PLATING APPARATUS AND METHOD

FIELD OF THE DISCLOSURE

The following disclosure relates to a method and apparatus for automated plating of multiple metal layers or complex structures using a single plating apparatus. BACKGROUND OF THE DISCLOSURE

Conventional plating systems generally utilize a plurality of different plating cells each containing a different chemical plating bath configured to plate a particular metal or alloy. The plurality of plating cells are generally part of a plating system that includes a plurality of cells each configured to perform a specific task, e.g., acid etch/clean, rinse, dry, anneal, metrology, plating, etc. Conventional plating systems require a large footprint within expensive clean room space. Additionally, conventional plating systems and plating cells are generally single chemistry cells, i.e., a plating cell uses a single chemistry to plate a single metal material. As such, complex chemical plating solutions and processes must be used for alloy plating, and deposition of distinct individual layers of metal is difficult and requires the sequential use of a plurality of plating cells. Use of multiple plating cells to plate alloys of layers of distinct metals presents several disadvantages. For example, the process of transferring a substrate from one plating cell to another increases the likelihood of oxidation forming on the substrate. Oxidation can cause defects in the plated layers if it is not removed prior to the subsequent layer being deposited, and the removal of the oxidation layer adds a cleaning and rinsing step to the plating process. These processes each increase the processing time for a substrate, and thus, inherently reduce the throughput of the plating system.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a process plating computer configured to use quick change chemistry tanks and is designed to provide customers more flexibility with multiple metal processing requirements and higher uptime. An object of the present disclosure is to provide cost-effective electroplating tools and reliable multi-layer processes to semiconductor back-end assembly. The compact electroplating deposition process tool of the present disclosure generally provides the electronics industry with a more cost effective way to fabricate high performance, low cost interconnects, including but not limited to those useful for flip chip technology.

Utilizing a unique single-wafer, multi-metal process cell enables manufacturing of very compact tools, generally comprising real-time feedback for plating process conditions, and provides major operation advantages over its competitor's single-metal process cells requiring much more space and maintenance. Process knowledge is also generally embedded within software / hardware enabling

widespread introduction and purchase of much simpler and productive bumping capability. This plating computer should enable most companies that want to develop and implement flip chip and wafer CSP to do so internally, as well as merchant suppliers with recipe portability.

Moreover, combining improved process technology with a novel closed-cell tool reduces the difficulty of introducing and supporting flip chip bumping technology in production. The compact plating computer of the present disclosure generally not only enables multi-metal capability in a continuous and repeatable manner but also replaces the traditional cell-to-cell and tank-to-tank wafer transfer with a more powerful single-cell plating computer concept. Thus the need to move the wafer through various plating chemistries may be eliminated, thereby reducing the need for substrate transfer related robotics and therefore reducing machine cost, footprint, and improving machine utilization rates. This single-cell approach expedites and improves production by minimizing wafer handling and, more importantly, generally enabling a wide range of lead-free solders to be applied in a single cell platform.

In addition, processes for encapsulated powders and solder bumps that would be used in conjunction with these tools are being developed. Additional work continues to develop high performance bumps and interconnect which is expected to improve thermal and electrical conductivity in copper as well as solder alloys. This will address the key high performance computing and handheld processor market segment that is demanding more thermal conductivity interconnect.

Objects, advantages and novel features, and further scope of applicability of the present disclosure will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the disclosure. The objects and advantages of the disclosure may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the following description.

Embodiments of the disclosure may provide a plating computer having a plating cell with an interior processing volume configured to contain a plating solution for a plating process, a cell mounting platform connected at least at a first point to an actuator and at a second point to a movable attachment member, a rotatable substrate support member positioned in the processing volume and having a longitudinally extending shaft extending from a non-substrate engaging side of the support member, a transducer coupled to the longitudinally extending shaft and being configured to impart energy to the substrate support member via the shaft, and at least one detachable chemistry module in fluid communication with the processing volume.

Embodiments of the disclosure may further provide a method for plating multiple metal layers onto a substrate in a single plating cell without removing the substrate from the plating cell between the

first and second metal deposition steps. The exemplary method may include positioning the substrate on a cathodic substrate support member in a processing volume of a plating cell, filling the processing volume with a first plating solution configured to plate a first metal layer onto the substrate, applying a first plating bias between the substrate and an anode assembly positioned in the processing volume to plate the first metal onto the substrate, and draining the first plating solution from the processing volume. The exemplary method may further include flooding the processing volume with an inert gas to prevent ambient oxygen from oxidizing the substrate that remains positioned in the processing volume, rinsing the processing volume with deionized water, filling the processing volume with a second plating solution configured to plate a second metal layer onto the substrate that remains positioned in the processing volume, and applying a second plating bias between the substrate and the anode assembly to plate the second metal onto the first metal layer.

Embodiments of the invention may further provide a plating computer for plating multiple different metal layers onto a substrate in a single plating process. The plating computer may include a means for positioning the substrate on a cathodic substrate support member in a processing volume of a plating cell, a first chemical supply means for filling the processing volume with a first plating solution configured to plate a first metal layer onto the substrate, and a means for applying a first plating bias between the substrate and an anode assembly positioned in the processing volume to plate the first metal onto the substrate. The plating computer may further include a means for draining the first plating solution from the processing volume, a gas supply means for flooding the processing volume with an inert gas to prevent ambient oxygen from oxidizing the substrate that remains positioned in the processing volume, a means for rinsing the processing volume with deionized water, a second chemical supply means for filling the processing volume with a second plating solution configured to plate a second metal layer onto the substrate that remains positioned in the processing volume, and a means for applying a second plating bias between the substrate and the anode assembly to plate the second metal onto the first metal layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure. The drawings are only for the purpose of illustrating a preferred embodiment of the disclosure and are not to be construed as limiting the disclosure.

