Plating device and plating liquid discharge method

Abstract

To suppress the occurrence of defective plating due to air bubbles generated from an anode, and to simplify a structure related to the supply of a plating solution.　This plating module 400 includes: a plating tank 410 for storing a plating solution; an anode 430 disposed in the plating tank 410; a substrate holder 440 configured to hold the substrate Wf with the to-be-plated surface Wf-a facing downward; a membrane 420 for partitioning an anode region 424 in which the anode 430 is disposed and a cathode region 422 in which the substrate Wf is disposed during the plating process, the membrane 420 having an inclined surface 423a facing the anode 430; a supply port 412 for supplying the plating solution to the anode region 424; gas-liquid piping 470 having a first end part 472 that opens in the vicinity of the upper edge of the inclined surface 423a of the membrane 420 and a second end part 474 that opens above the to-be-plated surface of the substrate while undergoing plating, the gas-liquid piping 470 being configured so as to supply the plating solution supplied from the supply port 412 to the anode region 424 to the cathode region 422 via the second end part 474.

Description

Plating apparatus and plating solution discharge method

[0001] The present application relates to a plating apparatus and a plating solution draining method.

[0002] A cup-type electroplating apparatus is known as an example of a plating apparatus. In a cup-type electroplating apparatus, a substrate (e.g., a semiconductor wafer) held by a substrate holder is immersed in a plating solution with the surface to be plated facing downward, and a voltage is applied between the substrate (cathode) and an anode to deposit a conductive film on the surface of the substrate.

[0003] Patent Document 1 discloses a cup-type plating apparatus, which is configured to prevent plating defects caused by bubbles by providing a sloped membrane between an anode and a cathode and trapping and discharging bubbles generated from the anode with the membrane.

[0004] U.S. Patent No. 6,126,798

[0005] The plating apparatus disclosed in Patent Document 1 takes into consideration the prevention of plating defects caused by air bubbles adhering to the plating surface of the substrate, but does not take into consideration the simplification of the structure related to the supply of plating solution to the plating tank.

[0006] That is, the plating apparatus disclosed in Patent Document 1 has pipes for supplying plating solution to both the anode region and the cathode region, which increases the number of pipes, resulting in a complex structure of the plating apparatus.

[0007] Therefore, one object of the present invention is to suppress the occurrence of plating defects caused by bubbles generated from the anode and to simplify the structure related to the supply of plating solution.

[0008] According to one embodiment, a plating apparatus is disclosed, comprising: a plating tank for accommodating a plating solution; an anode disposed in the plating tank; a substrate holder configured to hold a substrate with its surface to be plated facing downward; a membrane separating an anode region in which the anode is disposed and a cathode region in which the substrate is disposed during plating, the membrane having an inclined surface facing the anode; a supply port for supplying the plating solution to the anode region; and a gas-liquid piping having a first end opening near an upper end of the inclined surface of the membrane and a second end opening above the surface to be plated of the substrate during plating, the gas-liquid piping configured to supply the plating solution supplied from the supply port to the anode region to the cathode region via the second end.

[0009] FIG. 1 is a perspective view showing the overall configuration of a plating apparatus according to one embodiment. FIG. 2 is a plan view showing the overall configuration of a plating apparatus according to one embodiment. FIG. 3 is a vertical cross-sectional view showing a schematic configuration of a plating module according to one embodiment. FIG. 4 is a vertical cross-sectional view showing a schematic configuration of a check valve according to one embodiment. FIG. 5 is a vertical cross-sectional view showing a schematic configuration of a gas-liquid piping according to one embodiment. FIG. 6 is a flowchart of a plating treatment method including a plating solution discharge method according to one embodiment.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings described below, the same or corresponding components are designated by the same reference numerals, and redundant description will be omitted.

[0011] <Overall Configuration of Plating Apparatus> Fig. 1 is a perspective view showing the overall configuration of the plating apparatus of this embodiment. Fig. 2 is a plan view showing the overall configuration of the plating apparatus of this embodiment. As shown in Figs. 1 and 2, the plating apparatus 1000 includes a load port 100, a transfer robot 110, an aligner 120, a pre-wet module 200, a pre-soak module 300, a plating module 400, a cleaning module 500, a spin rinse dryer 600, a transfer device 700, and a control module 800.

