Plating method

Abstract

The invention provides a technology capable of realizing height uniformization of a bump. The plating method uses a plating apparatus (1000) provided with a plating tank (10), a substrate holder (30), a power source (80), and a stirring mechanism (60), and includes: performing plating treatment on a substrate (Wf) while performing plating treatment on the substrate (Wf); a control unit that controls the power supply so as to supply a plurality of times to the substrate and the anode (11) a forward current for precipitating the metal from the plating solution to the substrate, and a reverse current pulse, which is a current flowing in a pulse shape in the opposite direction of the forward current; and when the plating process is executed, acquiring the fluctuation range of the voltage of the substrate after the reverse current pulse is supplied, and executing control for changing the stirring intensity of the stirring mechanism according to the acquired fluctuation range.

Description

Technical Field

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

[0002] Conventionally, a plating method for plating a substrate is known (see, for example, Patent Documents 1, 2, and 3). A plating device used in such a plating method includes, for example, a plating tank storing a plating solution and provided with an anode; a substrate holder holding a 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. In addition, conventionally, in such a plating device, the plating solution in the plating tank contains an accelerator for promoting plating.

[0003] Patent Documents 2 and 3 disclose technologies for forming bumps by depositing metal on a substrate by plating. Patent Documents 2 and 3 disclose technologies for controlling a power supply so as to supply forward current and reverse current pulses to a substrate and an anode.

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

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

[0006] Patent Document 3: Japanese Patent Application Laid-Open No. 2006-131926

[0007] In recent years, there has been a demand for uniform heights of bumps formed on a substrate by plating. In this regard, the prior art has room for improvement. Summary of the invention

[0008] The present invention has been made in view of the above-mentioned problems, and one of its objects is to provide a technology capable of achieving uniform bump height.

[0009] (Form 1)

[0010] In order to achieve the above-mentioned object, a plating method according to one aspect of the present invention is a plating method using a plating device, wherein the plating device comprises: 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 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, wherein the plating method comprises: when performing a plating process for plating the substrate, supplying a current to the substrate and the anode multiple times for causing the metal to flow from the plating solution to the anode; The power supply is controlled in the form of a forward current deposited on the substrate and a current flowing in a pulsed manner in the opposite direction of the forward current, namely a reverse current pulse; and when performing the plating treatment, a variation range of the voltage of the substrate after the reverse current pulse is supplied is obtained, and control of changing the stirring intensity of the stirring mechanism is performed based on the obtained variation range, wherein the variation range is the difference between the voltage just before the reverse current pulse is supplied and the minimum value of the voltage generated after the reverse current pulse is supplied, 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, the voltage fluctuation range after the reverse current pulse is supplied can be contained within a predetermined range, thereby making it possible to achieve uniform height of bumps formed by metal deposited on the substrate.

[0012] (Form 2)

[0013] In the first aspect, the stirring mechanism may include a stirring rod, and the stirring rod may be disposed between the substrate and the anode and configured to stir the plating solution.

[0014] (Form 3)

[0015] In the first aspect, the stirring mechanism may include a rotating mechanism, and the rotating mechanism may be configured to stir the plating solution by rotating the substrate holder.

[0016] (Form 4)

[0017] In the first aspect, the stirring mechanism may include a plating solution flowing mechanism, and the plating solution flowing mechanism may be configured to stir the plating solution by flowing the plating solution in the plating tank.

[0018] (Form 5)

[0019] In any one of the above-mentioned forms 1 to 4, the above-mentioned variation range of the above-mentioned voltage of the above-mentioned substrate after the above-mentioned reverse current pulse is supplied may include: the variation range of the voltage between the above-mentioned substrate and the above-mentioned anode after the above-mentioned reverse current pulse is supplied, or the variation range of the voltage between the above-mentioned substrate and the reference electrode arranged in the above-mentioned plating tank after the above-mentioned reverse current pulse is supplied.

