CN116419991A

CN116419991A - Plating apparatus and plating method

Info

Publication number: CN116419991A
Application number: CN202180075320.1A
Authority: CN
Inventors: 高桥直人
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2021-06-01
Filing date: 2021-06-01
Publication date: 2023-07-11
Anticipated expiration: 2041-06-01
Also published as: WO2022254579A1; JPWO2022254579A1; JP7161646B1; CN116419991B; US20230399766A1; KR102650454B1; KR20230070063A

Abstract

The invention provides a plating apparatus and a plating method, which prevent or mitigate electric field detouring without physical/mechanical structure. According to one embodiment, there is provided a plating apparatus including: a substrate holder configured to hold a substrate; a plating tank configured to house the substrate holder holding the substrate, the plating tank including a first tank on a first surface side of the substrate and a second tank on a second surface side of the substrate, the first tank and the second tank communicating with each other through a gap; a first anode electrode disposed in the first groove of the plating groove; a first power supply configured to supply a plating current between the substrate and the first anode electrode; an auxiliary anode electrode disposed on the first groove side of the gap; an auxiliary cathode electrode disposed on the second groove side of the gap; and an auxiliary power supply configured to supply an auxiliary current between the auxiliary anode electrode and the auxiliary cathode electrode.

Description

Plating apparatus and plating method

Technical Field

The present invention relates to a plating apparatus and a plating method, and more particularly, to a technique for uniformizing a plating film thickness.

Background

A metal plating film of Cu or the like is formed on the surface of a substrate for a semiconductor device or an electronic component. For example, a substrate to be plated is often held by a substrate holder, and the substrate is immersed in a plating tank containing a plating solution together with the substrate holder, and then is plated. The substrate holder holds the substrate so that the plating surface of the substrate is exposed. The anode is disposed in the plating solution so as to correspond to the exposed surface of the substrate, and a voltage is applied between the substrate and the anode, whereby a plating film can be formed on the exposed surface of the substrate.

There are substrate holders having openings on both front and back surfaces thereof for plating both surfaces of a substrate. For example, there is a substrate holder for holding a substrate such that both the front and back surfaces of one substrate are exposed.

When a plating process is performed using a substrate holder having openings on both front and back surfaces, a large gap may exist between the substrate holder and the plating tank. If a large gap exists between the substrate holder and the plating tank, a detour may occur in an electric field from the anode toward the substrate. For example, a part of an electric field from the anode toward the surface of the substrate held by the substrate holder opposing the anode tends to wrap around the back surface of the substrate held by the substrate holder. If the electric field bypasses, it is difficult to form a plating film having a uniform thickness on the substrate. Patent document 1 discloses a plating apparatus configured to shield such electric field detouring using a physical/mechanical structure.

Patent document 1: japanese patent laid-open No. 2020-139206

Disclosure of Invention

It is an object of the present disclosure to provide a plating apparatus and a plating method that prevent or mitigate the detour of an electric field without physical/mechanical construction.

According to one embodiment, there is provided a plating apparatus including: a substrate holder configured to hold a substrate; a plating tank configured to house the substrate holder holding the substrate, the plating tank including a first tank on a first surface side of the substrate and a second tank on a second surface side of the substrate, the first tank and the second tank communicating with each other through a gap; a first anode electrode disposed in the first groove of the plating groove; a first power supply configured to supply a plating current between the substrate and the first anode electrode; an auxiliary anode electrode disposed on the first groove side of the gap; an auxiliary cathode electrode disposed on the second groove side of the gap; and an auxiliary power supply configured to supply an auxiliary current between the auxiliary anode electrode and the auxiliary cathode electrode.

Drawings

Fig. 1 is an overall configuration diagram of a plating apparatus according to an embodiment of the present invention.

Fig. 2 is a schematic view showing a structure of a plating tank according to an embodiment of the present invention.

Fig. 3 is a schematic view showing a structure of a plating tank according to an embodiment of the present invention.

Fig. 4 is a schematic view showing a structure of a plating tank according to an embodiment of the present invention.

Fig. 5 is a diagram schematically showing a plating current flowing in a plating tank according to an embodiment of the present invention.

Fig. 6 is a diagram schematically showing a plating current and an assist current flowing in a plating tank according to an embodiment of the present invention.

