PLATING SYSTEM FOR SEMICONDUCTOR MATERIALS

Abstract: A semiconductor workpiece processing tool (10) includes a processing module (20) having particular applicability to an electroplating process for semiconductor wafers. The processing module (20) has plural processing bowls assemblies (603) each having an outer bowl (616) and an inner cup (620). Fluid is provided to the cup (620) through an opening (628) in the bottom. Fluid overflows the cup (620) and drains into a fluid reservoir (604). Reservoir (604) is preferably used as both the supply and the return for the process fluid. FIlters (630) can be included in each cup to filter process fluid entering the cup. The plurality of the processing bowls can have a common reservoir.

Description: DESCRIPTION PLATING SYSTEM FOR SEMICONDUCTOR MATERIALS Technical Field This invention pertains to semiconductor manufacturing machines in general and in particular to semiconductor processing stations and more particularly semiconductor electroplating work stations. Background Art In the manufacture of semiconductors and microchips, one method of manufacture is to use a large wafer of semiconductor material such as silicon dioxide and manufacture many microchips out of a single wafer. The wafer is then separated into the individual microchips. Manufacturing by using the single wafer has the advantage of increasing throughput in the semiconductor manufacturing process. Obviously the larger the wafer that can be used the more efficiency is obtained and the higher the throughput will be . However, since microchips contain many circuits of minuscule dimensions, the manufacturing process must be very precise and accurate to ensure that all microchips manufactured out of a single wafer are of the same quality. One step in assuring quality and uniformity in the semiconductor manufacturing process is to manufacture the semiconductor wafer in a "clean" environment. Semiconductors are typically manufactured in what is known in the industry as a clean room. A clean room is designed to minimize the number of particulates in the air. The cost of manufacturing and maintaining these clean rooms is very expensive , and therefore any progress that can be made towards reducing the size of the semiconductor manufacturing machines will allow for smaller clean rooms. While minimizing the size of the manufacturing machine is essential in reducing cost of the clean rooms, it is also necessary to maintain the high quality of the manufacturing in the smaller machines. Since, as described earlier, it is advantageous to use larger wafers to increase throughput, any process to which the wafer is exposed must assure that all portions of the wafer are treated equally. Any unevenness in application of material to the wafer will result in semiconductor chips which are not of sufficient quality and must be destroyed. One of the processes in the manufacture of semiconductor wafers is electroplating a conductive metallic surface onto the wafer. The electroplating process requires the handling of a large volume of liquid which necessarily implies the use of pumps, piping, and other components, all of which take up valuable space in a clean room environment. Additionally, in the electroplating process, it is necessary to apply an electric current to the semiconductor wafer to cause the electrolytic solution to plate out the conductive metal on the surface of the semiconductor wafer. As described earlier, it is desirable to minimize processing time in the manufacture of the wafer. Therefore , it is desirable to find a fast and efficient method for making the electrical contact to the semiconductor wafer. It is also desirable that the semiconductor wafer be held in a precise position during the electroplating process to assure uniformity of the conductive metal surface plated onto the wafer. It is therefore desirable to have an apparatus that will present the wafer to the process and hold the wafer in the process in an accurate position. Finally, it is desirable to have an apparatus which will handle the wafers in a fast and efficient method to increase throughput. It is against this background that the apparatus of the present invention was developed. Brief Description of the Drawings Fig. 1 is an environmental view showing the apparatus of the electroplating module in a semiconductor workpiece process tool. Fig. 2 is an isometric view of the apparatus of the present invention showing a five station plating module . Fig. 3 is an isometric view of one embodiment of the apparatus of the system of Fig. 2 showing the internal components of the five unit plating module. Fig. 4 is an isometric view showing the plating tank and the process bowls of the system of Fig. 2. Fig. 5 is an isometric detail of a plating chamber of the apparatus of the present invention. Fig. 6 is front elevation sectional view of the present invention showing the plating tank, the plating chambers, and the associated plumbing. Fig. 7 is side elevation sectional view of the present invention showing the plating tank and a plating chamber. Fig. 8 is a side sectional view of the apparatus of the present invention showing a workpiece support positioned over an electroplating process bowl. Fig. 9 is a side sectional view of the apparatus of the present invention showing a workpiece support supporting a workpiece for processing within an electroplating process bowl. Fig. 10 is an isometric view of the semiconductor processing head of the present invention. Fig. 11 is a side elevation view of the processing head of the present invention showing the head in a "receive wafer" position. Fig. 12 is a side elevation view of the processing head of Fig. 3 showing the head in a rotated position ready to lower the wafer into the process station. Fig. 13 is a side elevation view of the processing head of Fig. 3 showing the head operator pivoted to deploy the processing head and wafer into the bowl of the process station. Fig. 14 is a schematic front elevation view of the processing head indicating the portions detailed in Figs. 15 and 16. Fig. 15 is a front elevation sectional view of the left half of the processing head of the apparatus of the present invention also showing a first embodiment of the wafer holding fingers. Fig. 16 is a front elevation sectional view of the left half of the processing head of the apparatus of the present invention also showing a first embodiment of the wafer holding fingers. Fig. 17 is an isometric view of the operator base and operator arm of the apparatus of the present invention with the protective cover removed. Fig. 18 is a right side elevation view of the operator arm of the present invention showing the processing head pivot drive mechanism. Fig. 19 is a left side elevation view of the operator arm of the present invention showing the operator arm drive mechanism. Fig. 20 is schematic plan view of the operator arm indicating the portions detailed in Figs. 21 and 22. Fig. 21 is a partial sectional plan view of the right side of the operator arm showing the processing head drive mechanism. Fig. 22 is a partial sectional plan view of the left side of the operator arm showing the operator arm drive mechanism. Fig. 23 is a side elevational view of a semiconductor workpiece holder constructed according to a preferred aspect of the invention. Fig. 24 is a front sectional view of the Fig. 1 semiconductor workpiece holder. Fig. 25 is a top plan view of a rotor which is constructed in accordance with a preferred aspect of this invention, and which is taken along line 3-3 in Fig. 24. Fig. 26 is an isolated side sectional view of a finger assembly constructed in accordance with a preferred aspect of the invention and which is configured for mounting upon the Fig. 25 rotor. Fig. 27 is a side elevational view of the finger assembly of Fig. 26. Fig. 28 is a fragmentary cross-sectional enlarged view of a finger assembly and associated rotor structure . Fig. 29 is a view taken along line 7-7 in Fig. 4 and shows a portion of the preferred finger assembly moving between an engaged and disengaged position. Fig. 30 is a view of a finger tip of the preferred finger assembly and shows an electrode tip in a retracted or disengaged position (solid lines) and an engaged position (phantom lines) against a semiconductor workpiece . Best Modes for Carrying Out the Invention and Disclosure of Invention TABLE 1 Listing of Subsections of Detailed Description and Pertinent Items with Reference Numerals and Page Numbers Workpiece Processing Station reservoir top 618 9 semiconductor workpiece process tool process bowl or plating chamber 616 . . 9 10 7 bowl side 617 9 electroplating module 20 7 bowl bottom 619 9 workpiece support 401 7 cup assembly 620 9 processing head 406 7 fluid cup 621 9 operator arm 407 7 cup side 622 9 operator base 405 7 cup bottom 623 9 fingers 409 7 fluid inlet line 625 9 beam emitter 81 7 bowl bottom opening 627 9 plating chamber assemblies 603 8 cup fluid inlet opening 624 9 process fluid reservoir 604 8 inlet line end point 631 9 immersible pump 605 8 Fluid outlet openings 628 9 module frame or chassis 606 8 inlet plenum 629 9 pump discharge filter 607 cup filter 630 9 outer reservoir wall 608 metallic anode 634 9 inner reservoir wall 609 annular gap or space 635 9 reservoir safety volume 611 outer cup wall 636 10 inner vessel 612 process fluid overflow space 632 10 reservoir overflow opening 610 cup upper edge 633 10 heat exchanger 613 bowl upper edge 637 10 exchanger inlet 614 crossbars 626 10 exchanger outlet 615 bowl bottom center plate 639 10 fluid return openings 638 10 Bowl Assembly 9 process module deck plate 666 11 levelers 640 11 Operator Arm-Processing Head Rotate compliant bowl seal 665 . . . . . . . . . . . 12 Mechanism 18 cup height adjuster 641 12 Processing head rotate mechanism 431 18 cup height adjustment jack 643 12 rotate shaft 432 18 adjustment tool access holes 667 12 securing collar 433 18 anode height adjuster 646 12 rotate motor support 434 18 threaded anode post 664 12 rotate encoder 435 18 threaded anode adjustment sleeve 663 . 12 rotate pulley inboard bearing 436 . . . . 19 sleeve openings 668 12 rotate belt 437 19 fluid outlet chamber 662 12 processing head pulley 438 19 rotate belt tensioner 439 19 Fluid Transfer Equipment 13 tensioner hub 468 19 pump suction 647 13 processing head shaft bearing 440 . . . . 19 pump body 653 13 processing head rotate bearing 469 . . . 19 pump discharge 648 13 processing head shaft bearing 441 . . . . 19 electric pump motor 650 13 cable brackets 442 and 443 20 removable filter top 649 13 rotate overtravel protect 444 20 supply manifold 652 13 rotate flag 447 20 fluid return line 654 14 Rotate optical switches 445 and 446 . . 20 optional end point 655 14 back pressure regulator 656 14 Operator Arm-Lift Mechanism 22 operator arm lift mechanism 448 22 Control Devices 14 lift motor shaft 454 22 flow sensors 657 14 lift gear drive 453 22 flow signal line 659 14 lift drive shaft 456 22 flow restrictors 658 14 lift bushing 449 22 flow control signal line 660 14 anchor plate 458 22 anchor fasteners 457 22 Workpiece Support 15 Lift bearing 450 22 operator base 405 15 lift bearing support 460 22 processing head 406 15 operator arm frame 461 22 operator arm 407 15 lift anchor 451 23 wafer holder 408 15 lift overtravel protect 462 23 fingers 409 15 lift optical switch low 463 23 Workpiece holder 408 15 lift optical switch high 464 23 workpiece spin axis 410 15 lift flag 465 23 process pivot axis 411 15 lift motor encoder 455 23 operator pivot axis 412 15 lift motor 452 23 workpiece W 16 slotted lift flag mounting slots 467 . . . 23 fingertips 414 16 lift flag fasteners 466 23 processing bowl 417 16 left and right forks 418 and 419 16 Processing Head 24 processing head housing 470 24 Operator Base 17 circumferential grooves 471 24 operator base back portion 420 17 rotate shaft openings 474 and 475 . . . . 24 operator base left yoke arm 421 17 left and right processing head mounts operator base right yoke arm 422 . . . . 17 472 24 yoke arm fasteners 423 17 processing head door 476 24 operator arm bearings 424 17 processing head void 477 24 operator arm 425 17 Processing Head Spin Motor 24 Operator Arm 17 workpiece holder 478 25 process arm rear cavity 426 17 spin axis 479 25 lift motor 452 17 spin motor 480 25 rotate motor 428 17 top motor housing 481 25 processing head left pivot shaft 429 . . . 17 spin motor shaft 483 25 processing head right pivot shaft 430 . . 17 workpiece holder rotor 484 25 rotor hub 485 25 rotor hub recess 486 25 Finger Assembly Drive System 32 workpiece shaft snap-ring 488 . . . . . . . 25 bearing 838 32 rotor recess groove 489 25 collet 840 32 spin encoder 498 26 bearing receptacle 839 32 optical tachometer 499 26 spring 842 32 spring seat 844 33 Processing Head Finger Actuators 27 Pneumatic piston 502 27 Finger Assembly Electrical System 33 actuator spring 505 27 pin connector 846 33 cavity end cap 507 27 finger 848 33 retaining ring 508 27 nut 850 33 pneumatic inlet 503 27 anti-rotation pin 852 33 pneumatic supply line 504 27 finger tip 854 33 actuator plate 509 27 electrode contact 858 34 actuator plate connect screw 510 27 Wave springs 529 27 Finger Assembly Drive System Interface 34 bushing 512 28 finger actuator 862 34 pneumatic piston recess 511 28 actuation ring 863 34 finger actuator contacts 513 28 first movement path axis 864 34 secondary linkage 865 34 Processing Head Workpiece Holder 28 link arm 867 34 finger actuator lever 514 28 actuator torque ring 869 34 finger stem 515 28 pneumatic operator 871 34 finger diaphragm 519 28 workpiece holder rotor 484 28 Engaged and Disengaged Positions 35 finger opening 521 28 arrow A 35 rotor diaphragm lip 523 28 workpiece standoff 865 36 finger spring 520 29 bend 866 36 finger actuator tab 522 29 finger collar or nut 517 29 Finger Assembly Seal 36 shoulder 518 29 seal 868 36 finger actuator mechanism 500 29 rim portion 870 36 cavity 501 29 Methods and Operation 37 Semiconductor Workpiece Holder - Electroplating Embodiment 29 Plating Methods 40 semiconductor workpiece holder 810 . . 