[0020] (Form 6)

[0021] In order to achieve the above-mentioned object, a plating method according to one aspect of the present invention is 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 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 comprising: before performing a plating treatment for plating the substrate, supplying a current, i.e., a reverse current pulse, to the substrate and the anode in a pulsed manner in the opposite direction of a forward current for causing metal to be deposited from the plating solution to the substrate; The power supply is controlled in a manner such that the voltage variation amplitude of the substrate after the reverse current pulse is supplied is controlled in advance, and a control map of the stirring intensity of the stirring mechanism is obtained in advance so that the variation amplitude of the voltage of the substrate after the reverse current pulse is supplied is converged within a specified range; and when performing the plating treatment, the stirring intensity of the stirring mechanism is controlled based on the control map obtained in advance, and the power supply is controlled in a manner such that the forward current and the reverse current pulse are supplied to the substrate and the anode multiple times, and the variation amplitude is the difference between the voltage immediately before the reverse current pulse is supplied and the minimum value of the voltage generated after the reverse current pulse is supplied, or the difference between the minimum value and the maximum value of the voltage generated after the minimum value is generated.

[0022] According to this aspect, the voltage fluctuation range after the reverse current pulse is supplied can be contained within a predetermined range. Thus, the height of the bumps formed of the metal deposited on the substrate by plating can be made uniform. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 2 It is a plan view showing the overall structure of the plating device according to the embodiment.

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

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

[0027] Figure 5 It is a schematic plan view of a paddle according to the embodiment.

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

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

[0030] Figure 8 (A) and Figure 8 (B) is a diagram for explaining the voltage variation range.

[0031] Fig. 9 This is an example of a flowchart for explaining the plating method according to the first embodiment.

[0032] Fig.10 (A) and Fig.10 (B) is a graph showing the experimental results of the substrate using the bump pattern 1.

[0033] Fig.11 (A) and Fig.11 (B) is a graph showing the experimental results of the substrate using the bump pattern 2.

[0034] Fig.12 This is an example of a flowchart for explaining the plating method according to the second embodiment. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the accompanying drawings are schematically illustrated to make the features of the components easier to understand, and the size ratios of the components are not necessarily the same as the actual ones. In addition, in some of the accompanying drawings, X-Y-Z orthogonal coordinates are illustrated as reference. In the orthogonal coordinates, the Z direction corresponds to the top, and the -Z direction corresponds to the bottom (the direction in which gravity acts).

[0036] (Implementation Method 1)

[0037] Figure 1 It is a perspective view showing the overall structure of the plating apparatus 1000 according to the embodiment. Figure 21 is a plan view (top view) showing the overall structure of the plating device 1000 involved in the embodiment. Figure 1 and Figure 2 As shown, the plating apparatus 1000 includes a loading port 100 , a transfer robot 110 , an aligner 120 , a pre-wetting module 200 , a pre-preg 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 loading port 100 is a module for carrying substrates contained in a box such as a FOUP (not shown) into the plating device 1000, and carrying substrates out of the plating device 1000 to the box. In the present embodiment, four loading ports 100 are arranged in a horizontal direction, but the number and arrangement of the loading ports 100 are arbitrary. The transport robot 110 is a robot for transporting substrates, and is configured to transfer substrates between the loading port 100, the aligner 120, the pre-wetting module 200, and the spin dryer 600. When the transport robot 110 and the transport device 700 transfer substrates between the transport robot 110 and the transport device 700, the substrates can be transferred 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 in a horizontal direction, but the number and configuration of the aligners 120 are arbitrary. The pre-wet module 200 wets the plated surface 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 surface of the substrate with the treatment liquid. The pre-wet module 200 is configured to implement a pre-wet process by replacing the treatment liquid inside the pattern with the plating liquid during plating so that the plating liquid is easily supplied to the inside of the pattern. In the present embodiment, two pre-wet modules 200 are arranged in a vertical direction, but the number and configuration of the pre-wet modules 200 are arbitrary.

[0040] The prepreg module 300 is configured to perform a prepreg treatment, for example, by etching away the oxide film with high resistance existing on the surface of the seed layer formed on the plated surface of the substrate before the plating treatment with a treatment solution such as sulfuric acid or hydrochloric acid to clean or activate the surface of the plated substrate. In the present embodiment, two prepreg modules 300 are arranged in the vertical direction, but the number and arrangement of the prepreg modules 300 are arbitrary. The plating module 400 plates the substrate. In the present embodiment, there are two units of 12 plating modules 400, in which three are arranged in the vertical direction and four are arranged in the horizontal direction, and a total of 24 plating modules 400 are provided, but the number and arrangement of the plating modules 400 are arbitrary.

