Plating method

Abstract

The present invention provides a technique capable of achieving uniform bump height. A plating method is a plating method using a plating apparatus (1000) having a plating bath (10), a substrate holder (30), a power supply (80), and a stirring mechanism (60), and includes: when performing a plating process for plating a substrate (Wf), controlling the power supply in such a manner that a forward current for causing metal to precipitate from the plating solution onto the substrate and an anode (11) is supplied to the substrate and the anode a plurality of times, and a current flowing in a pulsed manner in the opposite direction to the forward current, that is, a reverse current pulse; and when performing the plating process, obtaining a variation amplitude of the voltage of the substrate after supplying the reverse current pulse, and performing control to change the stirring intensity of the stirring mechanism based on the obtained variation amplitude.

Description

Technical Field

[0001] The present invention relates to a plating method. Background Art

[0002] Conventionally, a plating method for plating a substrate has been known (see, for example, Patent Documents 1, 2, and 3). A plating apparatus used in such a plating method includes, for example: a plating bath that stores a plating solution and is provided with an anode; a substrate holder that holds the substrate as a cathode so as to face the anode; a power supply configured to supply current to the substrate and the anode; and a stirring mechanism configured to stir the plating solution. Further, conventionally, in such a plating apparatus, the plating solution in the plating bath contains a promoter for promoting plating.

[0003] In addition, Patent Documents 2 and 3 also disclose a technique of forming bumps by plating metal on a substrate. Further, Patent Documents 2 and 3 also disclose a technique of controlling the power supply by supplying positive current and reverse current pulses to the substrate and the anode.

[0004] Patent Document 1: Japanese Patent No. 7079388

[0005] Patent Document 2: Japanese Patent No. 7357824

[0006] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2006-131926

[0007] In recent years, there has been a continuous demand for the height uniformity of bumps formed on a substrate by plating. In this regard, there is room for improvement in the prior art. Summary of the Invention

[0008] The present invention has been made in view of the above problems, and one of its objects is to provide a technique capable of achieving the height uniformity of bumps.

[0009] (Aspect 1)

[0010] To achieve the above object, a plating method according to one aspect of the present invention is a plating method using a plating apparatus, the plating apparatus including: a plating bath that stores a plating solution containing an accelerator for promoting plating and is provided with an anode; a substrate holder configured to hold a substrate as a cathode opposite to the anode; a power supply configured to supply current to the substrate and the anode; and a stirring mechanism configured to stir the plating solution, the plating method including: when performing a plating process of plating the substrate, controlling the power supply to supply a forward current for depositing metal from the plating solution onto the substrate and a current flowing in a pulsed manner in the opposite direction to the forward current, i.e., a reverse current pulse, to the substrate and the anode multiple times; and when performing the plating process, obtaining a variation amplitude of the voltage of the substrate after supplying the reverse current pulse, and performing control to change the stirring intensity of the stirring mechanism based on the obtained variation amplitude, the variation amplitude being the difference between the voltage immediately before supplying the reverse current pulse and the minimum value of the voltage generated after supplying the reverse current pulse, or the difference between the minimum value and the maximum value of the voltage generated after the minimum value is generated.

[0011] According to this aspect, it is possible to converge the variation amplitude of the voltage after supplying the reverse current pulse within a specified range. Thereby, it is possible to achieve the uniformity of the height of the bumps formed of the metal deposited on the substrate.

[0012] (Aspect 2)

[0013] In the above Aspect 1, the stirring mechanism may include a stirring rod, the stirring rod being disposed between the substrate and the anode and configured to stir the plating solution.

[0014] (Aspect 3)

[0015] In the above Aspect 1, the stirring mechanism may include a rotating mechanism configured to stir the plating solution by rotating the substrate holder.

[0016] (Aspect 4)

[0017] In the above Aspect 1, the stirring mechanism may include a plating solution flow mechanism configured to stir the plating solution by flowing the plating solution in the plating bath.

[0018] (Aspect 5)

[0019] In any one of the above-described Forms 1 to 4, the variation range of the voltage of the substrate after supplying the reverse current pulse includes: the variation range of the voltage between the substrate and the anode after supplying the reverse current pulse, or the variation range of the voltage between the substrate and a reference electrode disposed in the plating bath after supplying the reverse current pulse.

[0020] (Form 6)

[0021] To achieve the above object, a plating method according to one form of the present invention is a plating method using a plating apparatus including: a plating bath that stores a plating solution containing an accelerator for promoting plating and is provided with an anode; a substrate holder configured to hold a substrate as a cathode opposite to the anode; a power supply configured to supply current to the substrate and the anode; and a stirring mechanism configured to stir the plating solution. The plating method includes: before performing a plating process for plating the substrate, controlling the power supply so as to supply a reverse current pulse, which is a current flowing in a pulsed manner in a direction opposite to the direction of a forward current for depositing metal from the plating solution onto the substrate, to the substrate and the anode, and previously obtaining a control map of the stirring intensity of the stirring mechanism such that the variation range of the voltage of the substrate after supplying the reverse current pulse converges within a specified range; and during the plating process, while controlling the stirring intensity of the stirring mechanism based on the previously obtained control map, controlling the power supply so as to supply the forward current and the reverse current pulse to the substrate and the anode multiple times. The variation range is the difference between the voltage immediately before supplying the reverse current pulse and the minimum value of the voltage generated after supplying the reverse current pulse, or the difference between the minimum value and the maximum value of the voltage generated after the minimum value.

[0022] According to this form, it is possible to converge the variation range of the voltage after supplying the reverse current pulse within a specified range. Thereby, it is possible to achieve the uniformity of the height of bumps formed of metal deposited on the substrate by plating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a perspective view showing the overall structure of the plating apparatus according to the embodiment.

[0024] Figure 2 is a top view showing the overall structure of the plating apparatus according to the embodiment.

[0025] Figure 3 is a schematic view showing the structure of the plating module according to the embodiment.

[0026] Figure 4It is a schematic diagram showing the state where the substrate involved in the embodiment is immersed in the plating solution.

[0027] Figure 5 It is a schematic top view of the stirrer involved in the embodiment.

[0028] Figure 6 (A) of is a schematic diagram for explaining the surface structure of the substrate involved in the embodiment. Figure 6 (B) of is a schematic diagram showing an example of the opening pattern of the photoresist layer involved in the embodiment.

