Use of stacked anionic membranes to reduce copper ion transport

Abstract

Exemplary thief cartridges for an electroplating system may include a first body defining a thief electrode channel. The cartridges may include a second body defining a thief chamber. The cartridges may include at least one thief membrane disposed between and separating the thief electrode channel and the thief chamber. A collective thickness of the at least one thief membrane may be at least 35 mils. The cartridges may include a thief electrode disposed within the thief chamber.

Description

USE OF STACKED ANIONIC MEMBRANES TO REDUCE COPPER ION TRANSPORTCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit and priority of U. S. Patent Application No. 63 / 717,133, filed November 6, 2024, entitled “USE OF STACKED ANIONIC MEMBRANES TO REDUCE COPPER ION TRANSPORT”, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present technology relates to methods, components, and apparatuses for semiconductor manufacturing. More specifically, the present technology relates to electroplating components and other semiconductor processing equipment.BACKGROUND OF THE INVENTION

[0003] Microelectronic devices, such as semiconductor devices, are fabricated on and / or in wafers or workpieces. A typical wafer plating process involves depositing a metal seed layer onto the surface of the wafer via vapor deposition. A photoresist may be deposited and patterned to expose the seed layer. The wafer is then moved into the vessel of an electroplating processor where electric current is conducted through an electrolyte to the wafer, to apply a blanket layer or patterned layer of a metal or other conductive material onto the seed layer. Examples of conductive materials include permalloy, gold, silver, copper, cobalt, tin, nickel, and alloys of these metals. Subsequent processing steps form components, contacts and / or conductive lines on the wafer.

[0004] In many or most applications, it is important that the plated film or layer(s) of metal have a uniform thickness across the wafer or workpiece. Some electroplating processors use a current thief, which is an electrode having the same polarity as the wafer. ’The current thief operates by drawing current away from the edge of the wafer. This helps to keep the plating thickness at the edge of the wafer more uniform with the plating thickness over the rest of the wafer. The current thief may be a physical electrode close to the edge of the wafer.Alternatively, the current thief may be a virtual current thief where the physical electrode is remote from the wafer In this design, current from the remote physical electrode is conducted through electrolyte to positions near the wafer.

[0005] As part of this design, there may be a thiefolyte chemistry' that is in contact with the thief electrode and a catholyte chemistry that is near the wafer An anionic membrane may be positioned between the thiefolyte and catholyte to separate the different chemistries from one another while still enabling current to pass through both chemistries. The function of the anionic membrane is to reduce the transport of copper ions from the catholyte to the thiefolyte. However, during plating operations, there is some transport of positive copper ions through the anionic membrane and into the thiefolyte. The concentration of copper ions in the thiefolyte ultimately causes an undesirable buildup of copper on the thief electrodes that are disposed within thiefolyte.

[0006] Accordingly, engineering challenges remain in designing electroplating processors.BRIEF SUMMARY OF THE INVENTION

[0007] Exemplary thief cartridges for an electroplating system may include a first body defining a thief electrode channel. The cartridges may include a second body defining a thief chamber. The cartridges may include at least one thief membrane disposed between and separating the thief electrode channel and the thief chamber. A collective thickness of the at least one thief membrane may be at least 35 mils. The cartridges may include a thief electrode disposed within the thief chamber.

[0008] In some embodiments, the at least one thief membrane may include two membranes. The two membranes may be electrically coupled with one another. The two membranes may be in direct contact with one another. Each of the two membranes may include a thickness of between 15 mils and 35 mils. The collective thickness of the at least one thief membrane may be between 35 mils and 100 mils. The collective thickness of the at least one thief membrane may be between 40 mils and 80 mils. The cartridges may include an O-ring disposed on an exposed surface of the at least one thief membrane.

[0009] Some embodiments of the present technology may encompass electroplating systems. The systems may include a vessel assembly for holding an electrolyte. The vessel assembly may include an anode assembly having a plurality of anode chambers. The systems may include an upper cup disposed above the anode assembly. The upper cup may have aplurality of chambers corresponding to the plurality of anode chambers. The systems may include a vessel membrane between the plurality of anode chambers and the upper cup. The systems may include a weir thief electrode assembly disposed in the vessel assembly. The weir thief electrode assembly may include a plenum inside of a weir frame. The weir thief electrode assembly may have a plurality of virtual thief electrode segments. Each virtual thief electrode segment of the plurality of virtual thief electrode segments may include a thief cartridge. Each thief cartridge may include a first body defining a thief electrode channel. Each thief cartridge may include a second body defining a thief chamber. Each thief cartridge may include at least one thief membrane disposed between and separating the thief electrode channel and the thief chamber. A collective thickness of the at least one thief membrane may be at least 35 mils. Each thief cartridge may include a thief electrode disposed within the thief chamber.