[0041] The cleaning module 500 is configured to perform cleaning on the substrate in order to remove the plating liquid and the like remaining on the substrate after the plating treatment. In the present embodiment, two cleaning modules 500 are arranged in the up-down direction, but the number and configuration of the cleaning modules 500 are arbitrary. The rotary dryer 600 is a module for rotating the substrate after the cleaning treatment at high speed to dry it. In the present embodiment, two rotary dryers 600 are arranged in the up-down direction, but the number and configuration of the rotary dryers 600 are arbitrary. The transport device 700 is a device for transporting substrates between multiple modules in the plating device 1000. The control module 800 is configured to control multiple modules of the plating device 1000, and can be composed of, for example, a general computer or a special computer having an input / output interface with an operator.

[0042] An example of a series of plating processes performed by the plating device 1000 is described. First, a substrate contained in a box is loaded into the loading port 100. Next, the transport robot 110 takes out the substrate from the box of the loading port 100 and transports the substrate to the aligner 120. The aligner 120 aligns the orientation plane, notch, etc. of the substrate in a predetermined direction. The transport robot 110 delivers the substrate, which has been aligned by the aligner 120, to the pre-wetting module 200.

[0043] The prewetting module 200 performs a prewetting process on the substrate. The transport device 700 transports the substrate that has been prewetting to the prepreg module 300. The prepreg module 300 performs a prepreg process on the substrate. The transport device 700 transports the substrate that has been prepreg to the plating module 400. The plating module 400 performs plating on the substrate.

[0044] The transport device 700 transports the substrate that has been subjected to the plating process to the cleaning module 500. The cleaning module 500 performs a cleaning process on the substrate. The transport device 700 transports the substrate that has been subjected to the cleaning process to the spin dryer 600. The spin dryer 600 performs a drying process on the substrate. The transport robot 110 receives the substrate from the spin dryer 600 and transports the substrate that has been subjected to the drying process to the box of the loading port 100. Finally, the box containing the substrate is unloaded from the loading port 100.

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

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

[0048] As an example, Figure 3 and Figure 4 The plating device 1000 illustrated in the figure is a type of plating device (so-called cup-type plating device) that immerses the substrate Wf in the plating solution Ps with the surface direction being in a horizontal direction. However, the structure of the plating device 1000 is not limited thereto, and for example, it may be a type of plating device that immerses the substrate Wf in the plating solution Ps with the surface direction being in a non-horizontal direction (for example, a direction perpendicular to the ground).

[0049] Figure 3 and Figure 4 The plating module 400 of the plating device 1000 illustrated in FIG. 1 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. Figure 3 As shown in FIG. 4 , the plating module 400 includes a rotating mechanism 40, a tilting mechanism 45, and a lifting mechanism 50. Figure 3 As shown in FIG. 4 , the plating module 400 includes sensors 130. Figure 4 As illustrated in FIG. 4 , the plating module 400 includes a power source 80 and a plating solution flow mechanism 90 .

[0050] The plating tank 10 involved in this embodiment is composed of a bottomed container with an opening at the top. 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 involved in this embodiment has a cylindrical shape. The plating solution Ps is stored inside the plating tank 10.

[0051] The plating solution Ps may be any solution containing ions of metal elements constituting the plated film, and its specific example is not particularly limited. In the present embodiment, copper plating is used as an example of plating, and copper sulfate solution is used as an example of the plating solution Ps. In addition, the plating solution Ps may also contain a predetermined additive.

[0052] As the additive contained in the plating solution Ps, for example, an accelerator that accelerates plating (specifically, an accelerator that accelerates the formation of a plated 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 can 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, etc. can be used.

[0054] like Figure 3 , Figure 4 As shown in the example, an ion resistor 12 may be arranged inside the plating tank 10 at a position above the anode 11. Specifically, Figure 4 As shown in the partially enlarged view of FIG. 1 , the ion resistor 12 is composed of a porous plate member having a plurality of holes 12 a (fine pores). The holes 12 a are provided so that the lower surface and the upper surface of the ion resistor 12 communicate with each other.

[0055] The ion resistor 12 is provided to make the electric field formed between the anode 11 and the substrate Wf as the cathode uniform. By disposing the ion resistor 12 in the plating tank 10 as in the present embodiment, the thickness of the plating film (plating layer) formed on the substrate Wf can be easily made uniform.

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

[0057] like Figure 4As shown in the example, the plating solution flow mechanism 90 is configured to flow the plating solution Ps in the plating tank 10. The plating solution Ps in the plating tank 10 flows, thereby stirring the plating solution Ps in the plating tank 10. 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 flowing the plating solution Ps in the anode chamber 17a. The second flow mechanism 91b is a mechanism for flowing the plating solution Ps in the cathode chamber 17b. The first flow mechanism 91a is connected to the anode chamber 17a via the pipe 92a. The second flow mechanism 91b is connected to the cathode chamber 17b via the pipe 92b. In addition, the first flow mechanism 91a and the second flow mechanism 91b are respectively equipped with a pump for pressurizing the plating solution Ps.

