Conducting belt for use with anode holder and anode holder

A conducting belt is used with an anode holder for supplying an electric current to an anode for plating a surface of a substrate such as a semiconductor wafer. The anode and the substrate are vertically disposed so as to face each other in a plating tank of a plating apparatus. The conducting belt includes a belt capable of contacting an outer circumferential edge of the anode and holding the anode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a conducting belt for use with an anode holder and an anode holder, and more particularly to a conducting belt for supplying an electric current to an anode for plating a surface of a substrate such as a semiconductor wafer, and an anode holder for holding such an anode. The present invention is also concerned with a plating apparatus for plating a substrate using the conducting belt. The plating apparatus may be a bump plating apparatus for forming bumps on a surface of a semiconductor substrate or a plating apparatus for plating via holes having high aspect ratios and large depths, e.g., a diameter of 10 μm to 20 μm and a depth of 70 μm to 150 μm.

2. Description of the Related Art

In recent years, there has been used a method of forming metal films and organic films on substrates such as semiconductor wafers by a plating process in forming semiconductor circuit interconnections and bumps. For example, it has widely been practiced to form bumps (protruding connecting electrode) or interconnections of gold, silver, copper, solder, nickel or a multilayer of these metals at predetermined portions on a surface of a semiconductor wafer having semiconductor circuits and fine interconnections for connecting semiconductor circuits, thereby electrically connecting the semiconductor circuits via the bumps to electrodes of a package substrate or tape automated bonding (TAB) electrodes. The interconnections and the bumps may be formed by any of various methods including an electroplating method, an electroless plating method, a vapor deposition method, and a printing method. Of these methods, the electroplating process has been used most widely because it can produce finer patterns at a higher film deposition rate to produce semiconductor chips with more I/O terminals and smaller pitches. For details, reference should be made to Japanese laid-open patent publication No. 2000-96292. Metal films formed by the electroplating process that are most widely used have characteristics of high purity, high deposition rate, and easy film-thickness control.

FIG. 15of the accompanying drawings schematically shows a vertical-immersion plating apparatus in which a substrate and an anode are vertically placed in a plating tank. As shown inFIG. 15, the plating apparatus includes a plating tank101containing a plating solution Q therein. An anode103held by an anode holder102and a substrate W held by a substrate holder104are vertically immersed in the plating solution Q in such a manner that the anode103and the substrate W are spaced in confronting relation from each other and lie parallel to each other. When an electric current is supplied between the anode103and the substrate W by a plating power supply105, a surface W1of the substrate W which is exposed from the substrate holder104is electroplated. The plating tank101is combined with a plating solution circulator106for circulating the plating solution Q by supplying the plating solution Q from an inlet port111into the plating tank101and discharging the plating solution Q from the plating tank101through an outlet port112.

As shown inFIG. 15, the vertical-immersion plating apparatus performs plating of the substrate W by placing the substrate W so as to face the anode103that is held by the anode holder102. Although a plate-like anode is shown as an anode, an anode ball housed in a cage may be used as an anode. However, the plate-like anode held by the anode holder offers the following advantages:

1) A shield plate may be mounted on the anode holder, and such shield plate may make it possible to adjust the opening diameter of the anode, thereby easily controlling in-plane uniformity (see, for example, Japanese laid-open patent publication No. 2005-29863).

2) Because the anode is in the form of a plate, the anode can easily be held parallel to the substrate to improve in-plane uniformity.

As described above, using the anode holder to hold the anode while the substrate is being plated by the vertical-immersion plating apparatus is advantageous. However, the plating apparatus is required to have the following functions in order to meet growing demands for finer interconnections and increased throughputs:

1) Finer interconnections to be formed on substrates require certainty of supply of an electric current to the anode.

2) As the substrate to be processed is larger in size, the anode is also larger in size. Since the larger anode cannot easily be replaced manually with another anode due to their weight, a new jig is needed for anode replacement.

3) The replacement of the anode needs to be performed efficiently in a short period of time.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a conducting belt and an anode holder which can reliably supply an electric current to an anode, can allow easy replacement of the anode with a new anode, and can improve the efficiency in replacement work of an anode to shorten operation time.

