JP7701959B2 - Plating Equipment - Google Patents

Description

This invention relates to a plating device that plates at least one main surface of a rectangular substrate, such as a printed wiring board or a glass substrate.

The technology of forming a thin metal film by plating on the surfaces of various substrates such as semiconductor substrates, printed wiring boards, and glass substrates is widely used. For example, in the plating apparatus described in Patent Document 1, the substrate to be plated is held in a horizontal position with its face up, and an anode electrode is placed above the substrate immersed in a plating solution.

JP 2003-129286 A

For example, when a metal material is used as the anode electrode, as in the case of electrolytic copper plating, the metal material dissolves into the plating solution as the process progresses. It is known that at this time, a residue (also called anode slime) is generated that does not electrochemically dissolve in the solution and is liberated from the anode electrode. In the conventional technology described in Patent Document 1, the residue liberated from the anode electrode settles in the plating solution and adheres to the upper surface of the substrate supported face-up downward. This can cause a deterioration in the quality of the plating film.

To address this issue, technologies that have been put into practical use include adding chemical substances to the metallic material that is the anode electrode material to suppress the formation of anode slime, and using an insoluble anode to supply metal ions, which are the material for the plating film, from outside as salt.

However, these technologies require the use of special materials as anodes or the preparation of separate chemicals that serve as a source of metal ions, and there is also the possibility that substances that are not necessary for the actual electrochemical reaction may become mixed into the plating film and degrade its quality. For these reasons, there is a demand for technology that can prevent the deterioration of plating film quality due to the effects of anode slime, without using special anode materials or metal salts.

This invention was made in consideration of the above problems, and aims to provide a technology for plating the top surface of a substrate supported in a face-up state that can prevent deterioration of the quality of the plating film caused by anode slime without using special anode materials.

One aspect of the present invention is a plating apparatus for plating at least one main surface of a flat substrate. This plating apparatus includes a treatment tank for storing a first plating solution, a holding unit for holding the substrate in a horizontal position with the main surface facing upward within the treatment tank, a cathode electrode in contact with a portion of the main surface of the substrate held in the holding unit, an anode electrode disposed above the substrate held in the holding unit and facing the main surface, a power supply unit connected to the anode electrode and the cathode electrode, and an isolation unit for isolating the anode electrode from the first plating solution within the treatment tank by surrounding the sides and bottom of the anode electrode.

Here, the bottom of the isolating section is composed of an electrolytic diaphragm disposed between the lower surface of the anode electrode and the one main surface, the upper surface of the bottom is disposed opposite the lower surface of the anode electrode across a predetermined gap, the lower surface of the bottom is in contact with the first plating solution stored in the treatment tank, and the gap is filled with a second plating solution isolated from the first plating solution in the treatment tank.

In the invention configured in this manner, an anode electrode is disposed above a substrate supported in a horizontal position, facing the substrate, and a second plating solution, an electrolytic diaphragm, and a first plating solution are interposed between the anode electrode and the substrate, in that order. The upper and lower surfaces of the electrolytic diaphragm are in contact with the second plating solution and the first plating solution, respectively.

Therefore, while ion transfer is possible between the first plating solution and the second plating solution through the electrolytic diaphragm, the substances that cause insoluble anode slime in the second plating solution do not pass through the electrolytic diaphragm and transfer to the first plating solution. This prevents anode slime from adhering to the top surface of the substrate and impairing the quality of the plating film.

As described above, in the present invention, the anode electrode is placed above the substrate supported in a horizontal position, but the anode slime released from the anode electrode is blocked by the electrolytic diaphragm and does not adhere to the substrate. This prevents the anode slime from adhering to the upper surface of the substrate and degrading the quality of the plating film.

1 is a diagram showing a schematic configuration of an embodiment of a plating apparatus according to the present invention; FIG. 2 is a diagram showing a schematic configuration of a plating processing section. FIG. 2 is a diagram showing a schematic configuration of a plating processing section. FIG. 2 is a diagram showing a schematic configuration of a chuck mechanism. FIG. 2 is a diagram showing a schematic configuration of a main part of an anode electrode unit. FIG. 2 is a diagram showing a schematic diagram of an isolation tank immersed in a plating tank. FIG. 4 is an external perspective view showing a support mechanism for a separator in the anode electrode unit. FIG. 2 is a diagram showing a schematic diagram of supply and discharge of plating solution to and from an isolation tank. 11A and 11B are diagrams illustrating the lifting and lowering operation of the isolation tank in more detail. 11A and 11B are diagrams illustrating the lifting and lowering operation of the isolation tank in more detail. 11A and 11B are diagrams illustrating the lifting and lowering operation of the isolation tank in more detail. 11A and 11B are diagrams illustrating the lifting and lowering operation of the entire support mechanism. FIG. 2 is a block diagram showing the electrical configuration of the plating apparatus. 1 is a flowchart showing a plating process. FIG. 2 is a diagram showing a schematic operation of each unit. FIG. 13 is a diagram showing a modified example of the anode electrode. 13A and 13B are diagrams illustrating a modified example of the support mechanism in the anode electrode unit.

Specific aspects of the plating device according to the present invention will be described below with reference to specific embodiments.

Figure 1 is a diagram showing the schematic configuration of one embodiment of a plating apparatus according to the present invention. This plating apparatus 1 is an apparatus that forms a metal (e.g., gold) film by electrolytic plating on at least one main surface of various substrates S (hereinafter simply referred to as "substrate") such as semiconductor substrates, printed wiring boards, and glass substrates. For the following explanation, an XYZ Cartesian coordinate system is defined as shown in Figure 1. Figure 1 is a diagram showing a side view of the plating apparatus 1, with the horizontal direction perpendicular to the paper surface of Figure 1 being the X direction, and the horizontal direction perpendicular to this and along the paper surface of Figure 1 being the Y direction. The vertical direction is also referred to as the Z direction. In each figure, the dotted arrows indicate the movement direction of each component.

The plating apparatus 1 has a structure in which the various parts described below are assembled in a housing 10 formed by combining multiple frame members. Note that in FIG. 1 and the following figures, in order to avoid cluttering the drawings, some components may be omitted as appropriate. Specifically, components such as a holding mechanism for holding components, a cover for covering the components, and a mechanism for attaching them to the housing 10 may be omitted from illustration because they contribute relatively little to the establishment of the invention, and because appropriate publicly known technology can be applied to their structure and no special explanation is considered to be required.

Figure 1 is a front view of a plating apparatus 1. The plating apparatus 1 is provided with a transport section 2 that transports a substrate S along the Y direction. The transport section 2 includes a number of transport rollers 21 arranged along the Y direction. The transport rollers 21 are each supported by a support mechanism (not shown) so that they can rotate freely with the X direction as their axial direction. By rotating the transport rollers 21 with a drive mechanism (not shown), the transport section 2 transports the substrate S in the Y direction in a horizontal position. The rectangular substrate S is transported with one of the four peripheral sides at the front. In the following, the transport path of the substrate S is represented by the symbol P, and the transport direction is represented by the symbol Dt.

The plating apparatus 1 further includes a loading section 3, a plating processing section 4, a rinsing processing section 5, an unloading section 6, a power supply section 7, and a control section 9. The loading section 3, the plating processing section 4, the rinsing processing section 5, and the unloading section 6 are arranged in this order along the transport direction Dt (Y direction) of the substrate by the transport section 2. That is, in this plating apparatus 1, the substrate S is subjected to the necessary processing in each of the above-mentioned processing sections while being transported in the Y direction by the transport section 2.

The loading section 3 receives and temporarily holds the unprocessed substrate S transported from the outside, and supplies the substrate S to the plating processing section 4 at the required timing. The plating processing section 4 is the processing main body that carries out the plating method according to the present invention, and performs plating processing by immersing the substrate S in a plating solution. Its configuration and operation will be described in detail later.

The rinse processing unit 5 includes a rinse tank 51, a tray 52, and a rinse liquid supply/discharge unit 59. The rinse tank 51 is capable of storing rinse liquid in an internal space of sufficient size to accommodate a substrate S. An opening is provided on the Y-direction side surface of the rinse tank 51 at a portion that overlaps with the transport path P, and shutters 51a, 51b are provided for the opening so as to be freely opened and closed.

The tray 52 is disposed below the rinse tank 51 and receives the rinse liquid spilled from the rinse tank 51. The rinse liquid supply/discharge unit 59 supplies rinse liquid to the rinse tank 51 and discharges rinse liquid from the rinse tank 51 as necessary. The rinse processing unit 5 performs a rinse process on the substrate S immersed in the plating liquid in the plating processing unit 4. Water, for example, is used as the rinse liquid. The discharge unit 6 temporarily holds the substrate S after the rinse process until it is removed to a post-processing step by an external transport device.

The power supply unit 7 supplies the necessary power to each part of the apparatus. The control unit 9 controls each part of the apparatus configured as described above, and causes the plating apparatus 1 to perform a predetermined process. The hardware configuration of the control unit 9 can be the same as that of a general computer device, for example. That is, the CPU (FIG. 9) provided in the control unit 9 executes a control program prepared in advance to realize various processes described below. Although not specifically described below, each part of the apparatus operates based on control commands from the control unit 9.