[0059] Reference Figure 3 and Figure 4 The plating tank 10 is provided with a supply port for supplying the plating solution Ps to the plating tank 10. Specifically, the outer peripheral wall 10b of the plating tank 10 involved in the present embodiment is provided with 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. The plating solution Ps discharged from the first discharge port 14a is pressure-fed by the first flow mechanism 91a and is once again supplied from the first supply port 13a to the anode chamber 17a.

[0060] The overflow tank 20 is composed of a bottomed container arranged 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 (i.e., 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 pressure-fed by the second flow mechanism 91b and is once again supplied to the cathode chamber 17b from the second supply port 13b.

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

[0062] The substrate holder 30 is connected to a rotating mechanism 40 . The rotating mechanism 40 is a mechanism for rotating the substrate holder 30 . Figure 3The "R1" illustrated in the figure is an example of the rotation direction of the substrate holder 30. As the rotating mechanism 40, a known rotating motor or the like can be used. The tilting mechanism 45 is a mechanism for tilting the rotating 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 rotating mechanism 40, and the tilting mechanism 45 in the vertical direction. As the lifting mechanism 50, a known lifting mechanism such as a direct-acting actuator can be used.

[0063] The control module 800 includes a microcomputer including a processor 801 , a storage device 802 as a non-transitory storage medium, etc. The control module 800 controls the operation of the plating module 400 by the processor 801 operating based on instructions of a program stored in the storage device 802 .

[0064] Reference Figure 3 The sensors 130 detect various information used 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 a current value (A) between the anode 11 and the substrate Wf.

[0065] The sensors 130 include a voltage sensor that detects a voltage value (V) of the substrate Wf. The voltage sensor according to the present embodiment is configured to also detect a "variation width (Wd) of the voltage of the substrate Wf" described later.

[0066] In addition, the voltage sensor can also detect the voltage value between the substrate Wf and the anode 11, or can detect the "variation range (Wd) of the voltage between the substrate Wf and the anode 11". Alternatively, the voltage sensor can also detect the voltage between the substrate Wf and the reference electrode 18 ( Figure 4 In addition to the voltage value of the substrate Wf (exemplified in FIG), the "variation amplitude (Wd) of the voltage between the substrate Wf and the reference electrode 18" can also be detected. In addition, the reference electrode 18 is an electrode that is arranged inside the plating tank 10 and is used as a reference instead of the anode 11 when detecting the voltage and the voltage variation amplitude. The specific arrangement position of the reference electrode 18 inside the plating tank 10 is not particularly limited. In the present embodiment, as an example, it is arranged in a position near the anode 11 of the plating tank 10 (in the present embodiment, on the bottom wall 10a).

[0067] In addition, the sensor group 130 includes a speed sensor for detecting the moving speed (rpm or m / sec) of the stirring rod 70. In addition, the sensor group 130 includes a rotation speed sensor for detecting the rotation speed (rpm) of the substrate holder 30. In addition, the sensor group 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] like Figure 4 As illustrated in FIG. 8 , the power supply 80 is electrically connected to the substrate Wf and the anode 11 and supplies 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 involved in this embodiment controls the power supply 80 in a manner that supplies a "forward current" for causing metal to deposit from the plating liquid Ps onto the substrate Wf, and a current that flows in a pulsed manner in the opposite direction of the forward current, i.e., a "reverse current pulse", to the substrate Wf and the anode 11, at least during the "plating treatment" of plating the substrate Wf.

[0070] Specifically, as an example, the control module 800 controls the power supply 80 so as to supply a reverse current pulse after supplying a forward current. More specifically, as an example, the control module 800 according to the present embodiment controls the power supply 80 so as to supply a forward current and a reverse current pulse alternately.

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

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

[0073] like Figure 5As shown in FIG. 1 , as an example, the stirring bar 70 according to the present embodiment includes a plurality of stirring members 71 a extending in a direction (Y-axis direction) perpendicular to the first direction and the second direction of the stirring bar 70. A gap is provided between adjacent stirring members 71 a. One end of the plurality of stirring members 71 a is connected to the connecting member 72 a, and the other end is connected to the connecting member 72 b.