29 bottom half or bowl 811 29 * * * (End of Table 1) * * * Processing Head and Processing Head Operator 30 workpiece support 812 30 spin head assembly 814 30 lift/rotate assembly 816 30 motor 818 30 rotor 820 30 rotor spin axis 822 30 finger assembly 824 30 actuator 825 31 rotor center piece 826 31 spokes 828 31 rotor perimeter piece 830 31 Finger Assembly 31 finger assembly frame 832 32 angled slot 832a 32 finger assembly frame outer flange 834 32 inner drive plate portion 836 32 Workpiece Processing Station With reference to Fig. 1, a semiconductor workpiece process tool 10 is shown. The workpiece process tool may comprise several different modules for performing a variety of manufacturing process steps on the workpiece or semiconductor wafer. The workpiece processing tool may advantageously contain electroplating module 20, alternately known more generally as a workpiece processing station. The plating module 20 of Fig. 2 is shown as a 5 bay plating module. This allows for up to 5 workpieces to be processed simultaneously. Each of the 5 electroplating bays may alternately be known as a workpiece processing station. Each workpiece processing station is advantageously provided with a workpiece support 401. Each workpiece support is further advantageously provided with a processing head 406, an operator arm 407, and an operator base 405. The details of the workpiece support 401 are described below. The operator base 405 of the workpiece support 401 is mounted to the workpiece processing station by securing it to the chassis or shelf of the workpiece module. Workpiece support 601 is shown in a "open" or "receive wafer" position whereby a robotic arm or other means will provide a workpiece to the workpiece support. The workpiece support will positively engage the workpiece (described more fully below) by fingers 409 (or more precisely, by finger tips of finger assemblies, which are also described more fully below). The processing head 406 will then rotate about the operator arm 407 to place the workpiece in an essentially downward facing position. Operator arm 407 will then pivot about operator base 405 to place the workpiece in the processing bowl as shown at 602 of Fig. 2. The manufacturing step or process will then be performed upon the workpiece. Following the manufacturing step, the workpiece will be returned to the open position shown by workpiece support 601 at which time the workpiece will be removed from fingers 409. Although the invention is described for an electroplating process, it is to be noted that the general arrangements and configurations of the workpiece processing stations and their combination into a multi- workpiece processing station unit may be applied to a variety of processes used in manufacturing. Fig. 2 also shows an optional beam emitter 81 for emitting a laser beam detected by robotic wafer conveyors (not shown) to indicate position of the unit. Turning to Fig. 3, an isometric view of the electroplating module 20 with the front panel cut away reveals that the module is advantageously provided with a series of process bowl assemblies or plating chamber assemblies 603, a process fluid reservoir 604, and an immersible pump 605. Each process bowl assembly 603 is connected to the immersible pump 605 by fluid transfer lines which preferably are provided with instrumentation and control features described more fully below. The details of the bowl assemblies and their arrangement and configuration with the other components of the invention described herein are described more fully below. The process fluid reservoir 604 is mounted within the processing module 20 by attaching it to the module frame or chassis 606. Turning to Fig. 4, the fluid reservoir 604 is shown in isolation with process bowl assembly 603, immersible pump 605, and pump discharge filter 607. Turning briefly to Fig. 7, a side sectional view of the fluid reservoir 604 is shown. As can be seen in Fig. 7, process fluid reservoir 604 is advantageously a double-walled vessel having an outer reservoir wall 608 and an inner reservoir wall 609 defining a reservoir safety volume 611 therebetween. Fluid reservoir 604 is preferably a double-walled vessel in the event that the inner wall 609 should leak. A double-walled vessel construction design would allow the leak to be contained within the reservoir safety volume 611 between the outer wall 608 and the inner wall 609. Should the reservoir safety volume become filled with fluid leaking from the inner vessel 612, the fluid would overflow through reservoir overflow opening 610. Reservoir opening 610 is preferably provided with guttering or the like to channel overflow fluid to a safe collection point (not shown). Further, the reservoir safety volume may be provided with liquid detection sensors (not shown) to alert operators in the event that the inner wall of reservoir 604 should become breached and fluid enter the reservoir safety volume 611. The process module may also be provided with a heat exchanger 613. Turning to Fig. 6, the heat exchanger 613 is shown in front elevation view of the process fluid reservoir 604. The heat exchanger shown in Fig. 6 is a double helix-type having an exchanger inlet 614 and an exchanger outlet 615. The exchanger 613 may be used for either cooling or heating the process fluid by circulating respectively either a cooler or warmer fluid through the exchanger than is present in the reservoir. Alternate designs of heat exchangers may also effectively be used in the apparatus of the present invention. Bowl Assembly Returning to Fig. 4, a plurality of bowl assembly 603 are shown mounted in reservoir top 618. The indicated process chamber 603 is shown in isometric detail in Fig. 5. Turning to Fig. 5, it is seen that the bowl assembly 603 is secured within reservoir top 618. The process bowl assembly consists of a process bowl or plating chamber 616 having a bowl side 617 and a bowl bottom 619. The process bowl is preferably circular in a horizontal cross section and generally cylindrical in shape although the process bowl may be tapered as well. The invention further advantageously includes a cup assembly 620 which is disposed within process bowl 616. Cup assembly 620 includes a fluid cup 621 having a cup side 622 and a cup bottom 623. As with the process bowl, the fluid cup 621 is preferably circular in horizontal cross section and cylindrical in shape, although a tapered cup may be used with a tapered process bowl. Process fluid is provided to the process bowl 616 through fluid inlet line 625. Fluid inlet line rises through bowl bottom opening 627 and through cup fluid inlet opening 624 and terminates at inlet line end point 631. Fluid outlet openings 628 are disposed within the fluid inlet line 625 in the region between the cup fluid inlet opening 624 and fluid line end point 631. In this way, fluid may flow from the fluid inlet line 625 into the cup 621 by way of the inlet plenum 629. The cup assembly 620 preferably includes a cup filter 630 which is disposed above the fluid inlet openings and securely fits between the inner cup wall 622 and the fluid inlet line 625 so that fluid must pass through the filter before entering the upper portion of cup 621. In an electroplating process, the cup assembly 620 is advantageously provided with a metallic anode 634. Anode 634 is secured within the cup assembly by attaching it to the end point 631 of the fluid inlet line . Anode 634 is thus disposed above the cup filter 630 as well as above fluid inlet opening 628. Anode 634 is preferably circular in shape and of a smaller diameter than the inside diameter of cup 621. Anode 634 is secured to the end point 631 of fluid inlet line 625 so as to center the anode 634 within cup 621 creating an annular gap or space 635 between the inner cup wall 622 and the edge of anode 634. Anode 634 should be so placed such as to cause the anode annular opening 635 to be of a constant width throughout its circumference. The outer cup wall 636 is advantageously of a smaller diameter than the inside diameter of bowl 616. Cup assembly 620 is preferably positioned within bowl 616 such that a first annular space or process fluid overflow space 632 is formed between bowl side 617 and cup outer wall 636. The cup assembly is more preferably positioned such that the annular fluid overflow space 632 is of a constant width throughout its circumference . Cup assembly 620 is further advantageously positioned within bowl 616 such that cup upper edge 633 is below bowl upper edge 637. Cup 621 is preferably height-adjustable with respect to bowl upper edge 637, as more fully described below. Bowl bottom 619 is preferably configured so as to have a large open area allowing the free transfer of fluid therethrough. In the preferred embodiment, this is achieved by the structure shown in Fig. 5 wherein the process bowl bottom 619 is composed of crossbars 626 which intersect at bowl bottom center plate 639 creating fluid return openings 638. Bowl bottom center plate 639 is provided with bowl bottom opening 627 to allow fluid inlet line 625 to pass therethrough. In the preferred embodiment, the bowl sides 617 below the reservoir top 618 are also similarly constructed so that bowl sides below reservoir top 618 are essentially composed of 4 rectangular sections which then turn inward towards bowl bottom center plate 639 intersecting thereat. Such a configuration allows for a high degree of fluid flow to pass through the bowl lower portion which is disposed within reservoir 604. Thus, in operation, process fluid is provided through process fluid inlet line 625 and discharges through fluid outlet openings 628 within the lower part of the cup assembly 620. By virtue of cup filter 620, fluid entering the fluid inlet plenum 629 is distributed across the plenum and then flows upward through filter 630 to the bottom of anode 634. From the top side of filter 630, the process fluid continues to flow in an upward direction by virtue of continuing feed of process fluid through process inlet line 625. The process fluid flows around the annular gap 635 between the anode 634 and the inner cup wall 622. As the process fluid continues to well up within cup 621 , it will eventually reach upper cup edge 633 and will overflow into the overflow annular gap 632 between the outer cup wall 636 and the inner wall of bowl 616. The overflowing fluid will flow from the overflow gap 632 downward through the gap and back into reservoir 604 where it will be collected for reuse, recycling, or disposal. In this manner, no process fluid return line is required and no elaborate fluid collection system is necessary to collect surplus fluid from the process. As a further advantage, the location of the cup filter 630 and anode 634 within the cup 621 provides an even distribution of fluid inlet into the cup. The even distribution beneficially assists in providing a quiescent fluid surface at the top of cup 621. In like manner, maintaining a constant distance between the outer wall of cup 636 and the inner wall of bowl 616 in providing the overflow gap 632 will assist in providing an even flow of fluid out of cup 621 and into the reservoir 604. This further beneficially assists in providing the desired quiescence state of the process fluid at the top of cup 621. The material selection for cup filter 620 will be dictated by the process and other operating needs. Typically, the filter will have the capability of filtering particles as small as 0.1 microns. Likewise, the choice of materials for anode 634 will be dictated by the desired metal to be electroplated onto the workpiece. While the above bowl assembly has been described particularly for an electroplating process, it can be seen that for a process where a flow of fluid is required but no anode is required removing the anode 634 from the cup assembly 603 will provide a quiescent pool of liquid for the process. In such an arrangement, the end point 631 of the fluid inlet line 625 would be capped or plugged by a cap or plug rather than by the anode 634. To assist in ensuring that process fluid overflows into the annular gap 632 evenly, it is necessary to ensure that the cup upper edge 633 is level such that fluid does not flow off of one side of cup 621 faster than on another side. To accomplish this objective, levelers are preferably provided with the process bowl assembly 603. Turning now to Fig. 8, the process bowl assembly of Fig. 5 is shown in cross section along with the workpiece support 401. The process bowl assembly 603 is shown mounted to the process module deck plate 666. Plating chamber assembly 603 is preferably provided with levelers 640 (only one of which is shown in this view) which allow the plating chamber assembly to be leveled relative to the top of reservoir 618. The levelers may consist of jack screws threaded within the edge of module deck plate 666 and in contact with the process module frame 606 so as to elevate the process bowl assembly 603 relative to the process module 20. The process bowl assembly 603 is preferably provided with three such bowl levelers distributed about the bowl periphery. This allows for leveling in both an X and Y axis or what may be generically described as 'left and right leveling and front and rear leveling." Since process bowl assembly 603 is free to move with respect to fluid reservoir 604, when process bowl assembly 603 is fit closely within fluid reservoir 604 as shown in Fig. 8, the process bowl/fluid reservoir junction preferably has a compliant bowl seal 665 disposed therebetween to allow movement of the process bowl 616 with respect to reservoir inner wall 609. Compliant seal 665 further prevents process fluid from passing through the opening between the process bowl and the reservoir wall. Cup assembly 620 is preferably provided with cup height adjuster 641. The cup height adjuster shown and described herein consists of a cup height adjustment jack 643 which is positioned about an externally portion of inlet line 625. Cup 621 is secured to cup height adjustment jack 643 with cup lock nut 642. Cup lock nut 642 is used to secure cup 621 in its height position following adjustment. The upper end of cup height adjustment jack 641 is provided with adjustment tool access holes 667 to allow for adjusting of the height of the cup from the top of the bowl rather than the underside . The cup height adjuster 641 may additionally be provided with a fluid seal such as an o-ring (not shown) disposed within the annular space formed between the adjustment jack 643 and the cup bottom 623. The process bowl assembly 603 is more preferably provided with an additional height adjuster for the anode 634. Since it is desirable to be able to adjust the distance between the anode 634 and the