[0029] Figure 7 It is shown as having Figure 6 It is a chart showing an example of measuring the height of bumps in each pattern region when bumps are formed on the substrate of the photoresist layer illustrated in (B) of.

[0030] Figure 8 (A) of and Figure 8 (B) of are diagrams for explaining the variation range of the voltage.

[0031] Figure 9 It is an example of a flowchart for explaining the plating method according to Embodiment 1.

[0032] Figure 10 (A) of and Figure 10 (B) of are charts showing the experimental results of the substrate using the bump pattern 1.

[0033] Figure 11 (A) of and Figure 11 (B) of are charts showing the experimental results of the substrate using the bump pattern 2.

[0034] Figure 12 It is an example of a flowchart for explaining the plating method according to Embodiment 2. Detailed Embodiment

[0035] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the drawings are schematically illustrated to make the features of the constituent elements easy to understand, and the dimensional ratios of the respective constituent elements are not necessarily the same as the actual ones. Further, in several drawings, an orthogonal coordinate of X - Y - Z is illustrated for reference. In this orthogonal coordinate, the Z direction corresponds to the upper side, and the - Z direction corresponds to the lower side (the direction of gravity).

[0036] (Embodiment 1)

[0037] Figure 1 It is a perspective view showing the overall structure of the plating apparatus 1000 according to the embodiment. Figure 2is a top view (plan view) showing the overall structure of the plating apparatus 1000 according to the embodiment. As Figure 1 and Figure 2 shown, the plating apparatus 1000 includes a load port 100, a transfer robot 110, an aligner 120, a pre-wetting module 200, a pre-dipping module 300, a plating module 400, a cleaning module 500, a spin dryer 600, a transfer device 700, and a control module 800.

[0038] The load port 100 is a module for loading a substrate accommodated in a cassette such as a FOUP (not shown) into the plating apparatus 1000 and unloading the substrate from the plating apparatus 1000 to the cassette. In the present embodiment, four load ports 100 are arranged and configured in the horizontal direction, but the number and configuration of the load ports 100 are arbitrary. The transfer robot 110 is a robot for transferring a substrate, and is configured to transfer the substrate between the load port 100, the aligner 120, the pre-wetting module 200, and the spin dryer 600. When transferring the substrate between the transfer robot 110 and the transfer device 700, the transfer robot 110 and the transfer device 700 can transfer the substrate via a temporary placement table (not shown).

[0039] The aligner 120 is a module for aligning the orientation plane, notch, etc. of the substrate in a specified direction. In the present embodiment, two aligners 120 are arranged and configured in the horizontal direction, but the number and configuration of the aligners 120 are arbitrary. The pre-wetting module 200 wets the surface to be plated of the substrate before the plating process with a treatment liquid such as pure water or degassed water, thereby replacing the air inside the pattern formed on the substrate surface with the treatment liquid. The pre-wetting module 200 is configured to perform a pre-wetting process that facilitates the supply of the plating liquid into the pattern by replacing the treatment liquid inside the pattern with the plating liquid during plating. In the present embodiment, two pre-wetting modules 200 are arranged and configured in the vertical direction, but the number and configuration of the pre-wetting modules 200 are arbitrary.

[0040] The pre-dipping module 300 is configured to perform a pre-dipping process of, for example, etching and removing an oxide film having a relatively high resistance present on the surface of the seed layer formed on the surface to be plated of the substrate before the plating process with a treatment liquid such as sulfuric acid or hydrochloric acid to clean or activate the surface of the plating substrate. In the present embodiment, two pre-dipping modules 300 are arranged and configured in the vertical direction, but the number and configuration of the pre-dipping modules 300 are arbitrary. The plating module 400 performs plating on the substrate. In the present embodiment, there are two sets of twelve plating modules 400 arranged and configured in three in the vertical direction and four in the horizontal direction, and a total of 24 plating modules 400 are provided, but the number and configuration of the plating modules 400 are arbitrary.

[0041] The cleaning module 500 is configured to perform a cleaning process on the substrate in order to remove plating solutions and the like remaining on the substrate after the plating process. In the present embodiment, two cleaning modules 500 are arranged and configured in the vertical direction, but the number and configuration of the cleaning modules 500 are arbitrary. The rotary dryer 600 is a module for drying the substrate by rotating it at high speed after the cleaning process. In the present embodiment, two rotary dryers 600 are arranged and configured in the vertical direction, but the number and configuration of the rotary dryers 600 are arbitrary. The transfer device 700 is a device for transferring the substrate 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 constituted by, for example, a general computer or a dedicated computer having an input / output interface with the operator.

[0042] An example of a series of plating processes performed by the plating apparatus 1000 will be described. First, a substrate housed in a cassette is loaded into the load port 100. Next, the transfer robot 110 takes out the substrate from the cassette in the load port 100 and transfers the substrate to the aligner 120. The aligner 120 aligns the orientation plane, notch, and other positions of the substrate in a specified direction. The transfer robot 110 transfers the substrate whose direction has been aligned by the aligner 120 to the pre-wetting module 200.

[0043] The pre-wetting module 200 performs a pre-wetting process on the substrate. The transfer device 700 transfers the substrate on which the pre-wetting process has been performed to the pre-dipping module 300. The pre-dipping module 300 performs a pre-dipping process on the substrate. The transfer device 700 transfers the substrate on which the pre-dipping process has been performed to the plating module 400. The plating module 400 performs plating on the substrate.

[0044] The transfer device 700 transfers the substrate on which the plating process has been performed to the cleaning module 500. The cleaning module 500 performs a cleaning process on the substrate. The transfer device 700 transfers the substrate on which the cleaning process has been performed to the rotary dryer 600. The rotary dryer 600 performs a drying process on the substrate. The transfer robot 110 receives the substrate from the rotary dryer 600 and transfers the substrate on which the drying process has been performed to the cassette in the load port 100. Finally, the cassette containing the substrate is unloaded from the load port 100.

[0045] In addition, Figure 1 , Figure 2 The structure of the plating apparatus 1000 described Figure 1 , Figure 2 is only an example, and the structure of the plating apparatus 1000 is not limited to

[0046] Next, the plating module 400 will be described. In addition, since the plurality of plating modules 400 included in the plating apparatus 1000 according to the present embodiment have the same structure, one plating module 400 will be described.