The plating processing section 4 includes a plating tank 41, vats 42 and 44, a chuck section 40, a moving mechanism 43, an anode electrode unit 45, a cleaning mechanism 48, and a plating solution supply/discharge section 49. The plating tank 41 is capable of storing plating solution in an internal space having a size sufficient to accommodate the substrate S. The vat 42 is disposed below the plating tank 41 and receives spilled plating solution. The chuck section 40 is disposed above the plating tank 41 and holds the substrate S to be plated. The vat 44 is disposed adjacent to the vat 42 below the plating tank 41 on the (-Y) side. The cleaning mechanism 48 cleans the chuck section 40 with an appropriate cleaning solution (e.g., water). For this purpose, the cleaning mechanism 48 includes a cleaning nozzle 481 (FIG. 2) provided in the vat 44 and a cleaning solution supply/discharge section 482 that supplies cleaning solution to the cleaning nozzle 481. The plating solution supply/discharge unit 49 supplies plating solution to the plating tank 41 and discharges plating solution from the plating tank 41 as needed.

Figures 2 and 3 are diagrams showing the schematic configuration of the plating processing section. More specifically, Figure 2 is a front view of the main parts of the plating processing section 4 as seen in the (-X) direction, and Figures 3(a) and 3(b) are side views of the plating processing section 4 as seen in the (+Y) direction. Note that to avoid cluttering the figures, the anode electrode unit 45 is omitted from Figures 2 and 3(a).

As shown in Figures 1 and 2, openings are provided on the (-Y) side and (+Y) side of plating tank 41 at the portions that overlap with transport path P, and shutters 41a, 41b that can be opened and closed are provided at the openings. When shutters 41a, 41b are open, substrate S transported along transport path P by transport unit 2 can pass through the openings provided on the sides of plating tank 41. This makes it possible to transport unprocessed substrates S into plating tank 41 and to transport processed substrates S out of plating tank 41.

On the other hand, in the closed state, the opening on the side of the plating tank 41 is closed. At this time, the transport path P for the substrate S is blocked, but the plating solution can be stored inside the plating tank 41 beyond the height of the opening. After the substrate S is accommodated in the plating tank 41 with the (-Y) side shutter 41a open, the shutter 41a is closed and the internal space of the plating tank 41 is filled with plating solution L, so that the substrate S is immersed in the plating solution L and plated. After that, when the plating solution is discharged and the (+Y) side shutter 41b is opened, the liquid level of the plating solution L drops below the bottom end of the opening, and the substrate S after plating is transported to the rinsing section 5. The shutters 41a and 41b may be opened and closed independently of each other, or may be opened and closed integrally.

As shown in FIG. 3(a), a rotary motor 23 is coupled to the rotating shaft 22 of the transport roller 21. The rotary motor 23 rotates in response to a control command from the control unit 9, causing the transport roller 21 to rotate, thereby transporting the substrate S in the Y direction. Note that some of the rollers may be driven rollers that are not connected to a drive source.

As shown in FIG. 3(a), two sets of chuck parts 40 are arranged corresponding to both ends in the X direction of the substrate S contained in the plating tank 41. Only one set on the (+X) side is shown in FIG. 1 and FIG. 2. The two sets of chuck parts 40 are arranged symmetrically with respect to the YZ plane, but have the same basic structure. That is, each chuck part 40 includes at least one chuck mechanism 400, a support frame 430 that supports the chuck mechanism 400, and a movement mechanism 43 that moves the support frame 430 in the Y direction.

The support frame 430 is supported so as to be freely movable in the Y direction by a moving mechanism 43 attached to the upper frame 11, one of the frame members constituting the housing 10. More specifically, the moving mechanism 43 includes a guide rail 431 fixed to the upper frame 11 above the plating processing section 4 and extending in the Y direction, a slider 432 engaged with the guide rail 431, and a drive source (not shown) that moves the slider 432 in the Y direction along the guide rail 431. As these configurations, an appropriate linear motion mechanism, such as a linear motor, a linear motion guide mechanism, a chain drive mechanism, or a belt drive mechanism, can be applied. For example, a single-axis robot in which such a drive mechanism is integrated in advance can be preferably applied.

The support frame 430 is connected to the lower end of the slider 432, and the chuck mechanism 400 is fixed to the support frame 430. Therefore, when the slider 432 moves in the Y direction along the guide rail 431, the support frame 430 and the chuck mechanism 400 attached thereto move integrally in the Y direction. In other words, the movement mechanism 43 operates in response to a control command from the control unit 9 to move the slider 432, thereby moving the chuck mechanism 400 in the Y direction.

In this embodiment, three sets of chuck mechanisms 400 are attached to one support frame 430 in a line in the Y direction, and they move together in the Y direction as the support frame 430 moves. This allows each chuck mechanism 400 to move back and forth in the Y direction between a "plating position" P1 located above the plating tank 41 and a "cleaning position" P2 located above the vat 44. In FIG. 2, the chuck mechanism 400 at the plating position P1 is shown by a solid line, and the chuck mechanism 400 at the cleaning position P2 is shown by a dotted line. Meanwhile, in FIG. 1, the chuck mechanism 400 at the cleaning position P2 is shown by a solid line.

The chuck mechanism 400 grips the substrate S to stably maintain the position of the substrate S in the plating tank 41, and electrically contacts the built-in cathode electrode with one main surface of the substrate S. A DC voltage is then applied between the anode electrode and cathode electrode, which will be described later, to form a coating on the one main surface by electrolytic plating. In this case, it is assumed that the coating is formed on the top surface of the substrate S.

The chuck mechanisms 400 grip the substrate S at both ends in the X direction, i.e., at both ends in the width direction perpendicular to the transport direction Dt. A large portion of the substrate S is gripped at both ends in the X direction by a plurality of chuck mechanisms 400 provided along the Y direction, i.e., the transport direction Dt of the substrate S. The chuck mechanisms 400 grip the substrate S to stably maintain its position, and can apply a uniform potential over a wide area by contacting the cathode electrode 412 extending in the Y direction with the substrate S. This allows the plating device 1 to form a plating film with good uniformity on the substrate S.

Figure 4 is a diagram showing the schematic configuration of the chuck mechanism. More specifically, Figure 4(a) is a perspective view showing the structure of the chuck mechanism 400, and Figure 4(b) is a diagram showing the state in which the chuck mechanism 400 grips the substrate S. Note that, when explaining the structure and operation of the chuck mechanism 400 below, the chuck mechanism 400 that mainly holds the (-X) side end of the substrate S is used as an example, but it is possible to understand the structure and operation of the chuck mechanism that holds the (+X) side end of the substrate S by considering the same structure inverted around the Z axis. Also, in order to improve the visibility of the figure, part of the configuration of the chuck mechanism 400 is omitted in Figure 4(a).

The chuck mechanism 400 grips the X-direction end of the substrate S with an upper chuck 411 and a lower chuck 421 that can be raised and lowered independently of each other. Specifically, the upper chuck 411 and the lower chuck 421 are each flat, elongated members with the Y direction as their longitudinal direction, and grip the substrate S by the lower surface 411b of the upper chuck 411 abutting against the (-X) end of the upper surface Sa of the substrate S and the upper surface 421a of the lower chuck 421 abutting against the (-X) end of the lower surface Sb of the substrate S. In practice, a cathode electrode 412 is attached to the lower surface 411b of the upper chuck 411, and the cathode electrode 412 comes into contact with the upper surface Sa of the substrate S.

The cathode electrode 412 is electrically connected to the power supply unit 7. In addition, a sealing member 415 formed in a ring shape from an elastic material is provided so as to surround the periphery of the cathode electrode 412. When the upper chuck 411 is separated from the substrate S, the lower end of the sealing member 415 extends below the lower surface of the cathode electrode 412.

As a result, as shown in FIG. 4(b), when the cathode electrode 412 comes into contact with the upper surface Sa of the substrate S, the seal member 415 elastically deforms to surround the cathode electrode 412 in an airtight state. Therefore, even when the substrate S is immersed in the plating solution, the cathode electrode 412 is maintained in a dry state without coming into contact with the plating solution. This makes it possible to prevent corrosion of the cathode electrode 412 or the formation of a film due to contact with the plating solution.

As shown in FIG. 4(b), the lower chuck 421 abuts against the lower surface Sb of the substrate S from below, thereby determining the position of the substrate S in the height direction (Z direction). The lower chuck 421 also acts as a backup when the cathode electrode 412 provided on the upper chuck 411 is brought into contact with the substrate S. This ensures that the height position of the substrate S is stably maintained and that electrical contact between the cathode electrode 412 and the substrate upper surface Sa is ensured.

A shaft member 413 extending in the Z direction is attached to the upper surface 411a of the upper chuck 411, and the shaft member 413 is supported by a lifting mechanism 414 so that it can be raised and lowered. The upper chuck 411 is fixed to the shaft member 413 using a screw, for example, and is detachable (i.e. replaceable). The lifting mechanism 414 has an appropriate linear motion mechanism such as a solenoid, linear motor, or ball screw mechanism, and raises and lowers the shaft member 413. This raises and lowers the upper chuck 411 attached to the lower end of the shaft member 413. Here, the unit integrally formed including the upper chuck 411, shaft member 413, lifting mechanism 414, etc. is referred to as the "upper chuck unit 410."