[0010] In some embodiments, the systems may include a weir ring attached to the weir frame. The weir frame may define a plurality of spaced apart openings that extend through the weir frame into the plenum. The at least one thief membrane may include two membranes. The two membranes may be in direct contact with one another. Each of the two membranes may include a thickness of between 15 mils and 35 mils. Each thief electrode channel may be configured to receive a catholyte. Each thief chamber may be configured to receive a thiefolyte. The at least one thief membrane may be configured to separate the thiefolyte and the catholyte while permitting transfer of negative ions from the catholyte to the thiefolyte. Each thief electrode channel may be fluidly coupled with the upper cup.

[0011] Some embodiments of the present technology may encompass methods of assembling a thief cartridge for an electroplating system. The methods may include wetting a first thief membrane and a second thief membrane. The methods may include positioning the first thief membrane against an interface region of a body defining a thief chamber, with a bowed center of the first thief membrane facing away from the body. The methods may include positioning the second thief membrane against the first thief membrane, with a bowed center of the second thief membrane facing toward the body and the first thief membrane. The methods may include positioning an O-ring against an exposed surface of the second thief membrane. The methods may include coupling a body defining a thief electrode channel to the body defining the thief chamber.

[0012] In some embodiments, wetting the first thief membrane and the second thief membrane may include soaking each of the first thief membrane and the second thief membrane in a solution. The solution may include one or both of de-ionized water and sulfuric acid. Positioning the O-ring against the exposed surface of the second thief membrane may cause the first thief membrane and the second thief membrane to substantially flatten.

[0013] Such technology may provide numerous benefits over conventional systems and techniques. For example, embodiments of the present technology may slow down and / or otherwise limit transport of positive copper ions into the thiefolyte. By slowing the transport of positive copper ions, a buildup of copper on the thief electrode is slowed, which reduces the frequency of maintenance of the thief electrode and reduces system downtime. Thus, not only is maintenance frequency reduced, but system downtime is reduced, resulting in higher throughput efficiency. These and other embodiments, along with many of their advantages and features, are described in more detail in conjunction with the below description and attached figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A further understanding of the nature and advantages of the disclosed technology may be realized by reference to the remaining portions of the specification and the drawings.

[0015] FIG. 1 shows an exploded perspective view of an electroplating system according to some embodiments of the present technology.

[0016] FIG. 2 shows a perspective view of the vessel assembly of the electroplating system of FIG. 1.

[0017] FIG. 3 shows a perspective section view of the vessel assembly of the electroplating system shown in FIG. 2.

[0018] FIG. 4 shows an orthogonal section view of the vessel assembly of FIG. 2.

[0019] FIG. 5 shows a top perspective view of a segmented weir thief electrode assembly of the electroplating system of FIG. 1.

[0020] FIG. 6 shows a perspective section view of the segmented weir thief electrode assembly of the electroplating system of FIG. 1.

[0021] FIG. 7 shows a schematic cross-sectional side elevation view of a thief cartridge according to some embodiments of the present technology.

[0022] FIG. 8 shows operations of an exemplary method of assembling a thief cartridge according to some embodiments of the present technology.

[0023] Several of the figures are included as schematics. It is to be understood that the figures are for illustrative purposes and are not to be considered of scale unless specifically stated to be of scale. Additionally, as schematics, the figures are provided to aid comprehension and may not include all aspects or information compared to realistic representations and may include exaggerated material for illustrative purposes.

[0024] In the appended figures, similar components and / or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a letter that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the letter.DETAILED DESCRIPTION OF THE INVENTION

[0025] Some conventional electroplating systems use thief electrodes (e.g., a current thief) to facilitate the plating of substrates. The thief electrode is an electrode having the same polarity as the wafer that operates by drawing current away from the edge of the wafer. This helps to keep the plating thickness at the edge of the wafer more uniform with the plating thickness over the rest of the wafer. In some systems, the current thief may be a virtual current thief, where the physical electrode is remote from the wafer. In such designs, current from the remote physical electrode is conducted through electrolyte to positions near the wafer. For example, the thief electrode may be submerged in an electrolyte, which may be a thiefolyte solution. The thiefolyte may be separated from a catholyte solution by an anionic membrane. The anionic membrane may enable transport of negative ions between the catholyte (which is in contact with the wafer) and the thiefolyte. The anionic membrane is designed to block positive ions, such as copper ions, from being transported to the thiefolyte. However, in practice some positive ions are transported through the anionic membrane. Copper transported across the anionic membrane is then plated onto the thief electrodes.Copper build-up on the thief electrodes requires periodic maintenance for removal, which adversely affects tool uptime.

[0026] The present technology overcomes these challenges by incorporating additional and / or thicker anionic membranes that separate the catholyte and thiefolyte. The increased collective thickness of the anionic membrane(s) helps reduce copper ion transport into the thiefolyte chemistry and subsequently reduces the rate of copper plating onto the thief electrodes. In fact, testing has demonstrated that tripling the collective thickness of the anionic membrane(s) from 20 mils to 60 mils may reduce the rate of copper transfer by 2.6 times. The reduced copper plating onto the thief electrodes enables longer intervals between preventative maintenance on thief cartridges and lower risk of copper dendrites growing through membrane. Accordingly, the present technology may increase plating throughput during electroplating operations.