Figure Ia illustrates a top perspective view of an exemplary plating computer of the invention; Figure Ib illustrates a side sectional view of an exemplary plating computer of the invention; Figure Ic illustrates a side sectional view of an exemplary plating computer of the invention;

Figure Id illustrates a side sectional view of an exemplary plating computer of the invention from a bottom perspective;

Figure Ie illustrates a side view of an exemplary chemical supply module of the invention;

Figure Ig illustrates side and perspective views of an exemplary plating computer of the invention;

Figure 11 illustrates a side sectional view of an exemplary plating computer of the invention;

Figure Im illustrates a partially exploded perspective view of an exemplary control rack system or chassis for a plating computer of the invention;

Figure 2 illustrates a simplified side view of an exemplary plating computer of the invention; Figure 3 illustrates a bottom perspective view of exemplary transducers of an exemplary plating computer of the invention;

Figure 4 illustrates a perspective view of a side ring for an exemplary plating computer of the invention;

Figure 5 illustrates a perspective view of a mounting plate, transducers, and side ring for an exemplary plating computer of the invention;

Figure 6 illustrates a detailed sectional view of a portion of an exemplary plating computer of the invention;

Figure 7 illustrates a top perspective view of an exemplary contact ring of an exemplary plating computer of the invention; Figure 8 illustrates a partial sectional view of an exemplary contact ring of an exemplary plating computer of the invention;

Figure 9 illustrates a perspective view of a portion of a contact ring of an exemplary plating computer of the invention;

Figure 10 illustrates a side sectional view of a contact ring assembly and plating cell of an exemplary plating computer of the invention;

Figure 11 illustrates a side sectional view of an exemplary contact ring of an exemplary plating computer of the invention;

Figure 12 illustrates a bottom perspective and partial sectional view of an exemplary contact ring of the invention; Figure 13 illustrates a bottom perspective view of an exemplary contact ring of the invention;

Figure 14 illustrates an exemplary contact member of a contact ring for an exemplary plating computer of the invention;

Figure 15 illustrates an exemplary contact member of a contact ring for an exemplary plating computer of the invention; Figure 16 illustrates an exemplary contact member assembly for an exemplary plating computer of the invention;

Figure 17 illustrates a perspective view of an exemplary contact ring assembly of the invention;

Figure 18 illustrates two exemplary bump tests generated by an embodiment of the plating computer of the invention; and Figure 19 illustrates a flowchart of an exemplary method of the invention.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in various ways, i.e., any element from one embodiment may be used in any other embodiment, without departing from the invention.

Figures Ia-Im illustrate various exemplary embodiments of closed plating cells of the invention, which may be used to plate any size wafer, including but not limited to 200mm or 300mm wafers. The closed-cell technology of the present disclosure provides end users with reduced wafer breakage and high speed plating not found in traditional wafer plating systems. The closed-cell generally provides an embedded multiple zoned anode. This feature along with energy, mechanical and fluid management kinetics offer excellent plating uniformity. Some features and advantages of the present disclosure may include: Manual or Automated (cassette feed) Wafer Handling Automation; GUI Interface;

Programmable Process Recipe Control and custom recipe configuration; Containerized Chemistry Farm holding up to six specific metals; Single-Cell Jetting Anode System, which may include a four or six-zone

programmable, nonsoluble anode; the zones may include concentric rings each having an independently programmable voltage; High speed plating, maximizing wafers per day with deposition rates of up to 6 μ/min for copper and up to 4.5 μ/min for Sn/Pb; Lead free Sn/Ag with deposition rates of up to 4.5 μ/min; Multiple metal capabilities to meet several interconnect requirements (multi-stack metals) within a single cell; Fast chemistry conversion; Embedded energy and fluid agitation for maximum kinetics within the single-cell; and Embedded chemistry jetting with programmable energy system for kinetics control.

The single closed-cell reduces evaporation and eliminates wafer breakage which can occur when the wafer is transferred to additional rinsing and plating stations in a multi-station process or system. The small-cell processing volume provides more accurate process control, and requires less water for rinsing, thus enabling a single tank to be used. The closed-cell also provides excellent thickness uniformity across the wafer: < 10% for copper, Sn/Pb, and lead free Sn/Ag, proven particle plating and alloy plating possible, low cost of ownership, and a small factory footprint: For 200mm wafers: Current: 1.32m w x .99m d x 1.88m h (Planned: Im w x Im d x 2.2m h) and for 300mm wafers: Current: 1.5m w x 1.5m d x 1.88m h (Planned: 1.3m w x 1.3m d x 2.2m h). The single closed-cell provides a scaleable business model, scaleable capacity model for maximum utilization, quick process and chemistry change-over, flexibility to process multiple constructions, leading edge production utilization rates and multi-metal plating. The single closed-cell provides wafer level processing for wafer bumping and utilizes metal seal rings that are beneficial, for example, in manufacturing MEMS devices, solar cells, and semiconductor processing aspects, including glass throughhole (via) plating. For example, Figure Ia illustrates a top perspective view of an exemplary plating computer 100 of the invention and Figures Ib and Ic illustrate side sectional views of an exemplary plating computer 100. Figure Ib illustrates the exemplary plating computer 100 in a closed or processing position, and Figure Ic illustrates the exemplary plating computer 100 in an open or substrate loading position. The plating computer 100 may generally include a processing volume 102 that is configured to contain processing chemistry and the substrate to be plated therein. A substantially planar substrate support member 104 is generally configured to support a substrate thereon for processing, and the substrate support member 104 may also be rotatable about a vertical axis, and further, the substrate support member 104 may be tilted from a horizontal plane in some exemplary embodiments. The plating computer 100 may also include a fluid delivery manifold or valve assembly 106 configured to deliver selected chemistries, deionized water, and other liquids to the plating computer processing volume 102. The exemplary processing computer 100 may also include at least one bottom transducer 108 configured to impart energy to the substrate support member 104. The energy imparted to the processing computer 100 by the transducer 108 is generally a sonic-type energy, i.e. ultra sonic or mega sonic. In one embodiment of the invention, the energy generated by the transducer 108 may be about 40 kHz. The

energy is transferred to the substrate via the drive mechanism 112. The processing volume 102 may include an anode 1 10 that is generally positioned in a substantially parallel relationship with the substrate to be plated, which is generally supported on the substrate support member 104, which may be rotatably supported by the substrate support member drive mechanism 112. The drive mechanism 112 and the substrate support member 104 may be lowered (as shown in Figure Ic) to allow for a substrate to be loaded onto the substrate support member 104.

A contact ring 1 14, as shown in the partial sectional and perspective view of Figure Id, is used to electrically contact a periphery of the substrate to be plated and to provide an electrical bias thereto to support an electrochemical deposition process. The contact ring 1 14 may generally include a plurality of electrically conductive fingers radially positioned about a semi-rigid and substantially planar ring. The positioning of the conductive fingers is generally configured to electrically contact a perimeter portion of a substrate being processed in the plating computer 100 to deliver an electrical bias sufficient to support a plating process to the substrate. Various configurations and exemplary embodiments of contact rings that may be used in the exemplary plating computer 100 of the invention will be further discussed herein. Figure Id shows the plating computer anode 1 10, which is positioned in an upper portion of the processing volume 102. The anode 1 10 generally includes a plurality of concentrically positioned conductive elements that may be individually biased with selected electrical power to facilitate uniform plating deposition across the surface of the substrate being plated in the plating computer 100. The anode 1 10 is generally positioned just above the contact ring 114, and more particularly, the anode 110 is generally positioned immediately above the central aperture formed by the contact ring 114. As such, when a substrate being plated is positioned in the plating computer 100 and is brought into electrical communication with the contact ring 1 14, the anode 1 10 will generally be positioned immediately above the substrate being plated.