[0012] The load port 100 is a module for loading substrates stored in a cassette such as a FOUP (not shown) into the plating apparatus 1000 and unloading substrates from the plating apparatus 1000 to the cassette. In this embodiment, four load ports 100 are arranged horizontally, but the number and arrangement of the load ports 100 are optional. The transfer robot 110 is a robot for transporting substrates and is configured to transfer substrates between the load port 100, the aligner 120, the pre-wet module 200, and the spin rinse dryer 600. When transferring substrates between the transfer robot 110 and the transfer apparatus 700, the transfer robot 110 and the transfer apparatus 700 can transfer the substrates via a temporary stage (not shown).

[0013] The aligner 120 is a module for aligning the positions of the substrate's orientation flat, notch, and the like in a predetermined direction. In this embodiment, two aligners 120 are arranged horizontally, but the number and arrangement of the aligners 120 are optional. The prewet module 200 wets the surface of the substrate to be plated with a treatment liquid such as pure water or degassed water before plating, thereby replacing air within the pattern formed on the substrate surface with the treatment liquid. The prewet module 200 is configured to perform a prewet process that replaces the treatment liquid within the pattern with a plating liquid during plating, thereby making it easier to supply the plating liquid within the pattern. In this embodiment, two prewet modules 200 are arranged vertically, but the number and arrangement of the prewet modules 200 are optional.

[0014] The presoak module 300 is configured to perform a presoak process, which involves etching away, for example, an oxide film with high electrical resistance present on the surface of a seed layer formed on the surface of a substrate to be plated before plating, using a treatment solution such as sulfuric acid or hydrochloric acid to clean or activate the surface of the substrate to be plated. In this embodiment, two presoak modules 300 are arranged vertically, but the number and arrangement of the presoak modules 300 are optional. The plating module 400 performs plating on the substrate. In this embodiment, two sets of 12 plating modules 400 are arranged vertically, three vertically and four horizontally, for a total of 24 plating modules 400, but the number and arrangement of the plating modules 400 are optional.

[0015] The cleaning module 500 is configured to perform a cleaning process on the substrate to remove plating solution and the like remaining on the substrate after plating. In this embodiment, two cleaning modules 500 are arranged vertically, but the number and arrangement of the cleaning modules 500 are optional. The spin rinse dryer 600 is a module for drying the substrate after cleaning by rotating it at high speed. In this embodiment, two spin rinse dryers are arranged vertically, but the number and arrangement of the spin rinse dryers are optional. The transport device 700 is a device for transporting substrates between multiple modules within the plating apparatus 1000. The control module 800 is configured to control the multiple modules of the plating apparatus 1000 and can be configured, for example, as a general computer or a dedicated computer equipped with an input / output interface with an operator.

[0016] An example of a series of plating processes performed by the plating apparatus 1000 will be described. First, a substrate stored in a cassette is loaded into the load port 100. Next, the transfer robot 110 removes the substrate from the cassette in the load port 100 and transfers the substrate to the aligner 120. The aligner 120 aligns the positions of the orientation flat, notch, etc. of the substrate to a predetermined direction. The transfer robot 110 delivers the substrate, whose direction has been aligned by the aligner 120, to the pre-wet module 200.

[0017] The pre-wet module 200 performs a pre-wet process on the substrate. The transport device 700 transports the substrate that has been subjected to the pre-wet process to the pre-soak module 300. The pre-soak module 300 performs a pre-soak process on the substrate. The transport device 700 transports the substrate that has been subjected to the pre-soak process to the plating module 400. The plating module 400 performs a plating process on the substrate.

[0018] The transfer device 700 transfers the substrate after plating to the cleaning module 500. The cleaning module 500 performs a cleaning process on the substrate. The transfer device 700 transfers the substrate after cleaning to the spin rinse dryer 600. The spin rinse dryer 600 dries the substrate. The transfer robot 110 receives the substrate from the spin rinse dryer 600 and transfers the dried substrate to a cassette on the load port 100. Finally, the cassette containing the substrate is removed from the load port 100.