[0074] However, the structure of the paddle 70 is not limited thereto, and various known paddles as exemplified in Patent Document 1 may be used, for example.

[0075] In addition, the stirring rod 70 only needs to be arranged inside the plating tank 10 at least when stirring the plating solution Ps, and does not need to be arranged inside the plating tank 10 all the time. For example, it is also possible to configure the stirring rod 70 not to be arranged inside the plating tank 10 when the driving of the stirring rod 70 is stopped and the stirring of the plating solution Ps by the stirring rod 70 is not performed.

[0076] In addition, "the moving speed of the stirring rod 70 is N (rpm)" specifically means that the stirring rod 70 performs one reciprocation N times in one minute (that is, the stirring rod 70 moves from a predetermined position, for example, in a first direction, then moves in a second direction, and then moves in the first direction again and returns to the predetermined position). The faster the moving speed of the stirring rod 70, the stronger the stirring intensity of the plating solution Ps by the stirring rod 70. That is, the moving speed of the stirring rod 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. Specifically, the bumps 143 are formed of a metal (for example, Cu) deposited on the substrate Wf.

[0078] As an example, Figure 6 As shown in (A), a relatively thin metal seed layer 140 is pre-set on the entire surface of the substrate Wf involved in this embodiment. During the plating process, the surface of the substrate Wf is powered through the seed layer 140. A photoresist layer 141 is set on the surface of the seed layer 140 on the opposite side of the substrate Wf side. The photoresist layer 141 has an opening 142 in the portion where the bump 143 is to be formed. In addition, Figure 6 “φ” illustrated in (A) is the diameter (μm) of the opening 142 of the photoresist layer 141 , and “BH” is the height (μm) of the bump 143 .

[0079] Figure 6 (B) is a schematic diagram showing an example of the opening pattern of the photoresist layer 141 . Figure 6Figures No. 1 and No. 2 of (B) show examples where the diameter φ of the opening 142 is relatively small (as an example, 30 μm), and Figures No. 3 and No. 4 show examples where the diameter φ of the opening 142 is relatively large (as an example, 75 μm). If No. 1 and No. 2 are compared, the openings 142 are arranged at a higher density in No. 1 than in No. 2. If No. 3 and No. 4 are compared, the openings 142 are arranged at a higher density in No. 3 than in No. 4.

[0080] The substrate Wf provided with the photoresist layer 141 as described above is held by the substrate holder 30, immersed in the plating solution Ps of the plating tank 10, and subjected to plating treatment. During the plating treatment, the portion of the surface of the substrate Wf other than the opening 142 of the photoresist layer 141 is shielded from the plating solution Ps by the photoresist layer 141. As a result, the plated film grows only on the portion of the opening 142 of the photoresist layer 141, thereby forming a bump 143 on the substrate Wf. In addition, the photoresist layer 141 may be removed after the plating treatment.

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

[0082] Figure 7 The left graph of shows the measurement results of the case where the bump 143 is formed by supplying a forward current throughout the entire period of the plating process. Figure 7 The right graph of shows the measurement results in the case where a reverse current pulse is supplied once during the plating process to form the bump 143 .

[0083] from Figure 7 It can be seen that in the entire pattern area, the height (BH) of the bump 143 in the pattern area P1 is the lowest, and the height (BH) of the bump 143 in the pattern area P4 is the highest. This is because: the smaller the diameter φ of the opening 142, and the higher the configuration density of the opening 142, the more difficult it is to fully replenish the metal ions in the opening 142, and the lower the formation rate of the plated film. Here, the difference between the maximum and minimum values ​​of the height (BH) of the bump 143 is defined as "bump height deviation (ΔBH)".

[0084] from Figure 7 It can be seen that when a reverse current pulse is supplied during the plating process ( Figure 7 right graph) compared to the case where no reverse current pulse is supplied ( Figure 7 As shown in the left graph of FIG. 1 , 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) and Figure 8 (B) is a diagram for explaining the voltage variation range (Wd). Figure 8 (A) and Figure 8 The horizontal axis of (B) represents time, and the vertical axis represents the voltage of the substrate Wf during the plating process (specifically, the voltage between the substrate Wf and the anode 11). Figure 8 (A) Figure 8 As shown in (B), during the plating process, when a forward current is supplied and then a reverse current pulse is supplied, the voltage drops and a minimum voltage is generated. This is considered to be because the accelerator contained in the plating solution Ps is adsorbed again on the substrate Wf due to the reverse current pulse, so that the voltage drops and a minimum voltage is generated.

