Die-level wafer contact for direct-on-barrier plating

Abstract

The present invention provides a semiconductor workpiece support and contact assembly for providing localized electrical connections with the device side of the workpiece. The additional contact points help overcome the terminal effect caused by very high sheet resistance of thin barrier layers and enable plating a conformal seed layer or feature filling directly on thin barrier layers. By utilizing the streets that separate individual dice on a workpiece to make electrical connections with the workpiece and provide localized distribution of plating chemistry, the present invention provides a more uniform and conformal metallization layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a nonprovisional of U.S. Provisional Patent Application No. 60/669,312, filed Apr. 7, 2005, now pending. Priority to this application is claimed under 35 U.S.C. §§ 119, and the disclosure of this application is incorporated herein by reference in its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

TECHNICAL FIELD

The invention relates to a workpiece support used in semiconductor plating systems having electrodes which engage the workpieces for electroplating metals, such as copper and others, onto seed, barrier and other layers formed on semiconductor wafers and other semiconductor workpieces.

BACKGROUND OF THE INVENTION

In the production of semiconductor wafers and other semiconductor articles it is necessary to plate metals onto the semiconductor surface to provide conductive areas which transfer electrical current. There are two primary types of plating layers formed on the wafer or other workpiece. One is a blanket layer used to provide a metallic layer which covers large areas of the wafer. The other is a patterned layer which is discontinuous and provides various localized areas that form electrically conductive paths within the layer and to adjacent layers of the wafer or other device being formed. Plating can occur on a flat metal layer, through a non-conducting mask to an underlying metal layer or onto a patterned non-flat substrate.

There are a wide range of manufacturing processes that may be used to deposit the metallization on the workpiece in the desired manner. Such processes included chemical vapor deposition (“CVD”), physical vapor deposition (“PVD”), electroplating, and a damascene process where holes, more commonly called vias, trenches and other recesses are formed in the layer of semiconductor material in which a pattern of copper is desired. 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. The seed layer is a very thin layer of metal which can be laid down using several processes. The seed layer of metal can be laid down using PVD or CVD processes to produce a layer on the order of 1000 angstroms thick. The seed layer can advantageously be formed of copper, gold, nickel, palladium, and most or all other metals. The seed layer is formed over a surface which is convoluted by the presence of vias, trenches, or other device features which are recessed. This convoluted nature of the exposed surface provides increased difficulties in forming the seed layer in a uniform manner. Non-uniformities in the seed layer can result in variations in the electrical current passing from the exposed surface of the wafer during the subsequent electroplating process. This in turn can lead to non-uniformities in the blanket layer electroplated onto the seed layer. Such non-uniformities can cause deformities and failures in the resulting semiconductor device being formed.

In the damascene processes, after the seed layer is laid down, then it is typical to plate additional metal (e.g., copper) onto the seed layer in the form of a blanket layer formed thereon. The blanket layer is typically electroplated and is used to fill the vias and trenches. The blanket layer is also typically plated to an extent which forms an overlying layer. Such a blanket layer will typically be formed in thicknesses on the order of 3,000-15,000 angstroms (0.3-1.5 microns). Chemical mechanical polishing (“CMP”) is used to remove any excess copper and other metal above the features.

As damascene-interconnect feature sizes shrink, the barrier layer and seed layers used for manufacturing device metal interconnects (i.e. the dual-damascene process) become thinner and more resistive. Furthermore, it becomes more difficult to provide a uniform seed-layer thickness on the sidewalls of features as the features shrink. The seed layers are typically deposited using relatively expensive PVD vacuum processes and it may be necessary to improve the sidewall coverage by using a process such as the “seed layer repair” and “seed layer enhancement” processes developed by Semitool and disclosed in U.S. Pat. No. 6,197,181. It would be of great benefit to plate the seed layer directly on the barrier in a conformal manner, thereby, insuring good sidewall coverage and omitting the expense of the PVD process altogether.

To plate directly on a thin barrier layer, the very strong terminal effect created by the high sheet resistance must be overcome. This is very challenging when contacting the wafer around its circumference because a high voltage is required to pass current from the contact to the center of the wafer in order to plate at the center. The current will preferentially plate near the contact to avoid the sheet resistance. An electrolytic bath with a low conductivity reduces the terminal effect, but untested ultra low conductivity bath formulations (less than 1 mS/cm² and down to 0.001 mS/cm²) would be required to enable relative uniform plating on the barrier layers expected below 45 nm feature sizes.