According to a first aspect of the present invention, there is provided a conducting belt for use with an anode holder for supplying an electric current to an anode, the anode and a substrate being vertically disposed so as to face each other in a plating tank of a plating apparatus, the conducting belt comprising: a belt capable of contacting an outer circumferential edge of the anode and holding the anode.

According to the present invention, the conductive belt can hold a disk-shaped anode by tightening the outer circumferential edge of the anode by a circular belt. Since the belt tightens the outer circumferential edge of the anode, an electric current is reliably supplied through the conducting belt to the anode. Thus, there is no need to perform positional alignment between the anode and the conducting belt, and the time required to replace the anode can be shortened. As the conducting belt usually has a width of 1 cm to 2 cm, the area of contact between the conducting belt and the anode is large, and any contact resistance between the conducting belt and the anode can be reduced.

In the preferred aspect of the present invention, the belt is capable of contacting the outer circumferential edge of the anode substantially in its entirety.

In a preferred aspect of the present invention, the belt has opposite ends fastened to each other by a fastener to hold the anode.

In a preferred aspect of the present invention, the fastener comprises a bolt and a nut.

In a preferred aspect of the present invention, there is provided a conducting belt further comprising an electrically conductive bracket fixed to an end of the belt, the electrically conductive bracket having a contact for supplying the electric current.

According to a second aspect of the present invention, there is provided an anode holder for vertically holding an anode, the anode and a substrate being vertically disposed so as to face each other in a plating tank of a plating apparatus, the anode holder comprising: an anode holder base having a hole defined therein for housing a conducting belt for supplying an electric current to the anode; and an anode mask mounted on the anode holder base for covering a portion of a front surface of the anode. The conducting belt comprises a belt capable of contacting an outer circumferential edge of the anode and holding the anode.

According to the present invention, the exposed area of the anode can be adjusted by the anode mask. Further, the conducting belt is masked by the anode holder and is not exposed to a plating solution during a plating process.

In a preferred aspect of the invention, an anode holder further comprises: a rear cover mounted on a rear surface of the anode holder base for covering a rear surface of the anode.

In a preferred aspect of the present invention, the anode mask has a circular opening, and the circular opening has a diameter smaller than the diameter of the anode.

In a preferred aspect of the present invention, the anode holder base includes a hand for transferring the anode holder.

In a preferred aspect of the present invention, the anode holder base includes a solution discharge hole for allowing a solution to be discharged therethrough.

According to a third aspect of the present invention, there is provided a plating apparatus comprising: a plating tank for vertically placing therein an anode holder holding an anode and a substrate holder holding a substrate thereon in confronting relation to each other; a temporary storing unit for exchanging the anode holder; and a transfer robot for transferring the anode holder between the plating tank and the temporary storing unit. The anode holder comprises an anode holder base having a hole defined therein for housing a conducting belt for supplying an electric current to the anode; and an anode mask mounted on the anode holder base for covering a portion of a front surface of the anode. The conducting belt comprises a belt capable of contacting an outer circumferential edge of the anode and holding the anode.

According to the present invention, the anode holder, which has such a structure as to cope with the transfer robot, can be conveyed by the transfer robot.

In a preferred aspect of the present invention, a plating apparatus further comprises: a cleaning tank for cleaning the anode holder.

In a preferred aspect of the present invention, a plating apparatus further comprises: a blowing tank for removing water droplets from the anode holder.

According to the present invention, the anode holder can be transferred by the transfer robot through a removal section to the outside of the apparatus after the anode holder is cleaned by cleaning water, and water droplets are removed from the anode holder.

According to a fourth aspect of the present invention, there is provided an anode held by a conducting belt for use with an anode holder for supplying an electric current to an anode. The anode and a substrate are vertically disposed so as to face each other in a plating tank of a plating apparatus. The conducting belt comprises a belt capable of contacting an outer circumferential edge of the anode and holding the anode.

In a preferred aspect of the present invention, the anode is disk-shaped.

The conducting belt according to the present invention offers the following advantages:

1) Since the conducting belt is brought into contact with the entire or substantially entire outer circumferential edge of the anode, the conducting belt can supply an electric current to the anode from the entire or substantially entire outer circumferential edge of the anode. Therefore, a contact failure is prevented from occurring between the conducting belt and the anode.

