WO2001071780A2

WO2001071780A2 - Apparatus and method for electrochemically processing a microelectronic workpiece

Info

Publication number: WO2001071780A2
Application number: PCT/US2001/009149
Authority: WO
Inventors: Kyle M. Hanson; Scott Grace; Matt Johnson; Ken Gibbbons
Original assignee: Semitool, Inc.
Priority date: 2000-03-21
Filing date: 2001-03-21
Publication date: 2001-09-27
Also published as: WO2001071780A3; US6368475B1; US20060191795A1; US20020084183A1; US20060191790A1; AU2001287255A1

Abstract

A method and apparatus for electrochemically processing a microelectronic workpiece. The apparatus can include one or more walls defining a processing space configured to contain a processing fluid. The processing space can include at least a first fluid flow region and a second fluid flow region. A first electrode can be disposed in the processing fluid of the first fluid flow region while a second electrode can be coupled to a portion of the microelectronic workpiece, and can be disposed in the processing fluid of the second fluid flow region. Fluid flow within the first fluid flow region can be directed generally toward the first electrode and away from the second electrode while fluid flow within the second fluid flow region can be directed generally toward the second electrode and away from the first electrode. The first electrode may include either an anode or a cathode. A third electrode can be positioned external to the processing space to clean the second electrode and/or control the electrochemical process.

Description

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APPARATUS AND METHOD FOR ELECTROCHEMICALLY PROCESSING A MICROELECTRONIC WORKPIECE

BACKGROUND

The present invention is directed to an apparatus for electrochemically processing a microelectronic workpiece. More particularly, the present invention is directed to a reactor assembly for electrochemically depositing, electrochemically removing and/or electrochemically altering the characteristics of a thin film material, such as a metal or dielectric, at the surface of a microelectronic workpiece, such as a semiconductor wafer. For purposes of the present application, a microelectronic workpiece is defined to include a workpiece formed from a substrate upon which microelectronic circuits or components, data storage elements or layers, and/or micro- mechanical elements are formed.

Production of semiconductor integrated circuits and other microelectronic devices from workpieces, such as semiconductor wafers, typically requires formation and/or electrochemical processing of one or more thin film layers on the wafer. These thin film layers are often in the form of a deposited metal that is used, for example, to electrically interconnect the various devices of the integrated circuit. Further, the structures formed from the metal layers may constitute microelectronic devices such as read/write heads, etc.

The microelectronic manufacturing industry has applied a wide range of thin film layer materials to form such microelectronic structures. These thin film materials include metals and metal alloys such as, for example, nickel, tungsten, tantalum, solder, platinum, copper, copper-zinc, etc., as well as dielectric materials, such as metal oxides, semiconductor oxides, and perovskite materials.

A wide range of processing techniques have been used to deposit and/or alter the characteristics of such thin film layers. These techniques include, for example, chemical vapor deposition (CND), physical vapor deposition (PND), anodizing, electroplating, and electroless plating. Of these techniques, electrochemical processing techniques (i.e., electroplating, anodizing, and electroless 1 plating) tend to be the most economical and, as such, the most desirable. Such electrochemical processing techniques can be used in the deposition and/or alteration of blanket metal layers, blanket dielectric layers, patterned metal layers, and patterned dielectric layers.

One of the process sequences used in the microelectronic manufacturing industry to deposit a metal onto semiconductor wafers is referred to as "damascene" processing. In such processing, holes, commonly called "vias", trenches and/or other micro-recesses are formed onto a workpiece and filled with a metal, such as copper and/or a copper alloy. In the damascene process, the wafer is first provided with a metallic seed layer which is used to conduct electrical current during a subsequent metal electroplating step. If a metal such as copper is used, the seed layer is disposed over a barrier layer material, such as Ti, TiN, etc. The seed layer is a very thin layer of metal, such as copper, gold, nickel, palladium, etc., which can be applied using one or more of several processes. The seed layer is formed over the surface of the semiconductor wafer, which is convoluted by the presence of the vias, trenches, or other recessed device features.

A metal layer is then electroplated onto the seed layer in the form of a blanket layer. The blanket layer is plated to form an overlying layer, with the goal of providing a metal layer that fills the trenches and vias and extends a certain amount above these features. Such a blanket layer will typically have a thickness on the order of 10,000 to 15,000 angstroms (1-1.5 microns).

After the blanket layer has been electroplated onto the semiconductor wafer, excess metal material present outside of the vias, trenches, or other recesses is removed. The metal is removed to provide a resulting pattern of metal layer in the semiconductor integrated circuit being formed. The excess plated material can be removed, for example, using chemical mechanical planarization. Chemical mechanical planarization is a processing step which uses the combined action of a chemical removal agent and an abrasive which grinds and polishes the exposed metal surface to remove undesired parts of the metal layer applied in the electroplating step.

The electroplating of the semiconductor wafers takes place in a reactor assembly. In such an assembly, an anode electrode is disposed in a plating bath, and the wafer with the seed layer thereon is used as a cathode. Only a lower face of the 2 wafer contacts the surface of the plating bath. The wafer is held by a support system that also conducts the requisite electroplating power (e.g., cathode current) to the wafer.

Several technical problems must be overcome in designing reactors used in the electrochemical processing of microelectronic workpieces, such as semiconductor wafers. One such problem relates to the formation of particulates contamination, gas bubbles, etc., that form at the surface of the anode (or, in the case of anodization, both the cathode and anode) during the electrochemical process. Although such problems exist in connection with the wide range of electrochemical processes, the discussion below focuses on those problems associated with electroplating a metal onto the surface of the microelectronic workpiece.

Generally stated, electroplating occurs as a result of an electrochemical reduction reaction that takes place at the cathode, where atoms of the material to be plated are deposited onto the cathode by supplying electrons to attract positively charged ions. The atoms are formed from ions present in the plating bath. In order to sustain the reaction, the ions in the plating bath must be replenished. Replenishment is generally accomplished through the use of a consumable anode or through the use of an external chemical source, such as a bath additive, containing the ions or an ion- forming compound.

As the thin film layer is deposited onto the cathode, a corresponding electrochemical oxidation reaction takes place at the anode. During this corresponding electrochemical reaction, byproducts from the electrochemical reaction, such as particulates, precipitates, gas bubbles, etc., may be formed at the surface of the anode.

Such byproducts may then be released into the processing bath and interfere with the proper formation of the thin-film layer at the surface of the microelectronic workpiece. Furthermore if these byproducts are allowed to remain present in the processing fluid at elevated levels near the anode, they can affect current flow during the plating process and/or affect further reactions that must take place at the anode if the electroplating is to continue. For example, if copper concentrations are allowed to increase excessively, copper sulfate will precipitate due to the common ion effect. In order to reduce and or eliminate this problem, electrolyte flow near the 3 anode is maintained at a sufficient level to allow mixing of the dissolved species in the electrolyte.