[0086] Here, the difference between the voltage immediately before the reverse current pulse is supplied and the minimum value is referred to as the "variation width (Wd)" ( Figure 8 Alternatively, the difference between the minimum value and the maximum value generated after the minimum value is generated can be used as the "variation range (Wd)" ( Figure 8 (B)).

[0087] However, even when a reverse current pulse of a constant value is supplied, the variation range (Wd) sometimes changes with the passage of plating time. As a specific example, even when a reverse current pulse of a constant value is supplied, for example, the variation range (Wd) sometimes decreases with the passage of plating time (see the following). Fig.10 (A) Fig.11 In this case, the variation range (Wd) does not converge within the specified range, and as a result, the bump height may not be sufficiently uniform. In addition, the variation of the variation range (Wd) can be converged within the specified range by changing the stirring intensity. Therefore, in this embodiment, the following is performed Fig. 9 Controls described in .

[0088] Fig. 9This is an example of a flow chart for describing the plating method according to the present embodiment (embodiment 1). First, the control module 800 performs a "power supply control process" (step S10) for controlling the power supply 80 in a manner of supplying forward current and reverse current pulses to the substrate Wf and the anode 11 disposed inside the plating solution Ps multiple times during the plating process. Specifically, as an example, in step S10, the control module 800 according to the present embodiment causes the power supply 80 to supply forward current and reverse current pulses alternately multiple times.

[0089] Furthermore, as an example, in step S10 , the control module 800 according to the present embodiment supplies a forward current of a constant value and supplies a reverse current pulse of a constant value.

[0090] In addition, the supply time of the forward current is not particularly limited, and it can also be the time that occupies most of the length of the entire time of the plating process. In addition, in the present embodiment, the value of the forward current is a constant value, but it is not limited to this, and it can also change with the passage of time. In addition, the specific value of the period during which the reverse current pulse is supplied is not particularly limited, for example, it can also be a value of about 0.1 seconds to several seconds. In addition, the size of the reverse current pulse is not particularly limited, for example, it is preferably set to a value that can fully carry out the detachment of the accelerator.

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

[0092] In step S20, the control module 800 executes the "agitation intensity control process" when performing the plating process. Specifically, the control module 800 according to the present embodiment executes the "agitation intensity control process" during the power supply control process in step S10 when performing the plating process.

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

[0094] In addition, as a specific example of the “variation range (Wd) of the voltage of the substrate Wf after the reverse current pulse is supplied”, the “variation range (Wd) of the voltage between the substrate Wf and the anode 11 after the reverse current pulse is supplied” may be used. Alternatively, the “variation range (Wd) of the voltage between the substrate Wf and the reference electrode 18 after the reverse current pulse is supplied” may be used. In the following description of this embodiment, as a specific example of the “variation range (Wd) of the voltage of the substrate Wf after the reverse current pulse is supplied”, the “variation range (Wd) of the voltage between the substrate Wf and the anode 11 after the reverse current pulse is supplied” is used.

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

[0096] For example, the control map defines the relationship between the voltage fluctuation range (Wd) and the stirring intensity such that the smaller the voltage fluctuation range (Wd), the smaller the stirring intensity (eg, the slower the moving speed of the stirring rod 70).

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

[0098] Furthermore, “squeezing the voltage fluctuation range (Wd) within a prescribed range” specifically means converging the voltage fluctuation range (Wd) within a range of more than a “predetermined lower limit value” and less than a “predetermined upper limit value”. That is, “squeezing the voltage fluctuation range (Wd) within a prescribed range” means suppressing the voltage fluctuation range (Wd) from being too small below the lower limit value and suppressing it from being too large above the upper limit value.

[0099] When changing the stirring intensity of the stirring mechanism 60 , the control module 800 may change the stirring intensity of the stirring mechanism 60 stepwise or continuously as the plating process time passes.

[0100] In this specific example, the control module 800 may also slow down the moving speed of the stirring rod 70 in stages, such as 150 (rpm), 135 (rpm), and 100 (rpm) as time passes (see the following description). Fig.10 Alternatively, the control module 800 may also continuously slow down the moving speed of the stirring rod 70 as time passes, for example, to 150 (rpm), 149 (rpm), 148 (rpm) ... 100 (rpm).

