Plating apparatus

Abstract

Provided is a plating apparatus capable of improving the uniformity of the thickness of a plating film formed on an object to be plated.　A resistor of the plating apparatus comprises a first resistance member and a second resistance member, the second resistance member being disposed between the first resistance member and a substrate holder or between the first resistance member and an anode. The first resistance member has a plurality of first through-holes, each of the first through-holes forming an opening between the substrate holder side and the anode side. At least some of the first through-holes overlap the second resistance member so that the anode is invisible when the anode side is viewed from the substrate side. The second resistance member is configured so that the distance from the first resistance member is variable.

Description

Plating Equipment

[0001] The present application relates to a plating apparatus.

[0002] One example of a plating apparatus using electroplating is a so-called dip-type plating apparatus in which a substrate (e.g., a semiconductor wafer) and an anode are arranged horizontally facing each other (see, for example, Patent Document 1). Another example of a plating apparatus using electroplating is a cup-type plating apparatus (see, for example, Patent Document 2). In the cup-type plating apparatus, a substrate 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 and the anode to deposit a conductive film (plating film) on the surface of the substrate.

[0003] In such plating apparatuses, the substrate generally has an electrical contact on its periphery. Due to differences in distance from the electrical contact, a potential difference occurs between the periphery and center of the substrate during plating, which can result in a bias in the plating current. For this reason, it has been known to place a resistor for adjusting the electric field between the substrate and the anode to improve the uniformity of the thickness of the plating film formed on the substrate. Furthermore, a plating apparatus has been proposed in which the size of the resistor hole is variable to allow for greater freedom in adjusting the electric field (see Patent Document 3).

[0004] Patent No. 7462125 Patent No. 7079388 Patent No. 7204060

[0005] In plating equipment, uneven plating film thickness can occur due to factors other than the distance from the electrical contacts, such as the resist pattern formed on the substrate. In other words, if the substrate surface to be plated contains a certain number of areas without resist openings (non-opening areas), the plating current does not flow through the non-opening areas, and instead concentrates around the non-opening areas, resulting in a thicker plating film. As a specific example, if resist openings are formed only in a roughly cross-shaped area on the substrate, the area outside the cross does not have resist openings and current does not flow, potentially resulting in a loss of uniformity in the thickness of the plating film. For example, Patent Document 1 uses an anode mask with adjustable anode opening dimensions to adjust the electric field between the anode and the substrate. However, conventional configurations are designed to address variations in plating film thickness due to the configuration of the plating equipment, such as electrical contacts, and may not adequately address variations in plating film thickness due to the resist pattern on the substrate. While forming dummy openings in the non-opening areas to achieve uniform plating film thickness is conceivable, this increases plating process costs due to the additional processing required to form the dummy openings and the formation of unnecessary plating in the dummy openings.

[0006] The present invention has been made in view of the above problems, and one of its objects is to propose a plating apparatus that can improve the uniformity of the thickness of a plating film formed on an object to be plated.

[0007] According to one embodiment, a plating apparatus is proposed, the plating apparatus comprising: a plating tank; a substrate holder configured to hold a substrate; an anode arranged in the plating tank so as to face the substrate held by the substrate holder; and a resistor for adjusting an electric field arranged between the substrate holder and the anode, the resistor comprising a first resistance element and a second resistance element arranged between the first resistance element and the substrate holder or between the first resistance element and the anode, the first resistance element having a plurality of first through holes formed therein that open to the substrate holder side and the anode side, at least some of the plurality of first through holes overlap with the second resistance element so that the anode is not visible when viewed from the substrate side to the anode side, and the second resistance element is configured so that the distance between the second resistance element and the first resistance element is variable.

[0008] 1 is a perspective view showing the overall configuration of the plating apparatus of the present embodiment; FIG. 2 is a plan view showing the overall configuration of the plating apparatus of the present embodiment; FIG. 3 is a longitudinal sectional view schematically showing the configuration of the plating module of the present embodiment; FIG. 4 is a top view of a first resistor element of the present embodiment; FIG. 5 is a top view of a second resistor element of the present embodiment; FIG. 6 is a longitudinal sectional view schematically showing a resistor in a state where the first resistor element and the second resistor element are spaced apart; FIG. 7 is a longitudinal sectional view schematically showing a resistor in a state where the first resistor element and the second resistor element are in contact; FIG. 8 is a flowchart showing an example of a method for setting an operation recipe for a resistor, an anode mask, and a shield by a control module; FIG. 9 is a diagram schematically showing a resist pattern formed on a surface to be plated of a substrate of an embodiment; FIG. 10 is a flowchart showing an example of a method for setting an operation recipe for a resistor, an anode mask, and a shield by a control module during plating processing; FIG. 11 is a longitudinal sectional view schematically showing a resistor in a state where the first resistor element and the second resistor element are spaced apart in a first modified example; FIG. 12 is a longitudinal sectional view schematically showing a resistor in a state where the first resistor element and the second resistor element are in contact in a first modified example. 10A and 10B are enlarged schematic longitudinal sectional views of a resistor in a second modified example in which the first and second resistance members are spaced apart by a first distance, a longitudinal sectional view of a resistor in a second modified example in which the first and second resistance members are spaced apart by a second distance, and a longitudinal sectional view of a resistor in a second modified example in which the first and second resistance members are spaced apart by a third distance.

[0009] 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.

[0010] <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.

[0011] 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, and the transfer device 700. When transferring substrates between the transfer robot 110 and the transfer device 700, the transfer robot 110 and the transfer device 700 can transfer the substrates via a temporary stage (not shown).

