on or for a semiconductor wafer or to a system. In some embodiments, the operating parameters may be a part of a recipe for one or more processing steps in the manufacturing process of one or more (kinds) layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or bare chips defined by a process engineer to complete a wafer.

[0074] In some embodiments, the controller can be a part of or coupled to a computer that is integrated with the system, coupled, or connected to the system or a combination thereof through a network. For example, the controller can be in the "cloud" or all or part of a wafer factory (fab) host system, which can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of the manufacturing operation, check the history of past manufacturing operations, check the trends or performance standards of multiple manufacturing operations, change the parameters of the current processing, set the processing steps to follow the current processing or start a new processing. In some examples, a remote computer (e.g., a server) can provide a processing recipe to the system through a network, which can include a local network or the Internet. The remote computer can include a user interface that allows input or programming of parameters and / or settings, which are then transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data, which specify the parameters of each processing step to be performed during one or more operations. It should be understood that these parameters can be for the type of processing to be performed and the type of tool, and the controller is configured to connect or control the tool type. Thus, as described above, the controller may be distributed, for example, by including one or more discrete controllers that are networked together and work toward a common goal (e.g., the processing and control described herein). Examples of distributed controllers for these purposes may be one or more integrated circuits within the room that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer) that combine to control the processing within the room.

[0075] Exemplary systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, chamfer edge etching chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing system that may be associated with or used in the preparation and / or manufacture of semiconductor wafers.

[0076] As described above, depending on one or more processing steps to be performed by the tool, the controller can communicate with one or more other tool circuits or modules, other tool components, combination tools, other tool interfaces, adjacent tools, adjacent tools, tools located throughout the factory, a host computer, another controller, or tools used in material handling to move containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing facility.

[0077] In some embodiments, the apparatus includes a controller having program instructions for causing performance of any of the method steps described herein.

[0078] In one aspect, a system for electroplating a metal onto a semiconductor substrate is provided, wherein the system comprises: (a) a first electroplating apparatus configured to electro-deposit a first metal onto the semiconductor substrate, the first electroplating apparatus comprising a substrate holder having a first lip seal; and (b) a second electroplating apparatus configured to electro-deposit a second metal onto the semiconductor substrate, the second electroplating apparatus comprising a substrate holder having a second lip seal, wherein the second lip seal has a larger diameter than the first lip seal. In some embodiments, the difference between the inner radius of the second lip seal and the inner radius of the first lip seal is less than about 1 mm. In some embodiments, the system also includes a controller having program instructions for causing: (i) electroplating a first metal in a first electroplating device to partially fill recessed features through the mask; (ii) transferring the semiconductor substrate to a second electroplating device; and (iii) electroplating a second metal on the first metal in the second electroplating device such that the second lip seal does not contact the electrodeposited second metal during deposition and such that at least some of the recessed through-mask features are filled above the plane of the mask.

[0079] The above-described apparatus / processes may be used in conjunction with photolithographic patterning tools or processes, for example, for preparing or manufacturing semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, but not necessarily, such tools / processes will be used or performed with common manufacturing facilities. Photolithographic patterning of films generally includes some or all of the following steps, each of which may be performed using a number of possible tools: (1) applying photoresist to a workpiece, i.e., a substrate, using a spin-coating or spray-coating tool; (2) curing the photoresist using a hot plate or oven or a UV curing tool; (3) exposing the photoresist to visible light or UV or EUV or X-ray light using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist and patterning the resist using a tool such as a wet bench; (5) transferring the resist pattern into an underlying film or workpiece using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

Claims

1. A method for electrodepositing metal onto a semiconductor substrate having a plurality of recessed features through a mask while preventing or reducing deposition of metal on a lip seal of an electroplating apparatus, the method comprising: (a) electrodepositing a first metal into the recessed features of the through-mask of the semiconductor substrate in a first electroplating bath using a first lip seal; as well as (b) After (a), electrodepositing a second metal into the recessed features of the through mask in a second electroplating tank using a second lip seal having an inner diameter greater than that of the first lip seal, wherein the semiconductor substrate includes selected areas that are shielded from exposure to the electrolyte by the first lip seal but not by the second lip seal, such that the first metal is not electrodeposited in the selected areas and such that the second metal is allowed to be electrodeposited in the selected areas.

2. The method according to claim 1, wherein: Electrodeposition of the second metal in the selected areas in (b) does not result in electrodeposition above the plane of the mask.

3. The method according to claim 1, wherein: Electrodepositing the second metal in the selected area in (b) does not result in the electrodeposited second metal contacting the second lipseal.