[0027] Although the remaining disclosure will routinely identify specific electroplating systems and processes utilizing the disclosed technology, it will be readily understood that the systems and methods are equally applicable to other plating chambers and systems, as well as processes as may occur in the described systems. Accordingly, the technology should not be considered to be so limited as for use with these specific plating processes or systems alone. The disclosure will discuss one possible system that may include electroplating components according to embodiments of the present technology before additional variations and adjustments to this system according to embodiments of the present technology are described.

[0028] FIG. 1 illustrates an exemplary electroplating system 20 for electroplating a substrate, such as a semiconductor substrate, according to embodiments of the present technology. The electroplating system 20 may have a head 30 that may be positioned above a vessel assembly 36. A single electroplating system 20 may be used as a standalone unit in some embodiments. Alternatively, multiple electroplating systems 20 may be provided in arrays within an enclosure, with wafers or workpieces loaded and unloaded into and out of the electroplating systems 20 by one or more robots. The head 30 may be supported on a lift or a lift / rotate unit 34, which may lift and / or invert the head 30 to load and unload a wafer into a rotor 32 disposed within the head. The lift or lift / rotate unit 34 may lower the head 30 into engagement with a vessel assembly 36 for processing. The rotor 32 may have a contact ring which makes electrical contact with a wafer held in the rotor 32 during processing.Electrical control and power cables 40 linked to the lift / rotate unit 34 and / or to internal head components may extend between components of the electroplating system 20 to facility connections, or to connections within multi-processor automated system. A rinse assembly 28 having tiered drain rings may be provided above a vessel frame 50.

[0029] As shown in FIGs. 2 and 3, a segmented weir thief electrode assembly 52 may be located near the top of the vessel frame 50. A paddle 54 may be provided in the vessel assembly 36 below the level of the segmented weir thief electrode assembly 52. The paddle 54 may be an insert having parallel spaced apart blades extending upward from a surface of the paddle 54. The paddle 54 may be removably attached to a paddle frame 55 disposed within the vessel frame 50. The connection between the paddle 54 and the paddle frame 55 may allow the paddle 54 to be more easily removed and replaced. A paddle actuator (not shown) on a vessel mounting plate 38 may move the paddle 54, such as by linearly reciprocating and / or otherwise translating the paddle 54.

[0030] Turning to FIGs. 3 and 4, the vessel assembly 36 may include an anode assembly 64 having a lower cup 68. The lower cup 68 may include a first ring 70, a second ring 72, and / or a third ring 74 that may each extend upward from a base of the lower cup 68. The rings may divide the anode assembly 64 into a first or inner anode chamber 76, a second or middle anode chamber 78, and / or a third or outer anode chamber 80. First, second, and / or third anode electrodes 82, 84, and 86 may be positioned respectively at the bottom of the first, second, and / or third anode chambers. Although various forms of anode electrodes may be used, in the example shown, each of the first, second, and third anodes may be a flat metal ring. Each of the first, second and third anode electrodes may be connected to a separately controllable power supply and / or to a separate channel of a multi-channel power supply 98 (shown schematically in FIG. 3) to allow the electric current supplied by each anode to be independently controlled.

[0031] The lower cup 68 of the anode assembly 64 may be formed from and / or otherwise include a dielectric material. The lower cup 68 may be supported on a rigid base plate 66, which may be formed from a metallic material in some embodiments. Multiple latches 90 on the lower cup 68 and / or on the base plate 66 may engage latch rings 92 on the vessel frame 50 or on the vessel mounting plate 38, to allow quick installation and removal of the anode assembly 64.

[0032] An upper cup 60, which may also be made of a dielectric material, may be positioned on top of the lower cup 68. The upper cup 60 may have rings and chambers corresponding to and / or aligned with the rings and chambers of the lower cup 68. A vessel membrane 62 may be disposed between the lower cup 68 and the upper cup 60 and may pass electric current while preventing movement of electrolyte or particles. The upper cup 60 and the vessel membrane 62 may form a vessel or bowl for holding an electrolyte, specifically catholyte. The lower cup 68 may hold a second electrolyte, specifically anolyte, separated from the catholyte by the vessel membrane 62.

[0033] During processing, the paddle actuator may move the paddle 54 to agitate the catholyte contained in the upper cup 60. The paddle 54 may move back and forth within a paddle travel dimension, with an oscillating motion in some embodiments. For some applications the paddle may use other movements, such as start / stop, stagger, etc. The tiered drain rings in the rinse assembly 28, if present, may be connected to drain and vacuum facilities via one or more drain fittings 42 and aspiration fittings 44 as shown in FIG. 2. The vessel assembly 36 may be mounted on the vessel mounting plate 38 to support the vessel assembly 36 and other components and / or for alignment and positioning of the vessel assembly 36.

[0034] Referring back to FIGs. 3 and 4, the vessel assembly 36 may include the anode assembly 64, the upper cup 60, and / or the segmented weir thief electrode assembly 52, which may be attached or supported directly or indirectly by the vessel frame 50. A weir overflow channel 58 formed in the vessel frame 50 may connect to one or more recirculation ports 57 which may be connected to catholyte recirculation lines which may provide a continuous flow of catholyte through the upper cup 60 during processing and / or idle states.