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 transfer apparatus 700.

[0016] The transfer device 700 transfers the substrate received from the transfer robot 110 to the prewet module 200. The prewet module 200 performs a prewet process on the substrate. The transfer device 700 transfers the substrate that has been subjected to the prewet process to the presoak module 300. The presoak module 300 performs a presoak process on the substrate. The transfer device 700 transfers the substrate that has been subjected to the presoak process to the plating module 400. The plating module 400 performs a plating process on the substrate.

[0017] The transfer device 700 transfers the substrate that has been plated to the cleaning module 500. The cleaning module 500 performs a cleaning process on the substrate. The transfer device 700 transfers the substrate that has been cleaned to the spin rinse dryer 600. The spin rinse dryer 600 dries the substrate. The transfer device 700 delivers the substrate that has been dried to the transfer robot 110. The transfer robot 110 transfers the substrate received from the transfer device 700 to a cassette on the load port 100. Finally, the cassette containing the substrate is removed from the load port 100.

[0018] <Configuration of Plating Module> Next, a description will be given of the configuration of the plating module 400. Since the 24 plating modules 400 in this embodiment have the same configuration, only one plating module 400 will be described.

[0019] 3 is a longitudinal cross-sectional view schematically illustrating the configuration of a plating module 400 according to this embodiment. As shown in FIG. 3, the plating module 400 includes a plating tank 410 for containing a plating solution. The plating tank 410 includes a cylindrical inner tank with an open top and an outer tank (not shown) that is provided around the inner tank to collect plating solution that overflows from the upper edge of the inner tank.

[0020] The plating module 400 includes a substrate holder 440 for holding the substrate Wf with its plating surface Wf-a facing downward. The substrate holder 440 also includes a power supply contact (not shown) for supplying power to the substrate Wf from a power source (not shown). In one embodiment, the power supply contact contacts contact the outer edge of the substrate Wf to supply power to the outer edge of the substrate Wf. The plating module 400 also includes a lifting mechanism 442 for raising and lowering the substrate holder 440. In one embodiment, the plating module 400 also includes a rotation mechanism 448 for rotating the substrate holder 440 around a vertical axis. The lifting mechanism 442 and the rotation mechanism 448 can be realized by known mechanisms such as motors.

[0021] The plating module 400 includes a membrane 420 that vertically separates the interior of a plating tank 410. The interior of the plating tank 410 is divided into a cathode region 422 and an anode region 424 by the membrane 420. The cathode region 422 and the anode region 424 are each filled with a plating solution. Note that, although an example in which the membrane 420 is provided has been shown in this embodiment, the membrane 420 need not be provided.

[0022] An anode 430 is provided on the bottom surface of the anode region 424 of the plating tank 410. The anode 430 is, for example, a circular member having a surface dimension approximately equal to that of the substrate Wf. An anode mask 426 is also provided in the anode region 424 to adjust the electric field between the anode 430 and the substrate Wf. The anode mask 426 is provided near the anode 430 and is, for example, a substantially plate-shaped electric field shield made of a dielectric material. The anode mask 426 has an opening through which a current flows between the anode 430 and the substrate Wf. In this embodiment, the anode mask 426 is configured to have variable opening dimensions, and the opening dimensions are adjusted by the control module 800. Here, the opening dimension refers to the diameter if the opening is circular, and to the length of one side or the longest opening width if the opening is polygonal. The opening dimensions of the anode mask 426 can be adjusted using a known mechanism. In addition, although the present embodiment shows an example in which the anode mask 426 is provided, it is not necessary to provide the anode mask 426. Furthermore, the membrane 420 described above may be provided in the opening of the anode mask 426.

[0023] The plating module 400 includes a resistor 450 disposed between the substrate Wf and the anode 430. In this embodiment, the resistor 450 is disposed in the cathode region 422. The resistor 450 is a component for adjusting the electric field to achieve uniformity in the plating process on the plating surface Wf-a of the substrate Wf. The resistor 450 increases the resistance between the anode 430 and the substrate Wf, making it difficult for the electric field to spread. As a result, the distribution of the plating film thickness formed on the plating surface Wf-a of the substrate Wf can be made uniform. Therefore, increasing the distance between the substrate Wf and the resistor 450 increases the space available for the electric field to spread between the substrate Wf and the resistor 450. For this reason, the resistor 450 is preferably disposed near the plating surface Wf-a of the substrate Wf. The resistor 450 will be described in detail later.

[0024] The plating module 400 also includes a paddle 480 disposed between the substrate Wf held by the substrate holder 440 and the resistor 450, and a paddle stirring mechanism 482 for moving the paddle 480 through the plating solution to stir the plating solution. The paddle 480 may be configured, for example, but not limited to, a plate member with numerous honeycomb-shaped holes formed therein. The paddle stirring mechanism may be realized by a known mechanism, such as a motor. The paddle stirring mechanism 482 is configured to stir the plating solution near the plating surface Wf-a of the substrate Wf by reciprocating the paddle 480 along the plating surface Wf-a of the substrate Wf. However, the present invention is not limited to this example, and the paddle stirring mechanism 482 may, for example, be configured to reciprocate the paddle 480 perpendicular to the plating surface Wf-a. Although the present embodiment illustrates an example in which the paddle 480 and the paddle stirring mechanism 482 are provided, the paddle 480 and the paddle stirring mechanism 482 may not be provided.