[0019] <Configuration of Plating Module> Next, the configuration of the plating module 400 will be described. Since the 24 plating modules 400 in this embodiment have the same configuration, only one plating module 400 will be described. Figure 3 is a vertical cross-sectional view schematically showing the configuration of a plating module in one embodiment.

[0020] 3, the plating module 400 includes a plating tank 410 for containing a plating solution. The plating tank 410 has a disk-shaped bottom wall 411 and a cylindrical side wall 413 that surrounds the periphery of the bottom wall 411, and is configured to have an open top. The side wall 413 includes a cylindrical first side wall 413-1 that is connected to the periphery of the bottom wall 411 and has a first thickness, and a cylindrical second side wall 413-2 that is disposed above the first side wall 413-1 and has a second thickness that is thinner than the first thickness.

[0021] The plating module 400 includes an anode 430 disposed at the bottom of the plating tank 410. The anode 430 may be a soluble anode or an insoluble anode. The plating module 400 includes a membrane 420 that vertically separates the interior of the plating tank 410. The membrane 420 is a film that separates an anode region 424 in which the anode 430 is disposed from a cathode region 422 in which the substrate Wf is disposed during plating. A resistor 450 is disposed in the cathode region 422 facing the membrane 420. The resistor 450 is a member for ensuring uniformity in the plating process on the plating surface Wf-a of the substrate Wf, and is formed of a plate-like member with a large number of holes formed therein.

[0022] The plating module 400 includes a substrate holder 440 for holding a substrate Wf (e.g., a disk-shaped substrate) with its surface Wf-a to be plated facing downward. The substrate holder 440 includes a power supply contact for supplying power to the substrate Wf from a power source (not shown). The substrate holder 440 includes a seal ring holder 442 for supporting the outer edge of the surface Wf-a to be plated of the substrate Wf, and a frame 446 for holding the seal ring holder 442 to a substrate holder main body (not shown). The substrate holder 440 also includes a back plate 444 for pressing the back surface of the surface Wf-a to be plated of the substrate Wf, and a shaft 448 attached to the back surface of the back plate 444 that presses against the back surface.

[0023] The plating module 400 includes a lifting mechanism 443 for lifting and lowering the substrate holder 440, and a rotation mechanism 447 for rotating the substrate holder 440 so that the substrate Wf rotates around a virtual axis of a shaft 448 (a virtual rotation axis extending vertically through the center of the surface Wf-a to be plated). The lifting mechanism 443 and the rotation mechanism 447 can be realized by known mechanisms such as a motor. The plating module 400 is configured to perform plating processing on the surface Wf-a to be plated of the substrate Wf by immersing the substrate Wf in the plating solution in the cathode region 422 using the lifting mechanism 443 and applying a voltage between the anode 430 and the substrate Wf.

[0024] The plating module 400 also includes a paddle 460 disposed between the anode 430 and the substrate Wf, specifically between the resistor 450 and the substrate Wf. The paddle 460 is disposed opposite the plating surface Wf-a of the substrate Wf. The plating module 400 also includes a drive mechanism 462 for reciprocating the paddle 460 along the plating surface Wf-a of the substrate Wf. The drive mechanism 462 can be realized by a known mechanism such as a motor. The plating module 400 can improve the uniformity of the plating formed on the plating surface by reciprocating the paddle 460 to agitate the plating solution.

[0025] The plating module 400 includes a supply port 412 for supplying a plating solution to the anode region 424. The supply port 412 is formed in the center of a bottom wall 411 of the plating tank 410. The plating module 400 includes a common pipe 414 connected to the supply port 412, and a supply pipe 414-1 and a discharge pipe 414-2 branching from the common pipe 414. A reservoir tank 416 for storing the plating solution, a pump 417 for pressure-feeding the plating solution stored in the reservoir tank 416, and a supply valve 418 for opening and closing the supply pipe 414-1 are connected to the supply pipe 414-1. A discharge valve 419 for opening and closing the discharge pipe 414-2 is connected to the discharge pipe 414-2.