Such byproducts can be particularly problematic in those instances in which the anode is consumable. For example, when copper is electroplated onto a workpiece using a consumable phosphorized copper anode, a black anode film is produced. The presence and consistency of the black film is important to ensure uniform anode erosion. This oxide/salt film is fragile, however. As such, it is possible to dislodge particulates from this black film into the electroplating solution. These particulates can then potentially be incorporated into the deposited film with the undesired consequences.

One technique for limiting the introduction of particulates and/or precipitates produced at the anode into the plating bath, has been to enclose the anode in an anode bag. The anode bag is typically made of a porous material, which generally traps larger size particulates within the anode bag, while allowing smaller size particulates to be released external to the bag and into the plating bath. As the features of the structures and devices formed on the microelectronic workpiece decrease in size, however, the performance of the structures and devices may be degraded by even the smaller size particulates. Furthermore, while the use of an anode bag will restrict the larger particulates from traveling toward the cathode and contaminating the plating surface or affecting the plating process taking place at the cathode, the anode bag will also trap the larger particulates within the proximity of the anode creating elevated levels of these byproducts, which may limit the forward electrochemical reaction taking place at the anode. Still further, the larger particulates can eventually block the porous nature of the anode bag and ultimately restrict even the regular fluid flow.

The present inventors have recognized the foregoing problems and have developed a method and apparatus that assists in isolating byproducts that form at an electrode of an electrochemical processing apparatus to prevent them interfering with the uniform electrochemical processing of the workpiece. 4

SUMMARY

A reactor for use in electrochemical processing of a microelectronic workpiece is set forth and described herein. In one aspect of the invention, the apparatus includes one or more walls defining a processing space configured to contain a processing fluid. The processing space can include at least a first fluid flow ' region and a second fluid flow region. A first electrode can be disposed in the first fluid flow region and a second electrode configured to electrically couple to at least a portion of the microelectronic workpiece, can be disposed in the second fluid flow region. The processing space can be configured to direct fluid flow within the first fluid flow region generally toward the first electrode and away from the second electrode, and direct fluid flow within the second fluid flow region generally toward the second electrode and away from the first electrode. The first electrode can include either an anode or a cathode.

In a further aspect of the invention, the reactor can include a pressure drop member disposed in the processing space in an intermediate position between the first and second fluid flow regions. The pressure drop member can include a membrane that is disposed over an open end of a housing, which can house the first electrode. The membrane can be permeable to at least one of the ionic species in the processing fluid. The housing can have a rim with a downwardly facing channel. The reactor can further include an outlet conduit having an aperture in the downwardly facing channel of the housing to provide a path for processing fluid, gas bubbles, and particulates to exit the processing space. The pressure drop member can restrict movement of these constituents into the second fluid flow region of the housing.

In a further aspect of the invention, the reactor can include a third electrode positioned at least proximate to the processing space and configured to be in fluid communication with the second electrode when the second electrode is cleaned. For example, the third electrode can be positioned adjacent to an outer surface of the at least one wall defining the processing space. The third electrode can at least partially encircle the wall and can include a ring of platinized titanium material.

The invention is also directed to a method for processing a microelectronic workpiece. In one aspect of the invention, the method can include dividing a process space configured to contain a process fluid into at least a first fluid 5 flow region and a second fluid flow region. A first electrode can be located withm the processing fluid of the first fluid flow region and a second electrode coupled to at least a portion of the microelectronic workpiece can be located within the processing fluid of the second fluid flow region. A flow of the processing fluid in the first fluid flow region can be directed generally toward the first electrode and generally away from the second electrode, while a flow of the processing fluid within the second fluid flow region can be directed generally toward the second electrode and generally away from /■ the first electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a cross sectional side view of a plating reactor in accordance with the present invention.

Figure 2 illustrates an isometric view of a conically shaped frame of a pressure drop member for use in the plating reactor illustrated in Figure 1.

Figure 3 illustrates an isometric view of the pressure drop member including the conically shaped frame, illustrated in Figure 2, and a membrane attached thereto.

Figure 4 illustrates an enlarged cross-sectional view of a portion of the plating reactor illustrated in Figure 1.

Figure 5 illustrates an isometric view of one example of a field shaping element for use in the plating reactor illustrated in Figure 1.

Figure 6 illustrates an isometric view of another example of a field shaping element for use in the plating reactor illustrated in Figure 1.

Figure 7 illustrates an enlarged cross-sectional view of a portion of the plating reactor illustrated in Figure 1, with the field shaping elements illustrated in Figures 5 and 6 similarly shown.

DETAILED DESCRIPTION

Figure 1 illustrates a cross-sectional side view of a reactor, shown generally at 10, for electrochemical processing of a microelectronic workpiece in accordance with one embodiment of the present invention. In the particular embodiment of the invention shown here, the reactor is adapted for electrochemical 6 deposition of a metal, such as copper or copper alloy, in the surface of the microelectronic workpiece. Accordingly, the following description includes express references to elements used in such electrochemical deposition processes. It will be recognized, however, that the reactor architecture is suitable for a wide range of electrochemical processing operations including, for example, anodization of a surface of the workpiece.

The reactor 10 has a reactor head assembly 20 that assists in supporting the workpiece during processing, and a corresponding processing space in the form of a reactor bowl assembly 30. Reactor bowl assembly 30 includes one or more walls that define a processing space that contains a processing fluid, as will be set forth in further detail below. This type of reactor assembly is particularly suited for effecting electroplating of semiconductor wafers or like workpieces, in which the wafer is electroplated with a blanket or patterned metallic layer.

The reactor head assembly 20 and the reactor bowl assembly 30 of the illustrated embodiment may be moved relative to one another. For example, a lift and rotate mechanism, not shown, may be used in conjunction with the head and bowl assemblies 20, 30 to drive the reactor head 20 in a vertical direction with respect to the reactor bowl assembly 30 and to rotate the reactor head assembly 20 about a horizontally disposed axis. By lifting and rotating the reactor head assembly 20, a workpiece 45, such as a semiconductor wafer, may be moved between a load position that allows the workpiece 45 to be placed upon the head assembly 20, and a processing position in which at least a portion of the workpiece 45 is brought into contact with processing fluid in the processing space of the reactor bowl assembly 30. When the workpiece is in the processing position, it is generally oriented with the process side down within the processing space. When the workpiece 45 is in the load position, the workpiece 45 is generally exposed outside of the reactor bowl assembly 30 with the process side directed upward, for loading and unloading by, for example, a robotic wafer transfer mechanism. One example of a suitable lift and rotate mechanism is described in connection with U.S. Patent Application Serial No. 09/351,980, filed July 12, 1999, entitled "Lift and Rotate Mechanism for Use in a Workpiece Processing Apparatus", the disclosure of which is incorporated herein by reference. — 7

Preferably, the reactor head assembly 20 includes a stationary assembly 50 and a rotor assembly 55. The rotor assembly 55 is configured with one or more structures that serve to support the workpiece and to rotate the workpiece 45 about a generally vertical axis during, for example, workpiece processing.