Similarly, a shaft member 423 extending in the Z direction is attached to the upper surface 421a of the lower chuck 421, and the shaft member 423 is supported by a lifting mechanism 424 so that it can be raised and lowered freely. The lower chuck 421 is fixed to the shaft member 423 using, for example, a screw, and is detachable. The lifting mechanism 424 has an appropriate linear motion mechanism, for example, a solenoid, a linear motor, or a ball screw mechanism, and raises and lowers the shaft member 423. This raises and lowers the lower chuck 421 attached to the lower end of the shaft member 423. Here, the unit integrally formed including the lower chuck 421, the shaft member 423, the lifting mechanism 424, etc. is referred to as the "lower chuck unit 420."

The upper chuck unit 410 is fixed to the support member 401. Therefore, the upper chuck 411 can only move up and down relative to the support member 401. On the other hand, the lower chuck unit 420 is attached to the support member 401 via the advance/retract mechanism 402. Specifically, the support member 403 to which the lower chuck unit 420 is attached is connected to the movable part of the advance/retract mechanism 402, whose movable direction is the X direction. The advance/retract mechanism 402 has an appropriate linear motion mechanism, such as a solenoid, air cylinder, linear motor, or ball screw mechanism, and its main body is fixed to the support member 401.

As a result, by operation of the advance/retract mechanism 402, the lower chuck unit 420 can move in the X direction within a movable range defined by a stopper (not shown). Therefore, the lower chuck 421 can move up and down relative to the support member 401 by operation of the lifting mechanism 424, and can move forward and backward in the X direction by the advance/retract mechanism 402 moving the lifting mechanism 424.

When the lower chuck 421 has advanced to the furthest position on the (+X) side within its movable range, as shown by the solid line in FIG. 4(b), the (+X) side tip of the lower chuck 421 is located on the (+X) side of the edge face of the substrate S, and the upper surface 421a of the lower chuck 421 can support the lower surface Sb of the substrate S. On the other hand, as shown by the dotted line in FIG. 4(b), when the lower chuck 421 has retreated to the furthest position on the (-X) side within its movable range, the (+X) side tip of the lower chuck 421 is retreated to the (-X) side of the edge face of the substrate S. This prevents the lower chuck 421 from coming into contact with the substrate S when it is raised or lowered.

In the chuck mechanism 400, the upper chuck 411 and the lower chuck 421 cooperate to grip the substrate S in the plating tank 41. Specifically, the upper chuck 411 and the lower chuck 421 are lowered from the chuck mechanism 400 positioned at the plating position into the plating tank 41, and grip the edge of the substrate S at the same height as the substrate S supported by the transport rollers 21. Therefore, the substrate S is held in the plating tank 41 in a horizontal position with a flat upper surface. The Z direction positions of the upper chuck 411 and the lower chuck 421 at this time will be referred to as the "lower position" below.

As shown in Figures 1 and 3(b), an anode electrode unit 45 is disposed above the transport path P in the plating tank 41. The anode electrode unit 45 is divided into a plurality of plate-shaped members, and includes a plurality of anode electrodes 451, each of which is electrically connected to the power supply unit 7. The anode electrodes 451 are housed in a box-shaped isolation tank 450 that is open at the top.

Figure 5 is a diagram showing a schematic configuration of the main parts of the anode electrode unit. The anode electrode 451 has multiple electrode plates arranged in the horizontal direction. In the example shown in Figure 5 (a), nine electrode plates 451a to 451i arranged in a 3 x 3 matrix form the anode electrode 451. The lower surfaces of the electrode plates 451a to 451i that face the substrate S are mutually in the same horizontal plane.

The anode electrode 451 is electrically connected to the power supply unit 7 and receives a supply of electrical energy. More specifically, the power supply unit 7 has multiple output units 71a-71i that can set the output current independently of each other, and the multiple electrode plates and the multiple output units are electrically connected one-to-one, such that the output unit 71a is connected to the electrode plate 451a and the main power unit 71b is connected to the electrode plate 451b. Each output unit 71a-71i can be configured, for example, by a DC constant current source, or a DC or pulsating voltage source that can set an upper limit for the output current.

The output current of each output unit 71a-71i is determined in response to a control command from the control unit 9. Specifically, the power supply unit 7 is provided with a setting memory unit 72, which stores information about the current value to be output by each output unit 71a-71i. Each output unit 71a-71i outputs a current having a predetermined current value based on the information stored in the setting memory unit 72. The current value of each output unit 71a-71i stored and saved in the setting memory unit 72 can be changed in response to a control command from the control unit 9 or by user input.

The isolation tank 450 includes a frame 452 that laterally surrounds the anode electrode 451, and an electrolytic diaphragm 453 that closes the lower part of the frame 452 to form the bottom of the isolation tank 450. The frame 452 is roughly rectangular in plan view, penetrates in the vertical direction, and is made of a material that is resistant to corrosion by the plating solution L, such as a resin material. The electrolytic diaphragm 453 is formed in a flat or sheet shape from a material that blocks non-ionized substances while allowing metal ions to pass through. For example, the electrolytic diaphragm 453 can be made of a porous resin material, an ion exchange resin material, or the like.

The electrolytic diaphragm 453 closes the lower part of the frame 452 and forms the bottom surface, forming a rectangular box-shaped isolation tank 450 that is open at the top. The anode electrode 451 is housed in the internal space 454 of this isolation tank 450, as indicated by the dashed-dotted arrow. To make this possible, the frame 452 that constitutes the isolation tank 450 has a rectangular shape whose inner wall is slightly larger than the outer size of the anode electrode 451 in a plan view. In addition, considering the convenience of replacement work due to wear and tear of the electrode material, it is preferable that the anode electrode 451 be freely attached and detached from the isolation tank 450.

As described below, the isolation tank 450 containing the anode electrode 451 is immersed in the plating solution L stored in the plating tank 41.

Figure 6 is a schematic diagram showing the state in which the isolation tank is immersed in the plating tank. As shown in Figure 6 (a), the isolation tank 450 is arranged so that at least the lower surface of the electrolytic diaphragm 453 forming the bottom surface of the isolation tank 450 is in contact with the plating solution L stored in the plating tank 41. In addition, the second plating solution L2 is poured into the internal space 454 of the isolation tank 450 to such an extent that the anode electrode 451 is immersed in the solution. The composition of the second plating solution L2 is not particularly limited, but it can be the same as the plating solution L stored in the plating tank 41, for example. Note that the "same composition" here refers to the composition at the time of supply, and the composition may differ as the process progresses. In addition, for example, the type of main component may be the same as that of the first plating solution, and the second plating solution may be substantially the same, but the concentration may be different, or at least one of the presence, absence, type, and content of additives may be partially different. In addition, depending on the purpose, a liquid having a different composition from that of the first plating solution may be used as the second plating solution.

Therefore, inside the plating tank 41, the substrate S supported by the chuck mechanism 400 (upper chuck 411, lower chuck 421) and the anode electrode 451 are positioned opposite each other via the plating solution L (+L2) and the electrolytic diaphragm 453.

A predetermined gap G1 larger than zero is provided between the lower surface of the anode electrode 451 and the upper surface of the electrolytic diaphragm 453. In addition, a predetermined gap G2 larger than zero is provided between the lower surface of the electrolytic diaphragm 453 and the upper surface of the substrate S. Therefore, the gap G between the lower surface of the anode electrode 451 and the upper surface of the substrate S is calculated using the thickness t of the electrolytic diaphragm 453 as follows:
G = G1 + G2 + t
It is expressed by:

As shown in FIG. 5 and FIG. 6(b), one output terminal of each output unit 71a to 71i is individually connected to each electrode plate 451a to 451i, while the other output terminal is collectively connected to the cathode electrode 412. And, as shown in FIG. 4(b), the cathode electrode 412 is provided at the lower end of the upper chuck 411 and is in contact with the upper surface of the substrate S.

Therefore, when a predetermined magnitude of output current is output from each of the output sections 71a to 71i of the power supply unit 7, a current is generated that flows from the anode electrode 451 through the electrolytic diaphragm 453 toward the upper surface of the substrate S, as shown by the arrow in FIG. 6(b). The electrochemical reaction caused by the action of this current produces a plating film on the upper surface of the substrate S.

In this electrochemical reaction, the non-uniformity of the current density distribution on the upper surface of the substrate S affects the quality of the plating film. That is, in order to obtain a film with a uniform composition and thickness, it is desirable to obtain a uniform current density distribution within the surface of the substrate S. However, it is not easy to maintain a uniform current density due to the fact that the substrate S is made of glass, which is an insulator, its outer shape is rectangular, and the electrical contact with the cathode electrode 412 is limited to the peripheral portion of the substrate S. In the electrolytic plating technique in which an anode electrode faces one main surface of the substrate and a cathode electrode contacts the peripheral portion of the substrate, as in this embodiment, current concentration is likely to occur on the peripheral portion of the substrate. For this reason, the film thickness on the peripheral portion tends to be larger than that in the center portion. In particular, when trying to shorten the tact time of the plating process, it is necessary to increase the amount of current supplied from the power supply unit 7, but this also increases the bias of the current.

One way to address this problem is to cover the periphery of the substrate with a shield plate to reduce current concentration. However, for a large substrate, such as a glass substrate for a display device, a large shield plate is required to cover the periphery, and the size of the shield plate must be optimized according to the substrate size, which increases the cost of the device. Furthermore, there is not yet sufficient knowledge about the size and shape of the shield plate that is effective for rectangular substrates.