workpiece based upon the particular electroplating process being used, anode height adjuster 646 is beneficially provided. Anode height adjuster 646 is formed by mounting the anode 634 on the threaded anode post 664. A threaded anode adjustment sleeve 663 is used to connect the threaded upper end of inlet line 625. Anode adjustment sleeve 663 is provided with sleeve openings 668 to allow fluid to pass from fluid outlet openings 628 into the inlet plenum 629. The space between the bottom of anode post 664 and the upper end of fluid inlet line 625, and bounded by the anode adjustment sleeve 663, defines a fluid outlet chamber 662. Fluid outlet chamber is of variable volume as the anode post 664 moves upward and downward with height adjustment of the anode 634. On the bowl leveler 640 and the height adjusters 641 and 646 described above, it is additionally desirable to provide them with locking mechanisms so that once the desired positioning of the device (i.e., the bowl, the cup, or the anode) is achieved, the position may be maintained by securing the adjusters so that they do not move out of adjustment as a result of vibration or other physical events. Allowing independent height adjustment of the cup and anode each with respect to the bowl provides a large degree of flexibility in adjusting the process bowl assembly 603 to accommodate a wide selection of processes. Fluid Transfer Equipment To provide process fluid to the process bowl assembly in the electroplating module of the present invention, the module is advantageously provided with fluid transfer equipment. The fluid transfer equipment is provided to draw process fluid from a reservoir, supply it to the process bowl assemblies, and return it to a common collection point. Turning now to Fig. 6, a cross section of the reservoir and process bowl assemblies and additional equipment shown in Fig. 4 is shown. Fig. 6 shows a immersible pump 605 which is mounted to the reservoir top 618. The plating module is advantageously provided with such a pump which further consists of a fluid suction or pump suction 647 which draws process fluid from the reservoir 604. The immersible pump pumps fluid from the pump suction 640 into the pump body 653 and out through the fluid discharge or pump discharge 648. Immersible pump 605 is preferably driven by an electric pump motor 650. In alternate embodiments of the present invention, a submersible pump may be deployed. However, the immersible pump has the advantage that it may be easily removed for servicing and the like. In yet another embodiment, individual pumps for each of the process bowl assemblies may be deployed or, process bowls assemblies may share a set of common pumps. Each such pump would have a process fluid inlet suction and a process fluid discharge. Returning to the preferred embodiment of Fig. 6, the plating module preferably has a pump discharge filter 607 which is connected in line with pump discharge 648. Pump discharge filter 607 is preferably provided with a removable filter top 649 so that filter cartridges within the filter may be replaced. The filter type, size and screen size will be dictated by the needs of the particular process being deployed at the time. From the pump discharge filter 607, the process fluid exits through filter outlet 651 and into supply manifold 652. The supply manifold supplies all of the process bowl assemblies 603 with process fluid. Branching off from the supply manifold 652 are the individual fluid inlet lines 625. The fluid inlet lines 625 are preferably provided with flow control devices which are more fully described below. At the downstream end of the supply manifold 652 after the final processing bowl assembly 661, the manifold is routed to fluid return line 654. Although the supply manifold could be terminated at an open ended point at optional end point 655, in the preferred embodiment, the supply manifold 652 is additionally provided with a back pressure regulator 656, which is described more fully below. Since it is advantageous to have the back pressure regulator outside of the fluid reservoir for ease of access, the fluid return line 654 is provided when the back pressure regulator 656 is employed. Control Devices In the preferred embodiment, the work station processing module of the present invention further includes devices for controlling the flow and distribution of the process fluid to the process bowl assemblies. With reference to Fig. 6, the apparatus of the present invention is beneficially provided with flow sensors 657 which are disposed within the fluid inlet line 625 for each individual process bowl assembly 603. The flow sensors 657 will measure the amount of process fluid flowing through each fluid inlet line and will generate a signal which will be transmitted by flow signal line 659. A signal will typically be an electrical signal but may also be a pneumatic or other type of signal. The processing modules 603 are also preferably provided with flow restrictors 658 which are disposed in fluid inlet lines 625 after the flow sensor 657 but before the fluid outlet opening 628 within cup 621 (shown in Fig. 5). The flow restrictor may alternately be known as a variable orifice or a control valve. The flow restrictor 658 may either be manually adjustable, or may be responsive to a signal provided by flow control signal line 660. The flow control signal line may be a pneumatic, electrical or other type of signal. The objective of the flow controller is to control the quantity of process fluid being provided to the fluid cup 621 during the processing step of manufacturing the semiconductor. When the flow restrictor is responsive to a control signal, the information provided from the flow signal line 659 may be used to modify or generate the flow control signal which is then provided to the flow controller 658. This control may be provided by a micro processor or by other control devices which are commercially available. More preferably, the semiconductor processing module is provided with back pressure regulator 656. As pump discharge filter 607 becomes restricted due to captured filtrate, the pressure within supply manifold 652 will drop, reducing flow of process fluid to the fluid cups 621. Back pressure regulator 656 is used to maintain a preselected pressure in the supply manifold 652 to ensure that sufficient pressure is available to provide the required flow of process fluid to the fluid cups. Back pressure regulator 656 further comprises an internal pressure sensor and preferably includes a signal generator for generating a control signal to open or close the back pressure regulator to increase or decrease the pressure in the supply manifold. The back pressure regulator may be controlled by an external controller such as a micro processor or it may have a local set point and be controlled by an internal local control mechanism. In an alternate embodiment, where a dedicated process pump is used for each process bowl assembly, a back pressure regulator would typically not be required. Workpiece Support Turning now to Fig. 10, an enlarged view of the workpiece support 401 is shown. Workpiece support 401 advantageously includes operator base 405, a processing head 406, and an operator arm 407. Processing head 406 preferably includes workpiece holder or wafer holder 408 and which further includes fingers 409 for securely holding the workpiece during further process and manufacturing steps. Workpiece holder 408 more preferably spins about workpiece spin axis 410. The processing head is advantageously rotatable about processing head pivot axis or, more briefly termed, process pivot axis 411. In this manner, a workpiece (not shown) may be disposed between and grasped by the fingers 409, at which point the processing head is preferably rotated about process head pivot axis 411 to place the workpiece in a position to be exposed to the manufacturing process. In the preferred embodiment, operator arm 407 may be pivoted about operator pivot axis 412. In this manner, the workpiece is advantageously lowered into the process bowl (not shown) to accomplish a step in the manufacture of the semiconductor wafer. Turning now to Figs. 11-13, the sequence of placing a workpiece on the workpiece support and exposing the workpiece to the semiconductor manufacturing process is shown. In Fig. 11 , a workpiece W is shown as being held in place by fingertips 414 of fingers 409. Workpiece W is grasped by fingertips 414 after being placed in position by robot or other means. Once the workpiece W has been securely engaged by fingertips 414, processing head 406 can be rotated about process head pivot axis 411 as shown in Fig. 12. Process head 406 is preferably rotated about axis 411 until workpiece If is at a desired angle, such as approximately horizontal. The operator arm 407 is pivoted about operator arm pivot axis 412 in a manner so as to coordinate the angular position of processing head 406. In the closed position, the processing head is placed against the rim of bowl 416 and the workpiece W is essentially in a horizontal plane . Once the workpiece W has been secured in this position, any of a series of various semiconductor manufacturing process steps may be applied to the workpiece as it is exposed in the processing bowl 417. Since the processing head 406 is engaged by the operator arm 407 on the left and right side by the preferably horizontal axis 411 connecting the pivot points of processing head 406, a high degree of stability about the horizontal plane is obtained. Further, since the operator arm 407 is likewise connected to the operator base 405 at left and right sides along the essentially horizontal line 412 connecting the pivot points of the operator arm, the workpiece support forms a structure having high rigidity in the horizontal plane parallel to and defined by axes 411 and 412. Finally, since operator base 405 is securely attached to the semiconductor process machine 400, rigidity about the spin axis 410 is also achieved. Similarly, since processing head 406 is nested within the fork or yoke shaped operator arm 407 having left and right forks 418 and 419, respectively, as shown in Fig. 10, motion due to cantilevering of the processing head is reduced as a result of the reduced moment arm defined by the line connecting pivot axes 411 and 412. In a typical semiconductor manufacturing process, the workpiece holder 408 will rotate the workpiece, having the process head 406 secured at two points, that is, at the left and right forks 418 and 419, respectively, the vibration induced by the rotation of the workpiece holder 408 will be significantly reduced along the axis 411. A more complete description of the components of the present invention and their operation and interrelation follows. Operator Base Turning now to Fig. 17, operator base 405 is shown. The present invention advantageously includes an operator base 405 which forms an essentially yoke-shaped base having an operator base back portion 420, an operator base left yoke arm 421 , and an operator base right yoke arm 422. Yoke arms 421 and 422 are securely connected to the base of the yoke 420. In the preferred embodiment, the yoke arms are secured to the yoke base by the yoke arm fasteners 423. The yoke arm base in turn is advantageously connected to the semiconductor process machine 400 as shown in Fig. 9. The upper portions of the yoke arm advantageously include receptacles for housing the operator arm bearings 424 which are used to support the pivot shafts of the operator arm 425, described more fully below. Operator Arm Still viewing Fig. 17, the present invention advantageously includes an operator arm 407. As described previously, operator arm 407 preferably pivots about the operator arm pivot axis 412 which connects the center line defined by the centers of operator arm pivot bearings 424. Operator arm or pivot arm 407 is advantageously constructed in such a manner to reduce mass cantilevered about operator arm pivot axis 412. This allows for quicker and more accurate positioning of the pivot arm as it is moved about pivot arm axis 412. The left fork of the pivot arm 418, shown more clearly in Fig. 19, houses the mechanism for causing the pivot arm to lift or rotate about pivot arm pivot axis 412. Pivot arm right fork 419, shown more clearly in Fig. 18, houses the mechanism for causing the processing head 406 (not shown) to rotate about the process head pivot axis 411. The process arm rear cavity 426, shown in Fig. 17, houses the lift motor 452 for causing the operator arm 407 to rotate about pivot arm axis 412. Process arm rear cavity 426 also houses rotate motor 428 which is used to cause the processing head 406 to rotate about the processing head pivot axis 411. The rotate motor 428 may more generally be described as a processing head pivot or rotate drive . Processing head 406 is mounted to operator arm 407 at processing head left pivot shaft 429 and processing head right pivot shaft 430. Operator arm 407 is securely attached to left yoke arm 421 and right yoke arm 422 by operator arm pivot shafts 425 and operator arm pivot bearings 424, the right of which such bearing shaft and bearings are shown in Fig. 17. Operator Arm-Processing Head Rotate Mechanism Turning now to Fig. 21, a sectional plan view of the right rear corner of operator arm 407 is shown. The right rear section of operator arm 407 advantageously contains the rotate mechanism which is used to rotate processing head 406 about processing head pivot shafts 430 and 429. Processing head rotate mechanism 431 preferably consists of rotate motor 428 which drives rotate shaft 432, more generally described as a processing head drive shaft. Rotate shaft 432 is inserted within rotate pulley 425 which also functions as the operator arm pivot shaft. As described previously, the operator arm pivot shaft/lift pulley is supported in operator arm pivot bearings 424, which are themselves supported in operator base yoke arm 422. Rotate shaft 432 is secured within left pulley 424 by securing collar 433. Securing collar 433 secures rotate pulley 425 to rotate shaft 432 in a secure manner so as to assure a positive connection between rotate motor 428 and rotate pulley 425. An inner cover 584 is also provided. Rotate motor 428 is disposed within process arm rear cavity 426 and is supported by rotate motor support 434. Rotate motor 428 preferably is a servo allowing