[0047] Figure 3 It is a schematic diagram showing the structure of the plating module 400 in the plating apparatus 1000. Specifically, Figure 3 The plating module 400 is schematically shown in a state before the substrate Wf is immersed in the plating solution Ps. Figure 4 It is a schematic diagram showing the state where the substrate Wf is immersed in the plating solution Ps.

[0048] As an example, Figure 3 and Figure 4 The plating apparatus 1000 exemplified in is a type of plating apparatus (so-called cup-type plating apparatus) in which the substrate Wf is immersed in the plating solution Ps with the plane direction being horizontal. However, the structure of the plating apparatus 1000 is not limited thereto. For example, it may also be a type of plating apparatus in which the substrate Wf is immersed in the plating solution Ps with the plane direction being non-horizontal (as an example, a direction perpendicular to the ground).

[0049] Figure 3 and Figure 4 The plating module 400 of the plating apparatus 1000 exemplified in includes a plating tank 10, an overflow tank 20, a substrate holder 30, and a stirring rod 70 as an example of a stirring mechanism 60. In addition, as exemplified in Figure 3 , the plating module 400 includes a rotating mechanism 40, an inclination mechanism 45, and a lifting mechanism 50. In addition, as exemplified in Figure 3 , the plating module 400 includes sensors 130. In addition, as exemplified in Figure 4 , the plating module 400 includes a power supply 80 and a plating solution flow mechanism 90.

[0050] The plating tank 10 according to the present embodiment is composed of a bottomed container having an opening at the upper part. Specifically, the plating tank 10 has a bottom wall 10a and an outer peripheral wall 10b extending upward from the outer peripheral edge of the bottom wall 10a, and the upper part of the outer peripheral wall 10b is open. In addition, the shape of the outer peripheral wall 10b of the plating tank 10 is not particularly limited. As an example, the outer peripheral wall 10b according to the present embodiment has a cylindrical shape. The plating solution Ps is stored inside the plating tank 10.

[0051] As the plating solution Ps, any solution containing ions of the metal elements constituting the plating film may be used, and specific examples thereof are not particularly limited. In the present embodiment, copper plating treatment is used as an example of the plating treatment, and a copper sulfate solution is used as an example of the plating solution Ps. In addition, a predetermined additive may be included in the plating solution Ps.

[0052] As the additive contained in the plating solution Ps, for example, an accelerator that promotes plating (specifically, an accelerator that promotes the formation of the plating film) can be used. For example, SPS (bis(3-sulfopropyl) disulfide) or the like can be used as the accelerator.

[0053] An anode 11 is disposed inside the plating tank 10. The specific type of the anode 11 is not particularly limited, and it may be an insoluble anode or a soluble anode. In the present embodiment, an insoluble anode is used as an example of the anode 11. The specific type of the insoluble anode is not particularly limited, and platinum, iridium oxide, or the like can be used.

[0054] As Figure 3 , Figure 4 illustrated in, an ion inhibitor 12 may also be disposed inside the plating tank 10 at a position above the anode 11. Specifically, as illustrated in the partial enlarged view of Figure 4 , the ion inhibitor 12 is composed of a porous plate member having a plurality of holes 12a (fine holes). The holes 12a are provided to communicate the lower surface and the upper surface of the ion inhibitor 12.

[0055] The ion inhibitor 12 is provided to equalize the electric field formed between the anode 11 and the substrate Wf as the cathode. As in the present embodiment, by disposing the ion inhibitor 12 in the plating tank 10, it is possible to easily equalize the film thickness of the plating film (plating layer) formed on the substrate Wf.

[0056] As Figure 3 , Figure 4 illustrated in, a film 16 may also be disposed inside the plating tank 10 at a position above the anode 11 and below the ion inhibitor 12. In this case, the inside of the plating tank 10 is divided by the film 16 into an anode chamber 17a below the film 16 and a cathode chamber 17b above the film 16. The anode 11 is disposed in the anode chamber 17a, and the ion inhibitor 12 and the substrate Wf are disposed in the cathode chamber 17b. The film 16 is configured to allow the ionic species containing metal ions contained in the plating solution Ps to pass through the film 16 and to inhibit the non-ionic plating additives contained in the plating solution Ps from passing through the film 16. For example, an ion exchange membrane can be used as such a film 16.

[0057] As Figure 4As exemplified above, the plating solution flow mechanism 90 is configured to cause the plating solution Ps in the plating tank 10 to flow. The plating solution Ps in the plating tank 10 flows, so that the plating solution Ps in the plating tank 10 is stirred. As an example, the plating solution flow mechanism 90 according to the present embodiment includes a first flow mechanism 91a and a second flow mechanism 91b.

[0058] The first flow mechanism 91a is a mechanism for causing the plating solution Ps in the anode chamber 17a to flow. The second flow mechanism 91b is a mechanism for causing the plating solution Ps in the cathode chamber 17b to flow. The first flow mechanism 91a communicates with the anode chamber 17a via a pipe 92a. The second flow mechanism 91b communicates with the cathode chamber 17b via a pipe 92b. In addition, the first flow mechanism 91a and the second flow mechanism 91b each include a pump or the like for pumping the plating solution Ps.

[0059] Refer to Figure 3 and Figure 4 , a supply port for supplying the plating solution Ps to the plating tank 10 is provided in the plating tank 10. Specifically, a first supply port 13a for supplying the plating solution Ps to the anode chamber 17a and a second supply port 13b for supplying the plating solution Ps to the cathode chamber 17b are provided on the outer peripheral wall 10b of the plating tank 10 according to the present embodiment. The plating solution Ps discharged from the first discharge port 14a is pumped by the first flow mechanism 91a and supplied again to the anode chamber 17a from the first supply port 13a.

[0060] The overflow tank 20 is composed of a bottomed container disposed outside the plating tank 10. The overflow tank 20 is provided to temporarily store the plating solution Ps that has exceeded the upper end of the outer peripheral wall 10b of the plating tank 10 (that is, the plating solution Ps that has overflowed from the plating tank 10). After the plating solution Ps stored in the overflow tank 20 is discharged from the second discharge port 14b, it is pumped by the second flow mechanism 91b and supplied again to the cathode chamber 17b from the second supply port 13b.