[0025] The cathode region 422 is also provided with a sensor 460 for detecting parameters related to the plating film formed on the plating surface Wf-a of the substrate Wf. In this embodiment, the parameters related to the plating film refer to physical quantities for estimating the thickness of the plating film or the formation rate of the plating film. The sensor 460 is disposed so as to face the plating surface Wf-a. In this embodiment, the sensor 460 is configured to be movable so that the detection position can be changed along the radial direction of the substrate Wf. However, this is not limited to this example, and multiple sensors 460 facing the plating surface Wf-a may be provided. In one embodiment, the detection end of the sensor 460 is disposed inside the resistor 450 (in the groove 454). However, this is not limited to this example, and the sensor 460 may be disposed in another location outside the resistor 450, for example.

[0026] The detection signal from the sensor 460 is input to the control module 800. In this embodiment, a potential sensor having a detection electrode (not shown) is used as the sensor 460. The detection electrode of the sensor 460 may be arranged so as to face the plating surface Wf-a, or may be arranged in a conduit arranged so as to face the plating surface Wf-a and filled with plating solution. Furthermore, when a potential sensor is used as the sensor 460, at least one reference potential sensor 462 is preferably provided in the plating tank 410. The reference potential sensor 462 is preferably provided outside the area between the substrate Wf and the anode 430. In other words, the reference potential sensor 462 is preferably provided in a position that does not overlap the substrate Wf and the anode 430 when viewed from a direction perpendicular to the plating surface Wf-a of the substrate Wf. Based on the potential difference between the potential sensor 460, which is a potential sensor, and the reference potential sensor 462, the control module 800 can estimate the formation rate of the plating film formed on the surface Wf-a to be plated and measure the thickness of the plating film. This is based on the correlation between the plating current and the potential during the plating process. However, the sensor 460 may be any sensor capable of detecting parameters related to the plating film, and other sensors, such as an optical distance sensor such as a white light confocal sensor, a magnetic field sensor, or an eddy current sensor, may be used instead of or in addition to the potential sensor. Note that, although the present embodiment illustrates an example in which the sensor 460 for detecting parameters related to the plating film is provided, the sensor 460 need not be provided.

[0027] A shield 470 is provided in the cathode region 422 to shield the current flowing from the anode 430 to the substrate Wf. In this embodiment, the shield 470 is provided at the same height as the paddle 480, but this is not limited to this example. The shield 470 is, for example, a substantially plate-shaped member made of a dielectric material. The shield 470 is configured to be movable between a shielding position interposed between the plating surface Wf-a of the substrate Wf and the anode 430, and a retracted position retracted from between the plating surface Wf-a and the anode 430. In other words, the shield 470 is configured to be movable between a shielding position below the plating surface Wf-a and a retracted position away from below the plating surface Wf-a. The position of the shield 470 is controlled by a drive mechanism 472 that receives commands from the control module 800. The drive mechanism 472 can be realized by a known mechanism such as a motor or a solenoid.

[0028] <Resistor> The resistor 450 of this embodiment will be described in detail. The resistor 450 of this embodiment includes a first resistor element 452 and a second resistor element 456. The first resistor element 452 and the second resistor element 456 are preferably dielectric elements having a higher electrical resistivity than the plating solution. The first resistor element 452 and the second resistor element 456 may be formed of the same material or different materials.

[0029] 4 is a top view of the first resistance member of this embodiment. In FIG. 4, the area occupied by the outline of the second resistance member 456, which is disposed on the reverse side of the first resistance member 452, is hatched. In one embodiment, the first resistance member 452 is a circular, plate-like member that is fixed to the plating tank 410 and is slightly larger than the substrate Wf when viewed from above. As an example, the first resistance member 452 may be configured to be movable up and down within the plating tank 410.

[0030] The first resistance member 452 is formed with a plurality of first through holes 453 that open toward the substrate holder 440 and the anode 430. In one embodiment, the plurality of first through holes 453 are through holes of the same size and define elongated openings whose circumferential length is approximately twice their radial length. However, this is not limited to this example, and each of the plurality of first through holes 453 may be a perfect circle when viewed from above, or may have any other shape, and may be through holes of different sizes. Also, in one embodiment, the first through holes 453 are arranged on three or more imaginary reference circles (see dashed dotted lines in FIG. 4 ) that are concentric but have different diameters. In this case, in one embodiment, the plurality of first through holes 453 arranged on adjacent reference circles are arranged at angular positions offset from each other on the reference circles. In other words, the centers of the first through holes 453 arranged on adjacent reference circles are not aligned on a straight line extending radially, but are arranged offset from each other in the circumferential direction. However, the multiple first through holes 453 are not limited to this example, and may be arranged side by side on a straight line extending in the radial direction.

[0031] In one embodiment, the first resistor 452 is formed with a groove 454 for accommodating at least a portion of the sensor 460. While FIG. 4 illustrates the groove 454 as penetrating from the substrate holder 440 side to the anode 430 side, the anode 430 side may be closed, for example. In one embodiment, the groove 454 extends inward from the outer periphery of the second resistor 456 when viewed from above. In one embodiment, as shown in FIGS. 3 and 4 , the sensor 460 is disposed within the groove 454 so as not to protrude above the upper surface of the second resistor 456. As described above, the resistor 450 is preferably disposed near the plating surface Wf-a, and the sensor 460 for detecting a parameter related to the plating film is also preferably disposed near the plating surface Wf-a of the substrate Wf. By disposing the sensor 460 in the groove 454, the distance between the resistor 450 and the plating surface Wf-a of the substrate Wf can be reduced, making it possible to suitably detect parameters related to the thickness of the plating film. Additionally, in this embodiment, a paddle 480 is disposed between the resistor 450 and the substrate Wf. By disposing the sensor 460 in the groove 454, interference between the sensor 460 and the paddle 480 can be prevented without restricting the movement of the paddle 480 for stirring.