Figure Ie illustrates a side view of an exemplary removable chemical supply module 129 of the invention. The chemical supply module 129 generally includes a main holding tank 130, a charge tank 132, a fluid manifold 138, at least one fluid valve 140, and a selectively actuated fluid pump 142. The charge tank 132 may also include a fluid heater 136 and a fluid filter 134. In operation, the chemical supply module 129 may be connected to a plating computer 100 to support a portion of a plating process. The fluid contained in the chemical supply module 129 may be configured to plate a particular metal onto a substrate. Additional chemical supply modules 129 may also be in communication with the plating computer 100 and may be configured to supply a different chemical solution to the plating computer 100 so that a different metal may be plated on the substrate. Thus, each plating computer 100 may be in communication with one or more chemical supply modules 129 if the particular plating process being conducted in the plating computer 100 requires different metals to be deposited on a single substrate in a

single processing sequence. The chemical supply module 129 generally operates to pull bulk chemical solution from the large volume holding tank 130 into the smaller volume charge tank 132 (which may be sized to about the same volume as the processing volume 102 of the plating computer 100) where the solution is heated and filtered prior to being delivered to the plating computer 100. The present disclosure generally provides separate container tanks (modules 129) for each chemistry, and optionally for waste, required for a particular process. Each tank may include a heater for heating the chemistry to an optimum process temperature. The containers may be configured to be easily replaceable and/or refillable. The used chemistry may be configured to be recycled back into the appropriate tank after processing, such as filtering. An optional pump heater filter module is disposed between the process cell and the tank, enabling the tank to be replaceable via a plug and play or "plug and plate" system. One or more optional metrology systems are generally utilized within a real-time feedback loop for automated process cycle control. Such systems may include conductivity (e.g. RTD), sonar, optimal level sensing, and depletion prediction. A thermoelectric cell (TEC) may be used to fine tune (heating or cooling) the process temperature. Conductivity sensors generally ensure the cleanliness between different chemicals, preventing cross contamination and estimating degradation of the chemicals.

An in-cell pressure monitor allows speed fill to control chemical flow and over flow, and in situ monitoring of uniformity of in-cell pressure. Bulk and at-wafer temperature monitoring maintains optimized plating conditions. A fill sensor may optionally be used. Resistivity contact points provide realtime feedback for optimal plating performance. In-cell thin film conductivity sensing determines cleanliness of the inner-cell wall. Integrated optical curvature measurement (in-line stress test) may be used to monitor distribution across the wafer. Depletion modeling may be used to monitor the power usage to regulate chemical performance and to provide real-time feedback to the system between plated wafers. And an electrochemical oxide indicator provides an impedance indication at the wafer/solution interface. Within a single chamber, multi-metal stacking may be performed. In one such example, a copper layer can be deposited, a rinse performed, a nickel layer is then deposited, and finally a palladium cap, all without removing the wafer from the cell. Although these steps are typically performed sequentially, different metals may optionally be co-deposited.

The cell generally provides the capability to be tilted and/or oscillated. In one embodiment, the cell is tilted in a first direction and is filled from the bottom. The entering chemistry then sweeps all gases out of the cell as it fills. During operation, the cell generally oscillates (either regularly or randomly), providing mechanical agitation for increased plating uniformity and elimination of standing wave nodes. The cell also generally oscillates during rinsing. The cell may tilt at any desired angle or multiple angles during plating if required, assisting with gas and bubble removal. The cell generally tilts in a second

direction to drain the rinse waste, thereby ensuring complete drainage and simplifying the chemistry connections to the cell.

Figure Ig illustrates side and perspective views of an exemplary plating computer 100 of the invention. The top right perspective of view of the plating computer 100 shows a substantially planar platform 153 upon which the plating computer 100 is mounted. An actuator 150 is connected at a first end to a rigid member 154 that is not connected to the platform 153, and is connected at a second end to the platform 153. On an opposite side of the platform 153 from the connection point of the actuator 150, the platform 153 is supported at a particular point, wherein the point has a vertical axis 151. Thus, the actuator 150 may oscillate the platform 153 in the direction indicated by the arrow 152 as the platform 153 moves around the axis 151 of the pivot point. This oscillation provided by actuator 150 may be used to apply a macro movement to the plating computer 100. This macro movement may be used to facilitate draining of fluids from the plating computer 100 and to further stir or agitate the chemical constituents in the plating solution contained in the processing volume 102. hi other embodiments of the invention, additional pivot points and/or actuators may be used to selectively tilt the platform 153 to facilitate minimal bubble adhesion to the substrate surface, for example.

The wafer chuck or support member 104 may be rotated, either during operation to shear the chemistry, thereby increasing uniformity, and/or after processing in order to dry the wafer (in which case spinning generally is performed at approximately 1500 rpm). The chuck 104 generally spins by insertion in a hollow-shaft rotary motor. In this embodiment, the wafer is disposed on the chuck. The chuck 104 moves slightly vertically upwards to provide contact between the wafer and the contact ring 114 for processing. For rinsing, the chuck 104 is lowered down for spinning. This process also ensures that the contact ring 114 is also rinsed. For increased process control, the chemistry may be jetted through holes or slots in the anode 110, or alternatively through one or more openings in an ultrasonic transducer ring (described below). In either case, the chemistry to be jetted may be recirculated from the chamber after initial use. The distance from the anode to the wafer (cathode) may also be adjustable, generally from about 0.8" to about 1.8". This may be accomplished manually via mechanical means such as a thumbscrew, or automatically via a programmable solenoid. The anode segments are generally controlled by a multiple channel rectifier which controls the distribution of each channel. This anode provides the ability to plate with forward current, and the reverse plating enhances the uniformity morphology of the bump surfaces.

Figure 11 illustrates a side sectional view of an upper portion of a processing cell of an exemplary plating computer 100 of the invention. The anode 110 may include a plurality of anode segments 1 10a, 110b, and 11 Oc. The anode segments generally include conductive members that are each in communication with an individual power supply terminal 1 1Od. Thus, each of the individual anode

segments 110 may be individually powered and controlled. The upper portion of the processing cell 100 may also include one or more sensors 111. Additionally, the electrolyte solution used in the plating process may also be circulated through the processing volume 110 in a manner that forces the electrolyte through holes, apertures, or slots formed in the anode 110. As such, the electrolyte used for the plating process may be forced through the anode 110 towards the substrate being plated in a manner that is similar to a high pressure nozzle.