Moreover, the difficulty of plating on a barrier layer (or seed layer) is aggravated when the layer covers features on the surface of the wafer. In general, these features increase the effective length of the conductive film and, thus, increase the film sheet resistance compared to a blanket film. Typically these features are via and trench geometries (e.g. dual-damascene features) to be filled with copper to form metal interconnects. But not only do the features add to the overall sheet resistance, they can also create regions of anisotropic sheet-resistance making some areas of the wafer extremely difficult to plate. For example, the barrier layer covering trenches aligned with the current flow (e.g. along radial lines) will be less resistive than trenches perpendicular to the current flow. In addition, there may be underlying layers or pads that are more conductive than the barrier layer or seed layer connecting various features that are to be plated. For example, one via array may be connected to another via array by such an underlying structure. This conductive structure can shunt current and influence local plating voltages, thereby, disrupting the plating on the barrier layer. Accordingly, there is a need for electroplating equipment and methods that overcome the challenges inherent in plating highly resistive barrier and seed layers.

The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior electroplating equipment and methods of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.

SUMMARY OF THE INVENTION

The present invention proposes mechanical schemes to increase the contact points across a semiconductor workpiece in an electroplating vessel, rather than (or in addition to) contacting the wafer around its circumference as is the case in typical electroplating equipment and processes. By utilizing the gaps called “streets” or “scribes” that separate the individual dice on a wafer, it is possible to contact or touch the wafer in these streets without harming the devices on the wafer. The additional contact locations help to overcome the terminal effect caused by the very high sheet resistance of thin barrier layers and enable plating a conformal seed layer or feature filling directly on thin barrier layers.

In some embodiments of the present invention, the contact to the wafer approaches the die or device level in order to provide localized plating in an electrochemical plating vessel. For example, in one embodiment the present invention provides a wafer support for use in electroplating a semiconductor workpiece. The wafer support comprises a plurality of discrete contacts that make point contacts at selected points with the streets of the wafer. The discrete point contacts may contact the wafer at each corner of a die (or less frequently). In another embodiment of the present invention, continuous contacts may run along the entire length of the streets formed between the devices formed in the semiconductor wafer. The contacts may run along only the vertical streets or the horizontal streets, or may run along both directions forming a grid-like support structure. In any of these embodiments, the circumference/periphery of the semiconductor workpiece may (or may not) also be electrically contacted.

Since a plurality of discrete contact points or a grid-like contact structure may disrupt the electrolyte flow and mass transfer to the wafer when it is added to a conventional fountain plater, another aspect of the present invention combines the street contacts with a sparger flow system. Such a system allows for device-scale delivery and removal of process fluid, and local control of the current to each die from the anode.

To eliminate the die-specific nature of the contact geometry associated with a certain aspects of the present invention, an alternative embodiment of the present invention provides for relatively high conductivity current paths (e.g., bus paths) to be formed or imbedded in the streets. Thus, even when a conventional circumferential contact is used, the highly conductive streets provide a low resistance path around each die, effectively achieving the same result as contacting the wafer locally around each device.

Even more uniform barrier and seed layer plating may be achieved by coupling the localized die-level contact schemes discussed above with localized plating. For example, local die level anode shapes (or smaller) may be moved and/or controlled to enable better die scale plating. By locally plating one die at a time, the terminal effect is reduced because the overall current passing though the barrier at a given time is reduced and the voltage variations throughout the film are correspondingly reduced. Similarly, localized/dynamic control of the individual contacts across the streets or the circumference can create more controlled localized plating. For example, only a portion of the circumferential or street contacts may be active at a certain time. This dynamic control could be cycled around the wafer creating varying current flow directions and potential drops across the wafer to overcome the effects of anisotropic sheet-resistance and shorting by underlying conductive pads.

Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a sectional view of a semiconductor processing station having a processing head, a workpiece support assembly and a plating bowl assembly.

FIG. 2 is a sectional view of the semiconductor processing station shown in FIG. 1 just after the processing head has placed the workpiece onto the workpiece support assembly.