[0035] Turning to FIGs. 5 and 6, the segmented weir thief electrode assembly 52 may include a weir frame 100 attached to a flat weir ring 104, both made of a dielectric material. In the example shown the weir frame 100 is a circular ring having radially spaced apart lugs 102 for attaching the segmented weir thief electrode assembly 52 to the vessel frame 50. A cylindrical weir lip 140 on the weir frame 100 may extend up and may determine the level of catholyte in the upper cup 60. During certain process steps, catholyte may flow out of the upper cup 60 over the weir lip 140 and into the weir overflow channel 58. As shown in FIG.6, the weir frame 100 may have an angled section 142 extending up from the weir ring 104 adjoining a planar section 106 which may be at least substantially perpendicular to the weirlip 140 in some embodiments. A plenum 146 containing catholyte may extend around an inside of the weir frame 100. The plenum 146 may be divided into a number (here, four) of virtual thief electrode segments by interior walls 148 shown by dotted lines in FIG. 5.

[0036] Referring still to FIG. 5, the four virtual thief electrode segments are labelled as AA, BB, CC and DD. The four segments are referred to as virtual thief electrode segments because they do not include a physical thief electrode. Rather, the physical thief electrodes associated with the virtual thief electrodes are located remotely from virtual thief electrode segments. Electrolyte in the vessel assembly provides a current flow path from the virtual thief electrode segments to the physical thief electrodes, as described below.

[0037] Segments AA and CC may both subtend a sector of 130 to 150 degrees and nominally 140 degrees. Segment BB may subtend a sector of 70 to 90 degrees and nominally 80 degrees. Segment DD may be a local narrow sector subtending 1 to 15 degrees and nominally 10 degrees, and may be fit in between the ends of the two adjacent segments AA and CC. It will be appreciated that other variations are possible.

[0038] Openings 145 formed through the planar section 106 may be aligned on a diameter of the plenum 146, which may be greater than the inner diameter of the weir ring 104. The openings 145 may allow the virtual thief electrode segments to influence the electric field in the vessel assembly primarily near the edges of the wafer, by providing a current flow pathway from the catholyte in the plenum 146 into the upper cup 60. Alternatively, or additionally, slots 147 adjoining the weir ring 104 as shown in dotted lines in FIG. 6, may be used instead of or in conjunction with the openings 145, although the slots 147 may be more susceptible to bubble trapping. The cross-sectional area of the plenum 146 may be maximized in order to increase minimum hole diameter or slot width, which simplifies manufacture of the segmented weir electrode thief 52. In some embodiments, the openings 145 and / or slots 147 may be spaced apart at intervals of 15 to 25 degrees, or at 20 degrees. The hole diameters may vary to provide uniform distribution of thief current in each segment.

[0039] For processing 300 mm wafers with plated areas extending out to 297 or 298 mm (i.e., within 1 or 1.5 mm of the wafer edge) the weir ring 104 may have an inside diameter of 298 mm in some embodiments. In the example shown, the seal on the contact ring in the head 30 is at least two millimeters from the edge of the wafer and the first plated feature often begins even further in from the seal. Thus, the weir ring 104 does not reside beneath the plated film. The weird ring 104 therefore does not interfere with the range of paddlemovement or block mass transfer to the edge of the plated film. The weir ring 104 operates to direct flow rather than act as an electric field shield. For smaller wafers, or for wafers with all plated areas further in from the wafer edge, a weir ring 104 having a smaller inside diameter may be used.

[0040] Referring to FIGs. 3 and 5, four (or other number) physical thief electrodes 110, 111, 112, and 113 may be provided in four thief electrode chambers 125, 127, 129, and 131 which may be attached to the bottom of the vessel frame 50 around the outside of the anode assembly 64. FIG. 3 shows the first physical thief electrode 110 and the third physical electrode 112 associated respectively with, and aligned vertically under, the first and third segments AA and CC. The second and fourth physical electrodes 111 and 113 shown schematically in FIG. 5 may be similarly associated with and aligned vertically under the second and fourth segments BB and DD. Each physical electrode may be electrically connected to a separate power supply channel by cables 115. A first thief electrolyte (first thief olyte) may be contained in a first chamber 124 in a first thief electrode cup 125 by one or more first thiefolyte membranes 130. The first thiefolyte may be electrically in contact with the first thief electrode 110. A first thief electrode channel or passageway 120 may be filled with the catholyte and may extend up from the first thiefolyte membranes 130 into the plenum of the first segment AA of the segmented weir thief electrode assembly 52.

[0041] As also shown in FIG. 3, similarly, a third thief electrolyte (third thiefolyte) may be contained in a third chamber 126 in a third thief electrode chamber 127 by one or more third thiefolyte membranes 132. The third thiefolyte may be electrically in contact with the third physical thief electrode 112. A third thief electrode channel or passageway 122 may be filled with the catholyte and may extend up from the third thiefolyte membranes 132 into the plenum of the third segment CC of the segmented weir thief electrode assembly 52.