In the reactor embodiment of Figure 1, the workpiece 45 is held in place, with respect to the rotor assembly 55 by contact assembly 60. In addition to holding the workpiece 45 in place, the contact assembly 60 may include one or more electrical ^■ contacts that are disposed to engage the workpiece 45 for applying electrical power used in the electrochemical processing operation. One embodiment of a contact assembly is described in detail in connection with U.S. Patent Application Serial No. 09/386,803, filed August 31, 1999, entitled "Method and Apparatus for Processing the Surface of a Microelectronic Workpiece" the disclosure of which is incorporated herein by reference. It will be recognized, however, that other contact architectures, such as discrete finger contacts or the like, are also suitable depending on the desired electrochemical processing that is to take place in the reactor 10. One such architecture is a J-hook design described in connection with U.S. Patent Application Serial No. 08/680,057, filed July 15, 1996, entitled "Electrode Semiconductor Workpiece Holder", the disclosure of which is similarly incorporated herein by reference.

During processing, the workpiece 45 is brought into contact with processing fluid located within the reactor bowl assembly 30. In the illustrated embodiment, reactor bowl assembly 30 comprises a reactor base assembly 65 that, in turn, includes process cup assembly 75 and an electrode housing assembly 70. The process cup assembly 75 includes a plurality of wall structures that define a processing space therebetween. The electrode housing assembly 70 is located within the process cup assembly 75 and includes therein an electrode 105 used in electrochemical processing of a workpiece 45.

Generally stated, the processing space within the process cup assembly 75 includes at least two process fluid flow regions. The first fluid flow region is proximate the upper end and interior to the electrode housing assembly 70 while the second flow region includes the region at the upper end of processing cup 75 proximate workpiece 45. As will be explained in further detail below, processing fluid 8 flow in the first fluid flow region is generally directed toward the interior of the electrode housing assembly 70 and, more particularly, toward a surface of the electrode 105, and generally away from the workpiece 45. In contrast, the flow of processing fluid in the second fluid flow region is generally directed toward the workpiece 45 and generally away from electrode 105. One arrangement of structures that can be used to accomplish this fluid flow pattern is described in detail below.

The electrode housing assembly 70 of the illustrated embodiment ^■ includes a housing member 72, which is generally bowl shaped and includes an end that is open toward the workpiece 45. A pressure drop member 90 is disposed over the open end of the housing member 72. The pressure drop member 90 assists in dividing the processing space into the aforementioned first fluid flow region 95 and second fluid flow region 100.

The housing member 72 may have a lip 80 located at the opening or the rim thereof that extends radially inwards and then downward toward the base of the assembly. The lip 80 may have a cross section in the shape of an inverted "u" that defines a space 85 located therein, which extends around the circumference of the electrode housing assembly 70. The lip 80 may serve as the locus of the engagement between the housing member 72 and the pressure drop member 90. Together, the housing member 72 and pressure drop member 90 define an interior electrode chamber in which the electrode 105 is disposed. The electrode 105 can be coupled to a source of positive electrical potential to operate as an anode, or the electrode 105 can be coupled to a source of negative electrical potential to operate as a cathode, depending on the electrochemical process performed on the microelectronic workpiece. In some embodiments, the electrode 105 can sequentially operate as an anode and a cathode during the same process.

In any of the foregoing embodiments, the pressure drop member 90 may be conically shaped, and can have an apex oriented so as to extend downward into the interior electrode chamber. To this end, the pressure drop member 90 may comprise a conically shaped frame 110, and a permeable membrane 115 that is fixed with the surface of the conically shaped frame 110. The conically shaped frame 110 is particularly illustrated in Figure 2 while the conically shaped frame 110 with the membrane 115 fixed thereto is particularly illustrated in Figure 3. The membrane 115 9 may be fluid permeable or only permeable to at least one of the ionic species in the processing fluid. In this latter instance, the reactor may be augmented with separate inlets and outlets respectively associated with each of the fluid flow regions.

Figure 2 is an isometric view of the conically shaped frame 110 of the pressure drop member 90. The conically shaped frame 110 can include a continuous circular base member 120, and a plurality of ribs 125 which extend between the circular base member 120 and the point 130 of the conical shape. In the frame 110 at the place where the point 130 of the conical shape would be located, the conically shaped frame 110 can include a circular opening 135. The opening 135 in the frame 110 can reduce the volume of frame material near the point 130 of the conical shape, which might otherwise trap fluid and/or substantially restrict fluid or current flow.

Located around the circumference of the circular base member 120 of the conically shaped frame 110 is a protrusion 140, which extends outward from the circular base member 120 and is adapted for engaging a groove 145 located in the inverted u-shaped lip 80 of the electrode housing assembly 70 (shown more clearly in Figure 4).

Figure 3 is an isometric view of the pressure drop member 90, including the conically shaped frame 110 illustrated in Figure 2, with the membrane 115 attached thereto. The membrane 115 may be comprised of a plastic filter type media, or other media that at least partially restricts the flow of processing fluid flow therethrough. The membrane 115 can also assist in preventing larger size particulates, precipitates, and/or gas bubbles from crossing the pressure drop member 90 and the second fluid flow region.

The membrane 115 can be formed into a conical shape, by cutting a triangular pie-shaped notch in the membrane material. The resulting edges formed by the triangular shaped notch may then be joined and held together with, for example, a single ultrasonic weld seam 150. The membrane 115 can then be attached to the conical shaped frame 110 using a similar ultrasonic weld along the ribs 125 and the continuous perimeter of the circular base member 120.

The circular base member 120, ribs 125 and membrane 115 can be formed from polypropylene, polyethylene, polyvinylidene fluoride, or other 10 fluorocarbon type plastic. Such plastics are generally chemically inert with respect to the processing which is likely to take place in the plating reactor 10.

In an alternative embodiment, the pressure drop membrane can be formed from a sufficiently resilient membrane which does not require an underlying frame structure. Further alternative embodiments include the pressure drop member being formed from a pressed disk of porous ceramic or porous glass.

Referring back to Figure 1, the plating reactor 10 can further include a fluid inlet 155 located within a riser tube 160 near the bottom of the cup assembly 75 for receiving processing fluid. The processing fluid is generally received from a fluid reservoir located external to the plating reactor 10.