[0026] The plating module 400 can supply plating solution to the plating tank 410 by opening the supply valve 418, closing the discharge valve 419, and starting the pump 417. On the other hand, the plating module 400 can discharge plating solution from the plating tank 410 by stopping the pump 417, closing the supply valve 418, and opening the discharge valve 419.

[0027] <Membrane> The membrane 420 serves to capture bubbles generated from the anode 430. The membrane 420 has a sloped shape to allow the captured bubbles to be discharged to the outside of the plating module 400. Specifically, the membrane 420 is formed in an inverted cone shape having a central part 421 disposed at the radial center of the plating tank 410 and a sloped membrane 423 extending obliquely upward from the central part 421. As a result, the membrane 420 has a sloped surface 423a facing the anode 430 on the bottom surface of the sloped membrane 423. Note that in this specification, the term "slope" refers to a surface that is inclined with respect to a horizontal plane. The membrane 420 is not limited to an inverted cone shape, and may have a sloped surface 423a facing the anode 430. The sloped membrane 423 may be made of any material capable of capturing bubbles generated from the anode 430.

[0028] According to the plating module 400 of this embodiment, the membrane 420 has an inclined surface 423a, so that the bubbles trapped by the membrane 420 can be moved obliquely upward along the inclined surface 423a, and as a result, the bubbles trapped by the membrane 420 can be moved to the upper end of the inclined surface 423a.

[0029] <Check Valve> The plating module 400 includes a check valve 425 disposed in the central part 421 of the membrane 420. Fig. 4 is a longitudinal cross-sectional view schematically illustrating the configuration of the check valve. Fig. 4 is an enlarged view of region α in Fig. 3, illustrating the check valve 425 in both the "closed" state (left side) and the "open" state (right side).

[0030] 4, the check valve 425 has a valve box 426 that forms a flow path 426a that connects the anode region 424 and the cathode region 422, a valve seat 426b that is provided in the flow path 426a, and a float-type valve element 427 that is disposed below the valve seat 426b of the flow path 426a and is formed so as to be able to abut against the valve seat 426b. The valve element 427 is made of a material with a specific gravity of less than 1.

[0031] When starting the plating process, plating solution is supplied from supply port 412 to anode region 424, and when the liquid level rises to valve element 427, valve element 427 rises and abuts against valve seat 426b. This closes check valve 425, preventing plating solution and air bubbles from being supplied from anode region 424 through flow path 426a to cathode region 422. On the other hand, when plating solution is discharged after plating, the liquid level of the plating solution in anode region 424 falls to valve element 427, which then descends and moves away from valve seat 426b. This opens check valve 425, allowing plating solution to flow from cathode region 422 through flow path 426a to anode region 424.

[0032] 3, the plating module 400 includes a gas / liquid pipe 470 for discharging bubbles trapped by the membrane 420 and supplying a plating solution to the cathode region 422. In this embodiment, the plating module 400 includes two gas / liquid pipes 470 facing each other across the center of the plating tank 410, but this is not limiting. The plating module 400 may include one gas / liquid pipe 470, or three or more gas / liquid pipes 470 arranged at equal or unequal intervals around the circumferential direction of the plating tank 410.

[0033] Figure 5 is a longitudinal cross-sectional view schematically illustrating the configuration of a gas-liquid pipe according to one embodiment. Figure 5 shows an enlarged view of region β in Figure 3, with appropriate components omitted. The two gas-liquid pipes 470 have the same configuration except for their different locations, and therefore only one of the gas-liquid pipes 470 will be described in Figure 5. As shown in Figure 5, the gas-liquid pipe 470 has a first end 472 that opens near the upper end of the inclined surface 423a of the membrane 420 in the anode region 424.

[0034] In this embodiment, a bubble trapping area BA where bubbles captured by the membrane 420 collect is formed near the upper end of the inclined surface 423a. That is, the end 423b of the inclined membrane 423 opposite the central component 421 is connected to the peripheral portion of the bottom surface of the resistor 450 at a predetermined distance from the inner surface of the first sidewall 413-1. This forms an annular flow path surrounded by the end 423b of the inclined membrane 423, the peripheral portion of the bottom surface of the resistor 450, and the inner surface of the first sidewall 413-1. Because the annular flow path is formed by these three surfaces, a certain amount of bubbles can be collected in the bubble trapping area BA. The first end 472 opens to the bottom surface of the resistor 450 toward the bubble trapping area BA.