2) As the area of contact between the conducting belt and the anode is large, any contact resistance between the conducting belt and the anode is reduced.

3) Since the entire or substantially entire outer circumferential edge of the anode is secured by the conducting belt, there is no need to perform positional alignment between the anode and the conducting belt. Further, the anode can easily be machined because the anode is in the form of a circular disk.

4) The anode can easily be replaced with a new one simply by loosening the conducting belt, placing the new anode in position, and retightening the conducting belt.

5) Since the anode is in the form of a circular disk and is held by the conducting belt, the anode is free of wasteful areas.

The anode holder according to the present invention offers the following advantages:

1) The anode can easily be replaced with a new one simply by removing the rear cover, loosening the fastener, placing the new anode in position, retightening the fastener, and attaching the rear cover again.

2) The anode mask has its inside diameter smaller than the diameter of the anode. Therefore, even if the anode held by the conducting belt is overused beyond its replacement period, the anode is prevented from falling out of the anode holder or suffering from a conductive fault.

3) The solution discharge hole defined in the lower end of the anode holder allows the plating solution to be discharged quickly and reliably from the anode holder through the solution discharge hole.

The plating apparatus according to the present invention offers the following advantages:

1) Since the anode holder is removed by the transfer robot which is fully automatized, the anode holder can easily be replaced.

2) For removing the anode holder from the plating apparatus, the anode holder is taken out of the plating tank by the transfer robot, and cleaned in the cleaning tank to remove the plating solution from the anode holder. Then, water droplets are removed from the anode holder in the blowing tank, and the anode holder is removed from the plating apparatus through the temporary storing unit. Thus, the operator is not required to touch the plating solution for the removal of the anode holder, and hence the safety of the operator can be ensured.

3) Since the anode holder can easily be removed, the anode mask can easily be replaced.

4) The transfer robot has a high level of positioning accuracy, and can perform fine adjustment of position. Consequently, the anode holder can be placed in a desired position with high reproducibility, and the interelectrode distance between the substrate and the anode can easily be changed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A conducting belt for use with an anode holder and an anode holder according to an embodiment of the present invention will be described with reference toFIGS. 1 through 8. The conducting belt and the anode holder are typically employed in the vertical-immersion plating apparatus as shown inFIG. 15. Structural details of the plating apparatus having a plating tank will not be described below in the following embodiments.

FIGS. 1 through 4show a conducting belt for use with an anode holder according to the embodiment of the present invention.FIG. 1is a front elevational view of a conducting belt which holds an anode, andFIG. 2is a side elevational view of the conducting belt.

As shown inFIGS. 1 and 2, the conducting belt, generally denoted by1, comprises a belt-like thin plate in the form of a ring composed of an electrically conductive material such as titanium. The conducting belt holds a disk-shaped anode5fitted therein. The conducting belt1has opposite ends1a,1b(holding portions) fastened to each other by a bolt6and nuts7(i.e., first fastener) to secure the anode5therein. The conducting belt1has a thickness of 1 mm to 3 mm and a width of 1 cm to 2 cm. Since a substrate W to be plated is in the form of a circular disk, the anode5is also in the form of a circular disk. The anode5has an outside diameter of 150 mm to 300 mm and a thickness of 10 mm to 20 mm.

FIG. 3is an enlarged view showing an encircled area A inFIG. 1, and showing a fastening assembly in detail. As shown inFIG. 3, the bolt6is inserted into the opposite ends1a,1bof the conducting belt1and the double nuts7are screwed onto the bolt6to fasten the anode5by the conducting belt1. The circular anode5has its outer circumferential edge which is entirely or substantially entirely in close contact with the inner circumferential surface of the conducting belt1.

As shown inFIGS. 1 and 3, an electrically conductive bracket2is fixed to an extended fixing portion of the end1aof the conducting belt1by a bolt8and double nuts9(i.e., second fastener). The electrically conductive bracket2has a contact3on its distal end. The contact3is brought into contact with a contact (not shown) provided in the plating tank, so that the contact3can be supplied with an electric current from a plating power supply.

FIG. 4is a perspective view of the conducting belt1.