[0061] The substrate holder 30 holds the substrate Wf as a cathode such that the surface to be plated Wfa of the substrate Wf faces the anode 11. Specifically, in the present embodiment, the surface to be plated Wfa of the substrate Wf is provided on the surface (lower surface) of the substrate Wf facing the lower side.

[0062] The substrate holder 30 is connected to the rotation mechanism 40. The rotation mechanism 40 is a mechanism for rotating the substrate holder 30. Figure 3"R1" exemplified therein is an example of the rotation direction of the substrate holder 30. A known rotation motor or the like can be used as the rotation mechanism 40. The tilt mechanism 45 is a mechanism for tilting the rotation mechanism 40 and the substrate holder 30. The lifting mechanism 50 is supported by a support shaft 51 extending in the vertical direction. The lifting mechanism 50 is a mechanism for lifting the substrate holder 30, the rotation mechanism 40, and the tilt mechanism 45 in the vertical direction. A known lifting mechanism such as a linear actuator can be used as the lifting mechanism 50.

[0063] The control module 800 includes a microcomputer having a processor 801, a storage device 802 as a non-transitory storage medium, and the like. The control module 800 operates based on instructions of a program stored in the storage device 802 by the processor 801 to control the operation of the plating module 400.

[0064] Refer to Figure 3 , the sensors 130 detect various information for various controls of the control module 800 and transmit the detection results to the control module 800. The sensors 130 include, for example, a current sensor that detects the current value (A) between the anode 11 and the substrate Wf.

[0065] In addition, the sensors 130 include a voltage sensor that detects the voltage value (V) of the substrate Wf. Further, the voltage sensor according to the present embodiment is configured to also detect "the change amplitude (Wd) of the voltage of the substrate Wf" described later.

[0066] In addition, the voltage sensor may detect the voltage value between the substrate Wf and the anode 11, or may detect "the change amplitude (Wd) of the voltage between the substrate Wf and the anode 11". Alternatively, the voltage sensor may detect the voltage value between the substrate Wf and the reference electrode 18 ( Figure 4 exemplified therein), or may detect "the change amplitude (Wd) of the voltage between the substrate Wf and the reference electrode 18". In addition, the reference electrode 18 is disposed inside the plating tank 10 and is referenced instead of the anode 11 when detecting the voltage and the change amplitude of the voltage. The specific disposition position of the reference electrode 18 inside the plating tank 10 is not particularly limited. In the present embodiment, as an example, it is disposed at a position near the anode 11 of the plating tank 10 (above the bottom wall 10a in the present embodiment).

[0067] In addition, the sensor class 130 includes a speed sensor for detecting the moving speed (rpm or m / sec) of the stirrer 70. In addition, the sensor class 130 includes a rotational speed sensor for detecting the rotational speed (rpm) of the substrate holder 30. In addition, the sensor class 130 includes a flow rate sensor for detecting the flow rate (m / sec) of the plating solution Ps in the plating tank 10. Specifically, the flow rate sensor includes a flow rate sensor for detecting the flow rate of the plating solution Ps in the anode chamber 17a and a flow rate sensor for detecting the flow rate of the plating solution Ps in the cathode chamber 17b.

[0068] As Figure 4 illustrated in the example, the power supply 80 is configured to be electrically connected to the substrate Wf and the anode 11 and supply current between the substrate Wf and the anode 11. The operation of the power supply 80 is controlled by the control module 800.

[0069] The control module 800 according to the present embodiment controls the power supply 80 in such a manner that, at least during "plating treatment" for plating the substrate Wf, a "positive current" for causing metal to precipitate from the plating solution Ps onto the substrate Wf and a current flowing in a pulsed manner in the opposite direction to the positive current, that is, a "reverse current pulse", are supplied to the substrate Wf and the anode 11.

[0070] Specifically, as an example, the control module 800 controls the power supply 80 in such a manner that a reverse current pulse is supplied after the supply of the positive current. More specifically, as an example, the control module 800 according to the present embodiment controls the power supply 80 in such a manner that the positive current and the reverse current pulse are alternately supplied.

[0071] Figure 5 is a schematic top view of the stirrer 70. Refer to Figure 3 , Figure 4 and Figure 5 , the stirrer 70 is disposed between the substrate Wf and the anode 11 (specifically, in the present embodiment, as an example, between the substrate Wf and the ion resistance body 12). The stirrer 70 is driven by a driving device 77 that receives an instruction from the control module 800. By driving the stirrer 70, the plating solution Ps in the plating tank 10 is stirred.

[0072] As an example, the stirrer 70 according to the present embodiment is driven alternately in the "first direction (as an example, the X direction in the present embodiment) parallel to the substrate Wf" and the "second direction (as an example, the -X direction in the present embodiment) opposite to the first direction". That is, as an example, the stirrer 70 according to the present embodiment reciprocates in the X-axis direction.

[0073] As Figure 5As exemplified above, as an example, the stirrer 70 according to the present embodiment has a plurality of stirring members 71a extending in a direction (Y-axis direction) perpendicular to the first direction and the second direction of the stirrer 70. A gap is provided between adjacent stirring members 71a. One ends of the plurality of stirring members 71a are connected to a connecting member 72a, and the other ends are connected to a connecting member 72b.

[0074] However, the structure of the stirrer 70 is not limited thereto. For example, various known stirrers exemplified in Patent Document 1 can be used.

[0075] In addition, the stirrer 70 only needs to be disposed inside the plating tank 10 at least when stirring the plating solution Ps, and does not need to be always disposed inside the plating tank 10. For example, it can also be configured such that when the driving of the stirrer 70 is stopped and the stirrer 70 does not stir the plating solution Ps, the stirrer 70 is not disposed inside the plating tank 10.

[0076] In addition, "the moving speed of the stirrer 70 is N (rpm)" specifically means that the stirrer 70 makes N reciprocations in one minute (that is, the stirrer 70 moves from a specified position, for example, moves in the first direction, then moves in the second direction, and then moves in the first direction again and returns to the specified position). The faster the moving speed of the stirrer 70, the stronger the stirring intensity of the stirrer 70 on the plating solution Ps. That is, the moving speed of the stirrer 70 is an example of "the stirring intensity of the plating solution Ps".