for accurate control of speed and acceleration of the motor. Servo motor 428 is advantageously connected to rotate encoder 435 which is positioned on one end of rotate motor 428. Rotate encoder 435, more generally described as a processing head encoder, allows for accurate measurement of the number of rotations of rotate motor 428, as well as the position, speed, and acceleration of the rotate shaft 432. The information from the rotate encoder may be used in a rotate circuit which may then be used to control the rotate motor when the rotate motor is a servo. This information is useful in obtaining the position and rate of travel of the processing head, as well as controlling the final end point positions of the processing head as it is rotated about process head rotate axis 411. The relationship between the rotate motor rotations, as measured by rotate encoder 435, may easily be determined once the diameters of the rotate pulley 425 and the processing head pulley 438 are known. These diameters can be used to determine the ratio of rotate motor relations to processing head rotations. This may be accomplished by a microprocessor, as well as other means. Rotate pulley 425 is further supported within operator arm 407 by rotate pulley inboard bearing 436 which is disposed about an extended flange on the rotate pulley 425. Rotate pulley inboard bearing 436 is secured by the body of the operator arm 407, as shown in Fig. 21. Rotate pulley 425 advantageously drives rotate belt 437, more generally described as a flexible power transmission coupling. Referring now to Fig. 18, rotate belt 437 is shown in the side view of the right arm 419 of the operator arm 407. Rotate belt 437 is preferably a toothed timing belt to ensure positive engagement with the processing head drive wheel, more particularly described herein as the processing head pulley 438, (not shown in this view). In order to accommodate the toothed timing belt 437, both the rotate pulley 425 and the processing head pulley 438 are advantageously provided with gear teeth to match the tooth pattern of the timing belt to assure positive engagement of the pulleys with the rotate belt. Rotate mechanism 431 is preferably provided with rotate belt tensioner 439, useful for adjusting the belt to take up slack as the belt may stretch during use, and to allow for adjustment of the belt to assure positive engagement with both the rotate pulley and the processing head pulley. Rotate belt tensioner 439 adjusts the tension of rotate belt 437 by increasing the length of the belt path between rotate pulley 425 and processing head pulley 438, thereby accommodating any excess length in the belt. Inversely, the length of the belt path may also be shortened by adjusting rotate belt tensioner 439 so as to create a more linear path in the upper portion of rotate belt 437. The tensioner 439 is adjusted by rotating it about tensioner hub 468 and securing it in a new position. Turning now to Fig. 21, processing head pulley 438 is mounted to processing head rotate shaft 430 in a secured manner so that rotation of processing head pulley 438 will cause processing head rotate shaft 430 to rotate. Processing head shaft 430 is mounted to operator arm right fork 419 by processing head shaft bearing 440, which in turn is secured in the frame of the right fork 419 by processing head rotate bearing 469. In a like manner, processing head shaft 429 is mounted in operator arm left fork 418 by processing head shaft bearing 441, as shown in Fig. 17. Processing head pivot shafts 430 and 429 are advantageously hollow shafts. This feature is useful in allowing electrical, optical, pneumatic, and other signal and supply services to be provided to the processing head. Service lines such as those just described which are routed through the hollow portions of processing head pivot shafts 429 and 430 are held in place in the operator arms by cable brackets 442 and 443. Cable brackets 442 and 443 serve a dual purpose. First, routing the service lines away from operating components within the operator arm left and right forks. Second, cable brackets 442 and 443 serve a useful function in isolating forces imparted to the service cables by the rotating action of processing head 406 as it rotates about processing head pivot shafts 429 and 430. This rotating of the processing head 406 has the consequence that the service cables are twisted within the pivot shafts as a result of the rotation, thereby imparting forces to the cables. These forces are preferably isolated to a particular area so as to minimize the effects of the forces on the cables. The cable brackets 442 and 443 achieve this isolating effect. The process head rotate mechanism 431 , shown in Fig. 21 , is also advantageously provided with a rotate overtravel protect 444, which functions as a rotate switch. Rotate overtravel protect 444 preferably acts as a secondary system to the rotate encoder 435 should the control system fail for some reason to stop servo 428 in accordance with a predetermined position, as would be established by rotate encoder 435. Turning to Fig. 21, the rotate overtravel protect 444 is shown in plan view. The rotate overtravel protect preferably consists of rotate optical switches 445 and 446, which are configured to correspond to the extreme (beginning and end point) portions of the processing head, as well as the primary switch component which preferably is a rotate flag 447. Rotate flag 447 is securely attached to processing head pulley 438 such that when processing head shaft 430 (and consequently processing head 406) are rotated by virtue of drive forces imparted to the processing head pulley 425 by the rotate belt 437, the rotate flag 447 will rotate thereby tracking the rotate motion of processing head 406. Rotate optical switches 445 and 446 are positioned such that rotate flag 447 may pass within the optical path generated by each optical switch, thereby generating a switch signal. The switch signal is used to control an event such as stopping rotate motor 428. Rotate optical switch 445 will guard against overtravel of processing head 406 in one direction, while rotate optical switch 446 will provide against overtravel of the processing head 406 in the opposite direction. Operator Arm-Lift Mechanism Operator arm 407 is also advantageously provided with an operator arm lift mechanism 448 which is useful for causing the operator arm to lift, that is, to pivot or rotate about operator arm pivot axis 412. Turning to Fig. 22, the operator arm lift mechanism 448 is shown in the sectional plan view of the right rear corner of operator arm 407. Operator arm lift mechanism 448 is advantageously driven by lift motor 452. Lift motor 452 may be more generally described as an operator arm drive or operator arm pivot drive. Lift motor 452 is preferably a servo motor and is more preferably provided with an operator encoder, more specifically described as lift motor encoder 456. When lift motor 452 is a servo motor coupled with lift encoder 456, information regarding the speed and absolute rotational position of the lift motor shaft 454 may be known from the lift encoder signal. Additionally, by virtue of being a servo mechanism, the angular speed and acceleration of lift motor 452 may be easily controlled by use of the lift signal by an electrical circuit. Such a lift circuit may be configured to generate desired lift characteristics (speed, angle, acceleration, etc.). Fig. 14 shows that the lift operator may also include a brake 455 which is used to safely stop the arm if power fails. Lift motor 452 drives lift motor shaft 454 which in turn drives lift gear drive 453. Lift gear drive 453 is a gear reduction drive to produce a reduced number of revolutions at lift drive shaft 456 as the function of input revolutions from lift motor shaft 454. Lift drive gear shaft 456 is secured to lift anchor 451 which is more clearly shown in Fig. 19. Lift anchor 451 is preferably shaped to have at least one flat side for positively engaging lift bushing 449. Lift anchor 451 is secured to lift drive shaft 456 by anchor plate 458 and anchor fasteners 457. In this manner, when lift drive shaft 456 is rotated, it will positively engage lift bushing 449. Returning to Fig. 22, it is seen that lift bushing 449 is mounted in operator left yoke arm 421, and is thus fixed with respect to operator base 405. Lift bearing 450 is disposed about the lift bushing shank and is supported in operator arm 407 by lift bearing support 460 which is a bushing configured to receive lift bearing 450 on a first end and to support lift gear drive 453 on a second end. Lift bearing support 460 is further supported within operator arm 407 by operator arm frame 461. The lift arm is thus free to pivot about lift bushing 449 by virtue of lift bearing 450. In operation, as lift motor 452 causes lift gear drive 453 to produce rotations at gear drive shaft 456, lift anchor 451 is forced against lift bushing 449 which is securely positioned within right operator yoke arm 421. The reactive force against the lift anchor 451 will cause lift bearing support 460 to rotate relative to lift bushing 449. Since lift bushing 449 is fixed in operator base 405, and since operator base 405 is fixed to processing machine 400, rotation of lift bearing support 460 will cause lift arm 407 to pivot about operator arm pivot axis 412, thereby moving the processing head 406. It is advantageous to consider the gear drive shaft (or "operator arm shaft") as being fixed with respect to operator base 405 when envisioning the operation of the lift mechanism. Operator lift mechanism 448 is also advantageously provided with a lift overtravel protect 462 or lift switch. The lift rotate protect operates in a manner similar to that described for the rotate overtravel protect 444 described above . Turning now to Fig. 19, a left side view of the operator arm 407 is shown which shows the lift overtravel protect in detail. The lift overtravel protect preferably includes a lift optical switch low 463 and a lift optical switch high 464. Other types of limit switches can also be used. The switch high 464 and switch low 463 correspond to beginning and endpoint travel of lift arm 407. The primary lift switch component is lift flag 465, which is firmly attached to left operator base yoke arm 421. The lift optical switches are preferably mounted to the movable operator arm 407. As operator arm 407 travels in an upward direction in pivoting about operator arm pivot axis 412, lift optical switch high 464 will approach the lift flag 465. Should the lift motor encoder 455 fail to stop the lift motor 454 as desired, the lift flag 465 will break the optical path of the lift optical switch high 464 thus producing a signal which can be used to stop the lift motor. In like manner, when the operator arm 407 is being lowered by rotating it in a clockwise direction about the operator arm pivot axis 412, as shown in Fig. 19, overtravel of operator arm 407 will cause lift optical switch low 463 to have its optical path interrupted by lift flag 465, thus producing a signal which may be used to stop lift motor 452. As is shown in Fig. 19, lift flag 465 is mounted to left operator base yoke arm 421 with slotted lift flag mounting slots 467 and removable lift flag fasteners 466. Such an arrangement allows for the lift flag to be adjusted so that the lift overtravel protect system only becomes active after the lift arm 407 has traveled beyond a preferred point. Processing Head Turning now to Fig. 14, a front elevation schematic view of the processing head 406 is shown. Processing head 406 is described in more detail in Figs. 15 and 16. Turning now to Fig. 15, a sectional view of the left front side of processing head 406 is shown. Processing head 406 advantageously includes a processing head housing 470 and frame 582. Processing head 406 is preferably round in shape in plan view allowing it to easily pivot about process head pivot axis 411 with no interference from operator arm 407, as demonstrated in Figs. 11-13. Returning to Fig. 15, processing head housing 470 more preferably has circumferential grooves 471 which are formed into the side of process head housing 470. Circumferential grooves 471 have a functional benefit of increasing heat dissipation from processing head 406. The sides of processing head housing 470 are advantageously provided with rotate shaft openings 474 and 475 for receiving respectively left and right processing head pivot shafts 429 and 430. Processing head pivot shafts 429 and 430 are secured to the processing head 406 by respective left and right processing head mounts 472 and 473. Processing head mounts 472 and 473 are affirmative connected to processing head frame 582 which also supports processing head door 476 which is itself securely fastened to processing head housing 470. Consequently, processing head pivot shafts 429 and 430 are fixed with respect to processing head 407 and may therefore rotate or pivot with respect to operator arm 407. The details of how processing head pivot shafts 429 and 430 are received within operator arm 407 were discussed supra. Processing head housing 470 forms a processing head void 477 which is used to house additional processing head components such as the spin motor, the pneumatic finger actuators, and service lines, all discussed more fully below. The processing head also advantageously includes a workpiece holder and fingers for holding a workpiece, as is also more fully described below. Processing Head Spin Motor In a large number of semiconductor manufacturing processes, is desirable to spin the semiconductor wafer or workpiece during the process, for example to assure even distribution of applied process fluids across the face of the semiconductor wafer, or to aid drying of the wafer after a wet chemistry process. It is therefore desirable to be able to rotate the semiconductor workpiece while it is held by the processing head. The semiconductor workpiece is held during the process by workpiece holder 478 described more fully below. In order to spin workpiece holder 478 relative to processing head 406 about spin axis 479, an electric, pneumatic, or other type of spin motor or workpiece spin drive is advantageously provided. Turning to Fig. 16, spin motor 480 has armatures 526 which drive spin motor shaft 483 in rotational movement to spin workpiece holder 478. Spin motor 480 is supported