[0042] Second and fourth thief electrolytes (second and fourth thiefolytes) may be similarly contained in second and fourth chambers 127 and 131 in second and fourth electrode cups by one or more second and fourth membranes 133 and 135 shown in FIG. 5. The second and fourth thiefolytes may be electrically in contact with the second and fourth physical thief electrodes 111 and 113, respectively. Second and fourth thief electrode channels 121 and 123 may be filled with the catholyte and may extend up from the second and fourth thiefolyte membranes into the plenums of the second and fourth segments BB and DD of the segmented weir thief electrode assembly 52. The designs of the second and fourth virtual thiefelectrodes shown in FIG. 5 may be the same as the first and third virtual thief electrodes shown in FIG. 3, other than their sector angles. Thiefolyte chemistries may be common. In the example shown, the channels 120-123 may be centrally aligned underneath the lugs 102. Depending on the angles subtended by the segments, each channel 120-123 may or may not be centered in its respective segment.

[0043] The cross sections of the thief electrode channels 120-123 may also vary based on the current flow requirements of each segment. The diameter of the openings 145 and / or size of the slots 147 may increase with their distance from catholyte-filled channel providing current to the segment, so that some or all of the holes or slots have largely equal influence on the electric field around the edge of pattern or plated metal on the wafer. All four thiefolytes may be the same. For example, in some embodiments, the thiefolyte may include diluted sulfuric acid. The vessel assembly 36 may then contain three electrolytes: anolyte in the lower cup 68 of the anode assembly, catholyte in the upper cup 60, the plenum, and the thief electrode channels 120-123, and thiefolyte in the thiefolyte chambers 124-127. In some embodiments, the electroplating system 20 may include thief cartridges 170. Each thief cartridge 170 may be associated with a respective one of the segments of the segmented weir thief electrode assembly 52 and may include all or a portion of the components of the virtual thief electrodes. For example, each thief cartridge 170 may include a respective one of the thief electrode channels (e.g., 120-123), the thiefolyte membranes (e.g., 130, 132, 133, 135), the chambers (e.g., 124, 126, 127, 131), the thief electrodes (e.g., 110-113), and / or other components of the electroplating system 20.

[0044] In addition to the number and configuration of the segments shown in FIG. 5, other numbers and configurations of segments may be used. For example, a segmented weir thief electrode assembly may alternatively have two, three, five, six or more segments, each linked to a separate power supply channel. One alternative embodiment of a segmented weir thief electrode assembly may have two local segments of 1 to 15 degrees separated by or between two segments of 165 to 179 degrees. Other variations are possible.

[0045] In use, a wafer having a metal seed layer may be loaded into the rotor of the head 30. The lift or lift / rotate unit 34 may flip over and lowers the wafer into the vessel assembly 36 until at least the seed layer contacts the catholyte in the upper cup 60. The head 30 may rotate the wafer to even out uneven plating factors. The paddle actuator may move the paddle 54 underneath the wafer, such as by reciprocating, oscillating, and / or otherwisetranslating the paddle within the catholyte. The power supply 98 may provide specified time varying direct (positive) current independently to the first, second and third anodes 82, 84, and / or 86 according to a preprogrammed schedule adapted to the specific wafer to be electroplated.

[0046] The power supply 98 may also provide specified time varying direct (negative) current independently to the first, second, third and fourth physical current thief electrodes, with the current flowing through the thiefolytes and the catholyte in thief channels of the first, second, third and fourth virtual electrodes. Each virtual thief segment may distribute the current circumferentially through a set of variable-sized openings, which may be openings 145 and / or slots 147. Catholyte from inlets into the thief channels 120-123, above the thief membranes, may flow into the plenum 146 and out the openings 145 in the top of the plenum 146. Use of the upward-facing openings 145 may allow trapped bubbles in the catholyte to escape from the plenum 146.

[0047] Since current density across the wafer may be controlled by adjusting the current of the anodes and the virtual current thieves, the electroplating system 20 can better process wafers over a range of parameters, without the need to replace fixed shields in the vessel assembly 36, which is a time-consuming process. The electroplating system 20 can also provide good performance of the entire process via current control.

[0048] The design of the virtual thief electrodes forces thief current to pass between lower surfaces of the contact ring in the head and the top surface of the weir ring 104. This causes the effect of the segments AA, BB, CC and DD to be focused near the edge of the wafer. As a result, required thief currents are lower and more focused control over the electric field at the edge of the wafer is provided. Since the thief currents are relatively low, unlike many known systems, the system 20 can continuously process large numbers of wafers without causing the physical thief electrodes to plate up and become inoperable.

[0049] Radial current density control and circumferential current density control may be achieved by adjusting anode and thief currents. Measurements of plating thickness of prior wafer can be used to adjust these currents. Initial currents can be set from a model that uses process conditions as inputs (e.g., bath conductivity of anolyte and catholyte, wafer current, seed resistance, pattern open area, pattern edge exclusion, pattern feature sizes, and intended plating thickness).