In this embodiment, the anode electrode 451 is divided into multiple electrode plates 451a-451i. Output units 71a-71i that can set the output current independently are individually connected to the electrode plates 451a-451i. Therefore, by individually adjusting the amount of current supplied to each electrode plate 451a-451i, it is possible to change the density distribution of the current flowing from the anode electrode 451 to the substrate S. This makes it possible to improve the uniformity of the plating film by correcting the bias of the current and bringing the current density closer to a uniform distribution.

As mentioned above, current concentration is likely to occur at the periphery of rectangular substrates. In light of this, it can be said that, among the electrode plates 451a to 451i, there is a tendency for the amount of current to be small in electrode plate 451e, which faces the center of substrate S, and larger in the other electrode plates arranged to surround it horizontally. Therefore, it is expected that the current distribution can be made more uniform by setting the amount of current to electrode plate 451e, which is arranged in the center, to be larger than that of the other electrode plates.

In addition, because the cathode electrode 412 is held in contact with both ends of the substrate S in the X direction, it is expected that the current will tend to be larger at the ends in the X direction than at the ends in the Y direction. For this reason, it can be said that it is desirable to apply a larger current to the electrode plates 451b and 451h located at both ends in the Y direction in terms of the arrangement of the electrode plates than to the electrode plates 451d and 451f located at both ends in the X direction.

In this way, the current input to each electrode plate 451a-451i can be determined in advance based on the shape of the substrate S and the electrode arrangement. In order to more accurately equalize the current density, the current distribution can be measured by a preliminary experiment, and the set value of the current to be supplied to each electrode plate 451a-451i can be determined for each output unit 71a-71i based on the results so as to correct any bias in the current distribution.

For the purpose of uniforming the current density near the substrate surface, the current setting value can be optimized, for example, as follows. Here, the value obtained by dividing the current value given to each electrode plate by the area of the lower surface (surface facing the substrate S) of the electrode plate (hereinafter referred to as the "electrode area") is defined as the "electrode current density." If this electrode current density is considered to represent the current density in the portion of the substrate upper surface Sa facing the electrode plate, the output current value to each electrode plate 451a to 451i can be determined so that the electrode current density is the appropriate current density at each position on the substrate S. In this way, it is possible to appropriately set the output current value for each electrode plate 451a to 451i whether the electrode areas of the electrode plates 451a to 451i are the same or different.

For example, as in the above example, when the current density tends to be high at the periphery of the substrate S and low at the center, the electrode current density is set to be high at the electrode plate 451e located at the center and low at the other electrode plates located around it, so that the overall current density distribution can be made uniform. Note that, for electrode plates with a part of the lower surface located outside the substrate S in a plan view and not facing the substrate S, the area of the part facing the substrate S may be considered as the effective electrode area. Also, unless the periphery of the electrode plate protrudes significantly outward from the substrate S, the current output from the part that is actually outside the substrate S can also reach the substrate S and contribute to the plating reaction. In this case, the entire electrode plate may be considered as an effective electrode and included in the electrode area.

The determined setting values are stored in advance as preset values in the setting memory unit 72 of the power supply unit 7, and can be read out to operate each of the output units 71a to 71i. The user and the control unit 9 can change these settings as necessary. This makes it possible to deal with cases where it is necessary to change the current distribution, for example, when changing the size of the substrate S.

It is also possible to construct the isolation tank 450 from a material that is permeable to ions not only on the bottom surface but also on the side wall surface. However, the movement of ions through the side wall surface can cause current concentration at the peripheral edge of the substrate, impairing the uniformity of the plating film. By only allowing ions to move through the bottom surface of the isolation tank that faces the top surface of the substrate S, such current concentration can be prevented.

For the same reason, if the cathode electrode 412 is placed directly below the electrolytic diaphragm 453 that forms the bottom of the isolation tank 450, a shorter current path is formed in that area than in other areas, causing current concentration. To avoid this, it is preferable that the cathode electrode 412 contacts the substrate S outside the area of the substrate upper surface Sa that faces the anode electrode 451, more preferably outside the bottom of the isolation tank 450, in a plan view.

In that sense, it is also effective to construct the frame 452 from a material that is not permeable to ions, and to make the external size of the isolation tank 450 in a plan view (more precisely, the external size of the electrolytic diaphragm 453 forming the bottom) smaller than the external size of the substrate S. In these configurations, ions are prevented from moving through any route other than the electrolytic diaphragm 453, so it can be said that the isolation tank itself performs the same function as a blocking plate in the prior art. As shown in FIG. 6(b), these conditions are met in this embodiment.

In the electrolytic plating process carried out in this manner, a metal that is soluble in the plating solution L, which is an electrolytic solution, is used as the anode electrode 451, and a plating film made of the metal can be formed on the surface of the substrate S. For example, to form a copper plating film on the substrate S, which is a glass substrate, it is suitable to use, for example, an aqueous copper sulfate solution as the plating solution L (L2) and, for example, a copper plate as the anode electrode 451.

When a DC voltage is applied between the anode electrode 451 and the cathode electrode 412 and a current is supplied to the anode electrode 451, the metal material (e.g., copper) from the anode electrode 451 is ionized and dissolved into the plating solution L2. The ionized metal passes through the electrolytic diaphragm 453 and the plating solution L and adheres to the upper surface of the substrate S to form a plating film. In other words, the anode electrode 451 in this plating reaction is a so-called soluble electrode that contains material that is consumed to form the plating film.

During this process, the anode electrode 451 gradually dissolves into the plating solution L (L2), and insoluble impurities contained in the electrode material are released from the anode electrode 451 into the solution. The insoluble residue that is thus produced in the plating solution is sometimes called "anode slime" or "anode mud."

In this embodiment, the substrate S is supported in a horizontal position with the surface to be plated facing upward, and the anode electrode 451 is disposed above it. As a result, anode slime consisting of impurities liberated from the anode electrode 451 settles in the plating solution toward the substrate S disposed below. If such impurities adhere to the top surface of the substrate S, which is the surface to be plated, this can cause plating defects and reduce the quality of the plating film.

To address this problem, in this embodiment, the anode electrode 451 and the substrate S are isolated by an isolation layer 450. Specifically, an electrolytic diaphragm 453 is disposed between the lower surface of the anode electrode 451 and the upper surface of the substrate S, and the sides of the anode electrode 451 are surrounded by a frame 452. The isolation tank 450 is immersed in the plating solution L in the plating tank 41, and its internal space 454 is filled with plating solution L2 having the same composition as the plating solution L.

Therefore, for the metal ions involved in the plating reaction, a path is secured from the anode electrode 451 to the substrate S via the plating solutions L, L2 and the electrolytic diaphragm 453, while for the liquid components and insoluble components in the plating solution, the anode electrode 451 and the substrate S are isolated from each other by the isolation tank 450. For this reason, the anode slime generated by the aggregation of insoluble components is blocked by the electrolytic diaphragm 453 and does not adhere to the substrate S.

In addition, since the box-shaped isolation tank 450 has an opening at the top, the anode electrode 451 contained in the isolation tank 450 is open above. This makes it easy to attach and detach the anode electrode 451 to the isolation tank 450. As the reaction progresses, the anode electrode 451 wears out and must be replaced periodically. The above structure also contributes to increasing the convenience of such replacement work.

The anode electrode 451 is divided into multiple electrode plates 451a to 451i. Therefore, replacement work can be performed for each electrode plate. This not only improves the workability of replacement, but also leads to effective use of resources, since only the electrode plates of the anode electrode 451 that need replacing can be replaced.

The horizontal spacing between each of the electrode plates 451a-451i can be, for example, smaller than the distance between the bottom surface of each of the electrode plates 451a-451i and the substrate S, and more preferably, less than half that distance. If the spacing between the electrode plates is large, there is a risk that sufficient current will not be supplied to areas of the substrate top surface Sa that do not face any of the electrode plates, resulting in uneven current density. It is known that the current flowing out of the electrode plate spreads to a certain extent from the outer edge of the electrode plate in the liquid. According to the inventor's knowledge in this regard, it is possible to suppress such current unevenness by setting the spacing as described above.

Next, a mechanism for supporting the isolation tank 450 in the anode electrode unit 45 will be described. Due to the structural constraints that the bottom surface of the isolation tank 450 is disposed opposite the substrate S and that the isolation tank 450 is immersed in the plating solution L stored in the plating tank 41, the support mechanism for the isolation tank 450 must be provided above the isolation tank 450. In addition, in order to refresh the plating solution L2 and to prevent the accumulation of anode slime on the electrolytic diaphragm 453, it is desirable to periodically replace the plating solution L2 stored in the isolation tank 450. The support mechanism described below meets such requirements.

Figure 7 is an external perspective view showing the support mechanism for the isolation tank in the anode electrode unit. Note that in Figure 7, the anode electrode 451 housed in the internal space 454 of the isolation tank 450 is omitted in order to clearly show the structure of the support mechanism. In the anode electrode unit 45, the isolation tank 450 is attached to the housing 10 via a support mechanism 460. The support mechanism 460 supports the isolation tank 450 so that it can be moved up and down freely relative to the plating tank 41 fixed to the frame 10.