The processing fluid received via the fluid inlet 155 initially enters the second fluid flow region 100 of the cup assembly 75 via the space 165 formed between the electrode housing assembly 70 and the cup assembly 75. The processing fluid generally follows a flow corresponding to the direction of arrows illustrated in Figure 1. While in the second fluid flow region 100, the processing fluid comes into contact with the workpiece 45 when in a processing position.

By placing the anode 105 in the first fluid flow region 95 within the electrode housing assembly 70 and having the processing fluid enter the cup assembly 75 via the second fluid flow region 100, the anode 105 is isolated from the fluid flow when the processing fluid initially enters the cup assembly 75. Correspondingly, the processing fluid does not directly impinge upon the anode 105, which may be a consumable anode. As a result the useful life of the anode 105 can be prolonged.

In connection with the electrode housing assembly 70, the plating reactor can include a fluid outlet tube 165, for example, a circular tube. The fluid outlet tube 165 has an opening 170, which extends into the space 85 formed within the inverted u-shaped lip 80 of the electrode housing assembly 70 to evacuate fluid from the first fluid flow region 95. Accordingly, fluid can flow from the second fluid flow region 100 through the pressure drop member 90 into the first fluid flow region 95 under the force of gravity. The fluid level will tend to rise within the first fluid flow region 95 until the fluid enters the inverted "u" shaped space 85. Fluid within the space 85 will flow circumferentially around the pressure drop member 90 until it reaches the fluid outlet tube 165. The fluid will then enter the opening 170 and drain 11 through the outlet tube 165. Accordingly, the addition of processing fluid into second fluid flow region 100 via the fluid inlet 155 and the exit of fluid from the first fluid flow region 95^*via the opening 170 in the fluid outlet tube 165, creates a pressure differential between the first fluid flow region 95 and the second fluid flow region 100 in which the pressure in the first fluid flow region 95 is lower than the pressure in the second fluid flow region 100.

The pressure drop member 90 provides some resistance to the flow of fluid across the semi-porous membrane 115. As such, the pressure equalizing flow of processing fluid is somewhat restricted. Restricting the flow of fluid across the pressure drop member 90 can have several effects. For example, the flow of process fluid across the pressure drop member 90 can be distributed more evenly along the surface of the pressure drop member 90. Further, the restricted flow can facilitate the formation of a pressure differential between the first fluid flow region 95 and the second fluid flow region 100. Because the pressure in the second fluid flow region 100 is maintained at a level that is slightly higher than the pressure in the first fluid flow region 95, fluid flow from the first fluid flow region 95 into the second fluid flow region 100 across the pressure drop member 90 is unlikely. The pressure differential, in turn, effectively restricts passage of any byproducts formed at electrode 105 during the electrochemical reaction to an area within the first fluid flow region 95 and assists in preventing such byproducts from reaching the surface of the workpiece 45. Rather, the byproducts generated within fluid flow region 95 can be directed from the processing space through the fluid outlet tube 165. Such an arrangement can allow the processing fluid overflowing weir 180 to be handled separately from the processing fluid exiting fluid outlet 165. Special filtering or processing of the processing fluid exiting the first fluid flow region 95 may remove any of the unwanted byproducts before the processing fluid is mixed and/or processed with the processing fluid overflowing weir 180 for recirculation to the plating reactor 10 via the fluid inlet 155. As a result, exposure of the workpiece 45 to potentially harmful byproducts produced at the electrode 105 can be substantially limited and/or can more easily be controlled than with reactors lacking the features described above.

Because the pressure drop member 90 can be conically shaped and can extend downward into the electrode housing assembly 70, it can have a surface at the 12 interior electrode chamber that is oriented at an angle. In one aspect 01 mis embodiment, the angle at which the surface of the pressure drop member 90 extends radially outwardly is selected so that the highest point of the pressure drop member 90 is proximate to the u-shaped lip 80 of the electrode housing assembly 70. The angled surface of the pressure drop member 90 can accordingly direct any particulates, precipitates or gas bubbles formed at the electrode 105 away from the center of the electrode housing assembly toward the periphery and into the space 85 within the u- shaped lip 80 of the electrode housing assembly 70. Not only can the angled surface of the pressure drop member 90 move the byproducts away from the center of the processing area where they can otherwise adversely affect uniform current flow, the pressure drop member 90 can also assist in driving the byproducts toward the opening of the fluid outlet tube 165. Eventually the particulates, precipitates and/or gas bubbles exit the cup assembly 75 along with the processing fluid via fluid outlet tube 165. This is more clearly shown in connection with Figure 4.

Figure 4 illustrates an enlarged cross-sectional view of an upper portion of the electrode housing assembly 70 of Figure 1. More particularly, it illustrates the portion of the reactor bowl assembly 30 at which the pressure drop member 90 engages the u-shaped lip 80 of the electrode housing assembly 70, and also illustrates the fluid outlet tube 165 and the opening 170 that facilitates fluid communication with the space 85 defined by the u-shaped lip 80. For example, the fluid flow can exit the first region 95 by travelling upwardly around the outlet tube 165 into the space 85 (as the fluid level in the first region 95 rises), and then spilling into the opening 170, as illustrated by arrow 175.

Specifically, the fluid pressure at the opening 170 and inside the fluid outlet tube 165 is lower than the fluid pressure located elsewhere in the cup assembly 65. This is in part because the opening 170 of the fluid outlet tube 165 is below the overall level of the processing fluid within the cup assembly 75 (Figure 1) as determined by the height of the weir 180 (Figure 1). As a result of the lower pressure proximate the opening 170 of the fluid outlet tube 165, fluid will migrate toward the opening 170 from elsewhere in the cup assembly. More specifically, the fluid from the first fluid flow region will generally migrate toward the space 85 within the U- shaped lip 80, which extends circumferentially around the outer perimeter of the cup 13 assembly 75, proximate the opening 170. The fluid then enters the tube 165 via the opening 170 and exits the reactor bowl assembly 30. In a further aspect of this embodiment, the pressure difference between the opening 170 and the top of the weir 180 can be increased by coupling the fluid outlet tube 165 to a vacuum source.

Although the fluid flow from the first fluid flow region 95 to the second fluid flow region 100 is restricted, charged particles required for electrochemical processing of the workpiece 45 can still flow from the first fluid flow region 95 to the second fluid flow region 100 across the pressure drop member 90, as charged particles will travel independently of the fluid flow. This is possible if the particles are suitably charged and are sized appropriately to pass through the pressure drop barrier.

In addition to fluid outlet tube 165, the processing fluid can further exit the cup assembly 75 via an overflow weir 180 located at the lip of the wall of the process cup assembly 75. The processing fluid, which has overflowed the overflow weir 180, can then be drained via a cup drain valve 185 located near the bottom of the reactor bowl assembly 30.