[0032] FIG. 5 is a top view of the second resistance member of this embodiment. In one embodiment, the second resistance member 456 is an annular plate-shaped member that is annular when viewed from above. In one embodiment, the inner diameter of the second resistance member 456 is 50% to 70% of the diameter of the first resistance member 452 or the substrate Wf, and preferably 55% to 65%. Also, in one embodiment, the outer diameter of the second resistance member 456 is 70% to 90% of the diameter of the first resistance member 452 or the substrate Wf, and preferably 80% to 90%. However, the second resistance member 456 is not limited to being an annular plate-shaped member and can have any shape. When viewing the anode 430 side from the substrate Wf side (when viewed from above), the second resistance member 456 overlaps at least some of the multiple first through holes 453 of the first resistance member 452 so that the anode 430 cannot be seen through those through holes. In other words, at least some of the first through holes 453 in the first resistance member 452 are covered by the second resistance member 456. In one embodiment, all of the first through holes 453 formed in a region overlapping with the contour of the second resistance member 456 when viewed from above (the hatched region in FIG. 4 ) are covered by the second resistance member 456. However, among the first through holes 453 formed in a region overlapping with the contour of the second resistance member 456 when viewed from above, some of the through holes may be covered by the second resistance member 456 and some of the through holes may not be covered by the second resistance member 456.

[0033] In one embodiment, the second resistance element 456 is disposed below the first resistance element 452 (between the first resistance element 452 and the anode 430). This is because, as described above, the resistance element 450 is preferably provided near the substrate Wf, and space above the resistance element 450 is limited, while space below the resistance element 450 is relatively more ample. However, the second resistance element 456 may also be disposed above the first resistance element 452 (between the first resistance element 452 and the substrate holder 440). The second resistance element 456 may be supported in the plating tank 410 by a support mechanism (not shown). The second resistance element 456 is disposed concentrically with the substrate Wf or the anode 430 when viewed from above. In one embodiment, the second resistance element 456 has dimensions smaller than those of the substrate Wf or the anode 430 when viewed from above, and is disposed closer to the center than the periphery of the substrate Wf or the anode 430 (see FIG. 3 ). Furthermore, in one embodiment, the thickness Th2 of the second resistor member 456 is smaller than the thickness Th1 of the first resistor member 452. As an example, the thickness Th2 of the second resistor member 456 is preferably equal to or smaller than one-half, one-third, one-fifth, or one-tenth of the thickness Th2 of the first resistor member 452.

[0034] The second resistance member 456 has a plurality of second through holes 457 formed therein, which open toward the substrate holder 440 and the anode 430. In this embodiment, the second through holes 457 are formed at positions different from the first through holes 453 of the first resistance member 452 when viewed from above. However, some of the second through holes 457 may be formed at the same positions as the first through holes 453 of the first resistance member 452. In one embodiment, the second through holes 457 are arranged on two or more imaginary reference circles (see the dashed dotted lines in FIG. 5 ) that are concentric but have different diameters. In other words, the second through holes 457 are arranged so as to be dispersed in the radial direction of the second resistance member 456. In another embodiment, each of the second through holes 457 has the same shape as the first through hole 453 of the first resistance member 452 when viewed from above. However, the second through holes 457 may have any shape. In this embodiment, an example in which a plurality of second through holes 457 are formed in the second resistance member 456 has been described, but the second through holes 457 do not necessarily have to be formed.

[0035] The second resistance member 456 is configured to be movable up and down so that the distance between it and the first resistance member 452 is variable. In one embodiment, the second resistance member 456 is configured to be movable between a position spaced apart from the first resistance member 452 and a position where it contacts the first resistance member 452 and blocks at least a portion of the first through-holes 453. However, the second resistance member 456 may not contact the first resistance member 452. In one embodiment, the plating module 400 includes a drive mechanism 451 configured to move the second resistance member 456 up and down. The drive mechanism 451 can be realized by a known mechanism such as a pneumatic actuator. For example, the drive mechanism 451 may utilize power from a power source (e.g., a compressed air source) of the lifting mechanism 442 of the substrate holder 440.

[0036] The resistor 450 can change the amount of electric field adjustment, mainly in the region where the second resistor 456 is disposed, by changing the distance between the first resistor 452 and the second resistor 456. FIG. 6 is a vertical cross-sectional view schematically showing the resistor 450 in a state where the first resistor 452 and the second resistor 456 are spaced apart, and FIG. 7 is a vertical cross-sectional view schematically showing the resistor 450 in a state where the first resistor 452 and the second resistor 456 are in contact. Note that in the examples shown in FIGS. 6 and 7 , dashed lines schematically show a portion of the current flowing near the resistor 450. As described above, in this embodiment, when viewed from above, at least a portion of the multiple first through-holes 453 of the first resistor 452 are covered by the second resistor 456. As shown in FIG. 6 , when the first resistance element 452 and the second resistance element 456 are sufficiently spaced apart, the current passing through the plurality of first through holes 453 of the first resistance element 452 is hardly blocked by the second resistance element 456. However, as the distance between the first resistance element 452 and the second resistance element 456 decreases, the distance between the plurality of first through holes 453 of the first resistance element 452 and the second resistance element 456 also decreases, making it difficult for current to flow through the first through holes 453. When the first resistance element 452 and the second resistance element 456 come into contact as shown in FIG. 7 , some of the first through holes 453 of the first resistance element 452 are blocked by the second resistance element 456, preventing current from flowing. In this way, the amount of electric field adjustment in the region where the second resistance element 456 is primarily located varies depending on the distance between the first resistance element 452 and the second resistance element 456.