Figure Im illustrates a partially exploded perspective view of an exemplary rack or chassis system 170 for a plating computer 100 of the invention. The rack 170 may include an enclosure 173, a substrate insertion window 172, and an interior volume 174 configured to contain the plating computer 100. A control system 171, such as a computer, may be used to control various features and processes of the plating computer 100. A detachable chemical supply tank 175 may be mounted proximate the rack 170 and may be removable therefrom.

The plating computer of the present disclosure is revolutionary in that it utilizes a single chamber to handle all metal deposition steps as well as all pre-cleaning and interim cleaning through the total process. Today's plating tools all use a series of separate tanks for the plating chemistry, cleaning chemistry, and rinsing operations. Much of the cost is robotics that enables very fragile wafers up to

300mm in diameter to move between tanks without damage.

An advantage of a single cell plating concept is that the environment over the wafer can be controlled to avoid oxygen entering the cell and causing oxidation between metal steps. Given that the industry is moving to more complex multi-metal flip chip bumping and wafer scale packaging interconnect, this tool offers major advantages in reduced handling, faster plating times as the cycle time to move wafers around the tool are eliminated and chemistry has to travel a very short distance to the cell from the tank enabling less risk of leakage of hazardous chemistry. An enlarged view of multi-metal bump Cu + Ni + PbSn and an array of copper bumps capped with solder is shown in Figure 18. This new single-cell embodiment is referred to as a plating computer since it enables the first complete plating process to be done all in a single chamber while moving both chemistry and subsequent rinse water past the wafer and not the wafer to the chemistry. This enables a new level of programmable recipes and repeatability due to the predictability enabled by having better feedback, feed-forward, and eventually predictive measures based on constant monitoring of the total process sequence and chemistry and electrical conditions, material, and environment.

Some advantages and preferred features optionally include: Reduced wafer handling and breakage as the total wafer plating and rinsing steps can be completed without moving the wafer step to step once loaded into the tool; More efficient single cell capacity enabling faster ROI and reduced capital

costs with much quicker payback; Capability to now program recipes in spreadsheet format and modify for any process changes or sequence changes as well as import to other machines with same results -just like a spreadsheet or program on a computer.

The difference with this tool versus other multi-tank systems is that very precise control and real- time monitoring as well as controlled environment are generally enabled; Plug and play chemistry tanks or "ink-jet plater" concept where much smaller tanks with denser metal-ion chemistry mixture are generally used that enable changing of tanks without a long heat-up process and much better tool uptime, the smaller tanks are designed for the shorter production runs but can still handle longer runs by using same chemistry in multiple tanks, the system monitors the tanks for metal-ion depletion and general degradation of chemistry to the point where it signals that the tank must be replaced; Much more consistent and repeatable process control with real-time in chamber and external monitoring of the chemistry and the plating cell with in-cell sensors; Active tilting agitation for the most active rinsing and cleaning of the cell chamber and wafer between metal depositions or pre and post rinse, this tilting agitation is not done in tools today and represents a very cost effective way to clean a large cell area with the least amount of water; and Fill and plate - the system is also designed to minimize chemistry leakage typically seen by constant circulation of hot fluid through long runs of tubing, this tool will fill the chamber with chemistry and plate using the same chemistry for the total process time or will periodically change the chemistry enabling the use of less electricity in heating the chemistry, pumping the chemistry and generally increasing the costs by moving so much fluid volume. Additionally, one single unit does multiple functions: Pre treat, plating, rinsing, drying; Replaces multiple footprint, robot, capital expense; Closed-cell generally provides inert gas to prevent oxidation; Plating-like open-cell; Software Program "Inteliplate"; Intelligent software receives feedback from metrology sensors in cell and in tank to adjusts plating parameters in the rectifier for constant plating rates; and Dual function conductivity sensor to advise when the cell is full and determine the concentration. The single unit also provides for Nanoparticle Plating-adding metallic particles to the chemicals to facilitate and improve uniformity after reflow; Strata Plating Processes where multiple layers of plating are formed using different chemicals in predetermined sequence, which dramatically speeds up plating processes as a result of the elimination of mass rinsing and requalification before a different layer can be deposited, as with convention plating systems. In general, improved performance includes uniformity of thickness, chemical efficiency, fast run rate of manufacturing as well as quality of deposited materials from the electroless electrolyte to the wafer surface in particular to the uniformity of distribution. Existing methods utilize temperature and chemical control in electroless plating to bring even plating results. Temperature is a key parameter influencing the plating process. Electroless plating happens at a wide range of temperatures once a bath

contacts an appropriate substrate. Manipulating temperature of a bath is a time response procedure, therefore, relying on temperature control for electroless plating is limited to a certain extent. Electrical contact with a very low power circuit provides a fast switch of stop/start for electroless plating, which opens capability of accurate control of electroless processes. Ultrasonic Agitation Conventional processes for electroplating silicon wafers and other electronic substrates produce plated deposits which vary in deposit height across the wafer surface. This is due in part to variations in the concentration of metal ions in the boundary layer immediately over the growing metal deposit. Agitation, such as boundary layer agitation, may be configured to be provided by the use of ultrasonic transducers. Existing methods utilize a single frequency generator and transducer to vibrate electrolytes to cause fluid exchange at the wafer surface. However, mass transfer and energy transfer in micro-scale are the key contributors to electroplating speed and power efficiency. To a certain material deposition on a specific geometry feature, a certain range of vibrating frequency, amplitude, and hardware configuration can optimize mass and energy transfer. A wider range of vibrating frequency generator, transducer, and operation model (vibration model and configuration model) optimize process parameters such as frequency range, power range, and connection of transducer to substrate or substrate holder for a particular process. This agitation disrupts the boundary layer stratification, inducing micron scale turbulent mixing, by driving multiple sonic frequencies through the plating electrolyte and across this boundary layer interface. In addition, there are air molecules directly at the wafer surface that are generally displaced to achieve strong and uniformed plating results. This disclosure generally enhances the ability to break the surface tension on the wafer to facilitate, as well as expedite, the electroplating process.