Returning to Figure 1, the reactor 10 can include an auxiliary electrode 67 in accordance with another embodiment to the invention. In one aspect of this embodiment, the auxiliary electrode 67 can be configured to clean the contact assembly 60 in situ after the microelectronic workpiece has been electrochemically processed. Alternatively, the auxiliary electrode 67 can operate as a "current thief during electrochemical processing to control an amount of material deposited on, or removed from the microelectronic workpiece, as described in greater detail below.

In either of the foregoing embodiments, the auxiliary electrode 67, the electrode 105, and the contact assembly 60 can be selectively coupled to one or more sources of electrical potential to produce the desired electrochemical effect. For example, in one embodiment, the contact assembly 60 and the electrode 105 can be coupled to a first voltage source 61 with a circuit that includes a first switch 63. The contact assembly 60 and the auxiliary electrode 67 can be coupled to a second voltage source 62 with a circuit that includes a second switch 64. For purposes of illustration, the connections between the voltage sources 61 and 62 and the electrode 105, the contact assembly 60, and the auxiliary electrode 67 are shown schematically in Figure 1. In operation, connections to the contact assembly 60 and the auxiliary electrode 67 14 can be routed through the reactor head assembly 20, and connections to the electrode 105 can be routed through a wet or dry portion of the riser tube 160. During a plating operation, the first switch 63 can be closed and the second switch 64 can be opened. Accordingly, the electrode 105 can operate as an anode and the contact assembly 60 (in combination with conductive material of the microelectronic workpiece) can operate as a cathode to attract conductive material to the microelectronic workpiece.

After the electroplating process is complete, the microelectronic ^• workpiece can be removed and the contact assembly 60 (including contact electrodes of the contact assembly, not visible in Figure 1) can be cleaned in situ. For example, the first switch 63 can be opened and the second switch 64 can be closed to connect the second voltage source 62 between the contact assembly 60 and the auxiliary electrode 67. Accordingly, the electrode contacts of the contact assembly 60 can operate as anodes, and the auxiliary electrode 67 can operate as a cathode. Processing fluid in the reactor bowl assembly 30 and spilling over the weir 180 can maintain electrical contact between the contact assembly 60 and the auxiliary electrode 67. Accordingly, a conductive material (such as copper) that was originally plated to electrodes of the contact assembly 60 during the electroplating process, may be partially or completely removed from the contact assembly 60 and attracted to the auxiliary electrode 67. In one aspect of this embodiment, the resulting reverse current between the contact assembly 60 and the auxiliary electrode 67 can be provided at a voltage potential in the range of from about 0.1 volt to about 100 volts. In alternate embodiments, the voltage can be provided in the range of from about 0.1 volt to about 20 volts, or in the range of from about 1 volt to about 10 volts. The voltage potential selected for the cleaning operation can depend on the number of microelectronic workpieces processed between cleaning cycles, as well as other factors.

In one embodiment, the auxiliary electrode 67 can include a split ring housed in a shallow circumferential channel just beneath the weir 180 of the process cup assembly 75. An advantage of this arrangement is that by-products resulting from the cleaning operation can settle exterior to the processing space within the process cup assembly 75 to reduce the likelihood for contaminating components within the process cup assembly 75. In alternate embodiments, the auxiliary electrode 67 can be positioned at other locations. For example, the auxiliary electrode 67 can be 15 positioned at the bottom of the reactor bowl assembly 30. In another alternative arrangement, the auxiliary electrode 67 can be positioned in an outlet flow conduit of the reactor bowl assembly 30. Still further embodiments of the auxiliary electrode 67 are described in International Application PCT/US98/00126 (published as WO99/16936), incorporated herein in its entirety.

The auxiliary electrode 67 can include platinized titanium in one embodiment, and in alternative embodiments, the auxiliary electrode 67 can include other conductive materials. In still a further alternative embodiment, the first and second voltage sources 61 and 62 can be replaced by a single voltage source having positive and negative terminals that can be selectively coupled to any of the auxiliary electrode 67, the contact assembly 60, and the electrode 105 to provide the desired electrical potential to these components.

In any of these embodiments, the in situ cleaning operation can be completed after electroplating a single microelectronic workpiece. Alternatively, the in situ cleaning process can be completed after electroplating five, ten, or other numbers of microelectronic workpieces. If more than fifty microelectronic workpieces have been processed between cleaning operations, the cleaning operation may become too time-consuming to take place during typical microelectronic workpiece manufacturing operations. Accordingly, it may be desirable to clean the content assembly 60 after fewer than fifty microelectronic workpieces have been processed. Another factor in determining how many microelectronic workpieces can be processed between cleaning cycles is the amount of copper (or other metal) plated onto the contact electrodes of the contact assembly 60 during such electroplating operation.

Deposits removed from the reactor bowl assembly 30 can be collected in a particulate filter (than can include materials such as fritted glass), or disposed of in an appropriate waste removal and handling operation. If the process fluid is passed through a particulate filter, the filtered solution may be reintroduced into the plating bath after being filtered. In one aspect of this embodiment, the particulate filter can allow for passage of ions along with the plating bath solution so that the reintroduced process fluid retains ions that may be beneficial during an electroplating process. 16

An advantage of any of the foregoing embodiments is that using the auxiliary electrode 67 can increase the number of microelectronic workpieces produced during a particular time interval. For example, the auxiliary electrode 67 can be activated quickly and easily either between or during electroplating process operation sequences. Accordingly, the electrode contacts of the contact assembly 60 can remain cleaner for longer periods of time, compared with reactors that do not include such auxiliary electrodes 67. Furthermore, the use of the auxiliary electrode ■ 67 can increase microelectronic workpiece throughput by eliminating or at least reducing the need for halting the operation of the reactor 10 to manually replace or clean components of the contact assembly 60.

Another advantage of an embodiment of the reactor 10 that includes the auxiliary electrode 67 is that it can improve the uniformity with which conductive material is electrochemically deposited onto the microelectronic workpieces. For example, clean electrode contacts of the contact assembly 60 can improve the uniformity of the current density on the surface of the microelectronic workpiece during electroplating, thereby improving the uniformity of the conductive material deposited on the surface of the microelectronic workpiece.

Yet another advantage of the auxiliary electrode 67 is that it can operate in the manner of a "current thief to control the rate at which conductive material attaches to the microelectronic workpiece during a plating operation. For example, the auxiliary electrode 67 can operate as a cathode concurrently with the contact assembly operating as a cathode to attract at least a portion of the conductive ions in the process fluid to the auxiliary electrode 67 instead of to the microelectronic workpiece.

In another aspect of an embodiment of the reactor 10 illustrated in Figure 1, the reactor bowl assembly 30 further provides for one or more mounting connections adapted for receiving one or more field shaping elements at the internal surface thereof near the lip of the wall of the process cup assembly 75. More specifically, in one embodiment the mounting connections include one or more generally horizontal grooves 190 extending around the circumference of the wall at different elevations.