by bottom motor bearing 492 in bottom motor housing 482. Bottom motor housing 482 is secured to processing head 406 by door 476. Spin motor 480 is thus free to rotate relative to processing head housing 470 and door 476. Spin motor 480 is preferably additionally held in place by top motor housing 481 which rests on processing head door 476. Spin motor 480 is rotationally isolated from top motor housing 481 by top motor bearing 493, which is disposed between the spin motor shaft 483 and top motor housing 481. The spin motor is preferably an electric motor which is provided with an electrical supply source through pivot shaft 429 and/or 430. Spin motor 480 will drive spin motor shaft 483 about spin axis 479. To secure workpiece holder rotor 484 to spin motor shaft 483, workpiece holder rotor 484 is preferably provided with a rotor hub 485. Rotor hub 485 defines a rotor hub recess 486 which receives a flared end of workpiece holder shaft 491. The flared end 487 of workpiece holder shaft 491 is secured within the rotor hub recess 486 by workpiece shaft snap-ring 488 which fits within rotor recess groove 489 above the flared portion 487 of workpiece holder shaft 491. The workpiece holder shaft 491 is fitted inside of spin motor shaft 483 and protrudes from the top of the spin motor shaft. The top of workpiece holder shaft 491 is threaded to receive thin nut 527 (see Fig. 15). Thin nut 527 is tightened against optical tachometer 499 (describe more fully below). Optical tachometer 499 is securely attached to spin motor shaft 483 such that as the spin motor 480 rotationally drives the spin motor shaft 483, the workpiece holder shaft 491 is also driven. Workpiece holders may be easily changed out to accommodate various configurations which may be required for the various processes encountered in manufacturing of the semiconductors. This is accomplished by removing spin encoder 498 (described below), and then thin nut 527. Once the thin nut has been removed the workpiece holder 478 will drop away from the processing head 406. The processing head is also advantageously provided with a spin encoder 498, more generally described as a workpiece holder encoder, and an optical tachometer 499. As shown in Fig. 15, spin encoder 498 is mounted to top motor housing 481 by encoder support 528 so as to remain stationary with respect to the processing head 406. Optical tachometer 499 is mounted on spin motor shaft 483 so as to rotate with the motor 480. When operated in conjunction, the spin encoder 498 and optical tachometer 499 allow the speed, acceleration, and precise rotational position of the spin motor shaft (and therefore the workpiece holder 478) to be known. In this manner, and when spin motor 480 is provided as a servo motor, a high degree of control over the spin rate, acceleration, and rotational angular position of the workpiece with respect to the process head 407 may be obtained. In one application of the present invention the workpiece support is used to support a semiconductor workpiece in an electroplating process. To accomplish the electroplating an electric current is provided to the workpiece through an alternate embodiment of the fingers (described more fully below). To provide electric current to the finger, conductive wires are run from the tops of the fingers inside of the workpiece holder 478 through the electrode wire holes 525 in the flared lower part of workpiece holder shaft 491. The electrode wires are provided electric current from electrical lines run through processing pivot shaft 429 and/or 430. The electrical line run through pivot shaft 430/429 will by nature be stationary with respect to processing head housing 470. However, since the workpiece holder rotor is intended to be capable of rotation during the electroplating process, the wires passing into workpiece support shaft 491 through electrode wire holes 525 may rotate with respect to processing head housing 470. Since the rotating electrode wires within workpiece shaft 491 and the stationary electrical supply lines run through pivot shaft 430/429 must be in electrical communication, the rotational/stationary problem must be overcome. In the preferred embodiment, this is accomplished by use of electrical slip ring 494. Electrical slip ring 494, shown in Fig. 15, has a lower wire junction 529 for receiving the conductive ends of the electrical wires passing into workpiece holder shaft 491 by electrode wire holes 525. Lower wire junction 529 is held in place within workpiece holder shaft 491 by insulating cylindrical collar 497 and thus rotates with spin motor shaft 483. The electrode wires terminate in a single electrical contact 531 at the top of the lower wire junction 529. Electrical slip ring 494 further has a contact pad 530 which is suspended within the top of workpiece holder shaft 491. Contact pad 530 is mechanically fastened to spin encoder 498, which, as described previously, remains stationary with respect to processing head housing 470. The stationary-to-rotational transition is made at the tip of contact pad 530, which is in contact with the rotating electrical contact 531. Contact pad 530 is electrically conductive and is in electrical communication with electrical contact 531. In the preferred embodiment, contact pad 530 is made of copper-beryllium. A wire 585 carries current to finger assemblies when current supply is needed, such as on the alternative embodiment described below. Processing Head Finger Actuators Workpiece holder 478, described more fully below, advantageously includes fingers for holding the workpiece W in the workpiece holder, as shown in Figs. 15 and 16. Since the workpiece holder 478 may be removed as described above, it is possible to replace one style of workpiece holder with another. Since a variety of workpiece holders with a variety of fingers for holding the workpiece is possible, it is desirable to have a finger actuator mechanism disposed within processing head 407 which is compatible with any given finger arrangement. The invention is therefore advantageously provided with a finger actuator mechanism. Turning to Fig. 15, a finger actuator mechanism 500 is shown. Finger actuator mechanism 500 is preferably a pneumatically operated mechanism. A pneumatic cylinder is formed by a cavity 501 within top motor housing 481. Pneumatic piston 502 is disposed within cavity 501. Pneumatic piston 502 is biased in an upward position within cavity 501 by actuator spring 505. Actuator spring 505 is confined within cavity 501 by cavity end cap 507, which is itself constrained by retaining ring 508. Pneumatic fluid is provided to the top of pneumatic piston 502 via pneumatic inlet 503. Pneumatic fluid is provided to pneumatic inlet 503 by pneumatic supply line 504 which is routed through processing head pivot shaft 429 and hence through the left fork 418 of the operator arm 407. Turning to Fig. 16, it can be seen that a second pneumatic cylinder which is identical to the pneumatic cylinder just described is also provided. Pneumatic piston 502 is attached to actuator plate 509 by actuator plate connect screw 510. Wave springs 529 provide flexibility to the connecting at screws 510. Actuator plate 509 is preferably an annular plate concentric with the spin motor 580 and disposed about the bottom motor housing 482, and is symmetrical about spin axis 479. Actuator plate 509 is secured against pneumatic piston 502 by bushing 512 which is disposed in pneumatic piston recess 511 about pneumatic piston 502. Bushing 512 acts as a support for wave springs 529 to allow a slight tilting of the actuator plate 509. Such an arrangement is beneficial for providing equal action against the finger actuator contracts 513 about the entire actuator plate or ring 509. When pneumatic fluid is provided to the space above the pneumatic piston 502, the pneumatic piston 502 travels in a downward direction compressing actuator spring 505. As pneumatic piston 502 travels downward, actuator plate 509 is likewise pushed downward by flexible bushing 512. Actuator plate 509 will contact finger actuator contacts 513 causing the fingers to operate as more fully described below. Actuator seals 506 are provided to prevent pneumatic gas from bypassing the top of the pneumatic piston 502 and entering the area occupied by actuator spring 505. Processing Head Workpiece Holder Workpiece holder 478 is used to hold the workpiece W, which is typically a semiconductor wafer, in position during the semiconductor manufacturing process. Turning now to Fig. 16, a finger 409 is shown in cross section. Finger 409 advantageously includes a finger actuator contact 513 which is contacted by actuator plate 509, as described above. Finger actuator contact 513 is connected to finger actuator lever 514 (more generally, "finger extension') which is cantilevered from and connected to the finger stem 515. Finger stem 515 is inserted into finger actuator lever 514. Disposed about the portion of the finger actuator lever which encompasses and secures finger stem 515 is finger diaphragm 519. Finger diaphragm 519 is preferably made of a flexible material such as Tetrafluoroethylene, also known as Teflon® (registered trademark of E. I. DuPont de Nemours Company). Finger 409 is mounted to workpiece holder rotor 484 using finger diaphragm 519. Finger diaphragm 519 is inserted into the finger opening 521 in rotor 484. The finger diaphragm 519 is inserted into the rotor from the side opposite that to which the workpiece will be presented. Finger diaphragm 519 is secured to rotor 484 against rotor diaphragm lip 523. Forces are intentionally imparted as a result of contact between the actuator plate 509 and the finger actuator contact 513 when the finger actuator mechanism 500 is actuated. Finger actuator lever 514 is advantageously biased in a horizontal position by finger spring 520 which acts on finger actuator tab 522 which in turn is connected to finger actuator lever 514. Finger spring 520 is preferably a torsion spring secured to the workpiece holder rotor 484. Finger stem 515 is also preferably provided with finger collar or nut 517 which holds the finger stem 515 against shoulder 518. Finger collar 517 threads or otherwise securely fits over the lower end of finger actuator lever 514. Below the finger collar 517, finger stem 515 extends for a short distance and terminates in fingertip 414. Fingertip 414 contains a slight groove or notch which is beneficially shaped to receive the edge of the workpiece W. In actuation, finger actuator plate 509 is pushed downward by finger actuator mechanism 500. Finger actuator plate 509 continues its downward travel contacting finger actuator contacts 513. As actuator plate 509 continues its downward travel, finger actuator contacts are pushed in a downward direction. As a result of the downward direction, the finger actuator levers 514 are caused to pivot. In the preferred embodiment, a plurality of fingers are used to hold the workpiece. In one example, six fingers were used. Once the actuator plate 509 has traveled its full extent, the finger stems 515 will be tilted away from the spin axis 479. The circumference described by the fingertips in this spread-apart position should be greater than the circumference of the workpiece W. Once a workpiece W has been positioned proximate to the fingertips, the pneumatic pressure is relieved on the finger actuator and the actuator spring 505 causes the pneumatic piston 502 to return to the top of the cavity 501. In so doing, the actuator plate 509 is retracted and the finger actuator levers are returned to their initial position by virtue of finger springs 520. Semiconductor Workpiece Holder - Electroplating Embodiment Fig. 23 is a side elevational view of a semiconductor workpiece holder 810 constructed according to a preferred aspect of the invention. Workpiece holder 810 is used for processing a semiconductor workpiece such as a semiconductor wafer shown in phantom at W. One preferred type of processing undertaken with workpiece holder 810 is a workpiece electroplating process in which a semiconductor workpiece is held by workpiece holder 810 and an electrical potential is applied to the workpiece to enable plating material to be plated thereon. Such can be, and preferably is accomplished utilizing a processing enclosure or chamber which includes a bottom half or bowl 811 shown in phantom lines in Fig. 1. Bottom half 811 together with workpiece holder 810 forms a sealed, protected chamber for semiconductor workpiece processing. Accordingly, preferred reactants can be introduced into the chamber for further processing. Another preferred aspect of workpiece holder 810 is that such moves, rotates or otherwise spins the held workpiece during processing as will be described in more detail below. Processing Head and Processing Head Operator Turning now to Fig. 23, semiconductor workpiece holder 810 includes a workpiece support 812. Workpiece support 812 advantageously supports a workpiece during processing. Workpiece support 812 includes a processing head or spin head assembly 814. Workpiece support 812 also includes a head operator or lift/rotate assembly 816. Spin head assembly 814 is operative ly coupled with lift/rotate assembly 816. Spin head assembly 814 advantageously enables a held workpiece to be spun or moved about a defined axis during processing. Such enhances conformal coverage of the preferred plating material over the held workpiece. Lift/rotate assembly 816 advantageously lifts spin head assembly 814 out of engagement with the bottom half 811 of the enclosure in which the preferred processing takes place. Such lifting is preferably about an axis j . Once so lifted, lift/rotate assembly 816 also rotates the spin head and held workpiece about an axis x 2 so that the workpiece can be presented face-up and easily removed from workpiece support 812. In the illustrated and preferred embodiment, such rotation is about 180° from the disposition shown in Fig. 23. Advantageously, a new workpiece can be fixed or otherwise attached to the workpiece holder for further processing as described in detail below. The workpiece can be removed from or fixed to workpiece holder 810 automatically by means of a robotically controlled arm. Alternatively, the workpiece can be manually removed from or fixed to workpiece holder 810. Additionally, more than one workpiece holder can be provided to support processing of