As shown inFIG. 4, the ends1a,1bof the conducting belt1are bent radially outwardly from the circular thin plate at an angle of substantially 90°. The ends1a,1bhave bolt insertion holes1cdefined therein for the insertion of the bolt6therethrough. The end1ais longer than the end1band has a notch1ddefined therein for the insertion of the bolt8therethrough.

The conducting belt1which is constructed as shown inFIGS. 1 through 4offers the following advantages:

1) Since the conducting belt1is brought into contact with the entire or substantially entire outer circumferential edge of the anode5, the conducting belt1can supply an electric current to the anode5from the entire or substantially entire outer circumferential edge of the anode5. Therefore, a contact failure is prevented from occurring between the conducting belt1and the anode5.

2) As the area of contact between the conducting belt1and the anode5is large, any contact resistance between the conducting belt1and the anode5is reduced.

3) Since the entire outer circumferential edge of the anode5is secured by the conducting belt1, there is no need to perform positional alignment between the anode5and the conducting belt1. Further, the anode5can easily be machined because the anode5is in the form of a circular disk.

4) The anode5can easily be replaced with a new one simply by loosening the conducting belt1, placing the new anode in position, and retightening the conducting belt1.

5) Since the anode5is in the form of a circular disk and is held by the conducting belt1, the anode5is free of wasteful areas.

The anode5and the conducting belt1shown inFIGS. 1 through 4are held by an anode holder10shown inFIGS. 5 through 7. The anode holder10will be described below with reference toFIGS. 5 through 7.

FIG. 5is a front elevational view, partly in cross section, of the anode holder10,FIG. 6is a cross-sectional view taken along line VI-VI ofFIG. 5, andFIG. 7is an exploded perspective view of the anode holder10. As shown inFIGS. 5 and 6, the anode holder10comprises an anode holder base11for mounting thereon the anode5held by the conducting belt1, a rear cover12mounted on the reverse surface of the anode holder base11for holding the reverse surface of the anode5, and an anode mask13mounted on the front surface of the anode holder base11for covering a portion of the front surface of the anode5.

As shown inFIG. 7, the anode holder base11is in the form of a substantially rectangular thin plate, and has a circular housing hole11adefined centrally therein for housing the anode5that is held by the conducting belt1. The anode holder base11has a pair of substantially T-shaped hands11b,11bon its upper end which can be gripped by a robot when the robot transfers the anode holder10for replacing the exhausted anode. As shown inFIG. 5, the contact3on the distal end of the electrically conductive bracket2connected to the conducting belt1is held on a lower surface of one of the hands11b. As shown inFIG. 6, the anode holder base11has a solution discharge hole11hdefined in a lower end thereof for allowing the plating solution to be discharged quickly and reliably therethrough from the anode holder10when the anode holder10is lifted out of the plating tank for anode replacement.

As shown inFIG. 7, the rear cover12is in the form of a substantially rectangular thin plate, and has a circular pressing portion12adisposed centrally thereon. As shown inFIG. 6, the circular pressing portion12ais slightly thicker than the outer circumferential region of the rear cover12. Thus, the circular pressing portion12ais fitted into the circular housing hole11aof the anode holder base11when the rear cover12is mounted on the anode holder base11. Consequently, the circular pressing portion12apresses the rear surface of the anode5that is housed in the circular housing hole11a.

The anode mask13is in the form of an annular plate having a central opening13adefined therein. The opening13aof the anode mask13has a diameter smaller than the diameter of the anode5, so that the anode mask13mounted on the anode holder base11covers or masks an outer peripheral portion of the anode5that is housed in the housing hole11a. The diameter of the opening13acan be selected to control the electric field on the front surface of the anode5. The anode mask13is made of vinyl chloride, PEEK (polyether ether ketone), PVDF (polyvinylidene difluoride), or the like.

InFIGS. 5 through 7, the anode5mounted on the anode holder base11has its rear surface pressed by the rear cover12. However, the anode5may have its front surface pressed by a front cover. In such a modification, the anode mask may be mounted on the front cover, or the front cover may double as the anode mask.

1) The anode5can easily be replaced with a new one simply by removing the rear cover12, loosening the double nuts7, placing the new anode5in position, retightening the double nuts7, and attaching the rear cover12again.