Field shaping elements can provide for fluid and/or current shaping or tailoring. The field shaping elements mounted in one of the lower generally horizontal 17 grooves 190 further from the workpieces 45 provides for more global shaping or tailoring of the flow of processing fluid and current, while field shaping elements mounted in one of the higher horizontal grooves 190 closer to the workpiece 45 provide for fluid and current shaping in connection with a more specific point on the workpiece 45.

In accordance with one embodiment used in the electroplating of copper onto the surface of the workpiece, a consumable phosphorized copper anode and two

^■ field shaping elements are used. The field shaping elements include a lower field shaping element 195 or diffuser plate (illustrated in Figure 5) and an upper field shaping element 200 or shield (illustrated in Figure 6).

Figures 5 and 6 are isometric views of two embodiments of field shaping elements 195, 200 that may be used in the reactor 10. The field shaping elements 195, 200 generally each comprise a single plate of material having one or more openings through which plating fluid and/or current is enabled to flow. Depending on the opening pattern a more controlled distribution of plating fluid and current across the surface of the workpiece 45 can be achieved. Although each of these elements is illustrated to include peripherally disposed notches, such notches are optional but may be used to assist in securing the respective elements in place within the reactor assembly in cooperation with other corresponding structures.

Figure 5 illustrates a first field shaping element 195 that may be concurrently used in the reactor bowl assembly 30. The first field shaping element 195 includes a plurality of openings 205 arranged approximately in a grid like pattern. However, a spiral pattern may also be used. In at least one of the preferred embodiments, the first field shaping element 195 is positioned in one of the lower horizontal grooves 190.

Figure 6 illustrates a second field shaping element 200 that may be used along with the first field shaping element 195 illustrated in Figure 5. The second field shaping element 200 can include a single larger opening 210 approximately centered in the field shaping element 200. The second field shaping element 200 directs the processing fluid and electrical current away from the edge of the workpiece 45. In at least one embodiment, the second field shaping element 200 may be positioned proximate to the workpiece 45 in one of the higher horizontal grooves 190. 18

Examples of field shaping elements or diffuser plates, including diffuser plates having alternative opening patterns, are further described in connection with U.S. Patent Application Serial No. 09/351,864, filed July 12, 1999, entitled "Diffuser with Spiral Opening Pattern for Electroplating Reactor Vessel", the disclosure of which is incorporated herein by reference.

Figure 7 illustrates an enlarged cross-sectional view of a portion of the plating reactor illustrated in Figure 1, further illustrating one particular embodiment - where the field shaping elements 195 and 200, illustrated in Figures 5 and 6, are each present in one of the plurality of horizontal grooves 190 for receiving a field shaping element. Specifically, Figure 7 illustrates the field shaping element 200 or shield (illustrated in Figure 6) in one of the higher horizontal grooves, and the field shaping element 195 or diffuser plate (illustrated in Figure 5) one of the lower horizontal grooves.

Use of the present invention in an electroplating process is not only envisioned with respect the plating of copper onto a workpiece using a consumable phosphorized anode, but is further envisioned as having utility in any electroplating process where there is a desire to limit exposure of the cathode/workpiece to the products produced at the anode. For example, the above noted electroplating process is further envisioned as having utility in connection with a process for plating nickel onto a workpiece using a consumable nickel sulfur anode, and a process for plating solder onto a workpiece using a consumable tin lead anode, or for anodic processing of a workpiece, in which gas is produced at the cathode.

Numerous modifications may be made to the foregoing system without departing from the basic teachings thereof. Although the present invention has been described in substantial detail with reference to one or more specific embodiments, those of skill in the art will recognize that changes may be made thereto without departing from the scope and spirit of the invention as set forth in the appended claims.

Claims

19 CLAIMS What is Claimed is:

1. A reactor for use in electrochemical processing of a microelectronic workpiece, comprising: one or more walls defining a processing space configured to contain a processing fluid; a first fluid flow region in the processing space; and a first electrode disposed in the first fluid flow region; a second fluid flow region in the processing space; a second electrode disposed in the second fluid flow region, the second electrode being configured to electrically couple to at least a portion of the microelectronic workpiece, the processing space being configured to direct fluid flow within the first fluid flow region generally toward the first electrode and away from the second electrode, and direct fluid flow within the second fluid flow region generally toward the second electrode and away from the first electrode.

2. The reactor of claim 1 wherein the first electrode includes an anode configured to electrochemically process the microelectronic workpiece.

3. The reactor of claim 1 wherein the first electrode includes a cathode configured to electrochemically process the microelectronic workpiece.

4. The reactor of claim 1 wherein the processing space is coupled to a single fluid inlet configured to provide processing fluid to both the first and second fluid flow regions.

5. The reactor of claim 1, further comprising at least one pressure drop member disposed in the processing space in an intermediate position between the first and second fluid flow regions. 20

6. The reactor of claim 1 wherein the first fluid flow region is adjacent the second fluid flow region.

7. The reactor of claim 1, further comprising a third electrode disposed at least proximate to the processing space and positioned to be in fluid communication with the second electrode.

8. The reactor of claim 1 wherein at least one wall defining the processing space has an inner surface facing toward the processing space and an outer surface facing away from the processing space, the wall further having an upper edge defining a weir over which processing fluid can exit the processing space, and wherein the reactor further comprises a third electrode adjacent to the outer surface of the vessel wall, the third electrode being positioned to be in fluid communication with the second electrode when the second electrode is cleaned.

9. The reactor of claim 1 , further comprising: an electrode housing positioned in the processing space and defining an interior region, the first electrode being positioned in the interior region, the electrode housing having a rim with a channel having a downwardly facing opening in fluid communication with the first fluid flow region; and an outlet conduit having an aperture in the channel of the electrode housing.

10. A reactor for electrochemically processing a microelectronic workpiece, comprising: one or more walls defining a processing space configured to contain a processing fluid; a microelectronic workpiece support including one or more conductive members disposed to electrically contact the microelectronic workpiece to provide electrical power for electrochemical processing of the microelectronic workpiece, the microelectronic workpiece support being disposed to bring at least one portion of the microelectronic workpiece into contact with the processing fluid; 21 at least one electrode positioned to contact processing fluid when processing fluid is disposed in the processing space, the at least one electrode being spaced from the microelectronic workpiece and positioned to provide electrical power for electrochemical processing of the microelectronic workpiece when the microelectronic workpiece is supported by the microelectronic workpiece support; at least one processing fluid inlet disposed to provide a flow of the processing fluid into the processing space; and at least one processing fluid outlet disposed to provide a flow of the processing fluid from the processing space, the at least one processing fluid outlet being positioned within the processing space to direct at least a portion of the flow of the processing fluid from the at least one electrode and away from the microelectronic workpiece as the flow exits from the processing space.

