Abstract:
A plating cell base design that utilizes a single connection that provides both fluid communication and electrical communication to the cell. The design eliminates many of the components previously necessary to effectuate fluid and electrical seals. With fewer connections, material cost is reduced, reliability is enhanced, and downtime is reduced.

Description:
This application claims the benefit of U.S. Provisional application No. 60/137,561 filed Jun. 4, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     In semiconductor manufacturing, a plating tool uses a negatively charged anode (usually a copper anode) to plate a positively charged (cathode) silicon wafer. The anode provides a source of replenishing metal ions. At the cathode, the metal ions are reduced to metal and deposited on the cathode surface. Sulfuric acid and a plating solution flows through a chamber around the anode and is used to dissolve a metal (copper) plate. As fluid (plating solution) flows past the anode, it becomes enriched with metal ions. The plating cell generally includes an anode (copper) held in anode holder, and a diffuser assembly. 
     Conventionally, numerous fluid and electrical connections are required for the plating tool. Such connections generally utilize O-rings, washers and fitting nuts to ensure a sealed connection. Some of these parts require complex machining. The fittings must be electrically conductive and compatible with the plating solution. Titanium is commonly used, as it meets these criteria. As a result, the fittings are a large percentage of the cost of the device. 
     The anode is replaced often, requiring removal of the plating cell from the tool, and significant disassembly. Simplified and reduced numbers of fluid and electrical connections would simplify this process. 
     It is therefore an object of the present invention to provide improved fluid and electrical connectology for a plating tool. 
     SUMMARY OF THE INVENTION 
     The problems of the prior art have been overcome by the present invention, which provides a plating cell base design that utilizes a single connection that provides both fluid communication and electrical communication to the cell. The design eliminates many of the components previously necessary to effectuate fluid and electrical seals. With fewer connections, material cost is reduced, reliability is enhanced, and downtime is reduced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of the electrical and fluid connection in accordance with the present invention; 
     FIG. 2 is a perspective view of another embodiment of the electrical and fluid connection in accordance with the present invention; 
     FIG. 3 is a cross-sectional view of a third embodiment of the electrical and fluid connection in accordance with the present invention; 
     FIG. 4 is a cross-sectional view of a fourth embodiment of the electrical and fluid connection in accordance with the present invention; 
     FIG. 5 is a perspective view of the embodiment of FIG. 4; and 
     FIG. 6 is a cross-sectional view of a cell base in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to FIG. 1, there is shown an anode holder for use in semiconductor manufacturing. The bowl  10  of the holder (only partially shown) is placed in an elbow  12 , preferably made of a plastic, which receives fluid flow as shown by the arrow in the figure. A sealing nose  15  seats in the elbow  12  as shown. Metal (e.g, copper) female fitting  16  is secured through the elbow  12  with washer  17  and nut assembly  18 . A power cable  20  in communication with a suitable power supply (not shown) is fixed to the fitting  16  and in electrical communication with metal (e.g., copper) connection  25 . The nose  15  sealing connects the bowl  10  to the elbow  12  and also engages the standard electrical connection simultaneously. The connection  25  is insulated from the fluid path formed in the elbow  12 . Those skilled in the art will appreciate that the elbow shape  12  is preferred, it is used for purposes of illustration; other shapes are within the scope of the present invention. 
     An alternative embodiment is shown in FIG.  2 . In this embodiment, a standard bayonet-type electrical connection  30  (similar to a thermocouple probe connection) is used. Nose  35  allows the bowl  10  to be interlocked into the fluid delivery system and the electrical rod to be interlocked with the electrical connect  36  (communicating with power cable  20 ) with a 90° twist. 
     Turning now to FIGS. 3-5, there is shown embodiments of the present invention which lend themselves to pre-assembly, thereby eliminating the need to install two O-rings during assembly of the anode package into the tool. Since the connectors come from outside the housing, the anode can be installed without the connectors, thereby avoiding potential damage to the connectors that can be caused by installing a relatively heavy part with delicate features. 
     More specifically, FIG. 3 is a low volume flow embodiment of this feature. Anode holder bowl  10 , preferably made of plastic, houses metal (preferably copper) anode  14 . A housing  20 , preferably also made of plastic, is secured to the bowl  10  with an electrically conductive nut  18 , preferably a copper nut. It is sealed to the bowl  10  by any suitable means, such as one or more O-rings  17  as shown. The nut  18  is in electrical communication with the anode  14  via a metal rod  16 , and in electrical communication with one or more external connect poles  21 . A fluid connection  25  is also provided in the housing  20 . This embodiment reduces four assemblies and four disposable copper parts with two assemblies and two disposable parts. 
     FIG. 4 illustrates a high flow embodiment of the present invention. Housing  20  secures to anode bowl  10  with copper nut  18 , sealed with a plurality of O-rings  17 . As best seen in FIG. 5, the nut  18  has a plurality of apertures  30  for fluid flow, the path of flow through one such aperture being shown in FIG. 4 by the arrows. Electrical communication is provided between the anode  14  and the external connection  21  by metal rod  16  and bolt  22  as shown. This embodiment replaces two disposable electrical connectors with one re-usable plastic housing and one disposable flow through nut. In addition, only two, not four, O-rings are needed for sealing. 
     Turning now to FIG. 6, another embodiment of the present invention is illustrated. Anode  14  is secured in cell base  100  by retaining bolt  44  and support ring  43 . Membrane  50  is positioned in cell base  100  downstream of the anode  14 , in the direction of fluid flow. A center bolt  45  is preferably centrally located in the cell base  100  and secured with a center nut  46 . The center bolt  45  includes a fluid path  48  as shown. The anode  14 , anode support ring  43  and membrane  50  are all removable such as when changing the anode, but the center bolt  45  can remain in the cell base  100 , thereby facilitating anode change. The bolt  45  can be secured to the anode  14  by any suitable means, such as with threads or other locking mechanisms known to those skilled in the art. The bolt  45  is electrically conductive, thereby providing electrical communication with an external power supply (not shown). An electrical pin  54 , which may or may not be of the same material as the bolt  45 , can be used to facilitate electrical communication between the power supply and the bolt  45 . 
     Fitting adapter  60  is preferably offset from the center of the cell base  100 , and includes external threads for connection to a main fluid supply. The fitting adapter  60  has a central bore  62  for fluid flow, which fluid feeds into passageway  65  and is deflected by flow deflector  66  for uniform and symmetrical distribution of the fluid in the cell base  100 . 
     Although copper is disclosed above for the electrically conductive fittings, other electrically conductive materials may be used, as long as they do not cause problems (such as contamination) with the other components of the system, including the plating bath. For example, other suitable electrically conductive materials include titanium, palladium, platinum, and coated platinum. 
     Any of the aforementioned embodiments reduce the amount of connections necessary, thereby reducing the potential for leakage. The connectology also allows for easy disassembly for maintenance or anode replacement, reducing the number of parts needed to provide a sealed connection.