2) The anode mask13has its inside diameter smaller than the diameter of the anode5. Therefore, even if the anode5held by the conducting belt1is overused beyond its replacement period, the anode5is prevented from falling out of the anode holder10or suffering from a conductive fault.

3) The solution discharge hole11hdefined in the lower end of the anode holder10allows the plating solution to be discharged quickly and reliably from the anode holder10when the anode holder10is lifted out of the plating tank.

FIG. 8shows the anode holder10which is immersed in the plating solution. As shown inFIG. 8, the anode holder10is disposed in the plating solution in such a manner that the hands11b,11bare positioned above a plating solution level L. The contact3held on one of the hands11b,11bis brought into contact with a contact plate16fixed to a holder15provided in the plating tank. The contact plate16is connected to the plating power supply (not shown inFIG. 8) through an electric supply line17. Therefore, the anode5held by the anode holder10that is connected to the contact3is supplied with an electric current from the plating power supply through the electric supply line17and the contact plate16.

FIG. 9is a schematic plan view of the plating apparatus incorporating the conducting belt1shown inFIGS. 1 through 4and the anode holder10shown inFIGS. 5 through 7.

As shown inFIG. 9, the plating apparatus comprises a loading/unloading unit U1for loading and unloading the substrate W, and a plating processing unit U2for performing various processing including plating of the substrate W, cleaning of the substrate W, and the like. The loading/unloading unit U1comprises three cassette tables22for placing thereon cassettes20which house substrates W such as semiconductor wafers, an aligner24for aligning an orientation flat or a notch of a substrate W with a predetermined direction, and a spin drier26for drying the plated substrate W by spinning the plated substrate at a high speed. The loading/unloading unit U1also has a substrate mounting/dismounting unit30for placing a substrate holder18thereon, and mounting the substrate W on the substrate holder18and dismounting the substrate W from the substrate holder18. The cassette tables22, the aligner24, the spin drier26, and the substrate mounting/dismounting unit30are disposed around a transfer robot32for transferring substrates W between the cassette tables22, the aligner24, the spin drier26, and the substrate mounting/dismounting unit30.

The plating unit U2comprises, successively in order from the substrate mounting/dismounting unit30, a stocker34for storing and temporarily placing substrate holders18, a pre-wetting tank36for immersing a substrate W in pure water to wet the substrate W for making the surface of the substrate W highly hydrophilic, a pre-soaking tank38for etching away an oxide film having large electric resistance from a surface of a seed layer formed on the substrate W with a chemical solution such as sulfuric acid or hydrochloric acid, a water cleaning tank40for cleaning the surface of the substrate W and the anode holder10with pure water, a plating tank44for plating the substrate W, another water cleaning tank40, another plating tank44, still another water cleaning tank40, and a blowing tank42for removing water from the cleaned substrate W and the cleaned anode holder10. Each of the plating tanks44serves to perform copper plating of the substrate W. Alternatively, each of the plating tanks44may perform nickel plating, solder plating, or gold plating of the substrate W.

A transfer apparatus50is disposed alongside of the stocker34and the tanks36,38,40,42,44for transferring the substrate holders18together with the substrates W between these stocker and tanks. The transfer apparatus50includes a transporter52for transporting the substrates W between the substrate mounting/dismounting unit30and the stocker34, and transporting the substrates W between the stocker34, the pre-wetting tank36, the pre-soaking tank38, the water cleaning tanks40, the plating tanks44, and the blowing tank42. The transporter52also serves to transport the anode holders10between a temporary storing unit70(described later), the pre-wetting tank36, the pre-soaking tank38, the water cleaning tanks40, the blowing tank42, and the plating tanks44.

The substrate mounting/dismounting unit30comprises a flat support plate46angularly movable about a rotational shaft45at an angle of 90° between a vertical position and a horizontal position. Two substrate holders18are placed parallel to each other on the support plate46when the flat support plate46is in the horizontal position. After the substrate W is transferred between one of the substrate holders18and the transfer robot32, the support plate46is angularly moved from the horizontal position to the vertical position, and transfers the substrate holder18to or from the transporter52.

The temporary storing unit70for replacing an anode holder10and temporarily placing an anode holder10is disposed between the water cleaning tank40and the plating tank44. Alternatively, the temporary storing unit70may be disposed in any position between any adjacent equipment located between the stocker34and the blowing tank42. Further, the temporary storing unit70may be disposed between the blowing tank42and a housing47as indicated by the imaginary lines inFIG. 9.