11. The reactor of claim 10 wherein the at least one electrode includes an anode configured to electrochemically process the microelectronic workpiece.

12. The reactor of claim 10 wherein the at least one electrode includes a cathode configured to electrochemically process the microelectronic workpiece.

13. The reactor of claim 10, further comprising at least one permeable membrane disposed between the microelectronic workpiece support and the at least one electrode.

14. The reactor of claim 13 wherein the at least one permeable membrane is disposed between a first fluid flow region of the processing space and a second fluid flow region of the processing space.

15. The reactor of claim 14 wherein the at least one processing fluid inlet is disposed in the second fluid flow region. 22

10. ine reactor oi claim 1 wnerem tne at least one processing iiuid outlet is disposed in the first fluid flow region.

17. The reactor of claim 14 wherein the at least one processing fluid outlet is disposed in the first fluid flow region.

18. The reactor of claim 17, further comprising another processing ■ fluid outlet disposed in the second fluid flow region proximate the microelectronic workpiece.

19. The reactor of claim 14 wherein the first and second fluid flow regions are adjacent one another.

20. The reactor of claim 10, further comprising a further processing fluid outlet disposed proximate the microelectronic workpiece when the microelectronic workpiece is supported by the microelectronic workpiece support.

21. The reactor of claim 10, further comprising: a housing disposed in the processing space and having an open end that opens toward the microelectronic workpiece when the microelectronic workpiece is supported by the microelectronic workpiece support; and a pressure drop member disposed over the open end of the housing, the at least one electrode being disposed in an interior chamber defined at least in part by the housing and the pressure drop member.

22. The reactor of claim 21 wherein the pressure drop member includes a permeable membrane having a conical shape with an apex directed toward the interior chamber.

23. The reactor of claim 21 wherein the at least one processing fluid outlet is positioned to exhaust processing fluid from the interior chamber. 23

24. The reactor of claim 21, further comprising a head assembly, the head assembly including the microelectronic workpiece support, the head assembly being movable with respect to the open upper end of the housing between a workpiece loading position and a workpiece processing position.

25. The reactor of claim 24 wherein the head assembly includes a rotor motor connected to the microelecfronic workpiece support to rotate the

• microelectronic workpiece during electrochemical processing.

26. The reactor of claim 10 wherein microelectronic workpiece support is rotatable relative to the one or more walls defining the processing space.

27. A reactor for electrochemically processing a microelectronic workpiece comprising: a processing cup defining a processing space configured to contain a processing fluid, the processing cup having an open top; a microelectronic workpiece support including one or more conductive members disposed to electrically contact the microelectronic workpiece to provide electrical power for electrochemical processing of the microelectronic workpiece, the microelecfronic workpiece support being disposed proximate the open top of the processing cup to bring at least one portion of the microelectronic workpiece into contact with the processing fluid for electrochemical processing; an electrode housing disposed in the processing cup and having an end that opens toward the microelectronic workpiece support; a pressure drop member disposed over the open end of the elecfrode housing; at least one elecfrode disposed in an interior region of the elecfrode housing; at least one processing fluid inlet disposed exterior to the interior region of the electrode housing to provide a flow of the processing fluid into the processing space; and 24 at least one processing fluid outlet in fluid communication with the interior region of the electrode housing to receive a flow of the processing fluid passing through the pressure drop member and into the interior region of the electrode housing.

28. The reactor of claim 27 wherein the at least one elecfrode includes an anode configured to electrochemically process the microelecfronic

• workpiece.

29. The reactor of claim 27 wherein the at least one elecfrode includes a cathode configured to electrochemically process the microelectronic workpiece.

30. The reactor of claim 27 wherein the at least one processing fluid outlet is positioned to draw at least a portion of the flow of the processing fluid adjacent to the at least one electrode as the processing fluid exits from the interior region.

31. The reactor of claim 27 wherein the open top of the processing cup forms a weir for receiving at least a portion of the processing fluid exiting from the processing space.

32. The reactor of claim 27 wherein the pressure drop member includes a permeable membrane.

33. The reactor of claim 32 wherein the permeable membrane is conical in shape and has an apex directed toward the interior region of the elecfrode housing.

34. The reactor of claim 27 wherein the pressure drop member is conical in shape and has an apex directed toward the interior region of the elecfrode housing. 25

35. An apparatus for elecfrochemically processing a microelecfronic workpiece, the apparatus comprising: one or more walls defining a processing space configured to contain a processing fluid; a pressure drop member disposed in the processing space to divide the processing space into at least a first fluid flow region and a second fluid flow region with the first fluid flow region being a fluid communication with the second fluid flow • region across the pressure drop member; a microelecfronic workpiece support positioned to support a microelectronic workpiece in contact with processing fluid when the processing fluid is in the second fluid flow region; and an elecfrode located in the first fluid flow region of the processing space.

36. The reactor of claim 35 wherein the at least one electrode includes an anode configured to electrochemically process the microelectronic workpiece.

37. The reactor of claim 35 wherein the at least one electrode includes a cathode configured to elecfrochemically process the microelecfronic workpiece.

38. The apparatus of claim 35 wherein the pressure drop member includes a permeable membrane.

39. The apparatus of claim 35 wherein the first and second fluid flow regions are adjacent one another.

40. An apparatus for electrochemically processing a microelecfronic workpiece comprising: means for containing a processing fluid to form a processing space; 26 means for providing electrical contact to one or more surfaces of the microelectronic workpiece to supply electrical power for electrochemical processing of the workpiece; elecfrode means for supplying electrical power for electrochemical processing of the microelecfronic workpiece; means for providing a first fluid flow region and a second fluid flow region within the processing space, the elecfrode means being disposed in the first fluid flow region, the means for providing electrical contact being disposed in the second fluid flow region, processing fluid flow within the first fluid flow region being generally directed toward the electrode means and generally away from the means for providing electrical contact, processing fluid flow within the second fluid flow region being generally directed toward one or more surfaces of a microelectronic workpiece contacted by the means for providing electrical contact and generally away from the elecfrode means.

41. The apparatus of claim 40 wherein the at least one electrode includes an anode configured to electrochemically process the microelectronic workpiece.

42. The apparatus of claim 40 wherein the at least one electrode includes a cathode configured to electrochemically process the microelecfronic workpiece.

43. An apparatus for electrochemically processing a microelectronic workpiece comprising: a processing space configured to contain a processing fluid; at least one fluid inlet disposed to provide a flow of processing fluid to the processing space; and an elecfrode assembly disposed in the processing space, the electrode assembly including an elecfrode housing having an open end, 27 a pressure drop member disposed over the open end of the elecfrode housing, the elecfrode housing and pressure drop member defining an interior elecfrode chamber, an elecfrode disposed in the interior elecfrode chamber, and at least one fluid outlet in fluid communication with the interior elecfrode chamber to thereby draw a flow of processing fluid through the pressure drop member and into the interior elecfrode chamber.