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

[0102] In this specific example, as the specified range of the voltage variation range (Wd), the uniformity of the bump height (specifically, the difference between the maximum and minimum heights of the bumps 143 in one mold) can be determined through experiments, for example, to be a numerical range of the voltage variation range (Wd) of 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 fluctuation range (Wd) may also be specified based on the voltage fluctuation range when the reverse current pulse is initially supplied during the plating process. Specifically, in this case, as the specified range of the voltage fluctuation range (Wd), a range of, for example, 10% to 100% of the voltage fluctuation range when the reverse current pulse is initially supplied may also be used (in addition, the specific percentage value may be appropriately set).

[0104] According to the present embodiment described above, the voltage fluctuation range after the reverse current pulse is supplied can be contained within a predetermined range, thereby making the height of the bump 143 formed of metal deposited on the substrate Wf uniform.

[0105] (Variation 1 of Implementation Example 1)

[0106] In the above embodiment, the stirring rod 70 is used as the stirring mechanism 60 , but the present invention is not limited to this structure. At least one selected from the stirring rod 70 , the rotating mechanism 40 for rotating the substrate holder 30 , and the plating solution flowing mechanism 90 may be used as the stirring mechanism 60 .

[0107] In addition, when the rotating 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 controls the rotating mechanism 40 according to the voltage fluctuation range, thereby controlling the rotation speed of the substrate holder 30 according to the voltage fluctuation range.

[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 controls the plating solution flow mechanism 90 according to the voltage variation range, thereby controlling the flow rate of the plating solution Ps according to the voltage variation range.

[0109] (Example)

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

[0111] [Table 1]

[0112]

[0113] Fig.10 (A) and Fig.10 (B) is a graph showing the experimental results of the substrate Wf using the bump pattern 1. Specifically, Fig.10 (A) shows a change in voltage between the substrate Wf and the anode 11 when a current is supplied to the substrate Wf and the anode 11 at a constant stirring intensity using the substrate Wf with the bump pattern 1 . Fig.10(B) shows the change in voltage between the substrate Wf and the anode 11 when current is supplied to the substrate Wf and the anode 11 using the bump pattern 1 and controlling the stirring intensity according to the voltage fluctuation range in a manner such that the voltage fluctuation range converges within a specified range as in the above-mentioned embodiment.

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

[0115] More specifically, in Fig.10 In (A), a substrate Wf having a bump pattern 1 is used, and plating is performed with a constant stirring intensity (the moving speed of the stirring rod 70 is 150 (rpm) and constant) until the film thickness of the plated film becomes 40 μm. As a result, Fig.10 As shown in (A) of FIG. 1 , the voltage fluctuation range decreases with the passage of time. 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, Fig.10 In (B), a substrate Wf having a bump pattern 1 is used, and a plating process is performed while controlling the stirring intensity according to the voltage variation range. Fig.10 In (B), a substrate Wf with a bump pattern 1 is used, and the stirring intensity of the stirring rod 70 is controlled in a manner such that the voltage fluctuation amplitude is within a range of 10% to 150% of the voltage fluctuation amplitude (Wd1) when the reverse current pulse is initially supplied, and the plating treatment is performed until the film thickness of the plated film becomes 40μm. More specifically, the plating treatment is performed while the moving speed of the stirring rod 70 is changed to 150 (rpm), 135 (rpm), and 100 (rpm) according to the reduction of the voltage fluctuation amplitude. As a result, as shown in Table 1, the uniformity of the bump height is 4.6μm. In this case, a value of 46% is obtained as the improvement rate of the uniformity of the bump height.

[0117] In addition, Fig.11In (A), the substrate Wf having the bump pattern 2 was plated with a constant stirring intensity (the moving speed of the stirring bar 70 was 50 (rpm) and constant) until the thickness of the plated film reached 40 μm. As shown in Table 1, the uniformity of the bump height was 5.2 μm.

[0118] On the other hand, Fig.11 In (B), a substrate Wf having a bump pattern 2 is used, and a plating process is performed while controlling the stirring intensity according to the voltage variation range. Specifically, Fig.11 In (B), a substrate Wf with a bump pattern 2 is used, and the stirring intensity of the stirring rod 70 is controlled in a manner such that the voltage fluctuation amplitude is within a range of 10% to 150% of the voltage fluctuation amplitude (Wd1) when the reverse current pulse is initially supplied, and the plating process is performed until the film thickness of the plated film becomes 40μm. More specifically, the plating process is performed while the moving speed of the stirring rod 70 is changed to 70 (rpm), 50 (rpm), and 30 (rpm) according to the reduction of the voltage fluctuation amplitude. As a result, as shown in Table 1, the uniformity of the bump height is 4.4μm. In this case, a value of 15% is obtained as the improvement rate of the uniformity of the bump height.