[0037] <Plating Process> Next, the plating process in the plating module 400 of this embodiment will be described in more detail. The substrate Wf is exposed to the plating solution by immersing it in the plating solution in the cathode region 422 using the lifting mechanism 442. In this state, the plating module 400 can perform plating on the plating surface Wf-a of the substrate Wf by applying a voltage between the anode 430 and the substrate Wf. In one embodiment, the plating process is performed while the substrate holder 440 is rotated using the rotation mechanism 448. As a result of the plating process, a conductive film (plating film) is deposited on the plating surface Wf-a of the substrate Wf-a.

[0038] The control module (controller) 800 of this embodiment controls the drive mechanism 451 to adjust the resistor 450 (the distance between the first resistor 452 and the second resistor 456), thereby improving the uniformity of the plating film thickness distribution over the entire substrate Wf. As an example, the adjustment of the resistor 450 using the drive mechanism 451 is performed before the plating process starts. Also, as another example, the adjustment of the resistor 450 using the drive mechanism 451 is performed in real time during the plating process based on the detection value by the sensor 460.

[0039] FIG. 8 is a flowchart illustrating an example of a method for setting operation recipes for the resistor 450, the anode mask 426, and the shield 470 by the control module 800. The method illustrated in FIG. 8 is executed, for example, when processing a new substrate lot. The control module 800 may set operation recipes for only some of the resistor 450, the anode mask 426, and the shield 470. The operation recipe for the resistor 450 is a recipe that indicates the vertical position of the second resistor 456, i.e., the distance between the first resistor 452 and the second resistor 456. The operation recipe for the anode mask 426 is a recipe that indicates the opening dimensions of the anode mask 426. The operation recipe for the shield 470 is a recipe that indicates the advance / retract position of the shield 470. Instead of being set by the control module 800 of the plating apparatus 1000, the operation recipes may be set by a computer external to the plating apparatus 1000 and transmitted to the plating apparatus 1000.

[0040] In the example shown in FIG. 8 , the control module 800 first acquires a resist pattern for the substrate Wf to be processed (step S110). The resist pattern refers to a pattern of a resist layer formed on the surface Wf-a to be plated so that a desired plating pattern is formed by plating. The resist pattern may be acquired by detecting the substrate Wf using a sensor provided in the plating apparatus 1000. As an example, the plating apparatus 1000 may be equipped with an imaging sensor (not shown), such as a camera, that captures an image of the surface Wf-a to be plated of the substrate Wf. The control module 800 may then acquire imaging data detected by the imaging sensor and analyze the imaging data to acquire the resist pattern for the surface Wf-a to be plated. The resist pattern may be acquired from the imaging data using a known method based on shading or feature points of the imaging data. Alternatively, the control module 800 may acquire the resist pattern via external input via wired or wireless communication, for example.

[0041] The control module 800 then sets operation recipes for the resistor 450, the anode mask 426, and the shield 470 based on the acquired resist pattern (step S120). As a specific example, the control module 800 calculates a plating growth coefficient for each predetermined region of the plating surface Wf of the substrate Wf based on the acquired resist pattern, and sets operation recipes for each control object based on the calculated plating growth coefficient. Here, the plating growth coefficient is a parameter indicating the growth rate (formation rate) of the plating film when each of the resistor 450, the anode mask 426, and the shield 470 least shields the current. As an example, the plating growth coefficient can be expressed as the amount (e.g., nanometers) of plating film formed per unit time (e.g., 1 second). As a specific example, the control module 800 can calculate the aperture ratio of the resist layer for each predetermined region based on the resist pattern, and then calculate the plating growth coefficient based on the calculated aperture ratio. This is because in areas where the aperture ratio of the resist layer is large, the area on which plating is deposited and the amount of plating required to form a certain amount of plating film are large, and the growth rate of the plating film tends to be slower than in areas where the aperture ratio of the resist layer is small.

[0042] FIG. 9 is a schematic diagram illustrating a resist pattern formed on the plating surface Wf-a of a substrate Wf according to one embodiment. In FIG. 9, resist openings are formed only in the cross-shaped region A1, which is hatched, and the region A2 outside the cross-shaped region A1 is a non-opening region where no resist openings are formed. When plating is performed on a substrate Wf with such a resist pattern, plating current does not flow through the non-opening region A2, but only through the opening region A1. In this embodiment, plating is performed while rotating the substrate holder 440 using the rotation mechanism 448. The plating current concentrates in the cross-shaped convex region of region A1, particularly in the circumferential direction, including region A2, resulting in a large plating film thickness. In this specification, the region in which resist openings are formed substantially entirely when viewed circumferentially is referred to as the "central region B1" (in the example shown in FIG. 11, the circular region surrounded by the inner dashed line C1). Furthermore, when viewed in the circumferential direction, a region that includes both a region where a resist opening is formed (opening region A1) and a region where a resist opening is not formed (non-opening region A2), and where the area of ​​the opening region A1 is larger in the circumferential direction than the area of ​​the non-opening region A2, is referred to as an "intermediate region B2" (in the example shown in FIG. 11, this is the annular region surrounded by dashed-dotted lines C1 and C2). Furthermore, when viewed in the circumferential direction, a region that includes both the opening region A1 and the non-opening region A2, and where the area of ​​the opening region A1 is smaller in the circumferential direction than the area of ​​the non-opening region A2, is referred to as an "outer peripheral region B3" (in the example shown in FIG. 11, this is the annular region surrounded by dashed-dotted lines C2 and C3). Note that in the example shown in FIG. 11, the central region B1, intermediate region B2, and outer peripheral region B3 are located in this order from the center to the outer periphery of the plating surface Wf-a, and no resist opening is formed on the outer periphery of the outer peripheral region B3. However, this is not limited to this example, and any resist pattern may be formed on the substrate Wf.