[0050] The current or voltage supplied by the power supply 98 to each thief segment may be independently controlled, for example with a current in the range of 10 mA to 5 A, a current rise time of 100 mS or less, and voltages of -0V to -60V. Current and / or voltage control may be synchronized with wafer position (via control of the motor in the head spinning the rotor) to enable precise circumferential uniformity control of the electroplating at the edge of the wafer. The wafer position may vary with a continuous wafer rotation. The wafer position may include pauses at fixed wafer angular positions or include changes in wafer rotational speed. The current and / or voltage may increase or decrease in time according to wafer position and angular rotation speed. The current and / or voltage may increase or decrease in time according to wafer position and angular rotation speed and based upon deposition thickness measurements of a prior wafer (i.e. feedback control). The current and / or voltage may increase or decrease in time according to wafer position and angular rotation speed and based upon a model or measurements of the local edge pattern density.

[0051] FIG. 7 shows a thief cartridge 200 that may be used in an electroplating system, such as electroplating system 20 described above. For example, the thief cartridge 200 may be used in electroplating system 20 such as for thief cartridges 170. In some embodiments, each thief cartridge 170 may include a first body 202 that defines a thief electrode channel 204 (which may be similar to thief electrode channels 120-123). For example, the first body 202 may include a first end 206 and a second end 208 opposite the first end 206. The first end 206 may be coupleable with a portion of the electroplating system, such as with the vessel frame 50. The thief electrode channel 204 may extend through a thickness of the first body 202. For example, the thief electrode channel 204 may extend from the first end 206 to the second end 208 in some embodiments. The thief electrode channel 204 may be designed to receive a catholyte, which may be pumped into the thief electrode channel 204 via one or more delivery channels 210. When coupled with the vessel frame 50, the thief electrode channel 204 may be fluidly coupled with the upper cup 60 of the electroplating system 20. For example, once the thief electrode channel 204 has been filled with catholyte, excess catholyte may flow upward and into the upper cup 60 through the openings 145 and / or slots 147 formed in the weir ring 104.

[0052] Each thief cartridge 200 may include a second body 220 that defines a thief chamber 222 (which may be similar to chambers 124, 126, 127, 131). For example, the second body 220 may include a first end 226 and a second end 228 opposite the first end 226. The first end 226 may be coupleable with the second end 208 of the first body 202 such that atop open end of the thief chamber 222 is at least partially aligned with the thief electrode channel 204. For example, the first end 226 of the second body 220 may be received within a recess formed in the second end 208 of the first body 202. As illustrated, the first body 202 and the second body 220 may be coupled at an angle relative to one another, while in other embodiments the first body 202 and the second body 220 may be coaxially aligned with one another.

[0053] The thief chamber 222 may extend partially through a thickness of the first body 220. For example, the thief chamber 222 may extend from the first end 226 part of the way along the length of the second body 220 toward the second end 228, with a base of the thief chamber 222 being disposed within a medial region of the second body 220. The thief chamber 222 may be designed to receive a thiefolyte, which may be pumped into the thief chamber 222 via one or more delivery channels 231 and / or drained via one or more outlet channels 232.

[0054] The thiefolyte may be constrained to the thief chamber 222 and prevented from contacting and / or mixing with the catholyte in the thief electrode channel 204 and / or other region of the electroplating system. For example, each thief cartridge 200 may include at least one thief membrane 230 that is disposed between and that separates the thief electrode channel 204 and the thief chamber 222. For example, the thief membrane(s) 230 (which may be similar to thiefolyte membranes 130, 132, 133, 135) may be positioned at a junction where the first body 202 receives the second body 220 and at the interface between the thief electrode channel 204 and the thief chamber 222. Each thief membrane 230 may be an anionic membrane that permits the transfer of negative ions between the catholyte and the thiefolyte while blocking positive ions (such as copper ions) from reaching the thiefolyte. Whether one thief membrane 230 or multiple thief membranes 230 are included at the interface, a collective thickness of the thief membrane(s) 230 may be at least 35 mils. For example, the collective thickness of the at least one thief membrane is between 35 mils and 100 mils or any intermediate range therebetween, such as (but not limited to) between 40 mils and 80 mils or between 50 mils and 60 mils. Conventionally, a single thin anionic membrane is utilized, typically having a total thickness of less than 30 mils, oftentimes being about 20 mils thick. However, with such a thin membrane, copper ions may pass through the anionic membrane and contaminate the thiefolyte at an undesirably high rate. The concentration of copper ions in the thiefolyte may cause build up of copper on thief electrodes housed within the thief chamber 222 and necessitate maintenance and system downtime to remove thebuildup. In contrast, testing demonstrated that the higher thicknesses of thief membranes 230 used in the present invention result in reduced copper transport, as shown in Table 1 below. Table 1

[0055] The increased thickness of the thief membranes 230 may be achieved by utilizing a single thicker thief membrane and / or by using multiple thief membranes that are stacked upon one another. In a particular example, each thief cartridge 200 may include multiple thief membranes 230. In such embodiments, each of the thief membranes 230 may have an individual thickness of between 15 mils and 55 mils, more commonly between 15 mils and 40 mils. Each thief membrane 230 within a membrane stack may have a same or different thickness. The membrane stack may include one or more thief membranes, two or more thief membranes, three or more thief membranes, four or more thief membranes, five or more thief membranes, or more. Where multiple thief membranes 230 are included, each thief membrane 230 may be electrically coupled with one another. For example, the thief membranes 230 may be in direct contact with one another. In some embodiments, to ensure that an electrically conductive path between the adjacent thief membranes 230 is sufficiently large, the thief membranes 230 may be pre-wetted prior to stacking. For example, the thief membranes 230 may be soaked in a solution (such as deionized water and / or sulfuric acid), which may help reduce or eliminate the present of air bubbles between the stacked thief membranes 230 once assembled. Such air bubbles may block current flowing through the membrane stack.