The support mechanism 460 includes support frames 461, 462, and 463 arranged in the vertical direction (Z direction). These support frames are related in such a way that the first support frame 461 arranged at the bottom supports the isolation tank 450, the second support frame 462 arranged above supports the first support frame 461, the third support frame 463 arranged above supports the second support frame 462, and the third support frame 463 is fixed to the upper frame 11 of the housing 10 (FIGS. 1 and 3(a)).

Each of the support frames 461 to 463 has a roughly rectangular outer shape and a frame-like structure with a vertically penetrating central portion. Four sets of lift guide mechanisms 466, whose operating direction is the vertical direction, are attached to the third support frame 463 at the top of these. Specifically, linear bushes 466a of the lift guide mechanisms 466 are provided at the four corners of the support frame 463. The linear bushes 466a are hollow tubular members that penetrate vertically, and a movable rod 466b is inserted into the hollow portion. The movable rod 466b extends downward from the linear bushes 466a, and its lower end is connected to the second support frame 462 below.

When the lifting mechanism 47, which will be described later, operates in response to a control command from the control unit 9, the movable rod 466b moves up and down within a predetermined movable range, thereby lifting and lowering the second support frame 462 connected to the lower end of the movable rod 466b. At this time, the first support frame 461 supported by the second support frame 462 and the isolation tank 450 supported by the first support frame 461 also lift and lower in the same manner.

Similarly, four sets of lift guide mechanisms 465, whose operating direction is the up-down direction, are attached to the second support frame 462. Specifically, bushes 465a of the lift guide mechanisms 465 are provided at the four corners of the support frame 462, and movable rods 465b are inserted into the linear bushes 465a. The movable rods 465b extend downward from the linear bushes 465a, and their lower ends are connected to the first support frame 461 below.

When the lifting mechanism 47 operates in response to a control command from the control unit 9, the movable rod 465b moves up and down within a predetermined movable range, thereby lifting and lowering the first support frame 461 connected to the lower end of the movable rod 465b. At this time, the isolation tank 450 supported by the first support frame 461 also lifts and lowers in the same manner.

In this way, the lifting guide mechanisms 465, 466 can work with the lifting mechanism 47 to move the isolation tank 450 in the vertical direction. As the lifting guide mechanisms 465, 466, various mechanisms other than the combination of a cylindrical linear bush and a movable rod described above can be applied. For example, various mechanisms that can restrict the movement of an object in one direction can be used, such as a linear guide mechanism that combines a guide rail and a slider. Note that the lifting guide mechanisms 465, 466 may be provided with a damper function, similar to the lifting guide mechanism 464 described next.

On the other hand, the first support frame 461 supports the isolation tank 450 so that it can move up and down and tilt around the X-axis. Specifically, four sets of lifting guide mechanisms 464 are attached to the first support frame 461, and movable rods 464b extend downward from linear bushings 464a of the lifting guide mechanisms 464. As described below, the lifting guide mechanisms 464 have a damper mechanism, which reduces the impact transmitted to the isolation tank 450 when it is raised or lowered.

A frame 455 made up of a combination of plate material 455a extending in the X direction and plate material 455b extending in the Y direction is attached to the top of the frame 452 that constitutes the isolation tank 450, and hinge members 455c are attached to four points on the top of the frame 455. The lower ends of movable rods 464b extending from each of the four lift guide mechanisms 464 are engaged with the hinge members 455c located directly below, and are attached so as to be freely rotatable around an axis parallel to the X axis. In this way, the isolation tank 450 is supported by the support frame 461 via the support mechanism 460.

A roller member 455f is provided between the two hinge members 455c, 455c located on the (-Y) side of the four hinge members 455c, and is rotatably supported by an appropriate support member. The roller member 455f is not connected to a drive mechanism and can rotate freely. The function of the roller member 455f will be explained later.

In addition, equipment for supplying and discharging plating solution L2 to and from the isolation tank 450 is arranged around the isolation tank 450. That is, a nozzle 491 is provided above the isolation tank 450 for discharging the plating solution sent from the plating solution supply and discharge unit 49 toward the internal space 454 of the isolation tank 450. The nozzle 491 is attached to the frame 455 via an appropriate fixing member.

The plating solution supply/discharge unit 49 and the nozzle 491 are connected by piping 492 to form a supply path for the plating solution, and a flexible joint 493 is provided on the piping 492 at a position close to the isolation tank 450. A flexible joint is a piping component in which at least a portion of the piping is made of a flexible material such as rubber, and is inserted into a portion of a piping system that is mainly made of non-flexible tubing material, thereby allowing the piping to bend at the insertion point. Flexible joints are widely used, for example, for the purpose of absorbing mutual misalignment and vibrations at the connection points between pipes.

As described below, in order to efficiently discharge the plating solution, the isolation tank 450 is provided so as to be freely rotatable around the X-axis. By inserting a flexible joint 493 into the piping 492, it is possible to form a supply path for the plating solution between the plating solution supply/discharge unit 49 and the nozzle 491 while allowing such rotation.

The isolation tank 450 is also provided with piping for discharging the plating solution stored in the internal space 454 to the plating solution supply/discharge section 49. Specifically, a through hole 452a is provided in the lower part of the side surface on the (+Y) side of the frame 452 constituting the isolation tank 450, and a discharge pipe 494 is connected to this through hole 452a. As with the plating solution supply pipe 492, a flexible joint 495 is also inserted into the discharge pipe 494.

Furthermore, above the anode electrode unit 45, a lifting mechanism 47 is provided that is fixed to the frame 11 of the housing 10. For the purpose of explaining the principle, the lifting mechanism 47 is assumed to be a winch mechanism that lifts and lowers an object by winding up a wire. That is, a wire 471 hangs downward from the lifting mechanism 47, and the wire 471 passes through openings in the center of each of the support frames 461 to 463 and reaches a position directly above the isolation tank 450. The lower end of the wire 471 is attached to a connecting portion 455d provided on the frame 455. The connecting portion 455d provided on the frame 455 is disposed at a position closer to the (-Y) side than the midpoint between the two hinge members 455c, 455c that are aligned in the Y direction.

The lifting mechanism 47 operates in response to a control command from the control unit 9, and moves the isolation tank 450 up and down together with the frame 455 connected to the wire 471. The up and down movement of the isolation tank 450 can be achieved using various drive mechanisms other than those described above. For example, a known ball screw mechanism, air cylinder mechanism, linear motor mechanism, or other linear motion mechanism, or a mechanism commercially available as a Zip Chain Actuator (registered trademark), can be suitably applied.

Figure 8 is a schematic diagram showing the supply and discharge of plating solution to and from the isolation tank. Although simplified in Figure 7, as shown in Figure 8(a), the lift guide mechanism 464 includes a linear bush (also called a linear bearing, linear bearing, etc.) 464a through which a movable rod 464b extending in the vertical direction (Z direction) is inserted, a base member 464c to which the linear bush 464a is attached, a plate-shaped bracket 464d attached to the upper end of the movable rod 464b, and a damper mechanism 464e provided between the plate member 464d and the base member 464c. As the damper mechanism 464e, for example, a known shock absorber can be applied.

The movable rod 464b is inserted into the linear bushing 464a so that it can move up and down. When the movable rod 464b moves up and down, the bracket 464d also moves up and down accordingly. When the bracket 464d descends, it comes into contact with the damper mechanism 464e, and further downward displacement is restricted. In other words, the damper mechanism 464e has the function of allowing the movable rod 464b to move up and down, while defining its range of movement, and also cushioning the impact when the descent stops.

Two sets of lift guide mechanisms 464 are provided at different positions in the Y direction. The lower ends of the movable rods 464b of each lift guide mechanism 464 are engaged with hinge members 455c attached to the frame 455 of the isolation tank 450. As a result, in the steady state, the isolation tank 450 is supported in a substantially horizontal position.

With the isolation tank 450 supported in a substantially horizontal position in this manner, plating solution L2 is supplied to the isolation tank 450 from the plating solution supply/discharge unit 49 through the piping 491, as shown by the outlined arrow in FIG. 8(a). The plating solution L2 is discharged from a discharge port provided on the underside of the nozzle 491 toward the internal space 454 of the isolation tank 450, and thus the plating solution L2 is supplied to the isolation tank 450. With the anode electrode 451 immersed in the plating solution L2, the plating process is carried out.

After the plating process is completed, the plating solution L2 in the internal space 454 can be refreshed by draining the existing plating solution and refilling with new plating solution. However, when draining the plating solution L2 from the isolation tank 450, it is not possible to provide a drain path below the isolation tank 450. This is because the substrate S is positioned directly below the isolation tank 450.

It is also possible to flow plating solution L2 from the isolation tank 450 into the plating tank 41 and discharge plating solution L2 through the plating tank 41. However, doing so would result in the anode slime contained in plating solution L2 being mixed into the plating tank 41, so it is preferable to discharge plating solution L2 through a route independent of the discharge from the plating tank 41.

For the same reason, when supplying plating solution to the isolation tank 450 and when tilting the isolation tank 450 to promote drainage, as described below, it is necessary to prevent plating solution L2 from overflowing from the isolation tank 450 and flowing into the plating tank 41.