[0119] As described above, it was confirmed that, for both the bump pattern 1 and the bump pattern 2, the uniformity of the bump height can be improved by controlling the stirring intensity according to the voltage variation range, that is, the height of the bump 143 can be made uniform.

[0120] In addition, as described above, regarding the case where the rotation speed of the substrate holder 30 is controlled according to the voltage fluctuation range, and the case where the flow rate of the plating solution Ps is controlled according to the voltage fluctuation range, the same experiment as the above case (the case where the moving speed of the stirring rod 70 is controlled according to the voltage fluctuation range) was also conducted using the bump pattern 1 and the bump pattern 2. As a result, in the case where the rotation speed of the substrate holder 30 is controlled according to the voltage fluctuation range, and the case where the flow rate of the plating solution Ps is controlled according to the voltage fluctuation range, similarly to the above case, a value with good bump height uniformity was obtained.

[0121] (Implementation Method 2)

[0122] Next, a second embodiment of the present invention will be described. The plating method according to this embodiment is performed by Fig.12 The flowchart above is replaced by Fig. 9 The plating method according to the first embodiment is different from the plating method according to the first embodiment in that the plating method according to the present embodiment has a hardware structure similar to that of the plating device used in the plating method according to the present embodiment. Figures 1 to 8 The plating device involved in the embodiment 1 described in Figures 1 to 8 This also applies to the present embodiment.

[0123] Fig.12 This is an example of a flow chart for explaining the plating method according to the present embodiment (embodiment 2). Fig.12 Step S100 is performed "before the plating process is performed" (ie, performed in advance). On the other hand, step S110 is performed "when the plating process is performed".

[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 so that the voltage variation range (Wd) of the substrate Wf after the reverse current pulse is supplied is within a specified range.

[0125] In addition, as a specific example of the “variation range (Wd) of the voltage of the substrate Wf after the reverse current pulse is supplied”, the “variation range (Wd) of the voltage between the substrate Wf and the anode 11 after the reverse current pulse is supplied” may be used. Alternatively, the “variation range (Wd) of the voltage between the substrate Wf and the reference electrode 18 after the reverse current pulse is supplied” may be used.

[0126] 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 a "dummy substrate for experiment".

[0127] Specifically, in step S100, the user obtains the above-mentioned Fig.10 (B) Fig.11 The stirring intensity of the stirring mechanism 60 is such that the voltage variation range (Wd) described in (B) is within a predetermined range. Then, the obtained stirring intensity of the stirring mechanism 60 is pre-stored in the storage device 802 of the control module 800 as a "stirring intensity control map".

[0128] That is, the control map of the stirring intensity specifies the stirring intensity of the stirring mechanism 60 so that the voltage fluctuation range (Wd) falls within a predetermined range in association with time (elapsed time of the plating process).

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

[0130] Next, in step S110 executed when performing the plating process, the control module 800 controls the stirring intensity of the stirring mechanism 60 based on the control map of the stirring intensity obtained in advance in step S100, and controls the power supply 80 in a manner that supplies forward current and reverse current pulses to the substrate Wf and the anode 11 multiple times.

[0131] By executing step S110, as described above, Fig.10 (B) Fig.11 As described in (B), the plating process is performed by supplying forward current and reverse current pulses multiple times while changing the stirring intensity over time (for example, changing the rotation speed of the stirring rod 70 to 150 rpm, 135 rpm, 100 rpm, or to 70 rpm, 50 rpm, 30 rpm).

[0132] In the present embodiment described above, the voltage fluctuation range after the reverse current pulse is supplied can also be contained within a predetermined range. Thus, the height of the bumps 143 formed of metal deposited on the substrate Wf can be made uniform.

[0133] As mentioned above, although embodiment and modification of this invention are described in detail, this invention is not limited to this specific embodiment and modification, and various modifications and changes can be made within the scope of this invention described in the claims.

[0134] Description of Reference Numerals

[0135] 10…plating tank; 11…anode; 18…reference electrode; 30…substrate holder; 40…rotating mechanism; 60…stirring mechanism; 70…stirring rod; 80…power supply; 90…plating solution flow mechanism; 1000…plating device; 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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