FIG. 3A is a sectional view of the workpiece support assembly and plating bowl assembly with a semiconductor workpiece resting on the workpiece support assembly.

FIG. 3B is an expanded partial view of the area identified by reference letter A in FIG. 3A.

FIG. 4A is a sectional view of the workpiece support assembly and plating bowl assembly with arrows showing the processing fluid flow paths through the workpiece support assembly and the bowl assembly.

FIG. 4B is a expanded partial view of the area identified by reference letter B in FIG. 4A with arrows showing the processing fluid flow paths through the workpiece support assembly.

FIG. 5 is a plan view of the workpiece support assembly and plating bowl assembly shown in FIG. 3A

FIG. 6A is a cross-sectional view taken along line C-C of the workpiece support assembly and plating bowl in FIG. 5.

FIG. 6B is an expanded partial view of the area identified by reference letter D in FIG. 6A.

FIG. 7 is the cross-sectional view of FIG. 6A with a partial semiconductor workpiece resting on the workpiece support assembly.

FIG. 8 is an exploded view of the workpiece, wafer support contact plate and sparger plate according to the present invention.

FIG. 9A is a perspective view of a wafer support contact plate according to one embodiment of the present invention.

FIG. 9B is a plan view of the wafer support contact plate shown in FIG. 9A.

FIG. 9C is a cross-sectional view taken along line A-A of the wafer support contact plate shown in FIG. 9B.

FIG. 9D is an expanded view of the detailed section labeled B in FIG. 9C.

FIG. 10A is a perspective view of a wafer support contact plate according to another embodiment of the present invention.

FIG. 10B is a plan view of the wafer support contact plate shown in FIG. 10A.

FIG. 10C is a cross-sectional view taken along line A-A of the wafer support contact plate shown in FIG. 10B.

FIG. 10D is a expanded view of the detailed section labeled B in FIG. 10C.

FIG. 11 is a plan view of a wafer support contact plate according to another embodiment of the present invention.

FIG. 12 is a plan view of a wafer support contact plate according to another embodiment of the present invention.

FIG. 13 is a perspective view of a device side of a semiconductor workpiece with high conductivity current paths formed in the streets formed between the devices on the workpiece.

FIG. 14A is a is a perspective view of a sparger plate to be used in a plating apparatus according to another aspect of the present invention.

FIG. 14B is a plan view of the sparger plate shown in FIG. 14A.

FIG. 14C is a cross-sectional view taken along line A-A of the sparger plate shown in FIG. 14B.

FIG. 14D is a expanded view of the detailed section labeled B in FIG. 14C.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

Turning to FIGS. 1 and 2, there is shown a semiconductor processing station 10 incorporating features of the present invention. The processing station 10 is comprised of four main components; a process head 15, a bowl assembly 20, a semiconductor workpiece contact assembly 25 and a process head operator 30. The bowl assembly 20 is generally comprised of a bowl 22 positioned within an outer receptacle 21. The bowl 22 shown in FIG. 1 is divided by a membrane 23 into an upper section 24 and a lower section 26. An anode 27 is positioned at the bottom of the lower section 26 of the bowl 22 and is in fluid communication with a process fluid, e.g., an electrolyte or anolyte. The lower section 26 has a process fluid inlet 28 and a process fluid outlet 29. The upper section 24 of the bowl 22 has a process fluid inlet 31.

The workpiece contact assembly 25 sits atop the bowl 22 and is generally comprised of a contact plate 32 which supports the workpiece and a sparger plate 33 for distributing process fluid to the device side of the workpiece. Appropriate electrical connections are made with the contact assembly 25 to provide controlled electrical power to the contact assembly 25. Various embodiments of the workpiece contact assembly 25 will be discussed in greater detail below.

The process head assembly 15 accepts the workpiece W for processing and introduces the workpiece to the bowl assembly 20 by placing the workpiece onto the contact plate 32 for processing, and removes the workpiece W from the bowl assembly 20 after processing for transition to, for example, another processing station. The process head assembly 15 is comprised of a process head 34 and a rotor 35. The process head 34 holds a rotor drive assembly (not shown) which includes, among other components, a motor for spinning the process head assembly about the axis R. The process head 34 also includes an actuator that cooperates with components in the rotor 35 which cause fingers 36, which extend outwardly from the face of rotor 35, to engage and disengage from the periphery of the workpiece W.