In order to discharge the liquid while satisfying these requirements, an outlet is provided on the side wall of the isolation tank 450 and the plating liquid is discharged to the side, but this inevitably impairs the smoothness of discharge compared to when an outlet is provided on the bottom surface. Therefore, in this embodiment, a through hole 452a is provided as an outlet on the (+Y) side surface of the isolation tank 450, and a discharge pipe 494 is connected to it, and when discharging the plating liquid L2, the isolation tank 450 is lifted on the side opposite the outlet, i.e., the (-Y) side, to tilt the bottom surface. This can promote the discharge of the plating liquid L2 from the internal space 454.

Specifically, the lifting mechanism 47 winds up the wire 471, which allows the frame 455 to be pulled up and the (-Y) end of the isolation tank 450 to be raised, as shown by the dashed arrow in FIG. 8(b). In this way, the isolation tank 450 is inclined in such a way that its bottom surface is inclined relative to the horizontal plane, and as shown by the hollow arrow in FIG. 8(b), the plating solution L2 stored in the internal space 454 flows toward the through hole 452a, which serves as the discharge outlet. In this way, discharge of the plating solution L2 is promoted. The waste liquid that flows into the piping 494 is collected by the plating solution supply and discharge unit 49.

The manner in which the isolation tank 450 is supported by the lift guide mechanism 464, which is connected via a rotatable hinge member 455c, allows for such tilting of the isolation tank 450. That is, in a pair of lift guide mechanisms 464, 464 arranged at different positions in the Y direction, the movable rods 464b move up and down independently of each other, thereby realizing a tilted state of the isolation tank 450.

Furthermore, flexible joints 493, 495 are inserted into the plating solution supply pipe 492 and the discharge pipe 494 connected to the isolation tank 450, respectively. Therefore, it is possible to tilt the isolation tank 450 while these pipes remain connected.

Figures 9 to 11 are diagrams for explaining the raising and lowering operation of the isolation tank in more detail, and more specifically, for explaining the action of the roller member 455f. In these diagrams, in order to facilitate understanding, some components that are not necessary for the explanation may be omitted or the structure may be simplified. Also, in order to explain the action of the roller member 455f, which is hidden by the hinge member 455c, its position is shown shifted to the (+Y) side from the actual position.

As shown in FIG. 9, a freely rotatable roller member 455f is provided on the top of the isolation tank 450. In addition, a tapered member 468, whose underside is inclined relative to the horizontal plane, is attached to the underside of the support frame 461 at a position directly above the roller member 455f. When the lifting mechanism 47 is operated and the wire 471 is wound up as shown by the dashed arrow, the isolation tank 450 is pulled upward while remaining in an inclined position, and the roller member 455f and the tapered member 468 gradually approach each other.

As shown in FIG. 10, the roller member 455f comes into contact with the lower surface, i.e., the inclined surface, of the tapered member 468, thereby restricting further upward displacement of the roller member 455f. If the isolation tank 450 is pulled further upward in this state, the rise of the (-Y) side end of the isolation tank 450 is restricted by the roller member 455f and the tapered member 468, while there is room for further rise at the (+Y) side end of the isolation tank 450.

As a result, the (+Y) end of the isolation tank 450 is further lifted, and ultimately, as shown in FIG. 11, the isolation tank 450 is held in a horizontal position. In this manner, in the process of lifting the isolation tank 450 from the plating tank 41, the isolation tank 450 is temporarily tilted to drain the plating solution L2, but the isolation tank 450 is eventually returned to a horizontal position.

When the isolation tank 450 descends from its retracted upward position, the above-mentioned operation is reversed. That is, the isolation tank 450 temporarily tilts from a horizontal position to a horizontal position, but returns to a horizontal position when it is accommodated in the plating tank 41. In this way, it becomes possible to receive a new supply of plating solution L2.

Figure 12 is a diagram showing the lifting and lowering operation of the entire support mechanism. Above, the operation of the lifting and lowering guide mechanism 464 that lifts and lowers the isolation tank 450 relative to the support frame 461 was described. As shown in Figure 7, this support mechanism 460 has a structure in which the support frame 461 is supported by a lifting and lowering guide mechanism 465 attached to the support frame 462, and the support frame 462 is further supported by a lifting and lowering guide mechanism 466 attached to the support frame 463.

The structure and operation of the lifting guide mechanisms 465 and 466 are the same as those of the lifting guide mechanism 464, except that the damper mechanism is omitted. Therefore, the support frame 461 can be raised and lowered relative to the support frame 462, and the support frame 462 can be raised and lowered relative to the support frame 463. Therefore, in the support mechanism 460, as shown in the upper diagram of FIG. 12, the support frames 461 and 462 can transition between a state in which they are lowered to their lowest relative to their respective supporting bodies, and a state in which they are raised to their highest relative to their respective supporting bodies, as shown in the lower diagram of FIG. 12. Since the support frame 463 is fixed to the upper frame 11 that constitutes the device housing 10, such a structure contributes to increasing the vertical movement range of the isolation tank 450.

Figure 13 is a block diagram showing the electrical configuration of this plating apparatus. In the plating apparatus 1 configured as described above, the control unit 9 controls each unit of the apparatus and causes the plating apparatus 1 to perform a predetermined process. The hardware configuration of the control unit 9 can be the same as that of a general computer device, for example. That is, the control unit 9 can be equipped with a CPU (Central Processing Unit) 91, memory 92, storage 93, input unit 94, display unit 95, interface unit 96, etc.

The memory 92 temporarily stores various data generated during the processing. The storage 93 stores various data and the control program 931 on a long-term basis. The input unit 94 and the display unit 95 perform the user interface function. The interface unit 96 is responsible for communication with external devices, etc.

The CPU 91 reads and executes a control program 931 stored in advance in the storage 93, and based on this, controls each part of the device to perform a predetermined operation, thereby realizing various operations described below. For this purpose, the CPU 91 realizes in software such functional blocks as a transport control unit 911 that controls the operation of the transport unit 2, a chuck control unit 912 that controls the operation of the chuck unit 40, a supply and discharge control unit 913 that controls the supply sources of various fluids and manages their supply and discharge, a flow control unit 914 that controls valves on the piping to adjust the flow rate of the circulating fluid, and a power supply control unit 915 that controls the power supply to the electrodes by the power supply unit 7. At least some of these functional blocks may be configured as dedicated hardware, for example.

The specification and drawings of Japanese Patent Application No. 2022-094449, previously disclosed by the applicant, disclose a plating apparatus similar in basic configuration to the plating apparatus 1 of this embodiment, and also provide detailed descriptions of the structure and functions of each part of the apparatus, as well as the operation of the apparatus.

Next, the operation of the plating apparatus 1 configured as described above will be described. The basic operational flow of the plating apparatus 1 is roughly as follows. An unprocessed substrate S is loaded into the loading section 3. The substrate S is transported from the loading section 3 to the plating processing section 4, which performs electrolytic plating on the substrate S to form a metal coating on its surface (upper surface Sa). The plated substrate S is rinsed in the rinsing processing section 5, and is finally unloaded to the unloading section 6.

Figure 14 is a flow chart showing the plating process. Figure 15 is a diagram showing the operation of each part. More specifically, Figure 15 shows the operation of each part as time T progresses, with the time axis running from top to bottom. After an unprocessed substrate S is provided to the loading section 3 at time T0, each part of the apparatus performs the following operations. In the figure, the parentheses indicate the initial state of each part. In Figure 15, the parts of each processing section that are shown with thick vertical lines indicate that the substrate S is present in that processing section.

Each part of the plating apparatus 1 is set in advance to a predetermined initial state. In the initial state, the chuck mechanism 400 is positioned at a plating position above the plating tank 41, and the upper chuck 411 and the lower chuck 421 are positioned at an upper position that does not interfere with the plating tank 41. Note that the upper chuck 411 and the lower chuck 421 may be positioned further down as long as they do not impede the transport of the substrate S along the transport path P.

In the loading section 3, the loaded substrate S is temporarily stored. In the plating processing section 4, the shutters 41a and 41b of the plating tank 41 are opened, allowing the substrate S to be transported along the transport path P. At this time, the plating tank 41 is stored to a height such that the plating solution supplied from the plating solution supply and discharge section 49 does not flow out of the opening. In the anode electrode unit 45, the isolation tank 450 is retracted upward, and no plating solution is stored in the internal space 454. In the rinsing processing section 5, the shutters 51a and 51b of the rinsing tank 51 are also opened, allowing the substrate S to be transported along the transport path P. At this point, there is no substrate S in the unloading section 6.

At time T1, the transport unit 2 starts transporting the substrate S, and the substrate S is transported in the transport direction Dt (+Y direction) along the transport path P, and is finally transported to the plating tank 41 (step S101). In FIG. 15, the dashed arrows represent the transfer of the substrate S by the transport unit 2.

When the substrate S is carried into the plating tank 41, the shutters 41a and 41b are closed. The upper chuck 411 and the lower chuck 421 of the chuck mechanism 400 are lowered toward the substrate S contained in the plating tank 41 to grip the substrate S (step S102). In the anode electrode unit 45, the isolation tank 450 is lowered and positioned opposite the upper surface of the substrate S held in the plating tank 41. Note that the isolation tank 450 may be lowered in advance before the substrate S is transported to the plating tank 41.