[0043] Here, the anode mask 426 or the shield 470 provided in the plating module 400 can suitably adjust the plating film formation rate near the outer periphery of the plating surface Wf-a. However, when a substrate Wf as shown in Figure 9 is plated, the plating film formation rate in the region (particularly the middle region B2) that is closer to the inner periphery than near the outer periphery may become relatively higher, which may impair the uniformity of the thickness of the plating film.

[0044] In contrast, in the plating module 400 of this embodiment, the resistor 450 includes a second resistor element 456 having an annular plate shape, allowing the electric field adjustment amount of the resistor element 450 to be adjusted mainly in the region where the second resistor element 456 is located. This allows the current flowing through the intermediate region B2 to be adjusted to adjust the plating formation rate in the intermediate region B2. For example, in the substrate Wf of FIG. 9 , if the plating formation rate in the intermediate region B2 surrounded by the dashed-dotted lines C1 and C2 is relatively high, the plating film thickness formed in the intermediate region B2 can be reduced by moving the second resistor element 456 closer to the first resistor element 452. This allows for improved thickness uniformity of the plating film, even when plating a substrate Wf such as that shown in FIG. 9 . Additionally, the plating module 400 of this embodiment includes an anode mask 426 and a shield 470. As a result, the plating speed can be adjusted in the intermediate region B2 by rotating the first resistor 452, and the plating speed can be adjusted in the outer peripheral region B3 by the anode mask 426 and the shield 470. Therefore, by controlling the resistor 450, the anode mask 426, and the shield 470, the plating speed can be adjusted for each region of the substrate Wf, thereby improving the uniformity of the thickness of the plating film. Note that the dimensions of the second resistor member 456 of the resistor 450 may be determined based on the intermediate region B2, for example, by making the dimensions approximately the same as those of the intermediate region B2.

[0045] Fig. 10 is a flowchart showing an example of a method for setting an operation recipe for the resistor 450, the anode mask 426, and the shield 470 during a plating process by the control module 800. The method shown in Fig. 10 is executed during a plating process in place of the method shown in Fig. 8 or to correct the operation recipe set by the method shown in Fig. 8. Note that the control module 800 may set operation recipes for only some of the resistor 450, the anode mask 426, and the shield 470.

[0046] When the plating process begins (step S210), the control module 800 acquires plating film parameters from the sensor 460 in real time (step S220). In this embodiment, the sensor 460 detects the plating film parameters as the substrate Wf rotates. In one embodiment, the sensor 460 detects the plating film parameters at multiple points along the radial direction on the plating surface Wf-a. The control module 800 calculates the thickness distribution of the plating film on the plating surface Wf-a based on the values ​​detected by the sensor 460 (step S230). Next, the control module 800 sets operation recipes for the resistor 450, the anode mask 426, and the shield 470 based on the calculated thickness distribution (step S240). The control module 800 repeats steps S220 to S240 until the plating process is completed (step S250), setting operation recipes for the controlled objects. The control module 800 then controls the resistor 450, the anode mask 426, and the shield 470 based on the set operation recipes. In this way, by setting or modifying the operating recipe for resistor 450, etc. during the plating process based on the parameters related to the plating film obtained from sensor 460, the uniformity of the thickness of the plating film can be further improved.

[0047] <First Modification> Fig. 11 is a longitudinal cross-sectional view schematically showing a resistor 450A in a first modification in which the first resistor member 452A and the second resistor member 456 are spaced apart, and Fig. 12 is a longitudinal cross-sectional view schematically showing a resistor 450A in a first modification in which the first resistor member 452A and the second resistor member 456 are in contact. Regarding the resistor 450A of the first modification, portions that overlap with the resistor 450 of the above-described embodiment will not be described. A groove 455 that is annular when viewed from below is formed on the lower surface of the first resistor member 452A of the resistor 450A of the first modification, and the second resistor member 456 can be accommodated in this groove 455. In one embodiment, as shown in FIG. 12 , when the second resistance member 456 is in contact with the first resistance member 452 and positioned in the groove 455, the lower surface 452-a of the first resistance member 452 and the lower surface 456-a of the second resistance member 456 are positioned on the same plane. However, this is not limited to this example, and the groove 455 of the first resistance member 452 may be formed shallower or deeper than the thickness Th2 of the second resistance member 456. As such, the first resistance member 452A in the first modified example is formed with a groove 455 that can accommodate at least a portion of the second resistance member 456. This makes it possible to increase the thickness Th2 of the second resistance member 456 and increase the range of vertical movement of the second resistance member 456 within the limited space within the plating tank 410.