4. The method according to claim 1, wherein: (b) causing electrodeposition of the second metal above the plane of the mask outside of the selected areas.

5. The method according to claim 1, wherein: (b) causing electrodeposition of the second metal above the plane of the mask outside the selected areas and below the plane of the mask in the selected areas.

6. The method according to claim 1, wherein: The first metal is copper and the second metal is a combination of tin and silver.

7. The method according to claim 1, wherein: The first metal is a combination of tin and silver, and the second metal is a combination of tin and silver.

8. The method according to claim 1, wherein: The width of the selected area is between about 0.05-1 mm.

9. The method according to claim 1, wherein: The width of the selected area is about 0.25 mm.

10. The method according to claim 1, wherein: The mask is a photoresist, and the second lipseal is in direct contact with the photoresist during an electroplating process.

11. The method according to claim 1, wherein: The recessed features through the mask have a width between about 10-50 μm.

12. The method according to claim 1, wherein: The mask has a thickness between about 10-100 μm.

13. The method of claim 1, wherein the first and second lip seals are made of an elastomeric material, wherein a width of the selected area is equal to a difference between an inner radius of the second lip seal and an inner radius of the first lip seal, and wherein the selected area has an annular shape.

14. A system for electroplating a metal onto a semiconductor substrate, the system comprising: (a) a first electroplating apparatus configured to electrodeposit a first metal onto the semiconductor substrate, the first electroplating apparatus comprising a substrate holder having a first lip seal; as well as (b) a second electroplating apparatus configured to electrodeposit a second metal onto the semiconductor substrate, the second electroplating apparatus comprising a substrate holder having a second lip seal, wherein the second lip seal has a larger inner diameter than the first lip seal.

15. The system of claim 14, wherein: A difference between an inner radius of the second lip seal and an inner radius of the first lip seal is less than about 1 mm.

16. The system of claim 14, wherein: The difference between the inner radius of the second lip seal and the inner radius of the first lip seal is between about 0.05-1 mm.

17. The system of claim 14, wherein: The difference between the inner radius of the second lip seal and the inner radius of the first lip seal is about 0.25 mm.

18. The system of claim 14, wherein: The first lip seal and the second lip seal include an elastomeric material.

19. The system of claim 14, wherein the first metal and the second metal are different, and wherein the first electroplating device comprises a copper anode and the second electroplating device comprises a tin anode.

20. The system of claim 14, wherein the first metal and the second metal are both a combination of tin and silver, and wherein the first electroplating apparatus and the second electroplating apparatus both include a tin anode.

21. The system of claim 14, further comprising a mechanism configured to transfer the semiconductor substrate from the first electroplating apparatus to the second electroplating apparatus.

22. The system of claim 14, wherein at least one of the first electroplating apparatus and the second electroplating apparatus is configured for electrodepositing a combination of tin and silver and comprises a membrane separating an anode chamber and a cathode chamber, wherein the membrane substantially prevents silver ions from passing through the membrane.

23. The system of claim 22, wherein: The first electroplating apparatus is configured for electrodepositing copper, and the second electroplating apparatus is configured for electrodepositing a combination of tin and silver.

24. The system of claim 14, further comprising a controller comprising program instructions for causing: (i) electroplating a first metal in the first electroplating device to partially fill a recessed feature on the semiconductor substrate that penetrates the mask; (ii) transferring the semiconductor substrate to the second electroplating device; as well as (iii) electroplating a second metal on the first metal in the second electroplating apparatus such that the second lip seal does not contact the plated second metal during the electroplating process and such that at least some of the recessed features through the mask are filled above the plane of the mask.

25. A method of electrodepositing metal onto a semiconductor substrate having a plurality of recessed features through a mask while preventing or reducing deposition of metal on a lipseal of an electroplating apparatus, the method comprising: (a) electrodepositing metal into the recessed features of the through-mask of the semiconductor substrate in an electroplating bath using a flexible lip seal, wherein the flexible lip seal is configured in a first position so that the metal is not electrodeposited in selected areas shielded by the seal in the first position, wherein the selected areas are located at a periphery of the substrate; as well as (b) after (a), configuring the flexible lip seal to a second position to remove the shielding of the selected area, and while the lip seal is in the second position, electrodepositing the metal into the recessed features of the through mask, wherein the electrodeposition in the selected area does not result in electrodeposition above the plane of the mask and does not result in contact of the electrodeposited metal with the lip seal, while the electrodeposition at other locations on the semiconductor substrate results in electrodeposition above the plane of the mask.

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