[0056] Each thief cartridge 200 may include a thief electrode 240 (which may be similar to thief electrodes 110-113). The thief electrode 240 may be disposed within the thief chamber 222. For example, the thief electrode 240 may be disposed at or near a base of the thief chamber 222 in various embodiments. Current may be supplied to the thief electrode 240, which may conduct the current through the thiefolyte, the thief membranes 230, and catholyte and to positions near the wafer to plate portions of the wafer.

[0057] Each thief cartridge 200 may include an O-ring 250 or other sealing member that may be disposed on an exposed surface of one of the thief membranes 230. For example, the O-ring 250 may be positioned on an upper surface of the topmost thief membrane 230, such as between the thief membranes 230 and the first body 202. The O-ring 250 may help seal the interfaces between the first body 202, the second body 220, and the thief membranes 230. Additionally, or alternatively, the O-ring 250 may help flatten the thief membranes 230 during assembly of the thief cartridge 200 as will be discussed in greater detail below.

[0058] FIG. 8 shows exemplary operations in a method 300 for assembling a thief cartridge for an electroplating system according to some embodiments of the present technology. Method 300 may be used to assemble a thief cartridge, such as thief cartridges 170 and 200, which may include a thief membrane stack. Method 300 may include operations prior to the assembly in some embodiments. Method 300 may include a number of operations that may be performed automatically within a system to limit manual interaction, and to provide increased efficiency and precision over manual operations.

[0059] Method 300 may include wetting a first thief membrane and a second thief membrane (such as thief membranes 130, 132, 133, 135, 230) at operation 305. The first and second thief membranes may be wetted simultaneously and / or at different time. In some embodiments, wetting the first thief membrane and the second thief membrane may include soaking each of the first thief membrane and the second thief membrane in a solution for a period of time. The solution may be or include, for example, de-ionized water and / or sulfuric acid. The period of time may vary based on the thickness of the respective thief membrane. In some embodiments, the period of time may be between 1 minute and 30 minutes, inclusive. For example, each thief membrane may be soaked in the solution for between 5 minutes and 20 minutes, or about 10 minutes in some embodiments. Upon being soaked, each thief membrane may be bowed.

[0060] At operation 310, the first thief membrane may be positioned against an interface region of a body (such as second body 220) defining a thief chamber (such as thief chamber 222), with a bowed center of the first thief membrane facing away from the body. For example, protruding peripheral edges of the first thief membrane may be positioned against a membrane seat formed on the body, while the center of the first thief membrane protrudes away from the body. The second thief membrane may be positioned against the first thief membrane at operation 315, with a bowed center of the second thief membrane facing towardthe body and the first thief membrane. For example, the bowed center of the second thief membrane may be brought into contact with the bowed center of the first thief membrane, with the peripheral edges of the respective thief membranes extending away from one another.

[0061] At operation 320, an O-ring may be positioned against an exposed surface of the second thief membrane. For example, the O-ring may be positioned against a top surface of the second thief membrane opposite the first thief membrane and the body. Positioning the O-ring against the exposed surface of the second thief membrane may cause both the first thief membrane and the second thief membrane to substantially flatten and may cause the inner surfaces of the thief membranes to be pressed into contact with one another. The O-ring may hold the thief membranes together in place on the body while an additional body (such as first body 202) is coupled with the body defining the thief chamber at operation 325. The additional body may define a thief electrode channel (such as thief electrode channel 204), which may include an opening that is closed off by the stacked thief membranes.

[0062] By wetting the thief membranes and initiating contact between the thief membranes at the bowed centers as described above, the presence of air bubbles may be reduced and / or eliminated at the interface between the stacked thief membranes. Such air bubbles would otherwise undesirably cause electrical conductance issues through the membrane stack, which ultimately impacts the plating performance of the electroplating system in which the thief cartridge is provided. Additionally, while described as including only two thief membranes, it will be appreciated that process 300 may be used to stack any number of thief membranes in various embodiments.

[0063] In the preceding description, for the purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. It will be apparent to one skilled in the art, however, that certain embodiments may be practiced without some of these details, or with additional details.

[0064] Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the embodiments. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Accordingly, the above description should not be taken as limiting the scope of the technology.