The sonic energy may be directed upward through the underside of the wafer, downward at the wafer surface, or across the wafer surface parallel to the plane of both the boundary layer and the wafer. The sonic energy is not a constant periodic pure function alone, but may consist of either a combination of a continuous periodic function and continuous multiple superimposed frequencies across the audible sonic range ('white noise') and the transonic range, or of a train of short duration-pulsed sonic energy packets in the audible sonic and/or transonic frequency ranges. In this technique, subsonic, sonic, ultrasonic and mega-sonic waves can be introduced into a liquid system, or systems to generate uniformly distributed energy, mass, and momentum in the system or systems. Applications include cleaning, electroplating, electroless plating, mixing purposes to be used in semiconductor, MEMS, miniaturization, and nanotechnology manufacturing. Waves can be introduced into the system or systems from any directions through holding, facilitating, and/or functioning materials. Waves can be original generated, amplified, direct, pulsing, with/without same amplitude, constant, and/or interval. Waves can be introduced by piezo, magnetic, horn, single, multiple, and/or transducers

with/without waveguides. The method provides for introducing energy and/or momentum into liquid systems and near solid surfaces to generate a uniform distribution of energy, momentum and mass in a macro-scale transfer up to the system dimension and in a micro-scale down to the nanometer level. One or more transducers may be coupled on the back of a holder, wafer chuck, substrate base, anode, electrode, horn, ring, weir, pad, frame, or screen to introduce waves into liquid systems and near solid surface and solid-liquid interface. The transducers may include a piezo-magnetic material. The waves produced may include a single frequency, multiple frequencies, and/or a range of sweeping frequency waves which may be controlled individually or simultaneously. The electrolyte may include a solution, colloid, liquid bulk majority, or particle suspension liquid, and may include water with or without metal ions, or metal particles, organic additives, or be neutral, acidic, or alkali. The part being vibrated and/or the solid surface may include metal, plastic, ceramic, Si, and/or glass. The near solid surface may be configured to be in the range of a few nm to several tens of μm. The solid-liquid interface may be configured to be in the range of nm. The solid surface may include one or more materials and may be flat or include a feature size ranging from a nm to 100 μm. Micro-solid agitation is preferable, because it promotes mass and energy transfer of plating materials to ensure plating material quality. With small micro or nano sized features, macro-mechanical agitation can not reach the mass/energy transfer efficiently, and unexpected reactions cause lower deposition quality and power efficiency. On the other hand, micro-solid agitation can penetrate into micro-feature and reach optimized mass/energy transfer. A wider frequency range of wave generator and transducer and power supply enable the optimization of frequency and amplitude conditions for plating system that include deposition material, chemicals, cell configuration, and substrate. Transducer coupling to plated objects and macro-agitation hardware provide more paths to modulate micro-solid agitation efficiency.

Operation models that eliminate standing wave nodes and their generated non-uniformity of plating material distribution may be used. Micro-solid agitation also opens the door to optimize related applications, such as physical and chemical cleaning, degassing, etc. Finally, micro-solid agitation enables solid nano-plating. Agitation improves uniformity of thickness, power efficiency, fast run rate of manufacturing as well as quality of deposited materials from the electrolyte to the wafer surface, in particular the surface of deep vias larger than 80 μm and having a high aspect ratio. In an exemplary embodiment, shown in Figures 2-5, two types of ultrasonic transducers are generally utilized. First, one or more (generally three) horns are located in the base of the cell. In addition, a ring may be configured to be disposed within the plating chamber between the cathode (wafer) and anode. The ring or band generally provides stainless steel and a plurality of slots. Each transducer generally provides an optimal frequency. Some frequencies may increase adhesion between the wafer and

the plating metal. Software controls may be employed to vary the frequencies to optimize the process, for example, by sweeping the frequencies to eliminate standing waves. Agitation also generally increases deposit uniformity, mass transfer, rinsing efficiency, degassing, etc. The ultrasonic transducers may also optionally be used for via activation and cleaning of the wafer and/or cell. In order to accommodate this vibration, the wafer chuck may optionally be mounted on a support base using shims, which provide some "give" during vibration.

The one or more electromechanical transducers are generally controlled by an electronic waveform generator capable of producing both pure periodic and arbitrary electrical waveforms. The transducers are generally connected to a vibrating surface by one or more stiff rods and/or a circular ring surrounding the entire wafer being processed constructed from non-magnetic material. The connecting rod members and ring are generally sufficiently low in mass so as not to attenuate the waveform being conveyed to the vicinity of the wafer. The rods and ring are also generally sufficiently stiff so as to convey the intended waveform(s) with fidelity. The transducer and connecting rods may be situated directly under the wafer itself, conveying sonic energy to the wafer via the wafer support, wafer platen or wafer chuck. In this particular embodiment, the vibrational energy imparted to the wafer support by the transducer and rods move upward through the wafer support into the wafer itself, causing the wafer to be translated vertically in a manner synchronous to the movement of the transducer. The range of translation distance (waveform amplitude) generally lies between 1 micron and 200 microns.

A second means of imparting vibrational energy to the wafer is to couple the transducer and connecting rod to the side wall of the plating cell or the wafer support in a manner such that the direction of motion is parallel to the wafer surface. Due to the fragile nature of wafers, the transducer force may be configured to be not coupled directly to the wafer support but rather to the wafer platen or wafer chuck, which in turn conveys the vibrational energy to the wafer itself. This sonic energy may be configured to be directed from the outer diameter of the wafer entirely through to the center. The medium for the transfer of energy is directly through the chemical to the wafer surface giving superior agitation for maximum electroplating. The effect of the vibrational energy in this case is to rapidly translate the wafer back and forth in the direction of the wafer plane, generally with an amplitude of between 1 micron and

200 microns.

In a third means of practicing this disclosure, the vibrational energy is imparted to the wafer in both axes simultaneously or in various sequences dictated by process considerations by the action of two separate transducers, one mounted directly below the wafer and the other mounted to the side of the wafer. The precise optimum vibrational frequencies will vary with the wafer size and the dimensions of the surface features on the wafer which are being plated. The frequencies employed generally in a range of between about 10 Hz and about 21 kHz, or between about 17 kHz and about 29 kHz. Pure periodic

frequencies by themselves are generally not employed in this disclosure in order to avoid the creation of harmonic resonance and/or standing waves inside the closed plating chamber. Rather, a mixture of superimposed frequencies out of phase with one another ('white noise') may be configured to be employed in combination with various periodic functions. The application of vibrational energy may be applied continuously during the electroplating duty cycle, or may be pulsed periodically.

The stiff wafer platen support structure generally accomplishes two functions: facilitating direct attachment of the wafer through vacuum, mechanical connection or other means, and being sufficiently stiff and of a construction such that the vibrational energy is conducted throughout the entire wafer in the same way (e.g., there should be as little flexure in the wafer platen and the wafer as is possible). The connector rod or pedestal is located between the wafer/wafer platen and the transducer. The connector rod may be configured to be connected firmly to the wafer platen support in such a manner that the vibrational energy of the transducer is conveyed faithfully and with a minimum of attenuation to the wafer. The connector rod should ideally be constructed of a non-magnetic mechanically-stiff material with a low moving mass such as, but not limited to titanium. The materials comprising the connection hardware to and from the transducer are generally mechanically stiff and have a low inertia. The hardware should also ideally be non-magnetic and non-inductive so as not to impact the quality of the plating deposit on the wafer or substrate.