The process head assembly 15 is preferably supported by process head operator 30. The operator 30 includes a linear drive 37 which is used to adjust the height of the process head assembly 15 with respect to the bowl assembly 20. The process head assembly 15 also includes a head rotor drive 38 which operates to rotate the process head assembly 15 about a horizontal axis H. The rotational movement of the process head assembly 15 allows it to be placed in a first position (approximately 180 degrees from the position of the process head assembly shown in FIG. 1) for loading and unloading the workpiece W and a second position (shown in FIG. 1) wherein the device side of the workpiece W is exposed and available for making contact with the contact assembly 25, which is positioned atop of the bowl 22. A variety of drives which provide linear and/or rotational drive movement are suitable for use in a plating system according to the present invention.

FIG. 1 illustrates the processing station 10 after the process head assembly 15 has accepted the workpiece W and the process head operator 30 has started to lower the workpiece into the bowl assembly 20. In FIG. 2, the process head assembly 15 has been completely lowered into the bowl assembly 20 such that the workpiece W rests on the contact assembly 25 with the device side of the workpiece W contacting the contact plate 32. As shown in FIG. 2 and discussed in detail below, the contact plate 32 has at least one and preferably a plurality of recesses 42 which allow clearance for the fingers 36 of the rotor 35. In this position, the device side of the workpiece W is exposed such that the contact plate 32 makes electrical contact with the workpiece W along the “streets” or “scribes” that separate the individual dice on a wafer. After all processing steps, the devices on the wafer are separated by cutting along these streets. Therefore, it is possible to contact or touch the wafer in these streets without harming the devices on the workpiece W. This position also allows the sparger plate 33 to locally deliver a plating chemistry to the device side of the workpiece W to effectuate a uniform deposition of metal. The present invention proposes utilizing the gaps called “streets” or “scribes” In operation, the anode 27 is connected to a positive potential terminal of a power supply (not shown). In the embodiment shown in FIGS. 1 and 2, and with reference to FIGS. 4A and 4b, an anolyte is introduced into the lower compartment 26 through inlet 28. The anolyte flows over the anode and exits the lower compartment 26 through exit 29. In a preferred embodiment, the anolyte is recirculated outside the processing station and re-introduced through the inlet 28. The contact plate 32 is connected to a positive potential terminal of the power supply. A catholyte is introduced into the upper compartment 24 through inlet 31. The catholyte is forced up through the sparger plate 33 to distribute the catholyte to the device side of the workpiece W, and more specifically to the individual devices formed on the device side of the workpiece W. The excess catholyte flows outside the bowl 22 and is caught in the outer receptacle 21 and eventually drained through a drain 40 located in the bottom of the inner receptacle 21. FIGS. 4A and 4B illustrate the anolyte flow (indicated by the arrows labeled A) and the catholyte flow (indicated by the arrows labeled C). In operation, the power supply provides an electrical potential difference between the anode and the workpiece W (due to the electrical connection with the contact plate 32) which results in a chemical plating reaction at the device side of the workpiece W in which the desired metal is deposited.

It should be understood by those having skill in the art that the contact assembly 25 of the present invention can be used in a plating reactor wherein the plating bath is comprised of a single electrolyte which is introduced into a bowl 22 having only a single compartment, rather than the multi-compartment bowl 22 and the use of a catholyte and an anolyte as disclosed in FIGS. 1, 2, 3A, 3B, 4A, 6A and 7. In either embodiment, the chemistries may be recirculated to the external supply and filtered or supplemented as needed to maintain chemistry constituent proportions.

With reference specifically to FIGS. 3A and 3B, there is shown a cross-sectional view of the bowl assembly 20 and contact assembly 25 with the semiconductor workpiece W being supported on the contact assembly 25. FIG. 3B is an expanded partial view of the area identified by reference letter A in FIG. 3A. The contact plate 32 has a plurality of conductive members 32a, which contact the streets formed in the device side of the workpiece W. The sparger plate 33 has a plurality of grooves 33a. The conductive members 32a of the contact plate 32 sit within the grooves 33a of the sparger plate 32. Although the conductive members 32a sit slightly above the sparger plate 32, the contact plate 32 and the sparger plate 33 are generally co-planar as they sit atop the bowl 22.