The substantially T-shaped hands11b,11bprovided on the upper end of the anode holder10serve as supports for transferring the anode holder10or suspending the anode holder10(seeFIGS. 5 and 8). In the temporary storing unit70, the anode holder10is vertically suspended by the hands11bhanging on an upper surface of a circumferential wall of the temporary storing unit70. Further, the anode holder10is transferred by the transporter52with the hands11bof the suspended anode holder10gripped by the transporter52. In each of the pre-wetting tank36, the pre-soaking tank38, the water cleaning tanks40, the blowing tank42, and the plating tanks44, the anode holder10is suspended by the hands11bhanging on an upper surface of a circumferential wall of the tank.

FIGS. 10 and 11show a linear motor unit85as a driving unit of the transfer apparatus50. Specifically,FIG. 10is a plan view of the linear motor unit58of the transfer apparatus50, andFIG. 11is a front elevational view of the linear motor unit58shown inFIG. 10. As shown inFIGS. 10 and 11, the linear motor unit85basically comprises an elongate base86and a slider87movable along the base86. The transporter52is mounted on an upper surface of the slider87. A cable conveyer bracket89and a cable conveyer receiver90are disposed alongside of the base86, and a cable conveyer92extends along the cable conveyer bracket89and the cable conveyer receiver90.

As shown inFIGS. 10 and 11, since the transporter52is driven by the linear motor unit85, the transporter52can be moved over a long distance and can be reduced in length to reduce the overall length of the transfer apparatus50. The transfer apparatus50can be free of components such as a long ball screw which require dimensional accuracy and maintenance.

FIGS. 12 through 14show the transporter52in detail. Specifically,FIG. 12is a front elevational view of transporter52,FIG. 13is a plan view of a gripping mechanism mounted on an arm of the transporter52, andFIG. 14is a vertical cross-sectional view of the gripping mechanism. The transporter52comprises a transfer robot for transferring the substrate holder18and also transferring the anode holder10. Hereinafter, the case where the transporter52transfers or transports the anode holder10will be described. As shown inFIGS. 12 and 13, the transporter52basically comprises a transporter body53, an arm54extending laterally from the transporter body53, an arm lifting/lowering mechanism55for lifting and lowering the arm54, and gripping mechanisms57disposed in the arm54for detachably gripping the hands11bof the anode holder10. The arm lifting/lowering mechanism55comprises a rotatable ball screw58extending vertically, and a nut59screwed onto the ball screw58. An LM base60is coupled to the nut59. A timing belt64is trained around a drive pulley62fixed to a drive shaft of a lifting/lowering motor61and a driven pulley63fixed to the upper end of the ball screw58. The drive shaft of the lifting/lowering motor61is fixed to the transporter body53. When the lifting/lowering motor61is energized, the ball screw58is rotated about its own axis by the timing belt64, and the LM base60coupled to the nut59which is screwed onto the ball screw58is vertically moved along an LM guide.

As shown inFIGS. 13 and 14, the arm54has a pair of spaced side plates74with the gripping mechanisms57disposed therebetween. Although the two gripping mechanisms57are shown in the illustrated embodiment, one of them will be described below as they are identical in structure to each other.

The gripping mechanism57comprises a fixed holder75having an end transversely movably disposed between the side plates74, guide shafts76extending through the fixed holder75, and a movable holder77coupled to ends (lower ends inFIG. 14) of the guide shafts76. The fixed holder75is coupled by a cylinder joint79to a transversely moving cylinder78mounted on one of the side plates74. A shaft holder82is connected to other ends (upper ends inFIG. 14) of the guide shafts76. The shaft holder82is coupled to a vertically moving cylinder80by a cylinder connector81.

When the transversely moving cylinder78is actuated, the fixed holder75is transversely moved between the side plates74together with the movable holder77. When the vertically moving cylinder80is actuated, the movable holder77is vertically moved while being guided by the guide shafts76.