multiple semiconductor workpieces. Other means of removing and fixing a semiconductor workpiece are possible. Fig. 24 is a front sectional view of the Fig. 23 semiconductor workpiece holder. As shown, workpiece support 812 includes a motor 818 which is operatively coupled with a rotor 820. Rotor 820 is advantageously mounted for rotation about a rotor spin axis 822 and serves as a staging platform upon which at least one finger assembly 824 is mounted. Preferably, more than one finger assembly is mounted on rotor 820, and even more preferably, four or more such finger assemblies are mounted thereon and described in detail below although only two are shown in Fig. 24. The preferred finger assemblies are instrumental in fixing or otherwise holding a semiconductor workpiece on semiconductor workpiece holder 810. Each finger assembly is advantageously operatively connected or associated with a actuator 825. The actuator is preferably a pneumatic linkage which serves to assist in moving the finger assemblies between a disengaged position in which a workpiece may be removed from or added to the workpiece holding, and an engaged position in which the workpiece is fixed upon the workpiece holder for processing. Such is described in more detail below. Fig. 25 is a top or plan view of rotor 820 which is effectively taken along line 3-3 in Fig. 24. Fig. 24 shows the preferred four finger assemblies 824. As shown, rotor 820 is generally circular and resembles from the top a spoked wheel with a nearly continuous bottom surface . Rotor 820 includes a rotor center piece 826 at the center of which lies rotor axis 822. A plurality of struts or spokes 828 are joined or connected to rotor center 826 and extend outwardly to join with and support a rotor perimeter piece 830. Advantageously, four of spokes 828 support respective preferred finger assemblies 824. Finger assemblies 824 are advantageously positioned to engage a semiconductor workpiece, such as a wafer W which is shown in phantom lines in the position such would occupy during processing. When a workpiece is so engaged, it is fixedly held in place relative to the rotor so that processing can be effected. Such processing can include exposing the workpiece to processing conditions which are effective to form a layer of material on one or more surfaces or potions of a wafer or other workpiece . Such processing can also include moving the workpiece within a processing environment to enhance or improve conformal coverage of a layering material. Such processing can, and preferably does include exposing the workpiece to processing conditions which are effective to form an electroplated layer on or over the workpiece . Finger Assembly Referring now to Figs. 26-28, various views of a preferred finger assembly are shown. The preferred individual finger assemblies are constructed in accordance with the description below. Fig. 26 is an isolated side sectional view of a finger assembly constructed in accordance with a preferred aspect of the invention. Fig. 27 is a side elevational view of the finger assembly turned 90° from the view of Fig. 26. Fig. 28 is a fragmentary cross-sectional enlarged view of a finger assembly and associated rotor structure. The finger assembly as set forth in Figs. 26 and 27 is shown in the relative position such as it would occupy when processing head or spin head assembly 814 (Figs. 23 and 24) is moved or rotated by head operator or lift/rotate assembly 816 into a position for receiving a semiconductor workpiece . The finger assembly is shown in Figs. 26 and 28 in an orientation of about 180° from the position shown in Fig. 28. This typically varies because spin head assembly 814 is rotated 180° from the position shown in Figs. 23 and 24 in order to receive a semiconductor workpiece . Accordingly, finger assemblies 824 would be so rotated. Lesser degrees of rotation are possible. Finger assembly 824 includes a finger assembly frame 832. Preferably, finger assembly frame 832 is provided in the form of a sealed contact sleeve which includes an angled slot 832a, only a portion of which is shown in Fig. 27. Angled slot 832a advantageously enables the finger assembly to be moved, preferably pneumatically, both longitudinally and rotationally as will be explained below. Such preferred movement enables a semiconductor workpiece to be engaged, electrically contacted, and processed in accordance with the invention. Finger assembly frame 832 includes a finger assembly frame outer flange 834 which, as shown in Fig. 28, engages an inner drive plate portion 836 of rotor 820. Such engagement advantageously fixes or seats finger assembly frame 832 relative to rotor 820. Such, in turn, enables the finger assembly, or a portion thereof, to be moved relative to the rotor for engaging the semiconductor workpiece . Finger Assembly Drive System Referring to Figs. 24 and 26-28, the finger assembly includes a finger assembly drive system which is utilized to move the finger assembly between engaged and disengaged positions. The finger assembly drive system includes a bearing 838 and a collet 840 operatively adjacent the bearing. Bearing 838 includes a bearing receptacle 839 for receiving a pneumatically driven source, a fragmented portion of which is shown directly above the receptacle in Fig. 28. The pneumatically driven source serves to longitudinally reciprocate and rotate collet 840, and hence a preferred portion of finger assembly 824. A preferred pneumatically driven source is described below in more detail in connection with the preferred longitudinal and rotational movement effectuated thereby. Such longitudinal reciprocation is affected by a biasing mechanism in the form of a spring 842 which is operatively mounted between finger assembly frame 832 and a spring seat 844. The construction develop a bias between finger assembly frame 832 and spring seat 844 to bias the finger into engagement against a wafer. Advantageously, the cooperation between the above mentioned pneumatically driven source as affected by the biasing mechanism of the finger assembly drive system, enable collet 840 to be longitudinally reciprocated in both extending and retracting modes of movement. As such, finger assembly 824 includes a biased portion which is biased toward a first position and which is movable to a second position away from the first position. Other manners of longitudinally reciprocating the finger assembly are possible. Finger Assembly Electrical System Referring to Figs. 24 and 27, the finger assembly preferably includes a finger assembly electrical system which is utilized to effectuate an electrical bias to a held workpiece and supply electrical current relative thereto. The finger assembly electrical system includes a pin connector 846 and a finger 848. Pin connector 846 advantageously provides an electrical connection to a power source (not shown) via wire 585 and associate slip ring mechanism, described above in connection with Fig. 15 and other Figs. This is for delivering an electrical bias and current to an electrode which is described below. Pin connector 846 also rides within angled slot 832a thereby mechanically defining the limits to which the finger assembly may be both longitudinally and rotationally moved. Finger 848 is advantageously fixed or secured to or within collet 840 by a nut 850 which threadably engages a distal end portion of collet 840 as shown best in Fig. 26. An anti-rotation pin 852 advantageously secures finger 848 within collet 840 and prevents relative rotation therebetween. Electrical current is conducted from connector 846 through collet 840 to finger 860, all of which are conductive, such as from stainless steel. The finger and collet can be coated with a suitable dielectric coating 856, such as TEFLON or others. The collet 840 and finger member 860 are in one form of the invention made hollow and tubular to conduct a purge gas therethrough. Finger assembly 824 may also optionally include a distal tip or finger tip 854. Tip 854 may also have a purge gas passage formed therethrough. Finger tip 854 advantageously engages against a semiconductor workpiece (see Fig. 28) and assists in holding or fixing the position of the workpiece relative to workpiece holder 810. Finger tip 854 also assists in providing an operative electrical connection between the finger assembly and a workpiece to which an electrical biased is to be applied and through which current can move. Finger tip 85 can include an electrode contact 858 for electrically contacting a surface of a semiconductor workpiece once such workpiece is secured as describe below. Finger Assembly Drive System Interface A finger assembly drive system interface is operatively coupled with the finger assembly drive system to effectuate movement of the finger assembly between the engaged and disengaged positions. A preferred finger assembly drive system interface is described with reference to Figs. 24 and 28. One component of the finger assembly drive system interface is a finger actuator 862. Finger actuator 862 is advantageously provided for moving the finger assembly between the engaged and disengaged position. Finger actuator 862 acts by engaging bearing receptacle 839 and moving finger assembly 824 between an engaged position and a disengaged position. In the engaged position, finger tip 854 is engaged against a semiconductor workpiece. In the disengaged position finger tip 854 is moved away from the workpiece. The finger assembly drive system interface includes pneumatic actuator 825 (Fig. 24). Pneumatic actuators 825 are operatively connected to an actuation ring 863 and operates thereupon causing the drive plate to move reciprocally in the vertical direction as viewed in Fig. 24. Finger actuator 862 is operatively connected to actuation ring 863 in a manner which, upon pneumatic actuation, moves the finger actuator into engagement with bearing receptacle 839 along the dashed line in Fig. 28. Such allows or enables the finger assembly to be moved longitudinally along a first movement path axis 864. Pneumatic actuator linkage 825 also includes a secondary linkage 865. Secondary linkage 865 is pneumatic as well and includes a link arm 867. Link arm 867 is connected or joined to an actuator torque ring 869. Preferably, torque ring 869 is concentric with rotor 820 (Fig. 25) and circuitously links each of the finger actuators together. A pneumatic operator 871 is advantageously linked with the secondary linkage 865 for applying force and operating the linkage by angularly displacing torque ring 869. This in turn rotates the finger assemblies into and away from the engaged position. Preferably finger actuator engagement bits 862, under the influence of pneumatic linkage 825, moves the finger assembly, and more specifically collet 840 and finger 848 along a first axial movement path along axis 864. The finger actuator engagement bits 862, then under the influence of pneumatic operator 871 are turned about the axes of each bit like a screwdriver. This moves collet 840 and finger 848 in a second angular movement. Such second movement turns the fingers sufficiently to produce the angular displacement shown in Fig. 29. According to a preferred aspect of this invention, such movement of the finger assemblies between the engaged and disengaged positions takes place when spin head assembly 814 has been moved 180° from its Fig. 23 disposition into a face-up condition. The engagement bits 862 can be provided with a purge gas passage therethrough. Gas is supplied via tube 893 and is passed through the finger assemblies. Engaged and Disengaged Positions Fig. 29 is a view of a portion of a finger assembly, taken along line 7-7 in Fig. 26. Such shows in more detail the above-described engaged and disengaged positions and movement therebetween relative to a workpiece W. In the disengaged position, finger 848 is positioned adjacent the semiconductor workpiece and the finger tip and electrode contact do not overlap with workpiece W. In the engaged position, the finger tip overlaps with the workpiece and the electrode is brought to bear against the workpiece. From the disengaged position, finger assembly 824, upon the preferred actuation, is moved in a first direction away from the disengaged position. Preferably, such first direction is longitudinal and along first movement path axis 864. Such longitudinal movement is linear and in the direction of arrow A as shown in Figs. 26 and 27. The movement moves the finger assembly to the position shown in dashed lines in Fig. 26. Such movement is effectuated by pneumatic operator 825 which operates upon actuation ring 863 (Fig. 24). This in turn, causes finger actuator 862 to engage with finger assembly 824. Such linear movement is limited by angled slot 832a. Thereafter, the finger assembly is preferably moved in a second direction which is different from the first direction and preferably rotational about the first movement path axis 864. Such is illustrated in Fig. 29 where the second direction defines a generally arcuate path between the engaged and disengaged positions. Such rotational movement is effectuated by secondary linkage 865 which pneumatically engages the finger actuator to effect rotation thereof. As so moved, the finger assembly swings into a ready position in which a semiconductor workpiece is ready to be engaged and held for processing. Once the finger assembly is moved or swung into place overlapping a workpiece, the preferred finger actuator is spring biased and released to bear against the workpiece. An engaged workpiece is shown in Fig. 28 after the workpiece has been engaged by finger tip 854 against a workpiece standoff 865, and spin head assembly 814 has been rotated back into the position shown in Fig. 23. Such preferred pneumatically assisted engagement takes place preferably along movement path axis 864 and in a direction which is into the plane of the page upon which Fig. 29 appears. As shown in Fig. 26, finger 848 extends away from collet 840 and preferably includes a bend 866 between collet 840 and finger tip 854. The preferred bend is a reverse bend of around 180° which serves to point finger tip 854 toward workpiece W when the finger assembly is moved toward or into the engaged position (Fig. 29). Advantageously, the collet 840 and hence finger 848 are longitudinally reciprocally movable into and out of the engaged position. Finger Assembly Seal The