The transducer may be configured to be firmly connected to the opposite end of the connector rod or pedestal. The transducer may be configured to be supported firmly and fixtured in such a way that nearly all of the kinetic energy of the transducer is directed into the wafer platen fixture. Either a magnetostrictive or a piezoelectric transducer may be used. Magnetostrictive transducers are characteristically operated at between about 0 and about 10 V. Piezoelectric transducers are characteristically operated at between 0-400V. A magnetostrictive transducer is a preferred embodiment over a piezoelectric transducer due to the greater reliability of the magnetostrictive transducer, the higher force constant of the magnetostrictive transducer, the lower operating voltage of the magnetostrictive transducer and the flatter response of the magnetostrictive transducer to temperature changes, when compared to a piezoelectric transducer. The transducer may be configured to be driven by a programmable arbitrary waveform generator capable of supplying both periodic and arbitrary waveforms generally in a frequency range between about 1 Hz and about 21,000 Hz. The waveform generator may be directly programmed or may be controlled by software working as one component of the plating device control system.

The transducer may be incorporated in an arrangement much closer to the wafer platen or directly under the wafer platen or integrated with the wafer platen. However, the electrical field generated by the transducer device may possibly couple with the electrical field above the wafer in the wafer cell, which

may impact the process consistency of the wafer plating process. The amplitude and density of vibrational energy coupled to the wafer may be increased by adding or subtracting one or more supplementary transducers to the primary transducer, oriented either in the same axis or along an axis at a right angle to the primary transducer. This disclosure could also be employed in electroless (autocatalytic) metal plating to increase the plating rate, remove gas bubbles evolved from the surface being plated, and create a more homogeneous plating deposit thickness distribution. The transducers are generally operated during the wafer plating process when the plating reactor cell is flooded with plating chemistry and the anode current is on (in the case of electrolytic plating) or the reactor cell is at the optimum process temperature (in the case of electroless or autocatalytic plating). The use of ultrasonic transducers is one aspect of providing solid state energy used for various plating and cell operation kinetics. The advantages of this technology drive a key differentiation for the present disclosure as they enable a wide range of functions beyond just the typical focus on plating functions. For example, the chamber design for directing energy to proper surface and the process expertise to know what energy to apply to what process and how to control properly for the required results with feedback, feed-forward, and predictive process control are provided by the present disclosure. Additionally, the software, measurement, and control expertise to know how to manage complex transducer outputs using DSP electronics ensuring expected waveforms and energy, and control software in real-time mode are facilitated by embodiments of the disclosure.

Further still, the present implementation of leading edge unique solid state Directed Energy Plating (DEP) controlled multi-frequency, multi-mode system is the ability to provide real-time feedback and feed-forward functions. The next step of predictive process monitoring and utilizing the sonic waves as "sonar" is to detect chemistry density and condition as well as metal thickness levels. The key process kinetics that should be expected from the present disclosure using this energy are powerful as they enable a lower cost cell with less chemistry flow and use as well as improved plating rates and product quality. Two broad ranges of frequencies are of interest, although other frequency ranges may be used. For example, frequencies of about 20 to about 20KHz may be used for general plating, soft metals, and agitation, where frequencies of about 500KHz to about 2MHz may be used for fine feature, fine pitch, and wafer cleaning, likely thru-via plating. For example, this later frequency range may be used for boundary layer agitation and via activation at the wafer level, via cleaning and initiation, cell wall and chamber cleaning, chemistry stirring and particle diffusion throughout bath, cavitation at metal layer to initiate for next layer plating, mixing of layered metal layers using our layered plating process, measuring bump height or film thickness using sonar measurements, adhesion promotion, plating rate acceleration, and/or thru-via plating diffusion stirring inside via well as well as wafer boundary layer.

The following summary details the research and experiments done by plating, transducer, and university groups looking for improved plating using high frequency energy waves. These results most typically involve small areas and small samples. The present disclosure may be used to extend these results over a larger 200mm or 300mm wafer surface as well as controlling using different frequencies. The method includes application of a uniform and controllable waveform energy - wafer backside, front side, and laterally across wafer face and selectively providing feedback based on different wafer metallization and surfaces. The method may further include measuring the resulting waveform and energy to ensure it is repeatable and calibrated. The method may further include a self-test of the system with a dummy or no load to ensure proper operation. Key process kinetics are wafer boundary layer agitation and via filling, cell chamber surface cleaning, and particle mixing and suspension in solution. Similar to pulse plating for rectifier control, a preferred approach for widespread ultrasonics waveform and frequency control is to use Pulse Shape Response Optimization using DSP controllers and software as well as feedback technology. Novel DSP sonic technology may include: Real-time continuous ultrasonic monitoring; Simplified mechanical coupling between transducers and chamber; Higher performance achievable with low cost transducers; Much larger equivalent bandwidth; No need for hard damping to shorten system pulse response; Modern DSP techniques applied to ultrasonic measurements and diagnostic Contact Ring Technologies.

Figure 4 illustrates a perspective view of a side ring 400 for an exemplary plating computer of the invention. The side ring 400 is generally positioned in the processing volume 102 at a position proximate to the perimeter of the substrate being plated. The side ring 400 may be attached to an interior surface of the plating cell 100 at a first point 401 and attached to a transducer at a second point 402. A plurality of apertures 403 may be formed into the side ring 400 to allow plating solution to flow there through, while also preventing harmonic oscillations from occurring in the side ring 400. Figure 5 illustrates the positioning of the transducers 108 and the side ring 400. The means of making electrical contact to the seed layer of a semiconductor wafer which is processed in an electroplating reactor for the result of deposition of metal to the working surface of the wafer devices is typically known as a contact ring. Wafers are typically prepared for electrodeposition of metal by first applying a seed layer by other methods to the surfaces of the wafer that receive subsequent electrodeposition of metal. Over the active area of the wafer, the seed layer may be patterned by photolithography methods to expose a pattern of seed layer to the electrolyte. The photo resist is removed from the outer edge of the wafer to provide a zone for making the electrical contact. The zone at the outer edge of the wafer is called the exclusion zone and is limited to about 1.5mm or 2.5mm annular width from the edge of the wafer toward the center. The exclusion zone is the area in which electrical contact is made. The exclusion zone may be sealed from exposure to the electrolyte to protect the contact/seed layer

interface. The amperage density at the contact/seed layer interface is relatively high compared to the rest of the wafer. If electrolyte is present at the interface the seed layer may be eroded creating an island of seed around the contact and therefore interrupt conduction through the seed layer to the rest of the wafer.