[0065] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly or conventionally understood. As used herein, the articles “a” and “an” refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. “About” and / or “approximately” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, encompasses variations of ±20% or ±10%, ±5%, or ±0.1% from the specified value, as such variations are appropriate to in the context of the systems, devices, circuits, methods, and other implementations described herein.“Substantially” as used herein when referring to a measurable value such as an amount, a temporal duration, a physical attribute (such as frequency), and the like, also encompasses variations of ±20% or ±10%, ±5%, or ±0.1% from the specified value, as such variations are appropriate to in the context of the systems, devices, circuits, methods, and other implementations described herein.

[0066] Where a range of values is provided, it is understood that each intervening value, to the smallest fraction of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Any narrower range between any stated values or unstated intervening values in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of those smaller ranges may independently be included or excluded in the range, and each range where either, neither, or both limits are included in the smaller ranges is also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0067] As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a heater” includes a plurality of such heaters, and reference to “the protrusion” includes reference to one or more protrusions and equivalents thereof known to those skilled in the art, and so forth.

[0068] Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”, “include(s)”, and “including”, when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or operations, butthey do not preclude the presence or addition of one or more other features, integers, components, operations, acts, or groups.

Claims

WHAT IS CLAIMED IS:

1. A thief cartridge for an electroplating system, comprising:a first body defining a thief electrode channel;a second body defining a thief chamber;at least one thief membrane disposed between and separating the thief electrode channel and the thief chamber, wherein a collective thickness of the at least one thief membrane is at least 35 mils; anda thief electrode disposed within the thief chamber.

2. The thief cartridge for an electroplating system of claim 1, wherein: the at least one thief membrane comprises two membranes.

3. The thief cartridge for an electroplating system of claim 2, wherein: the two membranes are electrically coupled with one another.

4. The thief cartridge for an electroplating system of claim 2, wherein: the two membranes are in direct contact with one another.

5. The thief cartridge for an electroplating system of claim 2, wherein: each of the two membranes comprises a thickness of between 15 mils and 35 mils.

6. The thief cartridge for an electroplating system of claim 1, wherein: the collective thickness of the at least one thief membrane is between 35 mils and 100 mils.

7. The thief cartridge for an electroplating system of claim 1, wherein: the collective thickness of the at least one thief membrane is between 40 mils and 80 mils.

8. The thief cartridge for an electroplating system of claim 1, further comprising:an O-ring disposed on an exposed surface of the at least one thief membrane.

9. An electroplating system, comprising:a vessel assembly for holding an electrolyte, the vessel assembly comprises an anode assembly having a plurality of anode chambers;an upper cup disposed above the anode assembly, the upper cup having a plurality of chambers corresponding to the plurality of anode chambers;a vessel membrane between the plurality of anode chambers and the upper cup;a weir thief electrode assembly disposed in the vessel assembly, the weir thief electrode assembly including a plenum inside of a weir frame, the weir thief electrode assembly having a plurality of virtual thief electrode segments, wherein each virtual thief electrode segment of the plurality of virtual thief electrode segments comprises a thief cartridge, each thief cartridge comprising:a first body defining a thief electrode channel;a second body defining a thief chamber;at least one thief membrane disposed between and separating the thief electrode channel and the thief chamber, wherein a collective thickness of the at least one thief membrane is at least 35 mils; anda thief electrode disposed within the thief chamber.

10. The electroplating system of claim 9, further comprising: a weir ring attached to the weir frame.

11. The electroplating system of claim 9, wherein:the weir frame defines a plurality of spaced apart openings that extend through the weir frame into the plenum.

12. The electroplating system of claim 9, wherein:the at least one thief membrane comprises two membranes.

13. The electroplating system of claim 12, wherein:the two membranes are in direct contact with one another.

14. The electroplating system of claim 12, wherein:each of the two membranes comprises a thickness of between 15 mils and 35 mils.

15. The electroplating system of claim 9, wherein:each thief electrode channel is configured to receive a catholyte;each thief chamber is configured to receive a thiefolyte; andthe at least one thief membrane is configured to separate the thiefolyte and the catholyte while permitting transfer of negative ions from the catholyte to the thiefolyte.

16. The electroplating system of claim 9, wherein:each thief electrode channel is fluidly coupled with the upper cup.

17. A method of assembling a thief cartridge for an electroplating system, comprising:wetting a first thief membrane and a second thief membrane;positioning the first thief membrane against an interface region of a body defining a thief chamber, with a bowed center of the first thief membrane facing away from the body;positioning the second thief membrane against the first thief membrane, with a bowed center of the second thief membrane facing toward the body and the first thief membrane;positioning an O-ring against an exposed surface of the second thief membrane; andcoupling a body defining a thief electrode channel to the body defining the thief chamber.

18. The method of assembling a thief cartridge for an electroplating system of claim 17, wherein:wetting the first thief membrane and the second thief membrane comprises soaking each of the first thief membrane and the second thief membrane in a solution.

19. The method of assembling a thief cartridge for an electroplating system of claim 18, wherein:the solution comprises one or both of de-ionized water and sulfuric acid.

20. The method of assembling a thief cartridge for an electroplating system of claim 17, wherein:positioning the O-ring against the exposed surface of the second thief membrane causes the first thief membrane and the second thief membrane to substantially flatten.

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