In this state, plating solution L is supplied from the plating solution supply/discharge unit 49 to the plating tank 41 (step S103). In parallel with this, plating solution L2 is supplied from the plating solution supply/discharge unit 49 to the isolation tank 450. This results in a state in which the substrate S is immersed in the plating solution L in the plating tank 41, the anode electrode 451 is immersed in the plating solution L2 in the isolation tank 450, and the lower surface of the electrolytic diaphragm 453 on the bottom surface of the isolation tank 450 is in contact with the plating solution L in the plating tank 41 (FIG. 6(a)).

Then, a predetermined current is output from each output section 71a of the power supply section 7 (step S104), and the substrate S is plated. By contacting the cathode electrodes extending in the Y direction with both ends of the upper surface Sa of the substrate S in the X direction, the variation in current density on the upper surface Sa of the substrate S is suppressed, and it is possible to form a plating film with good uniformity.

At this time, the chuck mechanism 400 and the transport rollers 21 work together to oscillate the substrate S in the plating tank 41 (step S105), thereby further improving the uniformity of the plating film. Specifically, the movement mechanism 43 is actuated to cause the support frame 430 supporting the chuck mechanism 400 to alternately move in the (+Dt) direction and the (-Dt) direction. As a result, the chuck mechanism 400 attached to the support frame 430 moves back and forth as a unit in the Y direction, and the substrate S held by the chuck mechanism 400 oscillates in the Y direction in the plating solution L.

At this time, the transport rollers 21 work in conjunction with the support frame 430. That is, when the support frame 430 moves in the (+Y) direction and the chuck mechanism 400 moves the substrate S in the (+Y) direction, the transport rollers 21 rotate forward, that is, in a direction that transports the substrate S in the transport direction Dt. On the other hand, when the support frame 430 moves in the (-Y) direction and the chuck mechanism 400 moves the substrate S in the (-Y) direction, the transport rollers 21 rotate reversely, that is, to transport the substrate S in the direction (-Dt) opposite to the transport direction Dt.

By oscillating the substrate S in the plating solution L in this manner, the plating solution L is stirred, reducing bias in the ion concentration in the solution and improving the uniformity of the plating film. The oscillation of the substrate S in the plating tank 41 is achieved by the cooperation of a chuck mechanism 400 that grips the edge of the substrate S and a transport roller 21 that supports the center of the substrate S from the underside. This makes it possible to prevent localized stress from being applied to the substrate S and to oscillate the substrate S while maintaining a horizontal position.

After the substrate S is immersed in the plating solution L and the state in which the substrate S is oscillated while a current is supplied between the electrodes is continued for a certain period of time, the current supply is stopped (step S106) to stop the plating process. Then, the plating solution L is discharged from the plating tank 41, and the plating solution L2 is discharged from the isolation tank 450 (step S107). When discharging from the isolation tank 450, the lifting mechanism 47 is operated to lift the (-Y) side end of the isolation tank 450 while the isolation tank 450 is retracted upward by the support mechanism 460.

Then, the grip of the substrate S by the chuck mechanism 400 is released (step S108), the shutter 41b is opened, and at time T2, the transport unit 2 transfers the substrate S from the plating processing unit 4 to the rinsing processing unit 5 (step S109). By releasing the grip of the substrate S after the plating solution L is discharged, it is possible to prevent the cathode electrode 412 from coming into contact with the plating solution. There is no such restriction for the anode electrode 451. Therefore, the discharge from the isolation tank 450 can be performed at any time after the current is stopped. In other words, it does not have to be performed simultaneously with the discharge of the plating solution L from the plating tank 41.

In the rinse processing section 5, when the substrate S is placed in the rinse tank 51, the shutters 51a and 51b are closed, and rinse liquid is supplied from the rinse liquid supply/discharge section 59 to rinse the substrate S (step S110). After the rinse process is performed for a predetermined time, the supply of rinse liquid is stopped, the shutter 51b is opened, and at time T3, the substrate S is discharged to the discharge section 6 (step S111).

When discharging the plating solution from the plating tank 41, it is not necessary to completely drain the liquid in the tank. In other words, as long as the liquid is discharged to the extent that the substrate S supported in the tank is exposed from the liquid and can be removed, there is no problem with liquid remaining in the tank. In fact, by leaving liquid remaining, it is possible to reduce the amount of liquid required to fill the tank when processing the next substrate S. This helps to reduce the amount of liquid consumed and the environmental impact.

After releasing the grip of the substrate S, the chuck mechanism 400 undergoes a cleaning process to remove the plating solution adhering to the upper chuck 411 and the lower chuck 421 (step S112). The cleaning process may be carried out in any manner, but an example is as follows. That is, the support mechanism 43 moves the support frame 430 in the (-Y) direction to position each chuck mechanism 400 at a cleaning position above the vat 44. In this state, the cleaning mechanism 48 cleans the chuck mechanism 400, more specifically the upper chuck 411 and the lower chuck 421, by supplying an appropriate cleaning solution or spraying air.

When the chuck mechanism 400 moves between the plating position and the cleaning position, the upper chuck 411 and the lower chuck 421 are retracted upward by the lifting mechanisms 412, 422, as shown by the dotted lines in FIG. 2. This prevents the upper chuck 411 and the lower chuck 421 from contacting the wall of the plating tank 41 during movement. The Z direction positions of the upper chuck 411 and the lower chuck 421 at this time will be referred to as the "upper position" below.

After cleaning, the chuck mechanism 400 is returned to the plating position (step S113). By cleaning the chuck mechanism 400 in this manner, it is possible to prevent any remaining plating solution from adhering to the substrate S when processing the next substrate S. If there are more substrates S to be processed, the process returns to step S101 and the above process is repeated.

As described above, in the plating apparatus of this embodiment, the substrate S, which is the object of plating, is supported in the plating tank 41 in a horizontal position with one main surface Sa, which is the surface to be plated, facing upward, that is, in a face-up state. The cathode electrode 412 contacts the peripheral portion of the substrate S, and the anode electrode 451 is disposed opposite the upper surface of the substrate S.

However, the anode electrode 451 and the substrate S are separated by an electrolytic diaphragm 453. This ensures a path between the anode electrode 451 and the substrate S for the metal ions that are the material for the plating film, while isolating the anode electrode 451 and the substrate S for the non-soluble components and liquid components. This prevents anode slime generated by liberation from the anode electrode 451 from adhering to the substrate S and degrading the quality of the plating film.

The anode electrode 451 is divided into multiple electrode plates 451a-451i, and output units 71a-71i, which are constant current sources of the power supply unit 7, are individually connected to each electrode plate. The output current from each output unit 71a-71i can be individually set. Therefore, even if the substrate S is large, it is possible to suppress bias in the current density distribution within the surface of the substrate S and to achieve a uniform thickness of the plating film.

In addition, with regard to replacing the plating solution in the isolation tank 450, since the bottom surface of the isolation tank 450 is disposed opposite the substrate S, it is difficult to provide a mechanism for draining the solution below the isolation tank 450. Therefore, in this embodiment, a drain outlet is provided on the side wall surface of the isolation tank 450. Furthermore, in order to efficiently drain the solution, a mechanism for lifting the end of the isolation tank 450 and tilting the bottom surface is provided on the side opposite the side wall surface on which the drain outlet is provided. This promotes the drainage of the plating solution.

In other words, the isolation tank 450 of this embodiment can be switched between a horizontal position where the bottom surface is horizontal and an inclined position where the bottom surface is significantly inclined with respect to the horizontal plane. In the horizontal position, the anode electrode 451 can be placed opposite the substrate S to perform plating processing, while in the inclined position, plating solution remaining in the internal space 454 of the isolation tank 451 can be efficiently discharged, and new plating solution can then be received, thereby keeping the plating solution stored in the internal space 454 fresh.

<Modification>
FIG. 16 is a diagram showing a modified example of the anode electrode. The anode electrode 451 in the above embodiment is formed by arranging nine electrode plates 451a to 451i having roughly the same shape in a 3×3 matrix. However, the pattern for dividing the anode electrode into a plurality of parts is not limited to this, and various patterns are possible. For example, in the anode electrode 456 shown in FIG. 16(a), electrode plates having roughly the same shape are arranged in a 5×4 matrix. In this way, the number of electrode plates arranged is not limited to that in the above embodiment, and can be any number.

In addition, in the anode electrode 457 shown in FIG. 16(b), a large-area electrode plate is placed in the center where it is easy to obtain a relatively uniform current density, while the area of the electrode plate is made smaller in the peripheral and corner areas where bias in the current density is likely to occur, making it easier to fine-tune the current density distribution. In this way, the shape and size of each electrode plate can be appropriately determined according to the purpose.

The anode electrode 458 shown in FIG. 16(c) has a structure in which a rectangular electrode plate placed in the center is surrounded by multiple frame-shaped electrode plates with a rectangular outer shape and an opening in the center. With such a structure, it is possible to achieve the objective of setting the current density independently at the center and the periphery of the substrate S.

As such, various division patterns of the anode electrode are possible. When setting the division pattern and allocating current to each electrode plate, for example, a method can be adopted in which the current density distribution is measured in a preliminary experiment and then determined based on the results. Specifically, in areas of the substrate surface where the current density fluctuation is small, there is little need to finely divide the opposing electrode plate, and conversely, in areas where the current density fluctuation is large, finely dividing the electrode plate makes it easier to adjust the current density distribution. Also, by reducing the current setting value in areas with higher current density, the current density can be made more uniform.