[0077] Figure 6 (A) is a schematic diagram for explaining the surface structure of the substrate Wf. Specifically, Figure 6 (A) schematically shows a cross-sectional view of a state where bumps 143 are formed on the substrate Wf by plating treatment. In addition, specifically, the bumps 143 are formed of a metal (such as Cu) deposited on the substrate Wf.

[0078] As an example, as Figure 6 (A) exemplified, on the entire surface of the substrate Wf according to the present embodiment, a relatively thin seed layer 140 of metal is provided in advance. During the plating treatment, the surface of the substrate Wf is powered through the seed layer 140. A photoresist layer 141 is provided on the surface of the seed layer 140 on the side opposite to the substrate Wf side. The photoresist layer 141 has an opening 142 at a portion where the bumps 143 are to be formed. In addition, Figure 6 "φ" exemplified in (A) is the diameter (μm) of the opening 142 of the photoresist layer 141, and "BH" is the height (μm) of the bumps 143.

[0079] Figure 6 (B) is a schematic diagram showing an example of the opening pattern of the photoresist layer 141. Figure 6Examples of (B) in which the diameter φ of the opening 142 is relatively small (for example, 30 μm) are shown in FIGS. No1 and No2, and examples of (B) in which the diameter φ of the opening 142 is relatively large (for example, 75 μm) are shown in FIGS. No3 and No4. When comparing No1 and No2, the openings 142 are arranged at a higher density in No1 than in No2. When comparing No3 and No4, the openings 142 are arranged at a higher density in No3 than in No4.

[0080] The substrate Wf provided with the photoresist layer 141 as described above is held by the substrate holder 30 and immersed in the plating solution Ps in the plating tank 10 to perform a plating process. During the plating process, the portions of the surface of the substrate Wf other than the openings 142 of the photoresist layer 141 are shielded from the plating solution Ps by the photoresist layer 141. As a result, the plating film grows only on the portions of the openings 142 of the photoresist layer 141, and thus bumps 143 are formed on the substrate Wf. In addition, the photoresist layer 141 can be removed after the plating process.

[0081] Figure 7 It shows a case where there is Figure 6 This is a graph showing an example of measuring the height (BH) of the bumps 143 in each pattern region when a plurality of bumps 143 are formed on the substrate Wf of the photoresist layer 141 illustrated in (B). Specifically, on the vertical axis of Figure 7 the height (BH) of each bump 143 corresponding to each pattern region P1, P2, P3, P4 in (B) of Figure 6 represents the average value of the heights of the plurality of bumps 143 included in the pattern region.

[0082] Figure 7 The left diagram of Figure 7 shows the measurement results in the case where a positive current is supplied throughout the plating process to form the bumps 143, and

[0083] The right diagram of Figure 7 shows the measurement results in the case where a reverse current pulse is supplied once during the plating process to form the bumps 143.

[0084] From Figure 7 it can be seen that, in the entire pattern region, the height (BH) of the bumps 143 in the pattern region P1 is the lowest, and the height (BH) of the bumps 143 in the pattern region P4 is the highest. This is because: the smaller the diameter φ of the opening 142 and the higher the arrangement density of the openings 142, the more difficult it is to sufficiently supply metal ions into the openings 142, and thus the formation rate of the plating film is lower. Here, the difference between the maximum value and the minimum value of the height (BH) of the bumps 143 is defined as the "bump height deviation (ΔBH)".

[0084] From Figure 7 it can be seen that, in the case where a reverse current pulse is supplied during the plating process (Figure 7 compared with the case where no reverse current pulse is supplied (the right graph in Figure 7 ), the bump height deviation (ΔBH) is small. Thus, by supplying a reverse current pulse, the height of the bump 143 can be made uniform.

[0085] Figure 8 (A) of Figure 8 and (B) of Figure 8 (A) of Figure 8 and (B) of Figure 8 (A) of Figure 8 are diagrams for explaining the voltage change amplitude (Wd).

[0086] Here, the difference between the voltage immediately before supplying the reverse current pulse and the minimum value is defined as the "change amplitude (Wd)" Figure 8 (A) of Figure 8 . Alternatively, the difference between the minimum value and the maximum value generated after the minimum value can also be used as the "change amplitude (Wd)"

[0087] (B) of Figure 10 (A) of Figure 11 (A) of Figure 9 . However, even in the case where a reverse current pulse of a constant value is supplied, the change amplitude (Wd) sometimes changes with the passage of the plating time. For a specific example, even in the case where a reverse current pulse of a constant value is supplied, for example, the change amplitude (Wd) sometimes becomes smaller with the passage of the plating time (refer to (A) of

[0088] Figure 9This is an example of a flowchart for explaining the plating method according to this embodiment (Embodiment 1). First, during the plating process, the control module 800 executes a "power supply control process" (step S10) that controls the power supply 80 to supply positive current and reverse current pulses to the substrate Wf and the anode 11 disposed inside the plating solution Ps multiple times. Specifically, as an example, in step S10, the control module 800 according to this embodiment causes the power supply 80 to supply positive current and reverse current pulses alternately multiple times.

[0089] In addition, as an example, in step S10, the control module 800 according to this embodiment supplies a positive current of a constant value and supplies reverse current pulses of a constant value.

[0090] In addition, the supply time of the positive current is not particularly limited, and it may also be a time that occupies most of the entire time of the plating process. In addition, in this embodiment, the value of the positive current is a constant value, but it is not limited thereto, and it may also change over time. In addition, the specific value of the period during which the reverse current pulse is supplied is not particularly limited. For example, it may also be a value of about 0.1 second to several seconds. In addition, the magnitude of the reverse current pulse is not particularly limited. For example, it is preferably set to a value that can sufficiently remove the accelerator.

[0091] In addition, as exemplified in Patent Document 2 above, a "rest period" may be provided in which the value of the supply current (current output of the power supply 80) from the power supply 80 becomes zero after the reverse current pulse is supplied. In this case, after the rest period has elapsed, a positive current is supplied again. In addition, the specific value of the length of the "rest period" is not particularly limited. For example, it may also be a value of about 0.1 second to several seconds.