The sparger plate 33 and the contact plate 32 will now be described in greater detail with reference to a preferred embodiment shown in FIGS. 5-10D. FIG. 5 is a plan view of a preferred embodiment of the workpiece support and contact assembly 25 and plating bowl assembly 20 shown in FIG. 3A. The contact plate 32 has a continuous shoulder or frame 41. At least one, and preferably a plurality of, recesses 42 are formed in the shoulder 41. As mentioned above, the recesses 42 allow for clearance of the fingers 36 of the rotor 35 when the process head assembly 15 is loading the workpiece onto the contact assembly 25. A plurality of conductive members 32a extend inwardly from the shoulder 41. The conductive members 32a lie within a common horizontal plane. In the embodiment shown in FIGS. 5-10D, the conductive members 32a are continuous, rail-like, intersecting members that form a grid-like structure. The intersecting, grid-like structure forms a plurality of open areas 32b (best shown in FIG. 8). In the preferred embodiment shown in FIG. 8, the open areas 32b are substantially square or rectangular shaped. However, the open areas 32b can take other configurations as well.

The sparger plate 33 is comprised of a base plate 43 having a plurality of spaced-apart, hollow cells 44 projecting outwardly therefrom. Each cell 44 has at least one aperture 44a, and preferably a plurality of apertures 44a for distributing the plating chemistry to the device side of the workpiece W. Because the cells 44 are spaced apart from one another, a groove 33a is formed between the cells 44. When the contact plate 32 and the sparger plate 33 are combined, the conductive members 32a of the contact plate 32 fit within the grooves 33a of the sparger plate 33 so that the sparger apertures 44a are positioned adjacent the workpiece W and in close proximity to the electrical contacts made with the workpiece W. As best shown in FIG. 6B, the conductive members 32a do not completely fill the grooves 33a. Accordingly, the grooves 33a also act as drain pathways for the plating chemistry as shown in FIG. 4B. Likewise, the cells 44 of the sparger plate 33 fit within the open areas 32b of the contact plate 32. In this regard, the sparger plate 33 provides inlet and drain sections that open upward toward the workpiece W to direct electrolyte fluid against the workpiece W and drain the fluid from contact with the workpiece W in a continuous flow manner.

Referring to FIG. 6B, when the sparger plate 33 and the contact plate 32 are properly combined in the plating vessel, there is a generally co-planar relation between the two plates even though the conductive members 32a extend above the adjacent cell 44 and apertures 44a of the sparger plate 33. In a preferred embodiment, the distal ends 32c of the conductive members 32a which make electrical contact with the streets of workpiece W are tapered to enhance the electrical contact with the workpiece W (see FIG. 9C). Preferably the conductive members 32a have a thickness slightly less than the thickness of the streets of the workpiece W, which may be approximately 100 to 250 microns wide. Accordingly, thickness ranges of the conductive members 32a may be 0.5 mm to 5 mm, and more preferably between 1 and 2 mm so that they fit within the streets formed in the workpiece W. In an even more preferred embodiment, with the exception of the tapered distal end or tip 32c, the conductive members 32a are coated or sealed in a suitable material resistant to plating (e.g., TEFLON or elastomeric material such as VITON) to withstand the wet and harsh conditions of the plating bath environment, and prevent plating or thieving on the contact end or tip 32c. Because plating will take place at an accelerated rate at the contact point, by sealing the conductive members 32a and minimizing the contact area by utilizing a tapered end or tip 32c to make contact with the workpiece W, a more uniform metallization will occur.

FIG. 7 shows a partial semiconductor workpiece W resting device side down on the contact assembly 25. FIG. 8 shows an exploded view of the workpiece W, contact plate 32 and sparger plate 33. A typical device side of a semiconductor workpiece W before plating is shown in FIG. 13. With reference to FIGS. 7, 8 and 13, the conductive members 32a of the contact plate 32 make electrical contact with the workpiece W at the streets 50. The microelectronic devices 55, which lie between the streets 50, rest adjacent the open areas 32b of the contact plate 32. The cells 44 of the sparger plate 33 fit within the open areas 32b and are adjacent the microelectronic devices 55. When combined, the sparger plate 33 and contact plate 32 allows for device-scale delivery and removal of plating fluid, and local control of the current to each device 55 from the anode 27. A preferred contact plate 32 is illustrated in FIGS. 9A-9D and a preferred sparger plate 33 is illustrated in FIGS. 14A-14D.