[0035] The gas-liquid piping 470 also has a second end 474 that is located above the plating surface Wf-a of the substrate Wf during plating processing and that opens to the inside of the plating tank 410. The gas-liquid piping 470 extends upward from the first end 472, penetrates the inside of the resistor 450, extends radially outward, penetrates the inside of the resistor 450 and the first sidewall 413-1, and further extends upward inside the second sidewall 413-2 to reach the second end 474. Bubbles that have collected in the bubble trapping area BA pass through the gas-liquid piping 470 and are discharged from the second end 474. Because the second end 474 opens above the plating surface Wf-a, it is possible to prevent bubbles discharged from the second end 474 from adhering to the plating surface Wf-a.

[0036] The gas-liquid piping 470 is configured not only to discharge air bubbles but also to supply the plating solution supplied from the supply port 412 to the anode region 424 to the cathode region 422 via the second end 474. That is, when the plating solution supplied from the supply port 412 fills the anode region 424 and is then pumped to the anode region 424 by the pump 417, the plating solution flows from the first end 472 to the gas-liquid piping 470. This is because the membrane 420 has a large flow resistance for the plating solution, while the first end 472 has a small flow resistance for the plating solution. When the plating solution is pumped from the pump 417 to the anode region 424, the plating solution that has flowed into the gas-liquid piping 470 is supplied to the cathode region 422 via the second end 474. This causes the cathode region 422 to be filled with plating solution.

[0037] In this embodiment, the second end 474 of the gas-liquid pipe 470 opens below the plating solution level OF contained in the plating tank 410 during plating. That is, the plating module 400 is configured to perform plating while allowing the plating solution supplied to the cathode region 422 to overflow from the second sidewall 413-2. Therefore, the plating solution level OF is at a height corresponding to the upper end of the second sidewall 413-2. By opening the second end 474 below the plating solution level OF, additives contained in the plating solution supplied from the second end 474 can contribute to the plating process.

[0038] However, the present invention is not limited to this, and the second end 474 of the gas-liquid pipe 470 may open above the surface OF of the plating solution contained in the plating tank 410 during the plating process. In other words, in this specification, "opening into the inside of the plating tank 410" refers to the second end 474 being located inside the second sidewall 413-2 of the plating tank 410 when the plating module 400 is viewed from above. Therefore, the second end 474 may open in a region below the upper end of the second sidewall 413-2 (the surface OF of the plating solution) or in a region above the upper end of the second sidewall 413-2 (the surface OF of the plating solution). In either case, as long as the second end 474 opens into the inside of the plating tank 410, the plating solution flowing from the second end 474 is supplied to the cathode region 422.

[0039] The plating module 400 of this embodiment can suppress plating defects caused by bubbles generated from the anode and simplify the structure related to the supply of plating solution. Specifically, bubbles generated from the anode 430 can be captured by the membrane 420 and discharged above the plating surface of the substrate via the gas-liquid piping 470, thereby suppressing plating defects caused by bubbles adhering to the plating surface. Furthermore, since the plating solution can be supplied from the anode region 424 to the cathode region 422 via the gas-liquid piping 470, there is no need to provide separate supply piping for each of the anode region 424 and the cathode region 422, thereby simplifying the structure related to the supply of plating solution.

[0040] Furthermore, according to the plating module 400 of this embodiment, the plating solution can be sent from the cathode region 422 to the anode region 424 via the check valve 425 and discharged from the discharge pipe 414-2, eliminating the need to provide separate discharge pipes for the anode region 424 and the cathode region 422, thereby simplifying the structure for discharging the plating solution. Furthermore, according to the plating module 400 of this embodiment, the plating solution is discharged by dropping from the cathode region 422 to the anode region 424 via the check valve 425, so that a greater amount of by-products (sludge) adhering to the surface of the anode 430 can be washed away.