[0092] In step S20, the control module 800 executes a "stirring intensity control process" during the plating process. Specifically, the control module 800 according to this embodiment executes a "stirring intensity control process" during the execution of the power supply control process related to step S10 during the plating process.

[0093] More specifically, in the stirring intensity control process related to step S20, the control module 800 obtains the fluctuation amplitude (Wd) of the voltage of the substrate Wf after the reverse current pulse is supplied. Then, the control module 800 executes control to change the stirring intensity of the stirring mechanism 60 according to the voltage fluctuation amplitude (Wd) so that the obtained fluctuation amplitude (Wd) converges within a specified range.

[0094] In addition, as a specific example of the "variation range (Wd) of the voltage of the substrate Wf after supplying a reverse current pulse", the "variation range (Wd) of the voltage between the substrate Wf and the anode 11 after supplying a reverse current pulse" can also be used. Alternatively, the "variation range (Wd) of the voltage between the substrate Wf and the reference electrode 18 after supplying a reverse current pulse" can also be used. In the following description of the present embodiment, as a specific example of the "variation range (Wd) of the voltage of the substrate Wf after supplying a reverse current pulse", the "variation range (Wd) of the voltage between the substrate Wf and the anode 11 after supplying a reverse current pulse" is used.

[0095] Specifically, in a storage device 802 of the control module 800 according to the present embodiment, for example, a control map (data map) that defines the relationship between the variation range (Wd) of the voltage between the substrate Wf and the anode 11 after supplying a reverse current pulse and the stirring intensity (as an example, the moving speed of the stir bar 70) is pre-stored (set). The control map defines the relationship between the variation range (Wd) of the voltage and the stirring intensity in such a way that if the stirring intensity is controlled based on the control map, the variation range (Wd) of the voltage converges within a specified range. The control map can be obtained, for example, by conducting experiments in advance and stored in the storage device 802.

[0096] For example, the control map defines the relationship between the variation range (Wd) of the voltage and the stirring intensity in such a way that the smaller the variation range (Wd) of the voltage, the smaller the stirring intensity (for example, the slower the moving speed of the stir bar 70).

[0097] In step S20, the control module 800 obtains the variation range (Wd) of the voltage between the substrate Wf and the anode 11 after supplying a reverse current pulse based on the detection result of the sensors 130 (for example, a voltage sensor). Then, the stirring intensity corresponding to the obtained variation range of the voltage is extracted from the control map, and the stirring mechanism 60 (as an example, the stir bar 70) is controlled to obtain the extracted stirring intensity. Thus, the actual variation range (Wd) can be converged within a specified range.

[0098] In addition, "converging the variation range (Wd) of the voltage within a specified range" specifically means converging the variation range (Wd) of the voltage within a range that is above a "specified lower limit value" and below a "specified upper limit value". That is, "converging the variation range (Wd) of the voltage within a specified range" means suppressing the variation range (Wd) of the voltage from being too small below the lower limit value and suppressing it from being too large exceeding the upper limit value.

[0099] When the control module 800 changes the stirring intensity of the stirring mechanism 60, the stirring intensity of the stirring mechanism 60 can be changed stepwise as the plating treatment time elapses, or the stirring intensity of the stirring mechanism 60 can be continuously changed as the plating treatment time elapses.

[0100] Taking this specific example, the control module 800 can also slow down the moving speed of the stirring rod 70 stepwise as time elapses, for example, to 150 (rpm), 135 (rpm), 100 (rpm) (refer to (B) described later Figure 10 . Alternatively, the control module 800 can also slow down the moving speed of the stirring rod 70 continuously as time elapses, for example, to 150 (rpm), 149 (rpm), 148 (rpm) ··· 100 (rpm).

[0101] In addition, the specific value of the specified range of the voltage change amplitude (Wd) in step S20 is not particularly limited, but the smaller the change (change with the passage of time) of the change amplitude (Wd), the more uniform the height of the bump 143 can be made. From this perspective, an appropriate value of the specified range can be obtained in advance through experiments or the like and stored in the storage device 802.

[0102] Taking this specific example, as the specified range of the voltage change amplitude (Wd), a numerical range of the voltage change amplitude (Wd) can also be obtained through experiments or the like so that the uniformity of the bump height (specifically, the difference between the maximum value and the minimum value of the height of the bump 143 in one mold) is, for example, 5.0 μm or less, and this numerical range can be used. In this case, the uniformity of the bump height can be suppressed to 5.0 μm or less.

[0103] Alternatively, the specified range of the voltage change amplitude (Wd) can also be specified based on the voltage change amplitude when the reverse current pulse is initially supplied during the plating treatment. Specifically, in this case, as the specified range of the voltage change amplitude (Wd), a range of, for example, 10% or more and 100% or less of the voltage change amplitude when the reverse current pulse is initially supplied can also be used (in addition, the specific percentage value can be set appropriately).

[0104] According to the present embodiment described above, the change amplitude of the voltage after the supply of the reverse current pulse can be converged within a specified range. Thereby, the uniformity of the height of the bump 143 formed of the metal deposited on the substrate Wf can be achieved.

[0105] (Modification 1 of Embodiment 1)

[0106] In addition, in the above-described embodiment, the stir bar 70 is used as the stirring mechanism 60, but the structure is not limited thereto. At least one selected from the stir bar 70, the rotation mechanism 40 that rotates the substrate holder 30, and the plating solution flow mechanism 90 may be used as the stirring mechanism 60.

[0107] In addition, when the rotation mechanism 40 is used as the stirring mechanism 60, the control module 800 may also use the rotation speed (rpm) of the substrate holder 30 as the stirring intensity used in step S20. Specifically, in this case, in step S20, the control module 800 may control the rotation mechanism 40 according to the fluctuation range of the voltage, so as to control the rotation speed of the substrate holder 30 according to the fluctuation range of the voltage.

[0108] Alternatively, when the plating solution flow mechanism 90 is used as the stirring mechanism 60, the control module 800 may also use the flow rate (m / sec) of the plating solution Ps in the plating tank 10 as the stirring intensity used in step S20. Specifically, in this case, in step S20, the control module 800 may control the plating solution flow mechanism 90 according to the fluctuation range of the voltage, so as to control the flow rate of the plating solution Ps according to the fluctuation range of the voltage.