finger assembly preferably includes a finger assembly seal 868 which is effectuated between finger 848 and a desired workpiece when the finger assembly is moved into the engaged position. Preferably, adjacent finger tip 854. Seal 868 is mounted adjacent electrode contact 858 and effectively seals the electrode contact therewithin when finger assembly 824 is moved to engage a workpiece. The seal can be made of a suitable flexible, preferably elastomeric material, such as VITON. More specifically, and referring to Fig. 30, seal 868 can include a rim portion 870 which engages workpiece surface W and forms a sealing contact therebetween when the finger assembly is moved to the engaged position. Such seal advantageously isolates finger electrode 860 from the processing environment and materials which may plate out or otherwise be encountered therein. Seal 868 can be provided with an optional bellows wall structure 894 (Fig. 30), that allows more axial flexibility of the seal. Fig. 30 shows, in solid lines, seal 868 in a disengaged position in which rim portion 870 is not engaged with workpiece W. Fig. 30 also shows, in phantom lines, an engaged position in which rim portion 870 is engaged with and forms a seal relative to workpiece W. Preferably and advantageously, electrode contact 858 is maintained in a generally retracted position within seal 868 when the finger assembly is in the disengaged position. However, when the finger assembly is moved into the engaged position, seal 868 and rim portion 870 thereof splay outwardly or otherwise yieldably deform to effectively enable the electrode and hence electrode contact 858 to move into the engaged position against the workpiece. One factor which assists in forming the preferred seal between the rim portion and the workpiece is the force which is developed by spring 842 which advantageously urges collet 840 and hence finger 860 and finger tip 858 in the direction of and against the captured workpiece. Such developed force assists in maintaining the integrity of the seal which is developed in the engaged position. Another factor which assists in forming the preferred seal is the yieldability or deformability of the finger tip when it is brought into contact with the workpiece. Such factors effectively create a continuous seal about the periphery of electrode contact 858 thereby protecting it from any materials, such as the preferred plating materials which are used during electroplate processing. Methods and Operation In accordance with a preferred processing aspect of the present invention, and in connection with the above-described semiconductor workpiece holder, a sheathed electrode, such as electrode 860, is positioned against a semiconductor workpiece surface in a manner which permits the electrode to impart a voltage bias and current flow to the workpiece to effectuate preferred electroplating processing of the workpiece. Such positioning not only allows a desired electrical bias to be imparted to a held workpiece, but also allows the workpiece itself to be mechanically held or fixed relative to the workpiece holder. That is, finger assembly 824 provides an electrical/mechanical connection between a workpiece and the workpiece holder as is discussed in more detail below. Electrode 856 includes an electrode tip or electrode contact 858 which engages the workpiece surface. A seal is thus formed about the periphery of the electrode tip or contact 858 so that a desired electrical bias may be imparted to the workpiece to enable plating material to be plated thereon. According to a preferred aspect of the processing method, the electrode is moved in a first direction, preferably longitudinally along a movement axis, away from a disengaged position in which the workpiece surface is not engaged by the electrode tip or contact 858. Subsequently, the electrode is rotated about the same movement axis and toward an engaged position in which the electrode tip may engage, so as to fix, and thereafter bias the workpiece surface. Such preferred movement is effectuated by pneumatic linkage 825 and pneumatic operator 871 as described above. According to a preferred aspect of the invention, the seal which is effectuated between the electrode member and the workpiece is formed by utilizing a yieldable, deformable seal member 868 which includes a rim portion 870. The rim portion 870 serves by contacting the workpiece surface to form a continuous seal as shown in Fig. 8. The preferred electrode tip is brought into engagement with the workpiece surface by advancing the electrode tip from a retracted position within the seal or other sheath to an unretracted position in which the workpiece surface is engaged thereby. Such movement of the electrode tip between the retracted and unretracted positions is advantageously accommodated by the yieldable features of the seal 868. In addition to providing the preferred electrical contact between the workpiece and the electrode tip, the finger assembly also forms a mechanical contact or connection between the assembly and the workpiece which effectively fixes the workpiece relative to the workpiece holder. Such is advantageous because one aspect of the preferred processing method includes rotating the workpiece about rotor axis 822 while the workpiece is exposed to the preferred plating material. Such not only ensures that the electrical connection and hence the electrical bias relative to the workpiece is maintained during processing, but that the mechanical fixation of the workpiece on the workpiece holder is maintained as well. The above described pneumatically effectuated movement of the preferred finger assemblies between the engaged and disengaged positions is but one manner of effectuating such movement. Other manners of effectuating such movement are possible. The invention also includes novel methods for presenting a workpiece to a semiconductor process. In such methods, a workpiece is first secured to a workpiece holder. The methods work equally well for workpiece holders known in the art and for the novel workpiece holders disclosed herein. In the next step in the sequence, the workpiece holder is rotated about a horizontal axis from an initial or first position where the workpiece holder was provided with the workpiece to a second position. The second position will be at an angle to the horizontal. The angle of the workpiece holder to the horizontal is defined by the angle between the plane of the workpiece and the horizontal. In the method, the workpiece holder is advantageously suspended about a second horizontal axis which is parallel to the first horizontal axis of the workpiece holder. At this point in the method, the angle between the first and second horizontal axes and a horizontal plane corresponds to the angle between the workpiece holder and the horizontal. The workpiece holder is then pivoted about the second horizontal axis to move the workpiece and the workpiece holder from its initial location to a final location in a horizontal plane. Advantageously, when the workpiece holder is pivoted about the second horizontal axis, the first horizontal axis also pivots about the second horizontal axis. Preferably, during the step of rotating the workpiece holder about the first horizontal axis, the angle of the workpiece holder with respect to some known point, which is fixed with respect to the workpiece holder during the rotation process, is continually monitored. Monitoring allows for precise positioning of the workpiece holder with respect to the horizontal surface. Likewise, during pivoting of the workpiece holder about the second horizontal axis, it is preferable that the angle defined by the line connecting the first and second horizontal axes and the horizontal plane be continually monitored. In this manner, the absolute position of the workpiece holder (and hence the workpiece itself) will be known with respect to the horizontal plane. This is important since the horizontal plane typically will contain the process to which the workpiece will be exposed. It should be noted that in the above and following description, while the workpiece is described as being presented to a horizontal plane, it is possible that the workpiece may also be presented to a vertical plane or a plane at any angle between the vertical and the horizontal. Typically, the processing plane will be a horizontal plane due to the desire to avoid gravitational effects on process fluids to which the workpiece is exposed. In one embodiment after the workpiece has been presented to the processing plane, the workpiece holder is rotated about a spin axis to cause the workpiece to spin in the horizontal plane. Although not required in all semiconductor manufacturing processes, this is a common step which may be added in the appropriate circumstance. The next advantageous step in the method consists of pivoting the workpiece holder about the second horizontal axis back along the path that the workpiece holder was initially pivoted along when presenting the workpiece to the horizontal process plane. There is no requirement that the workpiece holder be pivoted back to the same position whence it began, although doing so may have certain advantages as more fully described below. The method advantageously further consists of the step of rotating the workpiece holder about the first horizontal axis to return the workpiece to the position when it was initially presented to and engaged by the workpiece holder. It is advantageous to rotate the workpiece holder about the first axis in a direction opposite from the initial rotation of the workpiece holder. The advantage of having the workpiece holder terminate at an end position which corresponds to the initial position when the workpiece was loaded into the workpiece holder is efficiency. That is, additional machine movements are not required to position the workpiece holder to receive a new workpiece. The method more preferably includes the step of rotating the workpiece holder about the first horizontal axis at at least two support points along the first horizontal axis. This beneficially provides support and stability to the workpiece holder during the rotation process and subsequent movement of the apparatus. The method also more preferably includes the step of pivoting the workpiece holder along with the first horizontal axis about the second horizontal axis at at least two support points along the second horizontal axis. This beneficially provides additional support for the workpiece holder while allowing the workpiece holder to be moved in a vertical or "Z-axis" direction. Importantly, the only motion described in the above method is rotational motion about several axes. In the method described, there is no translational motion of the workpiece holder in a X-, Y-, or Z-axis without corresponding movement in another axis as a result of rotating through an arc. Plating Methods The present invention also includes a novel method for processing a semiconductor workpiece during manufacturing. In the preferred embodiments of the method, a semiconductor workpiece or wafer is presented to the semiconductor manufacturing process. This may be accomplished by use of the workpiece support 401 shown in Fig. 8 and described more fully herein. Fig. 9 shows the workpiece W being presented to the process. At the time that the workpiece is presented to the process, the process fluid, which in an electroplating process is an electrolytic solution, is cause to flow within a processing chamber (herein the cup 621) to the workpiece. This assures that a sufficient quantity of fluid is available for the required process step. The workpiece W is preferably presented to the process in a precisely located position so that all surfaces of the workpiece are exposed to the solution. In an electroplating process, it is advantageous to expose only the downward facing or working surface of the wafer to the electrolytic solution and not the backside of the wafer. This requires accurate positioning of the wafer with respect to the fluid surface. In an electroplating process, the method also requires the step of accurately positioning the workpiece with respect to the anode 634 so that the anode and workpiece are separated by an equal distance at all points. Once the workpiece has been positioned as the process may specifically require, the next step in the method is performing the actual processing step itself. For example, in an electroplating application, the processing step would include applying an electric current to the workpiece so as to generate the current through the electrolytic solution thereby plating out a layer of a desired metallic substance on the wafer. Typically a current will be applied to the anode as well, with a negative current being applied to the workpiece . The processing step is applied for the length of time which is dictated by the process itself. The process further includes the step of continuing a flow of the process fluid such that the process fluid overflows the processing chamber and falls under gravitational forces into a process fluid reservoir. Preferably the process fluid reservoir is the same reservoir which provides the process fluid or solution to the process. As an additional step in the method of processing the semiconductor wafer in the electroplating process, the method includes the further step of spinning or rotating the workpiece about a vertical axis while it is exposed to the electrolytic solution. The rate of rotation varies between about 5 and 30 rpm and is more preferably approximately 10 rpm. The rotation step provides the beneficial result of additional assurance of even distribution of the electrolytic solution across the face of the workpiece during the electroplating process. After the processing has been performed on the semiconductor wafer, the method advantageously includes the step of removing the workpiece from the process and returning it to a position where it may be removed for further processing or removal from the semiconductor workpiece process tool. The method preferably includes the step of performing the above-described steps at a series of process bowls having a common fluid reservoir such that the overflowing fluid gravity drains into a common fluid reservoir. Industrial Applicability This invention is useful in designing and manufacturing plating systems for semiconductor processing.