For gripping the hands11bof an anode holder10which is suspended in the temporary storing unit70or the like with the gripping mechanism57, the movable holder77is lowered to a position lower than the hands11bwhile the movable holder77is prevented from interferring with the hands11b. Thereafter, the transversely moving cylinder78is actuated to position the fixed holder75above the hands11band to position the movable holder77beneath the hands11b. Then, the vertically moving cylinder80is actuated to lift the movable holder77until the fixed holder75and the movable holder77grip the hands11btherebetween. The hands11bcan be released when the vertically moving cylinder80is actuated to lower the movable holder77.

As shown inFIG. 5, one of the hands11bof the anode holder10has a recess11edefined in a lower edge thereof. As shown inFIG. 14, the movable holder77has a projection77aon an upper surface thereof which can be fitted into the recess11eof the anode holder10. When the hands11bare gripped between the fixed holder75and the movable holder77, the projection77ais fitted into the recess11eto position and orient the hands11bproperly.

A processing operation of the plating apparatus constructed as shown inFIGS. 9 through 14will be described below. Hereinafter, the replacement work of the anode will be mainly described. First, a process of plating the substrate W will briefly be described below. After the substrate W is mounted on the substrate holder18in the loading/unloading unit U1, the transporter52of the transfer apparatus50grips the substrate holder18and suspends (temporarily places) the substrate holder18in the stocker34. Then, the transporter52removes the substrate holder18from the stocker34, and conveys the substrate holder18successively through the pre-wetting tank36, the pre-soaking tank38, the plating tanks44, and the water cleaning tanks40for successively pre-wetting, pre-soaking, plating, and cleaning the substrate W.

When the above plating process is repeated, the anode5is exhausted and needs to be replaced with a new one. A process of replacing the anode5will be described below.

The anode holder10which is immersed in the plating tank44and holds the exhausted anode5is lifted by the transporter52. At this time, the gripping mechanism57of the transporter52grips the anode holder10, and the arm54is lifted by the arm lifting/lowering mechanism55. Thereafter, the anode holder10is conveyed to the adjacent water cleaning tank40. Then, the arm54is lowered by the arm lifting/lowering mechanism55to bring the anode holder10into the water cleaning tank40in which the anode holder10is cleaned with water. The cleaned anode holder10is transferred by the transporter52to the blowing tank42in which water droplets are removed from the anode holder10.

Thereafter, the anode holder10is conveyed to the temporary storing unit70by the transporter52. Then, the anode holder10is taken out of the plating apparatus through the temporary storing unit70onto a working table (not shown). At this time, the anode holder10is removed from the lateral side of the plating apparatus. If the temporary storing unit70is positioned between the blowing tank42and the housing47as indicated by the imaginary lines inFIG. 9, then the anode holder10can be removed from the rear end of the plating apparatus. On the working table, the rear cover12is detached from the anode holder10, the conducting belt1is loosened, the exhausted anode5is replaced with a new anode5, and the conducting belt1is retightened. The conducting belt1can be loosened simply by loosening the nuts7, and can be retightened simply by retightening the nuts7.

Then, the rear cover12is attached to the anode holder base11, thereby completing the process of mounting the new anode5on the anode holder10. The anode holder10with the new anode5mounted therein is returned to the temporary storing unit70in the plating apparatus, and is then put back into the plating tank44by the transporter52.

The plating apparatus constructed as shown inFIGS. 9 through 14offers the following advantages:

1) Since the anode holder10is removed by the transporter (transfer robot)52which is fully automatized, the anode holder10can easily be replaced.

2) For removing the anode holder10from the plating apparatus, the anode holder10is taken out of the plating tank44by the transporter (transfer robot)52, cleaned in the water cleaning tank40, which is also used to clean the substrate W, to remove the plating solution from the anode holder10, dried in the blowing tank42, which is also used to dry the substrate W, and removed from the plating apparatus through the temporary storing unit70. The temporary storing unit70serves as an anode holder exchange area. Since the operator is not required to touch the plating solution for the removal of the anode holder10, the safety of the operator can be ensured.

3) Since the anode holder10can easily be removed, the anode mask13can easily be replaced.

4) The transporter (transfer robot)52has a high level of positioning accuracy, and can perform fine adjustment of position. Consequently, the anode holder10can be placed in a desired position with high reproducibility, and the interelectrode distance between the substrate W and the anode5can easily be changed.