[0109] (Example)

[0110] An experiment was conducted to confirm the effects of the above-described embodiment. Specifically, a substrate Wf of "bump pattern 1" in which bumps 143 with an opening ratio in the range of 5% to 40% are mixed as the arrangement pattern of the bumps 143 (hereinafter referred to as "bump pattern"), and a substrate Wf of "bump pattern 2" in which bumps 143 with an opening ratio in the range of 15% to 40% are mixed were prepared. Then, plating treatment was performed using the above substrate Wf. Table 1 shown below is a table for explaining the experimental results.

[0111] [Table 1]

[0112]

[0113] Figure 10 of (A) and Figure 10 of (B) are charts showing the experimental results of the substrate Wf using the bump pattern 1. Specifically, Figure 10 of (A) shows the change in the voltage between the substrate Wf and the anode 11 when a current is supplied to the substrate Wf and the anode 11 with a constant stirring intensity using the substrate Wf of the bump pattern 1. Figure 10(B) shows the change in the voltage between the substrate Wf and the anode 11 when a current is supplied to the substrate Wf and the anode 11 while using the substrate Wf with the bump pattern 1 and controlling the stirring intensity according to the change in voltage so that the change in voltage converges within a specified range as in the above-described embodiment.

[0114] Figure 11 of (A) and Figure 11 (B) is a graph showing the experimental results of the substrate Wf using the bump pattern 2. Specifically, Figure 11 (A) shows the change in the voltage between the substrate Wf and the anode 11 when a current is supplied to the substrate Wf and the anode 11 while using the substrate Wf with the bump pattern 2 at a constant stirring intensity. Figure 11 (B) shows the change in the voltage between the substrate Wf and the anode 11 when a current is supplied to the substrate Wf and the anode 11 while using the substrate Wf with the bump pattern 2 and controlling the stirring intensity according to the change in voltage so that the change in voltage converges within a specified range as in the above-described embodiment.

[0115] More specifically, in Figure 10 (A), the plating treatment is performed until the film thickness of the plating film becomes 40 μm while using the substrate Wf with the bump pattern 1 at a constant stirring intensity (the moving speed of the stirrer 70 is 150 (rpm) and constant). As a result, as exemplified in Figure 10 (A), the change in voltage becomes smaller over time. In addition, in this case, as shown in Table 1, the uniformity of the bump height (the difference between the maximum value and the minimum value of the height of the bump 143) is 8.5 μm.

[0116] On the other hand, in Figure 10 (B), the plating treatment is performed while using the substrate Wf with the bump pattern 1 and controlling the stirring intensity according to the change in voltage. Specifically, in Figure 10 (B), the plating treatment is performed until the film thickness of the plating film becomes 40 μm while using the substrate Wf with the bump pattern 1 and controlling the stirring intensity of the stirrer 70 so that the change in voltage is within a range of 10% or more and 150% or less of the change in voltage (Wd1) at the time of initially supplying the reverse current pulse. More specifically, the plating treatment is performed while changing the moving speed of the stirrer 70 as 150 (rpm), 135 (rpm), 100 (rpm) according to the decrease in the change in voltage. As a result, as shown in Table 1, the uniformity of the bump height is 4.6 μm. In this case, as the improvement rate of the uniformity of the bump height, a value of 46% is obtained.

[0117] In addition, in Figure 11In (A), the substrate Wf with the bump pattern 2 was used, and the plating process was carried out in such a way that the stirring intensity was constant (the moving speed of the stirrer 70 was 50 (rpm) and constant) until the film thickness of the plating film became 40 μm. As a result, as shown in Table 1, the uniformity of the bump height was 5.2 μm.

[0118] On the other hand, in Figure 11 (B), the substrate Wf with the bump pattern 2 was used, and the plating process was carried out while controlling the stirring intensity according to the variation range of the voltage. Specifically, in Figure 11 (B), the substrate Wf with the bump pattern 2 was used, and the stirring intensity of the stirrer 70 was controlled in such a way that the variation range of the voltage was within 10% or more and 150% or less of the variation range (Wd1) of the voltage when a reverse current pulse was initially supplied, and the plating process was carried out until the film thickness of the plating film became 40 μm. More specifically, the plating process was carried out while changing the moving speed of the stirrer 70 such as 70 (rpm), 50 (rpm), 30 (rpm) according to the decrease in the variation range of the voltage. As a result, as shown in Table 1, the uniformity of the bump height was 4.4 μm. In this case, as the improvement rate of the uniformity of the bump height, a value of 15% was obtained.

[0119] As described above, it was confirmed that for either the bump pattern 1 or the bump pattern 2, the uniformity of the bump height could be improved by controlling the stirring intensity according to the variation range of the voltage, that is, the uniformity of the height of the bump 143 was achieved.

[0120] In addition, as described above, regarding the case of controlling the rotation speed of the substrate holder 30 according to the variation range of the voltage and the case of controlling the flow rate of the plating solution Ps according to the variation range of the voltage, the same experiments as the above case (the case of controlling the moving speed of the stirrer 70 according to the variation range of the voltage) were also carried out using the bump pattern 1 and the bump pattern 2. As a result, in the case of controlling the rotation speed of the substrate holder 30 according to the variation range of the voltage and the case of controlling the flow rate of the plating solution Ps according to the variation range of the voltage, similarly to the above case, good values of the bump height uniformity were obtained.

[0121] (Embodiment 2)

[0122] Next, Embodiment 2 of the present invention will be described. The plating method according to the present embodiment is different from the plating method according to Embodiment 1 in that the flowchart of Figure 12 described later is used instead of the flowchart of Figure 9 above. In addition, the hardware structure of the plating apparatus used in the plating method according to the present embodiment is the same as that of the plating apparatus according to Embodiment 1 described in Figures 1 to 8 above, soFigures 1 to 8 is also applied to this embodiment.

[0123] Figure 12 is an example of a flowchart for explaining the plating method according to this embodiment (Embodiment 2). In addition, Figure 12 step S100 of is executed "before performing the plating process" (i.e., executed in advance). On the other hand, step S110 is executed "during the plating process".

[0124] In step S100, the user supplies a reverse current pulse from the power supply 80 to the substrate Wf and the anode 11, and obtains a control map of the stirring intensity of the stirring mechanism 60 such that the change amplitude (Wd) of the voltage of the substrate Wf after supplying the reverse current pulse converges within a specified range.