[0041] 6 is a flowchart of a plating method including a plating solution draining method according to one embodiment. The plating method is started with no plating solution stored in the plating tank 410 and the supply valve 418 and drain valve 419 closed.

[0042] The plating method first executes a step (S101) of opening the supply valve 418 and operating the pump 417. This opens the supply pipe 414-1, and the plating solution stored in the reservoir tank 416 is supplied from the supply port 412 to the anode region 424.

[0043] Next, the plating method executes a step (S102) of supplying a plating solution to the anode region 424 to raise the level of the plating solution in the anode region 424 and close the check valve 425. Specifically, S102 is executed by, when the level of the plating solution in the anode region 424 rises to the level of the valve element 427, the valve element 427 rises together with the rise in the plating solution level and abuts against the valve seat 426b, thereby closing the flow path 426a.

[0044] Next, the plating method executes a step (S103) of supplying plating solution from the gas-liquid pipe 470 to the cathode region 422 by increasing the flow resistance of the entire membrane 420 including the flow path 426a by closing the check valve 425.

[0045] The plating method includes a step (S104) of capturing bubbles generated from the anode 430 with the membrane 420 and discharging the captured bubbles above the plating surface Wf-a of the substrate Wf via the gas-liquid piping 470. Specifically, the bubbles captured by the membrane 420 move obliquely upward along the inclined surface 423a, gather in a bubble accumulation area BA near the upper end of the inclined surface 423a, and are discharged above the plating surface Wf-a of the substrate Wf via the gas-liquid piping 470.

[0046] Once the plating tank 410 is filled with the plating solution, the plating method performs plating by applying a voltage between the substrate Wf (cathode) and the anode (step S105). Once the plating is completed, the plating method performs a step of stopping the pump 417 and closing the supply valve 418 (step S106).

[0047] Next, the plating method executes a step (S107) of discharging the plating solution from the anode region 424 by opening the discharge valve 419 and the discharge pipe 414-2.

[0048] Next, the plating method executes a step (S108) of opening the check valve 425 provided in the membrane 420 separating the anode region 424 from the cathode region 422 by discharging the plating solution from the anode region 424 and lowering the level of the plating solution in the anode region 424. Specifically, S108 is executed by, when the level of the plating solution in the anode region 424 drops down to the valve element 427, the valve element 427 descends and separates from the valve seat 426b as the level of the plating solution drops, thereby opening the flow path 426a.

[0049] Next, the plating method executes a step (S109) in which the check valve 425 is opened to send the plating solution in the cathode region 422 to the anode region 424 via the flow path 426a and discharge the solution from the discharge pipe 414-2.

[0050] According to the plating method of this embodiment, bubbles generated from the anode 430 can be captured and discharged above the plating surface of the substrate, thereby preventing bubbles from adhering to the plating surface and causing plating defects. Furthermore, according to the plating method of this embodiment, the plating solution can be supplied from the anode region 424 to the cathode region 422 via the gas-liquid piping 470, eliminating the need to provide supply piping for each of the anode region 424 and the cathode region 422, thereby simplifying the structure related to the supply of the plating solution. Furthermore, according to the plating method of this embodiment, the plating solution can be sent from the cathode region 422 to the anode region 424 via the check valve 425 and discharged from the discharge piping 414-2, eliminating the need to provide discharge piping for each of the anode region 424 and the cathode region 422, thereby simplifying the structure related to the discharge of the plating solution. Furthermore, according to the plating method of this embodiment, the plating solution is discharged by dropping it from the cathode region 422 to the anode region 424 through the check valve 425, so that a larger amount of by-products (sludge) adhering to the surface of the anode 430 can be washed away.

[0051] Although several embodiments of the present invention have been described above, the above-described embodiments of the present invention are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention naturally includes equivalents thereof. Furthermore, any combination or omission of the components described in the claims and specification is possible within the scope of solving at least part of the above-described problems or achieving at least part of the effects.