44. The apparatus of claim 43 wherein the pressure drop member includes a permeable membrane.

45. The apparatus of claim 44, further comprising a membrane frame disposed over the open end of the elecfrode housing, the permeable membrane being connected to the membrane frame.

46. The apparatus of claim 43 wherein the pressure drop member has a conical shape with an apex directed toward the interior electrode chamber.

47. A reactor for elecfrochemically processing a microelecfronic workpiece, comprising: at least one wall defining a processing space configured to contain a processing fluid; first and second fluid flow regions in the processing space; a first elecfrode positioned in the first fluid flow region; a second elecfrode positioned in the second fluid flow region, the second electrode being configured to electrically contact the microelectronic workpiece, and wherein the first fluid flow region is configured to direct fluid toward the first electrode and away from the second electrode, and further wherein the second fluid flow region is configured to direct fluid toward the second electrode and away from the first electrode; and a third electrode positioned at least proximate to the processing space and configured to be in fluid communication with the second elecfrode. 28

48. The reactor of claim 47 wherein the at least one wall has an inner surface facing toward the processing space and an outer surface facing away from the processing space, and wherein the third elecfrode is positioned adjacent to the outer surface of the at least one wall.

49. The reactor of claim 48 wherein the at least one wall has a generally circular cross-sectional shape, and wherein the third elecfrode includes a ring

■ positioned to at least partially encircle the at least one wall, the ring including a platinized titanium material.

50. The reactor of claim 47 wherein the at least one wall has an inner surface facing toward the processing space and an outer surface facing away from the processing space, the at least one wall having an upper edge defining a weir over which processing fluid can exit the processing space, and wherein the third electrode is positioned adjacent to the outer surface of the at least one wall.

51. The reactor of claim 47, further comprising a pressure drop member positioned between the first and second fluid flow regions.

52. The reactor of claim 51 wherein the pressure drop member includes a permeable membrane.

53. The reactor of claim 47 wherein the at least one wall is a wall of a processing cup and has an inner surface and an outer surface facing away from the inner surface, the third elecfrode being positioned at least proximate to the outer surface, the wall further having an upper edge defining a weir over which process fluid can exit the vessel, and wherein the reactor further comprises: an elecfrode housing having a first housing wall at least proximate to the first elecfrode and a second housing wall depending from the first housing wall and extending upwardly from the first housing wall inwardly of the inner surface of the processing cup, the processing cup having a fluid inlet port positioned beneath the first 29 housing wall to direct process fluid upwardly around the first and second housing walls and into the processing space; a pressure drop member positioned between the first and second fluid flow regions; and an outlet conduit in fluid communication with the second flow region to remove process fluid from the processing space.

54. A method for electrochemically processing a microelecfronic workpiece comprising: dividing a processing space containing processing fluid into at least a first fluid flow region and a second fluid flow region; locating a first elecfrode within the processing fluid of the first fluid flow region; locating a second elecfrode coupled to at least a portion of the microelectronic workpiece within the processing fluid of the second fluid flow region; directing a fluid flow of the processing fluid within the first fluid flow region generally toward the first elecfrode and generally away from the second electrode; and directing a fluid flow of the processing fluid within the second fluid flow region generally toward the second elecfrode and generally away from the first elecfrode.

55. The method of claim 54, further comprising providing a negative potential to the first electrode with respect to the second electrode.

56. The method of claim 54, further comprising providing a negative potential to the second elecfrode with respect to the first elecfrode.

57. The method of claim 54 wherein directing the fluid flow of the processing fluid within the second fluid flow region includes supplying processing fluid from a fluid reservoir into the second fluid flow region of the processing space. 30

58. The method of claim 54 wherein directing the fluid flow of the processing fluid within the first fluid flow region includes exhausting at least a portion of the processing fluid from the first fluid flow region away from the processing space.

59. The method of claim 54, further comprising limiting the flow of processing fluid from the second fluid flow region into the first fluid flow region, thereby maintaining a pressure differential between the first fluid flow region and the second fluid flow region.

60. The method of claim 54 wherein limiting the flow includes providing a permeable membrane between the first fluid flow region and the second fluid flow region.

61. The method of claim 54 wherein the second electrode includes an electrical contact in electrical communication with the portion of the microelecfronic workpiece, and wherein the method further comprises: coupling the electrical contact to a source of electrical potential at a first polarity to dispose a conductive material on the microelecfronic workpiece; removing the microelectronic workpiece from the electrical contact; and coupling the electrical contact to a source of electrical potential having a second polarity opposite the first polarity to remove conductive material from the electrical contact.

62. The method of claim 61, further comprising placing a third elecfrode in fluid communication with the contact and coupling the third elecfrode to a source of electrical potential having a polarity opposite the second polarity.

63. A method for elecfrochemically processing a microelectronic workpiece, comprising: dividing a processing space containing processing fluid into at least a first fluid flow region and a second fluid flow region; 31 positioning a first elecfrode in fluid communication with the processing fluid in the first fluid flow region; positioning a second elecfrode in fluid communication with the processing fluid in the second fluid flow region; placing the microelecfronic workpiece in electrical contact with the second electrode; coupling the second electrode to a source of voltage potential having a first polarity; directing the processing fluid in the first fluid flow region generally toward the first elecfrode and generally away from the second elecfrode; directing the processing fluid in the second flow region generally toward the second elecfrode and generally away from the first elecfrode; decoupling the microelecfronic workpiece from the second elecfrode; and removing conductive material from the second elecfrode by coupling the second elecfrode to a source of voltage potential having a second polarity opposite the first polarity.

64. The method of claim 63 wherein the first and second fluid flow regions are positioned inward of a wall of defining the processing space, and wherein the method further comprises coupling a third elecfrode to a source of voltage potential having a polarity opposite the second polarity, the third elecfrode being positioned outside the processing space. ,

65. The method of claim 63, further comprising passing the processing fluid from the second region through a pressure drop member into the first region.

66. The method of claim 63, further comprising passing the processing fluid from the second region through a permeable membrane into the first region. 32

67. The method of claim 63, further comprising exhausting the processing fluid from the processing space by passing the processing fluid out of the first fluid flow region.

68. The method of claim 63 wherein directing the processing fluid in the first fluid flow region includes directing the fluid upwardly away from a positively charged anode and toward a negatively charged cathode, and wherein directing the processing fluid in the second fluid flow region includes directing the fluid downwardly away from the negatively charged cathode and toward the positively charged anode.