The wafer contact ring of the present disclosure generally provides one or more of the exemplary embodiments described below. These technologies provide a better exclusion zone seal and a more robust electrical contact, but with less masking of the wafer itself (i.e. minimization of the exclusion zone area).

This single unit contact ring seals to contain chemicals on the wafer while separating and protecting the electrical contact point within the same part.

Figure 6 shows a cross section of the reactor cut through its center on a vertical plane. The electrolytic fluid body is contained between the wafer and the convex anode. A voltage or current potential is applied to the anode and the contacts at the wafer are grounded. The substrate 600 is in communication with the contact ring 1 14. The contact ring 1 14 includes an annular seal 601 positioned radially inward of a plurality of electrical contacts 602. Each of the electrical contacts 602 are positioned to electrically contact an outer perimeter portion of the substrate 600 to apply a plating bias thereto to support the electrochemical deposition process. Figure 7 is a detailed cross section taken through the contact ring 114 subassembly shown packaged in Figure 6. Figure 8 is a detailed cross section of Figure 7 zoomed up on the contact/seal/wafer interface. Figure 9 is an isometric view of an exemplary buss ring 900 that communicates electrical current to each of the contacts of the contact ring 1 14 that mate with the wafer seed layer in the exclusion zone. In operation, the wafer may be configured to be forcibly mated with an o-ring contained in a gland just inboard of the contacts. The o-ring makes a seal to the wafer surface inboard of the exposed seed layer to prevent electrolyte exposure to the contact/seed layer interface. The contacts generally include spring loaded pogo pins, which in this embodiment are commercially available test probes. The pogo pins are generally capable of an axial stroke of 1 mm against the force of a spring contained within each pogo pin. The compliance of the axial stroke in the pogo pin allows the wafer to seek a sealed position against the o-ring while still making contact with the conductive portion of the pogo pin/seed interface. The ring contact subassembly generally contains 4 buss rings 900 as shown in Figure 9 that are generally packaged radially in each of 4 respective 90 degree quadrants. Each buss 900 generally provides 9 pogo pins arrayed radially. A total of 36 pogo pins make contact with the wafer seed layer spaced equally about its 360 degree circumference. The plurality of pogo pins achieves more uniform current distribution to the seed layer which improves the thickness uniformity of the metal deposition. The individual busses 900 are generally insulated from each other electrically thereby providing a means to measure the variability in resistance between each of the 4 quadrants. However, a plurality of busses 900 could be provided that increase the resolution of the measurement. Prior flexure designs are

manufactured by methods that make this discrete bussing and comparative measurement impractical. The relatively large stroke of the pogo pins achieves a compliant electrical interface to the wafer making the design tolerant to variable wafer thickness, machining tolerance, uncertain position of the wafer sealing against the o-ring and reuse of a proven test probe technology employed in a novel application. Prior ring contact designs attempt continuous contacts that make a rigid uninterrupted contact/seed interface. These designs lack the compliant interface that is tolerant of geometric variation described above.

Prior ring contact designs also utilize metal flexures which behave like small cantilevered beams which limit their axial compliance to values less than lmm when constrained to small dimensional envelopes. Rings that utilize metal flexures have higher cost due to complex assembly methods or costly manufacturing methods to form and cut the individual flexures.

Figure 10 shows a cross section of the ring contact cut through its center on a vertical plane. Figure 11 is a detailed cross section taken through the ring contact subassembly showing the wafer in contact with a conductive elastomer. The elastomer is compressed between the wafer and a conductive buss ring 900. The buss ring conducts electrical current to each of the conductive elements in the elastomer. The wafer exclusion zone and conductive elements are sealed from the electrolyte by the nonconductive portion of the elastomer. Figure 12 is a detailed cross section of Figure 1 1 with the wafer removed. Figure 13 is an isometric view of a segment of the conductive elastomer 1200. Conductive elements are co-molded inside nonconductive elastomer in a radial pattern matching the wafer radius.

In operation, the wafer generally is forcibly mated with the conductive elastomer 1200. The nonconductive portion makes a seal to the wafer surface inboard of the exposed seed layer to prevent electrolyte exposure to the conductive element/seed layer interface. The combination of conductive and nonconductive elastomer is capable of axial compliance when squeezed between the wafer and the buss ring 900. The compliance of the axial stroke in elastomer allows the wafer to seek a sealed position against the nonconductive portion while still making contact with the conductive portion of the elastomer interface. The ring contact subassembly generally contains a plurality of segmented conductive elastomers 1200. Each segment may be configured to be arrayed around the circumference of the wafer to provide 360 degree of sealed contacts. The plurality of conductive elements achieves more uniform current distribution to the seed layer which improves the thickness uniformity of the metal deposition.

Integration of the sealing element with the conductive elements of the elastomer eliminates an axial dimensional stack of contact plus seal thereby reducing the axial height of the ring contact from 3 mm to 2 mm which allows fluid agitation elements to be placed in closer proximity to the wafer surface without rubbing on the top of the buss ring 900. It also eliminates a radial dimensional stack of contact plus seal thereby reducing the radial annular dimension required to make the seal and contact to the seed layer within the confines of a narrow exclusion zone. The integrated seal/conductive elastomer generally

provides an industry-available component having proven reliability for electrical contact applications in flat panel display technology. Therefore, a metal fiber, sharp or blunt metal tip (generally made by drawing, molding, etching, or machining) may be configured to be embedded in elastomer, forming a contact/seal assembly and surface with the metal tips slightly shooting out, or sinking in, or at the same surface level of the elastomer to reach a tight liquid seal, insulation between the elastomer and the wafer surface and a good electrical contact between metal tips and the wafer seed metal. The tip optionally provides copper, a copper beryllium alloy, titanium, or steel, and may optionally be coated with gold, platinum, or palladium. The elastomer optionally provides silicone, viton, polystyrene, or polypropylene. The embedded contact/seal assembly may be configured to be made by molding, jetting, extruding, or machining. The electrical contact width from wafer edge toward wafer center may be configured to be about 0.5, 1 , 1.5, 2, or 2.5 mm or any width in approximately that range. The seal width from wafer edge toward wafer center may be configured to be about 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 mm or any width in approximately that range. The tips shooting out or sinking in from elastomer surface are generally approximately 0, 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6 mm or any length in approximately that range. The tips are generally uniform with less than about 0.2 mm variation. The elastomer surface waving may be configured to be uniformly less than about 0.2 mm variation. The tips, elastomer and metal total thickness may be configured to be in the range of about 2 to 8 mm. The relatively large axial compliance of the elastomer achieves a compliant electrical interface to the wafer making the design tolerant to variable wafer thickness, machining tolerance, and uncertain position of the wafer sealing against elastomer. Prior ring contact designs attempt continuous contacts that make a rigid uninterrupted contact/seed interface. These designs lack the compliant interface that is tolerant of geometric variation described above. Prior ring contact designs also utilize metal flexures which behave like small cantilevered beams which limit their axial compliance to values less than lmm when constrained to small dimensional envelopes. Rings that utilize metal flexures have higher cost due to complex assembly methods or costly manufacturing methods to form and cut the individual flexures.