In particular, when two opposing sides of the four sides of a rectangular substrate are held by the chuck, the cathode electrodes are placed near these two sides, so it is expected that the current distribution will be significantly different from the areas near the two sides that are not held. Even in such cases, it is possible to reduce bias in the current density distribution and improve the uniformity of the plating film by adjusting the division pattern of the anode electrodes and the current value supplied to each electrode plate.

Figure 17 is a schematic diagram showing a modified example of the support mechanism in the anode electrode unit. Note that here, common reference numerals are used for configurations common to or corresponding to the above embodiment, and description thereof is omitted. In the above embodiment, the isolation tank 450 is tilted by the lifting mechanism 47 winding up the wire 471 attached to the isolation tank 450 at a position offset in the Y direction from the midpoint of the two hinge members 455c arranged in the Y direction. Alternatively, as shown in FIG. 17(a), for example, a configuration can be adopted in which the isolation tank 450 is supported by two suspension mechanisms 467a, 467b having significantly different spring constants. That is, the isolation tank 450 is supported by the suspension mechanisms 467a, 467b attached to the support frame 461 being coupled to the frame 455 of the isolation tank 450.

In order to maintain the isolation tank 450 in a horizontal position, it is preferable to provide a stopper 469 that restricts downward displacement of the isolation tank 450 as appropriate. Note that the shape and location of the stopper are not limited to those shown in the figure, and are arbitrary as long as they can directly or indirectly restrict downward displacement of the isolation tank 450.

As shown in FIG. 17(b), when the support mechanism 460 raises the support frame 461, the spring constants of the two suspension mechanisms 467a, 467b are different from each other, so the isolation tank 450 is tilted. In the example shown in FIG. 17(b), the spring constant of the support mechanism 467a provided on the (-Y) side is greater than the spring constant of the suspension mechanism 467b provided on the (+Y) side, so the (-Y) side end of the isolation member 450 is raised. This provides the same effect as the above embodiment. Note that, in this case where the support mechanism 460 itself supports the isolation tank 450 via a structure for tilting the isolation tank 450, the lifting mechanism 47 may raise and lower the isolation tank 450 using the midpoint in the Y direction of the two hinge members 455c as the point of action.

＜Other＞
As described above, in the above embodiment, the plating apparatus 1 corresponds to the "plating apparatus" of the present invention, and the plating tank 41, the chuck mechanism 400, the cathode electrode 412, the anode electrode 451, the power supply unit 7, and the isolation tank 450 function as the "treatment tank", the "holding unit", the "cathode electrode", the "anode electrode", the "power supply unit", and the "isolation unit" of the present invention, respectively. In the isolation tank 450, the frame 452 and the electrolytic diaphragm 453 correspond to the "side wall" and the "bottom" of the present invention, respectively. In addition, the plating solution L and the plating solution L2 correspond to the "first plating solution" and the "second plating solution" of the present invention, respectively.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the chuck mechanism 400 is provided for two opposing sides of the rectangular substrate S. However, instead of this, all four sides or three of the four sides may be gripped by the chuck mechanism.

For example, in the above embodiment, the chuck mechanism 400 grips the substrate S transported into the plating tank 41 by the transport rollers 21. However, the transport means is not limited to rollers and is optional. On the other hand, a configuration in which the substrate is transported while being gripped by the chuck mechanism is also conceivable. In this case, the transport means is not a required configuration, but in order to stably maintain the posture of a large substrate, it is desirable to provide some kind of backup means that supports the center of the substrate S from below.

The substrate to be processed does not have to be a geometric rectangle in the strict sense. For example, even if one of the sides of the substrate has some unevenness, it is sufficient if the envelope outline can be considered roughly rectangular.

For example, the power supply unit 7 in the above embodiment includes a constant current output source that individually corresponds to each of the electrode plates that make up the anode electrode 451. Alternatively, the power supply unit may be configured, for example, by a combination of a single voltage source and multiple current limiting elements provided corresponding to each electrode plate.

For example, in the power supply unit 7 of the above embodiment, individual output units are provided for all of the electrode plates that make up the anode electrode 451. However, some of the electrode plates may be electrically connected in parallel and connected to a common output unit. For example, even with the anode electrode 456 having the division pattern shown in FIG. 16(a), it is possible to realize a division pattern that is substantially the same as that of the anode electrode 457 shown in FIG. 16(b) by connecting some electrode plates in parallel. Also, the connection relationship between the electrode plates and the power supply may be changed as necessary.

For example, in the above embodiment, the anode electrode 451 is divided into multiple electrode plates, but the effect of preventing adhesion of anode slime to the substrate, which is obtained by isolating the anode electrode and the substrate using an isolation tank, can also be obtained in a plating apparatus in which the anode electrode is composed of a single electrode plate.

In addition, in the above embodiment, the liquid stored in the plating tank 41 and the liquid stored in the isolation tank 451 are plating solutions of the same or substantially the same composition, but the above configuration is effective even when the compositions of these liquids are different. In other words, each liquid can be supplied and discharged independently, preventing the two from mixing.

The anode electrode 451 in the above embodiment is a soluble electrode that contains a metal (e.g., copper) that is the material of the plating film and is consumed as the plating process progresses. However, even in the case of a non-soluble electrode whose electrode material does not directly contribute to the plating reaction, problems such as uneven film thickness and film quality due to bias in the current density distribution can occur. For this reason, even in the case of a non-soluble electrode, allowing individual current adjustment as a divided structure as described above is effective in optimizing the current density distribution and achieving uniform film thickness.

As described above by way of example of specific embodiments, in the plating apparatus according to the present invention, for example, a porous membrane or an ion exchange resin membrane can be used as the electrolytic diaphragm. With such a configuration, it is possible to allow the movement of ions through the electrolytic diaphragm while preventing the passage of insoluble substances. Therefore, the plating process can be carried out without causing anode slime to adhere to the substrate.

For example, it is preferable that the top of the anode electrode in the isolating section is open, and the anode electrode is attached to the isolating section in a manner that allows it to be easily attached and detached. As the plating process progresses, the anode electrode wears out, so this configuration can improve the convenience of replacement work.

For example, the isolating section may be formed in a box shape with a bottom formed of an electrolytic diaphragm and side walls formed of a material that does not allow ions to pass through. With this configuration, the flow path of ions from the anode electrode to the substrate is limited only to the path via the electrolytic diaphragm, making it possible to obtain the same effect as the configuration with a blocking plate in the prior art.

More specifically, for example, in a plan view, the cathode electrode may be configured to contact the substrate outside the bottom of the separator. Also, for example, in a plan view, the separator may be configured so that the outer size is smaller than the outer size of the substrate. With these configurations, ions move through the electrolytic diaphragm that forms the bottom of the separator, improving the uniformity of the current on the upper surface of the substrate facing the electrolytic diaphragm.

For example, the outer shape of the substrate and isolating portion in plan view may be rectangular. With a rectangular substrate, it is difficult to achieve a uniform current density distribution across the entire top surface of the substrate. By applying the present invention to such technology, it becomes possible to uniformize the current density and form a plating film of uniform thickness on the substrate.

This invention is suitable for use in plating one main surface of a substrate to form a coating. It is particularly effective when processing large rectangular substrates.

1 Plating device 2 Transport section 4 Plating section 41 Plating tank (treatment tank)
40, 47 Chuck portion (holding portion)
400 Chuck mechanism (holding part)
412 Cathode electrode 413, 423 Lifting mechanism 450 Isolation tank (isolation section)
451 Anode electrode 452 Frame (side wall)
453 Anode electrode L Plating solution (first plating solution)
L2 Second plating solution (second plating solution)
S: Substrate Sa: Upper surface (one main surface) (of substrate S)

Claims (7)

A plating apparatus for plating at least one main surface of a flat substrate, comprising:
a treatment tank for storing a first plating solution;
a holder that holds the substrate in a horizontal position with the one main surface facing upward in the processing tank;
a cathode electrode in contact with a portion of the one main surface of the substrate held by the holding unit;
an anode electrode disposed above the substrate held by the holder and facing the one main surface;
a power supply unit connected to the anode electrode and the cathode electrode;
an isolation unit that surrounds the sides and bottom of the anode electrode to isolate the anode electrode from the first plating solution in the treatment tank;
a bottom of the isolating portion is composed of an electrolytic diaphragm arranged between a lower surface of the anode electrode and the one main surface, an upper surface of the bottom is arranged to face the lower surface of the anode electrode across a predetermined gap, and a lower surface of the bottom is in contact with the first plating solution stored in the treatment tank,
The gap is filled with a second plating solution isolated from the first plating solution in the treatment tank. The plating apparatus according to claim 1, wherein the electrolytic diaphragm is a porous membrane or an ion exchange resin membrane. The plating apparatus according to claim 1 or 2, wherein the isolation section has an open top above the anode electrode, and the anode electrode is detachably attached to the isolation section. The plating apparatus according to claim 1 or 2, wherein the isolating section is formed in a box shape with a bottom formed from the electrolytic diaphragm and side walls formed from a material that does not allow ions to pass through. The plating apparatus of claim 4, wherein, in a plan view, the cathode electrode contacts the substrate outside the bottom. The plating apparatus according to claim 4, wherein the outer size of the isolating portion is smaller than the outer size of the substrate in a plan view. The plating apparatus according to claim 1 or 2, wherein the outer shape of the substrate and the isolating portion is rectangular in a plan view.

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