The conductive members 32a of the contact plate 32 may take many different forms in the present invention. Turning to FIGS. 10A-10D there is shown a preferred embodiment of contact plate 32 wherein the conductive members 32a include a plurality of conductive fingers 32d to make discrete point contacts with the workpiece W. The fingers 32d are preferably made from a flexible, conductive material and can flex to adapt to non-uniform surfaces, ensuring a reliable electrical connection. In this preferred embodiment, the fingers 32d preferably contact the workpiece W at the four corners of each die, however, more or less fingers 32d may be used. For example, only the conductive members 32a that define four quadrants of the contact plate 32 (see FIG. 12) may include a plurality of fingers 32d (and may include more than necessary to contact the corners of the dice that run along the quadrant boundaries).

FIGS. 11 and 12 show alternative embodiments of the contact plate 32 of the present invention. In FIG. 11, the contact plate 32 includes a plurality of continuous conductive members 32a that run only along the vertical streets (or horizontal streets not shown) of the workpiece W. The contact plate 32 may have one continuous conductive member 32a connected at opposite ends to the shoulder 41 (effectively dividing the device side of the workpiece W into two zones). Or the contact plate may have a plurality of conductive members 32a (up to the number corresponding to the number of streets on the workpiece W. FIG. 12 shows two intersecting conductive members 32a splitting the contact plate 32 into quadrants. The localized contacts proposed by the present invention may (or may not) be utilized in conjunction with contacting the circumference or periphery of the wafer as is typical in conventional plating apparatuses. However, by creating device level contact schemes as discussed above, the challenges inherent in plating highly resistive films can be overcome.

To eliminate the die-specific nature of the contact geometry associated with a certain aspects of the present invention, an alternative embodiment of the present invention provides for relatively high conductivity current paths (e.g., bus paths) to be formed or imbedded in the streets. This can be accomplished by creating conductive streets or electrical bus paths on the workpiece W. For example, a PVD copper bus line is deposited on the workpiece W. The bus line may be only within a first layer and contact to the bus lines is maintained on subsequent layers by having vias connecting to the bus path. Thus, even when a conventional circumferential contact is used, the highly conductive streets provide a low resistance path around each die, effectively achieving the same result as contacting the wafer locally around each device.

In another aspect of the present invention, even more uniform barrier and seed layer plating may be achieved by coupling the localized die-level contact schemes discussed above with localized plating. For example, local die level anode shapes (or smaller) may be moved and/or controlled to enable better die scale plating. By locally plating one die at a time, the terminal effect is reduced because the overall current passing though the barrier at a given time is reduced and the voltage variations throughout the film are correspondingly reduced. Similarly, localized/dynamic control of the individual contacts across the streets or the circumference can create more controlled localized plating. For example, only a portion of the circumferential or street contacts may be active at a certain time. This dynamic control could be cycled around the wafer creating varying current flow directions and potential drops across the wafer to overcome the effects of anisotropic sheet-resistance and shorting by underlying conductive pads.

While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.

Claims

1. A semiconductor contact assembly for use in a semiconductor electroplating apparatus used to plate a metal or metals onto a semiconductor workpiece having a plurality of streets, comprising:

an outer continuous shoulder that defines an inner area;

a plurality of conductive contact members connected to the outer continuous shoulder and extending into the open area to form a plurality of openings in the inner area; and

at least one recess formed in the outer shoulder.

2. The semiconductor contact assembly of claim 1, wherein the plurality of conductive contact members lie within a common horizontal plane.

3. The semiconductor contact assembly of claim 1, wherein the plurality of openings in the contact assembly are substantially square shaped.

4. The semiconductor contact assembly of claim 1, wherein the plurality of openings in the contact assembly are substantially rectangular shaped.

5. The semiconductor contact assembly of claim 1, wherein the at least one recess formed in the outer shoulder comprises two opposed recesses.