[0125] In addition, as a specific example of the "change amplitude (Wd) of the voltage of the substrate Wf after supplying the reverse current pulse", the "change amplitude (Wd) of the voltage between the substrate Wf and the anode 11 after supplying the reverse current pulse" may also be used. Alternatively, the "change amplitude (Wd) of the voltage between the substrate Wf and the reference electrode 18 after supplying the reverse current pulse" may also be used.

[0126] In addition, the substrate Wf used in step S100 is different from the substrate Wf used in step S110 described later. That is, the substrate Wf used in step S100 is an "experimental dummy substrate".

[0127] Specifically, in step S100, the user experimentally obtains the Figure 10 of (B), Figure 11 the stirring intensity of the stirring mechanism 60 such that the change amplitude (Wd) of the voltage described in (B) converges within a specified range. Then, the obtained stirring intensity of the stirring mechanism 60 is stored in advance in the storage device 802 of the control module 800 as the "control map of the stirring intensity".

[0128] That is, this control map of the stirring intensity specifies the stirring intensity of the stirring mechanism 60 and the time (elapsed time of the plating process) in association with each other such that the change amplitude (Wd) of the voltage converges within a specified range.

[0129] If a specific example is given, the value of the stirring intensity specified in the control map changes over time. If one example is given, for the stirring intensity of the control map, for example, from the elapsed time since the start of the plating process to the first time, the stirring intensity is "the first value (as an example, 150 rpm)", and beyond the first time to the second time, the stirring intensity is "the second value (as an example, 135 rpm)", and beyond the second time to the third time, the stirring intensity is "the third value (as an example, 100 rpm)", so that the stirring intensity changes over time.

[0130] Next, in step S110 executed by the control module 800 during the plating process, while controlling the stirring intensity of the stirring mechanism 60 based on the control map of the stirring intensity previously obtained in step S100, the power supply 80 is controlled in such a way that positive current and reverse current pulses are supplied to the substrate Wf and the anode 11 multiple times.

[0131] By executing this step S110, it is possible to, as described in (B) of the above Figure 10 of (B), Figure 11 as described in (B), while changing the stirring intensity over time (for example, while changing the rotation speed of the stir bar 70 to 150 rpm, 135 rpm, 100 rpm, or for example, to 70 rpm, 50 rpm, 30 rpm), supply positive current and reverse current pulses multiple times and execute the plating process.

[0132] In the present embodiment described above, it is also possible to converge the variation range of the voltage after supplying the reverse current pulse within a specified range. As a result, it is possible to achieve the uniformity of the height of the bumps 143 formed of the metal deposited on the substrate Wf.

[0133] As described above, the embodiments and modification examples of the present invention have been described in detail, but the present invention is not limited to the specific embodiments and modification examples, and various further deformations / changes can be made within the scope of the present invention described in the claims.

[0134] Description of Reference Numerals

[0135] 10... plating bath; 11... anode; 18... reference electrode; 30... substrate holder; 40... rotating mechanism; 60... stirring mechanism; 70... stir bar; 80... power supply; 90... plating solution flow mechanism; 1000... plating apparatus; Ps... plating solution; Wf... substrate.

Claims

1. A plating method using a plating device, the plating device comprising: a plating tank storing a plating solution including an accelerator for promoting plating and provided with an anode; a substrate holder configured to hold a substrate as a cathode so as to face the anode; a power source configured to supply current to the substrate and the anode; and a stirring mechanism configured to stir the plating solution, The plating method is characterized by comprising: When performing a plating process for plating the substrate, the power supply is controlled in such a manner that a forward current for depositing metal from the plating solution onto the substrate and a reverse current pulse, which is a current flowing in a pulsed manner in the opposite direction of the forward current, are supplied to the substrate and the anode multiple times; and When performing the plating process, a variation range of the voltage of the substrate after the reverse current pulse is supplied is obtained, and control is performed to change the stirring intensity of the stirring mechanism according to the obtained variation range. The fluctuation range is a difference between the voltage immediately before supplying the reverse current pulse and a minimum value of the voltage generated after supplying the reverse current pulse, or a difference between the minimum value and a maximum value of the voltage generated after the minimum value is generated.

2. The plating method according to claim 1, characterized in that The stirring mechanism includes a stirring rod, and the stirring rod is disposed between the substrate and the anode and is configured to stir the plating solution.

3. The plating method according to claim 1, characterized in that The stirring mechanism includes a rotating mechanism configured to stir the plating solution by rotating the substrate holder.

4. The plating method according to claim 1, characterized in that The stirring mechanism includes a plating solution flowing mechanism configured to stir the plating solution by flowing the plating solution in the plating tank.

5. The plating method according to claim 1, characterized in that: The voltage variation of the substrate after the reverse current pulse is supplied includes: the voltage variation between the substrate and the anode after the reverse current pulse is supplied, or the voltage variation between the substrate and a reference electrode arranged in the plating tank after the reverse current pulse is supplied.

6. A plating method using a plating device, the plating device comprising: a plating tank storing a plating solution including an accelerator for promoting plating and provided with an anode; a substrate holder configured to hold a substrate serving as a cathode so as to face the anode; a power source configured to supply current to the substrate and the anode; and a stirring mechanism configured to stir the plating solution, The plating method is characterized by comprising: Before performing a plating process for plating the substrate, the power supply is controlled in such a manner that a current that flows in a pulsed manner in the opposite direction of a forward current for depositing metal from the plating solution onto the substrate, i.e., a reverse current pulse, is supplied to the substrate and the anode, and a control map of the stirring intensity of the stirring mechanism is obtained in advance so that the variation range of the voltage of the substrate after the reverse current pulse is supplied is within a specified range; and When performing the plating process, the power supply is controlled in such a manner that the forward current and the reverse current pulses are supplied to the substrate and the anode multiple times while controlling the stirring intensity of the stirring mechanism based on the control map obtained in advance. The fluctuation range is a difference between the voltage immediately before supplying the reverse current pulse and a minimum value of the voltage generated after supplying the reverse current pulse, or a difference between the minimum value and a maximum value of the voltage generated after the minimum value is generated.

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