[0048] 13 to 15 are enlarged longitudinal cross-sectional views schematically illustrating a resistor 450B according to a second modification, in which the first resistor 452 and the second resistor 456B are spaced apart by first to third distances. Regarding the resistor 450B of the second modification, portions that overlap with the resistor 450 of the above-described embodiment will not be described. The second resistor 456B of the modified resistor 450B has a plurality of protrusions 458 formed at positions corresponding to the plurality of first through-holes 453 of the first resistor 452, as viewed from above, that are insertable into the first through-holes 453. In one example, the plurality of protrusions 458 include a first protrusion 458a having a first height h1, a second protrusion 458b having a second height h2 that is shorter than the first height h1, and a third protrusion 458c having a third height h3 that is shorter than the second height h2. However, the plurality of protrusions 458 may include two or four or more types of protrusions having different heights, or may all have the same height.

[0049] In the second modification, the drive mechanism 451 for moving the second resistance member 456B up and down includes a cam 451B disposed in the plating tank 410 and a drive source (not shown) configured to rotate the cam 451B. The drive source may be a known mechanism such as a motor. In the second modification, the rotation of the cam 451B disposed in the plating tank 410 moves the second resistance member 456B up and down, thereby adjusting the distance between the first resistance member 452 and the second resistance member 456B.

[0050] In the resistor 450B of the second modification, as in the above embodiment, the amount of electric field adjustment can be changed mainly in the region where the second resistor 456B is located by changing the distance between the first resistor 452 and the second resistor 456B. As shown in FIG. 13 , when the first resistor 452 and the second resistor 456B are sufficiently spaced apart, the current passing through the plurality of first through holes 453 of the first resistor 452 is hardly blocked by the second resistor 456B. However, when the distance between the first resistor 452 and the second resistor 456B becomes shorter, the distance between the plurality of first through holes 453 of the first resistor 452 and the plurality of protrusions 458 formed on the second resistor 456B becomes shorter, making it difficult for the current to flow through the first through holes 453. Furthermore, in the second modified example, the multiple protrusions 458 have different heights h1 to h3. As shown in FIG. 14 , when the first resistance member 452 and the second resistance member 456 approach each other, the taller first protrusion 458a is inserted into the first through-hole 453 first. As a result, no current flows, or the current flows less easily, through the first through-hole 453 into which the first protrusion 458a is inserted. Then, when the first resistance member 452 and the second resistance member 456 approach each other further, the second protrusion 458b is inserted into the first through-hole 453 as shown in FIG. 15 . As a result, no current flows, or the current flows less easily, through the first through-hole 453 into which the first protrusion 458a is inserted and the first through-hole 453 into which the second protrusion 458b is inserted. In this way, in resistor 450B of the second modification, first to third convex portions 458a to 458c are inserted into first through-hole 453 according to the distance between first resistance member 452 and second resistance member 456, and can block current from flowing through first through-hole 453. Therefore, resistor 450B of the second modification can more finely change the amount of electric field adjustment in the region where second resistance member 456 is mainly disposed.

[0051] <Other Modifications> In the above-described embodiment, the plating module 400 is arranged so that the plating surface Wf-a of the substrate Wf faces downward during plating. However, this is not limited to this example, and as one example, the plating surface Wf-a of the substrate Wf and the anode 430 may be arranged to face each other in the horizontal direction.

[0052] The present invention can also be described as the following embodiments. [Embodiment 1] According to embodiment 1, a plating apparatus is proposed, comprising: a plating tank; a substrate holder configured to hold a substrate; an anode disposed in the plating tank facing the substrate held by the substrate holder; and a resistor disposed between the substrate holder and the anode for adjusting an electric field, the resistor comprising a first resistor element and a second resistor element disposed between the first resistor element and the substrate holder or between the first resistor element and the anode, the first resistor element having a plurality of first through holes opening toward the substrate holder and the anode, at least some of the plurality of first through holes overlap with the second resistor element so that the anode is not visible when viewed from the substrate side, and the second resistor element is configured so that the distance between the second resistor element and the first resistor element is variable. According to embodiment 1, a plating apparatus is proposed that can improve the uniformity of the thickness of a plating film formed on an object to be plated.

[0053] [Mode 2] According to Mode 2, the second resistance member in Mode 1 has an annular shape when viewed from the substrate holder side to the anode side. According to Mode 2, the thickness of the plating film can be adjusted, particularly in the annular region.

[0054] [Mode 3] According to Mode 3, in Mode 1 or 2, the second resistance member is formed with a plurality of second through holes that open to the substrate holder side and the anode side.

[0055] [Form 4] According to Form 4, in Form 3, the plurality of second through holes include a plurality of through holes formed on a first reference circle and a plurality of through holes formed on a second reference circle that is concentric with the first reference circle but has a different diameter.

[0056] [Mode 5] According to Mode 5, in any of Modes 1 to 4, the second resistance member is configured to be movable between a position spaced apart from the first resistance member and a position where the second resistance member contacts the first resistance member and blocks at least some of the first through-holes. According to Mode 5, the first resistance member and the second resistance member can be brought into contact with each other to block at least some of the first through-holes of the first resistance member.

[0057] [Mode 6] According to Mode 6, in Modes 1 to 5, the first resistance member has a groove formed therein that can accommodate at least a portion of the second resistance member. According to Mode 6, the thickness of the second resistance member can be increased, and the range of movement of the second resistance member can be increased.