Claims: CLAIMS 1. A workpiece processing station, comprising: a process fluid reservoir; a process bowl, said process bowl having a bowl bottom and bowl sides; a fluid cup disposed within said process bowl so as to form a first annular space between said fluid cup and said bowl sides, said fluid cup having a cup bottom and cup sides, said cup further comprising a fluid inlet disposed within said cup so as to admit fluid into said cup ; an anode disposed within said cup such that said fluid inlet is between said cup bottom and said anode, said anode forming a second annular space between said anode and said cup sides; and wherein said bowl bottom is in fluid communication with said reservoir such that fluid rising within said cup may overflow about said first annular space into said fluid reservoir. 2. A workpiece processing station, comprising: a process fluid reservoir; a process bowl, said process bowl having a bowl bottom and bowl sides; a fluid cup disposed within said process bowl so as to form a first space between said fluid cup and said bowl sides, said fluid cup having a cup bottom and cup sides, said cup further comprising a fluid inlet disposed within said cup so as to admit fluid into said cup; an anode disposed within said cup such that said fluid inlet is between said cup bottom and said anode, said anode electrode forming a second space between said anode and said cup sides; and wherein said bowl bottom is in fluid communication with said reservoir such that fluid rising within said cup may overflow about said first space and into said fluid reservoir. 3. The apparatus of claim 2 wherein said process bowl and said fluid cup are essentially circular in cross section; said wherein anode is essentially circular; and wherein said first and said second spaces are annular in shape . 4. The apparatus of claim 3 wherein said process bowl bottom has at least one opening disposed therethrough to allow fluid to freely pass from said bowl bottom to said fluid reservoir. 5. The apparatus of claim 2 further comprising a fluid filter, said fluid filter disposed between said fluid inlet and said anode . 6. The apparatus of claim 2 further comprising a finger actuator for moving said finger assembly between said engaged position and said disengaged position. 7. The apparatus of claim 2 wherein said process bowl bottom is suspended within said fluid reservoir, and further comprising a bowl leveler, said bowl leveler connected to said process bowl for leveling said process bowl relative to said fluid reservoir. 8. The apparatus of claim 2 wherein said process bowl bottom is suspended by a bowl chassis, and further comprising a bowl leveler, said bowl leveler connected to said process bowl for leveling said process bowl relative to said bowl chassis. 9. The apparatus of claim 7 further comprising a cup height adjuster, said cup height adjuster connected to said fluid cup for adjusting the height of said fluid cup relative to said bowl bottom. 10. The apparatus of claim 2 wherein said reservoir is a double walled vessel. 11. The apparatus of claim 2 further comprising a fluid inlet line in fluid communication with said fluid inlet, and further comprising a flow sensor, said flow sensor disposed within said fluid inlet line for sensing an amount of flow of fluid in said fluid inlet line . 12. The apparatus of claim 11 further comprising a flow controller, said flow controller disposed within said fluid inlet line before said fluid inlet. 13. The apparatus of claim 12 wherein said flow sensor generates a signal as a function of flow sensed, and further wherein said flow controller is responsive to said signal. 14. The apparatus of claim 12 wherein said flow controller is disposed within said fluid inlet line between said flow sensor and said fluid inlet. 15. The apparatus of claim 2 wherein said process bowl terminates at an upper bowl edge, said fluid cup terminates at an upper cup edge, and said cup edge is recessed below said bowl edge. 16. A workpiece processing station, comprising: a plurality of process bowls, each said process bowl having a bowl bottom and bowl sides; a process fluid reservoir having a reservoir top, said reservoir top containing a plurality of openings for receiving each of said process bowls therein; a plurality of fluid cups, an individual one of each said fluid cups being disposed within a corresponding individual one of each said process bowls, so as to form a first space between each said fluid cup and said each bowl sides, each said fluid cup having a cup bottom and cup sides, each said fluid cup further comprising a fluid inlet disposed within said cup so as to admit fluid into said cup; and wherein each said bowl bottom is in fluid communication with said reservoir such that fluid rising within said cup may overflow about said first annular space into said fluid reservoir. 17. The apparatus of claim 16 further comprising, within each said fluid cup, an anode disposed within each said cup such that said fluid inlet is between said cup bottom and said anode, said anode forming a second space, said second space being between said anode and said cup sides. 18. The apparatus of claim 17 wherein said each said fluid cup is essentially circular in cross section, each said anode is essentially circular, and wherein said first and said second spaces are annular in shape . 19. The apparatus of claim 18 further comprising within each said fluid cup a fluid filter, said fluid filter disposed adjacent to said cup walls between said fluid inlet and said anode within each said cup . 20. The apparatus of claim 19 further comprising for each said process bowl a bowl leveler, each individual said bowl leveler connected to an individual one said process bowls for leveling said process bowl. 21. The apparatus of claim 20 further comprising for each said fluid cup a cup height adjuster, each individual said cup height adjuster connected to an individual one of said fluid cups for adjusting the height of said fluid cup relative to said bowl in which said cup is disposed. 22. The apparatus of claim 21 further comprising for each said anode an anode height adjuster, each individual said anode height adjuster connected to an individual one of said anodes for adjusting the height of said anode within said bowl cup in which said anode is disposed. 23. The apparatus of claim 21 further comprising for each said fluid inlet a fluid inlet line in fluid communication with said fluid inlet, and further comprising for each said fluid inlet line a flow sensor, each said flow sensor disposed within each said fluid inlet line for sensing an amount of flow of fluid in each said fluid inlet line . 24. The apparatus of claim 23 further comprising for each said fluid inlet line a corresponding flow controller, each said flow controller disposed within each said fluid inlet line before each said fluid inlet. 25. The apparatus of claim 24 wherein each said flow sensor generates a signal as a function of flow sensed within each fluid inlet line corresponding to each said flow sensor, and further wherein each said flow controller corresponding to each said fluid inlet line is responsive to each said signal corresponding to said flow sensor and said fluid inlet line . 26. The apparatus of claim 25 further comprising a supply manifold, said supply manifold in fluid communication with each said fluid inlet line. 27. The apparatus of claim 26 further comprising a supply pump, said supply pump having a fluid suction in fluid communication with said fluid reservoir, and a fluid discharge in fluid communication with said supply manifold. 28. The apparatus of claim 27 wherein said supply pump is an immersible pump and is disposed within said fluid reservoir, and further comprising a pump discharge filter disposed within said supply line after said fluid discharge and before any said fluid inlet line. 29. The apparatus of claim 28 further comprising a fluid return line , said fluid return line disposed within said supply manifold after the all said fluid inlet lines and being in fluid communication with said fluid reservoir, and further comprising a backpressure regulator disposed with said fluid return line, said backpressure regulator in signal communication with said fluid pump to maintain a desired pressure at said backpressure regulator. 30. The apparatus of claim 25 further comprising for each said process bowl a dedicated process pump, each of said process pumps comprising: a process fluid discharge port in fluid communication with an individual one said fluid inlet lines, said process fluid discharge port configured such that said flow sensor and said flow controller within said individual one of said fluid inlet lines are disposed between said fluid inlet and said process fluid discharge port; and a process fluid suction in fluid communication with said process fluid reservoir. 31. A workpiece processing station, comprising: a process fluid reservoir; a process bowl, said process bowl having a bowl bottom and bowl sides; a fluid cup, said fluid cup having a cup bottom and cup sides, said fluid cup disposed within said process bowl so as to form a space between said fluid cup sides and said bowl sides, said fluid cup further comprising a fluid inlet disposed within said fluid cup so as to admit fluid into said fluid cup; and wherein said bowl bottom is in fluid communication with said reservoir such that fluid rising within said fluid cup may overflow about said space into said fluid reservoir. 32. Method for processing a workpiece in a semiconductor manufacturing process, comprising: providing a process fluid from a process fluid reservoir; presenting the portion of a workpiece to be processed to said process fluid such that said process fluid contacts said portion of workpiece to be processed; processing said workpiece by contacting said portion of said workpiece to be processed for a predetermined length of time with a sufficient quantity of said process fluid such that a residual volume of said process exists; allowing said residual volume of said process fluid to drain by gravity into said process fluid reservoir. 33. The method of claim 32 wherein said workpiece is presented to said process fluid in a horizontal position with said portion of said workpiece to be processed facing downward. 34. The method of claim 33 wherein said portion of said workpiece to be processed is contacted with a fluid surface of said process fluid, and further wherein said process fluid is provided in a continuing flow such that said surface is in a quiescent state when contacted with said process fluid. 35. The method of claim 34 wherein said fluid is an electrolytic solution, said workpiece is electrically conductive, and comprising the additional steps of: providing a metallic anode within said fluid; providing an electrical current to said workpiece so as to cause said workpiece to be electroplated. 36. The method of claim 35 further comprising the step of spinning said workpiece about a vertical axis within said process fluid while providing said electric current. 37. The method of claim 36 further comprising the step of maintaining a constant separation distance between said metallic anode and said workpiece while providing said electric current. 38. Method for processing a plurality of workpieces in a semiconductor manufacturing process, comprising: presenting the portion of each workpiece to be processed to a dedicated continually flowing pool of process fluid such that said process fluid contacts said portion of workpiece to be processed; processing each said workpiece by contacting said portion of each said workpiece to be processed for a predetermined length of time with a sufficient volume of said process fluid such that each said continually flowing pool of said process fluid overflows with process fluid during said processing; allowing said overflowing process fluid to drain by gravity into a common process fluid reservoir. 39. The method of claim 38 further comprising the step of controlling the flow of process fluid to each said continually flowing pool of process fluid to maintain a predetermined liquid level in said pool.

Inventors: BERNER ROBERT W, SCHMIDT WAYNE J, WOODRUFF DANIEL J, BERNER, ROBERT, W., SCHMIDT, WAYNE, J., WOODRUFF, DANIEL, J.
Applicants: SEMITOOL INC, SEMITOOL, INC.
Application year: 1997
Main classification: H01L21
IPC codes: C25D7, H01L21