[0052] In one embodiment, the present application discloses a plating apparatus including: a plating tank for accommodating a plating solution; an anode disposed in the plating tank; a substrate holder configured to hold a substrate with its surface to be plated facing downward; a membrane separating an anode region in which the anode is disposed and a cathode region in which the substrate is disposed during plating, the membrane having an inclined surface facing the anode; a supply port for supplying the plating solution to the anode region; and a gas-liquid piping having a first end that opens near an upper end of the inclined surface of the membrane and a second end that opens above the surface to be plated of the substrate during plating, the gas-liquid piping configured to supply the plating solution supplied from the supply port to the anode region to the cathode region via the second end.

[0053] Furthermore, the present application discloses, as one embodiment, a plating apparatus in which the second end of the gas-liquid pipe is configured to open below the surface of the plating solution contained in the plating tank.

[0054] Furthermore, as one embodiment, the present application discloses a plating apparatus in which the membrane has a central part arranged in the radial center of the plating tank and a gradient membrane extending radially and obliquely upward from the central part.

[0055] Furthermore, the present application discloses, as one embodiment, a plating apparatus in which a check valve configured to allow plating solution to flow only in a direction from the cathode region to the anode region is disposed in the central part of the membrane.

[0056] Furthermore, as one embodiment, the present application discloses a plating apparatus in which the check valve has a valve box that forms a flow path connecting the anode region and the cathode region, a valve seat that is provided in the flow path, and a float-type valve element that is positioned below the valve seat in the flow path and is formed so as to be able to abut against the valve seat.

[0057] Furthermore, the present application discloses, as one embodiment, a method for discharging plating solution contained in a plating tank of a cup-type plating apparatus, the plating solution discharging method including the steps of opening a discharge pipe communicating with an anode region of the plating tank to discharge the plating solution from the anode region, discharging the plating solution from the anode region to lower the level of the plating solution in the anode region, thereby opening a check valve provided in a membrane separating the anode region and the cathode region, and opening the check valve to send the plating solution in the cathode region to the anode region and discharge it from the discharge pipe.

[0058] 400 Plating module 410 Plating tank 412 Supply port 420 Membrane 421 Central part 422 Cathode region 423 Inclined membrane 423a Inclined surface 424 Anode region 425 Check valve 426 Valve box 426a Flow path 426b Valve seat 427 Valve body 430 Anode 440 Substrate holder 470 Gas-liquid piping 472 First end 474 Second end Wf Substrate Wf-a Surface to be plated

Claims

1. A plating apparatus comprising: a plating tank for containing a plating solution; an anode disposed in the plating tank; a substrate holder configured to hold a substrate with its surface to be plated facing downward; a membrane separating an anode region in which the anode is disposed and a cathode region in which the substrate is disposed during plating, the membrane having an inclined surface facing the anode; a supply port for supplying plating solution to the anode region; and a gas-liquid piping having a first end that opens near an upper end of the inclined surface of the membrane and a second end that opens above the surface to be plated of the substrate during plating, the gas-liquid piping configured to supply plating solution supplied from the supply port to the anode region to the cathode region via the second end.

2. The plating apparatus according to claim 1, wherein the second end of the gas-liquid piping is configured to open below the surface of the plating liquid contained in the plating tank.

3. The plating apparatus according to claim 2, wherein the membrane has a central part disposed at the radial center of the plating tank, and a gradient membrane extending obliquely upward radially from the central part.

4. The plating apparatus according to claim 3, wherein a check valve configured to allow plating solution to flow only in a direction from the cathode region to the anode region is disposed in the central part of the membrane.

5. The plating apparatus as described in claim 4, wherein the check valve comprises a valve body forming a flow passage connecting the anode region and the cathode region, a valve seat provided in the flow passage, and a float-type valve element disposed below the valve seat in the flow passage and formed so as to be able to abut against the valve seat.

6. A method for discharging plating solution contained in a plating tank of a cup-type plating apparatus, comprising the steps of opening a discharge pipe communicating with an anode region of the plating tank to discharge the plating solution from the anode region, opening a check valve provided in a membrane separating the anode region and the cathode region by discharging the plating solution from the anode region and lowering the level of the plating solution in the anode region, and opening the check valve to send the plating solution in the cathode region to the anode region and discharge it from the discharge pipe.

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