6. The semiconductor contact assembly of claim 1, wherein the plurality of conductive contact members intersect one another to form a grid.

7. The semiconductor contact assembly of claim 1, wherein the plurality of conductive contact members comprise a plurality of discrete contact points.

8. The semiconductor contact assembly of claim 1 further comprising an electrical connector to provide electrical power to the contact assembly.

9. The semiconductor contact assembly of claim 1, wherein the plurality of conductive contact members have a width in a range of 0.5 to 5 mm.

10. The semiconductor contact assembly of claim 9, wherein the width is in a range of 1 to 2 mm.

11. The semiconductor contact assembly of claim 1 further comprising a plate for distributing process fluid to the semiconductor workpiece that rests on the plurality of conductive contact members.

12. The semiconductor contact assembly of claim 11, wherein the plate comprises a plurality of spaced apart cells projecting outwardly from a base, the cells configured to rest within the openings of the inner area and the space between the cells configured to receive the conductive contact members.

13. The semiconductor contact assembly of claim 12, wherein each of the plurality of spaced apart cells has at least one aperture.

14. The semiconductor contact assembly of claim 13, wherein each of the plurality of spaced apart cells has a plurality of apertures.

15. A semiconductor support and contact assembly for use in plating a semiconductor workpiece having a plurality of microelectronic devices formed on one side, the plurality of microelectronic devices being separated from one another by streets, the semiconductor support and contact assembly comprising a plurality of point contacts provided on a frame having a plurality of openings, whereby upon placing the workpiece on the semiconductor support and contact assembly the plurality of point contacts make a plurality of electrical connections with the semiconductor workpiece along the streets.

16. An apparatus for plating a metal onto a semiconductor workpiece, comprising:

a bowl assembly adapted to hold a plating fluid;

an anode positioned in the bowl assembly;

a contact assembly located in the bowl assembly, the contact assembly having a frame that defines an inner area and a plurality of conductive contact members connected to the frame and forming a plurality of openings in the inner area; and

a process head for placing the semiconductor workpiece onto the contact assembly.

17. The apparatus of claim 16 further comprising a plate having a plurality of apertures for distributing the plating fluid to the semiconductor workpiece.

18. The apparatus of claim 16, wherein the contact assembly comprises a plurality of discrete contact points for making an electrical connection with the semiconductor workpiece.

19. The apparatus of claim 16 wherein the bowl assembly comprises a bowl having an inlet and outlet port for selectively introducing a electrolyte into the bowl.

20. The apparatus of claim 19, wherein a membrane divides the bowl into first and second compartments.

21. The apparatus of claim 16 further comprising a power supply for selectively powering the plurality of conductive members.

22. The apparatus of claim 16, wherein the workpiece has a plurality of streets and the contact members are electrically connected to the streets.

23. The apparatus of claim 22, wherein conductive members are positioned within the streets and the contact assembly is in electrical contact with the conductive members of the streets.

24. The apparatus of claim 16, wherein a portion of the contact members are covered with a material resistant to electrochemical plating.

25. A method for plating a metal onto a surface of a semiconductor workpiece, comprising:

providing a semiconductor workpiece having a plurality of microelectronic devices and streets formed on one side thereof;

placing the semiconductor workpiece on a contact assembly having a plurality of conductive members wherein the conductive members contact the semiconductor workpiece at one of the streets;

applying a plating bath fluid to the one side of the semiconductor workpiece; and

electroplating a metal onto the semiconductor workpiece by passing electrical current through the plurality of conductive members and between the semiconductor workpiece and the contact assembly.

26. The method of claim 25, wherein the contact assembly comprises a contact plate and a plate for distributing the plating bath fluid to the one side of the semiconductor workpiece.

27. The method of claim 26, wherein the contact plate and the fluid distribution plate are generally co-planar.

28. The method of claim 25, wherein the contact members lie within a common horizontal plane.

29. The method of claim 25, wherein electrical current is passed through some but not all of the conductive members.

30. The method of claim 25, wherein the contact assembly is comprised of a contact plate having a plurality point contacts and a plurality of openings.

31. The method of claim 30, wherein the contact further comprises a plate having a plurality of apertures for distributing the plating bath fluid to the one side of the semiconductor workpiece.