In another embodiment of the disclosure, a half-etched or wire EDM contact and seal ring are provided. This embodiment is the manufacturing of half mini-etched or wire EDM mini-etched metal contact and seal ring to optimize electroplating contact and seal for semiconductor and microelectronics. Improved performance includes optimized contact for uniform distribution of current on plating substrate and low electrical resistance; complete seal without chemical and electrical leakage and high tolerance of pressure and low tolerance deformation of photo resist and seal material; minimized influence of hydrodynamics by seal geometry; and high performance of fluid dynamics and plating reaction kinetics. Existing methods utilize conventional techniques of mechanical and molding processes to make contact and seal parts.

Semiconductor and microelectronics industries have been moving to the early stages of the nanotechnology era, the size of devices and feature size to be processed are continuing to shrink, making contact and seal more and more difficult. Half micro-etch or wire EDM mini-manufacturing generally utilizes MEMS technologies in manufacturing miniature contact and seal for electroplating parts, which enables standardized fast manufacturing of contact, seal, and combination, thus creating accurate dimensions of parts and low tolerance of deviation, high conductance of contact, uniform distribution of current, less seal area, low profile of seal, and high turbulence of fluid.

Figure 14 shows a scheme cross-section of the tip prior to etching. Figure 15 shows a scheme cross-section of the etched mini-contact at the contact tip generally made by a metal or alloy line with or without another metal or alloy utilizing MEMS techniques. Figure 16 shows a scheme cross-section of etched mini-contact with a coating or laminated layer of an insulating seal. Geometry and dimensions may vary. Figure 17 illustrates a perspective view of an exemplary contact ring 114 having a plurality of electrical contact fingers 1700 extending radially inward therefrom. The contact fingers 1700 are generally configured to electrically contact a perimeter or edge portion of a substrate being plated. Figure 17 also illustrates the electrically conductive bus ring 900 that is configured to supply electrical power to the contact ring 114.

The coating material for the contact ring 114 or the bus ring 900 may optionally include PVDF (Kynar), PVC (Tygon), or a material such as Viton. The contact of this embodiment provides continuity of contact ensuring uniform current distribution. A miniature or sharply designed plated contact tip can penetrate surface oxide or other insulation layer of conductive metal or alloy to make low contact resistance. The contact can be manufactured using available MEMS techniques to etch mini-features, or using wire EDM techniques to machine mini-features, and coating/lamination techniques for accuracy, precision, and cost effective manufacturing of contact and seal. The low profile of seal generally allows modulation of uniform fluidic flow on the substrate surface and distribution of diffusion layer thickness. The precision seal generally allows higher tolerance of pressure and improved seal and leakage prevention. Selection of a harder material makes the contact and seal harder to deform while still permitting flexure. As shown in Figure 16, prior to operation the contact ring may be configured to be lowered onto a plurality of circularly-arranged flexure comb fingers to make electrical contact with the power supply. The fingers bend only slightly. When contact is made, the contact tip generally scrapes each finger, thereby removing any oxide on the surface and providing improved electrical contact. The system is therefore self-cleaning.

Figure 19 illustrates a flowchart of an exemplary multi-metal plating method of the invention. The method begins at step 1900 and continues to step 1920, where a substrate is positioned in the processing volume of a plating cell. At step 1902, the substrate is generally positioned on a cathodic

substrate support member that may also provide rotation of the substrate in the processing volume. Once the substrate is positioned on the substrate support member, the plating cell may be closed or sealed in preparation for being filled with an electrolytic solution. At step 1904 the processing volume may be filled with a first plating solution that is configured to plate a first metal layer onto the substrate. For example, the first plating solution may be a solution that is configured to support copper electrodeposition. At step 1906 an electrical bias may be applied between the cathodic substrate support member and an anode assembly position in parallel orientation with the substrate being supported on the substrate support member. The electrical bias facilitates the electrodeposition process and may include both forward and reverse bias, pulses, and other waveforms known in the electrodeposition field. Generally, both the anode assembly and the substrate support member are contained within the processing volume of the plating cell and are immersed in the plating solution contained therein.

Once the electrical bias has been applied for a specified time period, then the plating process for the first metal is generally complete. The method then continues to step 1908, where the first plating solution may be drained from the processing volume. Once the plating solution is drained, the processing volume (and the substrate that remains positioned in the processing volume) may be rinsed or cleaned by introduction of a cleaning solution at step 1910. In one exemplary embodiment of the invention, a cleaning solution introduced at step 1910 may be deionized water. The cleaning solution may also be drained from the processing volume once the cleaning step is completed. The exemplary method may further include the introduction of an inert gas, such as nitrogen or argon, into the processing volume to prevent oxidation of the substrate or metal layers deposited thereon, as noted at step 1912. The inventors note that although the introduction of the inert gas will be beneficial throughout the entire plating process, the inert gas will be especially important during the processes of draining, rinsing, and refilling of the processing volume with a plating solution, as during these processes the substrate is not immersed in a plating solution. At step 1914 a second plating solution may be introduced into the processing volume. The second plating solution may be configured to support electrodeposition of a second metal, such as nickel. At step 1916 a second electrical bias may be applied between the anode assembly and the substrate to facilitate plating of the second metal onto the substrate. Once the deposition of the second metal is completed, the processing volume may again be drained of the plating solution rinsed while the substrate is still positioned in the processing volume, as noted by step 1918. Again, if desired the processing volume may also be flooded with an inert gas as at step 1912. If a third metal layer is to be deposited, the aforementioned process may be repeated. However, if the plating process is finished after the second metal layer, the substrate may also be removed from the processing volume at step 1918, and the exemplary method completes at step 1920.

The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this disclosure for those used in the preceding examples. Although the disclosure has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present disclosure will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above and/or in the attachments, and of the corresponding application(s), are hereby incorporated by reference.

Additionally, the foregoing outlines features of several exemplary embodiments of the invention so that those skilled in the art may better understand the various aspects of the present disclosure. Those skilled in the art will appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art will also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations to the disclosed exemplary embodiments without departing from the spirit and scope of the present disclosure.