[0058] [Mode 7] According to Mode 7, in any of Modes 1 to 6, the second resistance member has a plurality of protrusions that are formed at positions where the plurality of first through holes of the first resistance member are formed, when viewed from the substrate holder side to the anode side, and are insertable into the plurality of first through holes, the plurality of protrusions including first protrusions having a first height and second protrusions having a second height that is lower than the first height. According to Mode 7, the resistor can be adjusted between a state in which the first protrusions are inserted into some of the plurality of first through holes and a state in which the first protrusions are inserted into some of the plurality of first through holes and the second protrusions are inserted into other parts of the plurality of first through holes.

[0059] [Mode 8] According to Mode 8, in any of Modes 1 to 7, a drive mechanism configured to move the second resistance member to adjust the distance between the first resistance member and the second resistance member is provided. According to Mode 8, the distance between the first resistance member and the second resistance member can be adjusted by the drive mechanism.

[0060] [Mode 9] According to Mode 9, in Mode 8, the drive mechanism has a pneumatic actuator disposed outside the plating tank.

[0061] [Mode 10] According to Mode 10, in Mode 8, the drive mechanism includes a cam disposed in the plating tank and a drive source configured to rotate the cam.

[0062] [Mode 11] According to Mode 11, the device according to Modes 8 to 10 further includes a controller that controls the drive mechanism based on a resist pattern on the substrate held by the substrate holder. According to Mode 11, the controller can control the distance between the first resistance member and the second resistance member.

[0063] [Mode 12] According to Mode 12, the device according to Mode 11 further includes an anode mask disposed between the anode and the resistor, the anode mask having an anode opening penetrating from the anode side to the substrate holder side, the anode mask configured to be adjustable in size, and the controller controls the drive mechanism and the anode mask based on the resist pattern. According to Mode 12, the controller can control the distance between the first resistor member and the second resistor member and the size of the anode opening.

[0064] [Mode 13] According to Mode 13, in Modes 1 to 12, the substrate holder is configured to hold the substrate in the plating tank with the surface to be plated facing downward, and the second resistance member is positioned between the first resistance member and the anode.

[0065] Although the embodiments of the present invention have been described above, the above-described embodiments 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 of the embodiments and modifications is possible within the scope of solving at least part of the above-described problems or achieving at least part of the effects, and any combination or omission of the components described in the claims and specification is possible.

[0066] Wf-a...surface to be plated Wf...substrate 400...plating module 410...plating tank 420...membrane 422...cathode region 424...anode region 430...anode 440...substrate holder 442...lifting mechanism 448...rotation mechanism 450, 450A, 450B...resistor 451...drive mechanism 451B...cam 452, 452A...first resistance member 453...first through-hole 455...groove 456, 456B...second resistance member 457...second through-hole 458, 458a to 458c...convex portion 460...sensor 470...shield 480...paddle 482...paddle stirring mechanism 800...control module 1000...plating apparatus

Claims

1. A plating apparatus comprising: a plating tank; a substrate holder configured to hold a substrate; an anode arranged in the plating tank so as to face the substrate held in the substrate holder; and a resistor arranged between the substrate holder and the anode for adjusting an electric field, wherein the resistor comprises a first resistance element and a second resistance element arranged between the first resistance element and the substrate holder or between the first resistance element and the anode, wherein the first resistance element has a plurality of first through holes formed therein that open to the substrate holder side and the anode side, at least some of the plurality of first through holes overlap with the second resistance element so that the anode is not visible when viewed from the substrate side toward the anode side, and the second resistance element is configured so that the distance between it and the first resistance element is variable.

2. The plating apparatus according to claim 1, wherein the second resistance member is annular when viewed from the substrate holder side to the anode side.

3. The plating apparatus according to claim 1, wherein the second resistance member has a plurality of second through holes formed therein that open toward the substrate holder side and the anode side.

4. The plating apparatus of claim 3, wherein the plurality of second through holes include a plurality of through holes formed on a first reference circle and a plurality of through holes formed on a second reference circle that is concentric with the first reference circle but has a different diameter.

5. The plating apparatus of claim 1, wherein the second resistance member is configured to be movable between a position spaced apart from the first resistance member and a position in contact with the first resistance member so that at least a portion of the plurality of first through holes are blocked by the second resistance member.

6. The plating apparatus according to claim 1, wherein the first resistance member has a groove formed therein capable of accommodating at least a portion of the second resistance member.

7. The plating apparatus described in claim 1, wherein the second resistance member has a plurality of protrusions formed at positions where the plurality of first through holes of the first resistance member are formed when viewed from the substrate holder side to the anode side, and which are insertable into the plurality of first through holes, and the plurality of protrusions include first protrusions having a first height and second protrusions having a second height lower than the first height.

8. The plating apparatus according to claim 1, further comprising a drive mechanism configured to move the second resistance member to adjust the distance between the first resistance member and the second resistance member.

9. The plating apparatus according to claim 8, wherein the drive mechanism includes a pneumatic actuator disposed outside the plating tank.

10. The plating apparatus according to claim 8, wherein the drive mechanism comprises a cam disposed within the plating tank and a drive source configured to rotate the cam.

11. The plating apparatus according to claim 8, further comprising a controller that controls the drive mechanism based on a resist pattern on the substrate held by the substrate holder.

12. The plating apparatus according to claim 11, further comprising an anode mask disposed between the anode and the resistor, the anode mask having an anode opening penetrating the anode side and the substrate holder side, the anode mask being configured so that the size of the anode opening can be adjusted, and the controller controlling the drive mechanism and the anode mask based on the resist pattern.

13. A plating apparatus according to any one of claims 1 to 12, wherein the substrate holder is configured to hold the substrate in the plating tank with the surface to be plated facing downward, and the second resistance member is disposed between the first resistance member and the anode.

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