Fig. 7 is a diagram showing an equivalent circuit of a plating tank according to an embodiment of the present invention.

Fig. 8 is a diagram showing an equivalent circuit of a plating tank according to an embodiment of the present invention.

Fig. 9 is a diagram showing an equivalent circuit of a plating tank according to an embodiment of the present invention.

Fig. 10 is a diagram showing an equivalent circuit of a plating tank according to an embodiment of the present invention.

Fig. 11 is a diagram showing an equivalent circuit of a plating tank according to an embodiment of the present invention.

Fig. 12 is a diagram showing an equivalent circuit of a plating tank according to an embodiment of the present invention.

Fig. 13 is a view showing an example of the structure of a portion including a partition wall and a gap in a plating tank according to an embodiment of the present invention.

Fig. 14 is a view showing another example of the structure of a portion including a partition wall and a gap in a plating tank according to an embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and overlapping description thereof is omitted.

Fig. 1 is an overall configuration diagram of a plating apparatus 100 according to an embodiment of the present invention. The plating apparatus 100 is roughly divided into: a loading/unloading module 110 for loading or unloading a substrate to or from a substrate holder (not shown); a processing module 120 for processing a substrate; and a cleaning module 50a. The processing module 120 further includes: a pretreatment/post-treatment module 120A for performing pretreatment and post-treatment of the substrate; and a plating processing module 120B that performs a plating process on the substrate.

The load/unload module 110 has a process stage 26, a substrate transport apparatus 27, and a fixed station 29. As an example, in the present embodiment, the loading/unloading module 110 includes two processing stages 26, i.e., a processing stage 26A for loading that operates on a substrate before processing and a processing stage 26B for unloading that operates on a substrate after processing. In the present embodiment, the loading process stage 26A and the unloading process stage 26B have the same structure and are arranged so that the directions are 180 ° different from each other. The process stage 26 is not limited to the process stage 26A for loading and the process stage 26B for unloading, and may be used without being separately divided into the process stage for loading and the process stage for unloading. In addition, in the present embodiment, the loading/unloading module 110 has two fixed stations 29. The two fixing stations 29 are the same mechanism, and one of them (the one that does not operate the substrate) is left empty. In addition, the processing stage 26 and the fixing station 29 may be provided with one or three or more, respectively, depending on the space in the plating apparatus 100.

The robot 24 conveys the substrates from a plurality of (three in fig. 1 as an example) cassette tables 25 to a process stage 26 (a process stage 26A for loading). The cassette stage 25 includes a cassette 25a for accommodating substrates. The cassette is, for example, a front opening unified pod (Front Opening Unified Pod: FOUP). The process stage 26 is configured to adjust (align) the position and direction of the substrate to be placed. A substrate transfer device 27 for transferring a substrate between the process stage 26 and the fixed station 29 is disposed between them. The substrate transfer device 27 is configured to transfer substrates between the process stage 26, the fixing station 29, and the cleaning module 50a. Further, a stocker 30 for accommodating the substrate holders is provided near the fixing station 29.

The cleaning module 50a includes a cleaning device 50 for cleaning and drying the substrate after the plating process. The substrate transfer device 27 is configured to transfer the substrate after the plating process to the cleaning device 50, and to take out the cleaned substrate from the cleaning device 50. Then, the cleaned substrate is transferred to the process stage 26 (the process stage 26B for unloading) by the substrate transfer device 27, and returned to the cassette 25a by the robot 24.

The pre-treatment/post-treatment module 120A has a pre-wetting tank 32, a pre-soaking tank 33, a pre-rinsing tank 34, a blowing tank 35, and a rinsing tank 36. In the prewetting tank 32, the substrate is immersed in pure water. In the prepreg 33, an oxide film on the surface of a conductive layer such as a seed layer formed on the surface of the substrate is etched and removed. In the pre-rinse tank 34, the pre-immersed substrate is rinsed together with the substrate holder by a rinsing liquid (pure water or the like). In the air blowing tank 35, the substrate after cleaning is discharged. In the rinse tank 36, the plated substrate is rinsed with a rinse solution together with the substrate holder. The configuration of the pretreatment/post-treatment module 120A of the plating apparatus 100 is an example, and the configuration of the pretreatment/post-treatment module 120A of the plating apparatus 100 is not limited, and other configurations can be adopted.

The plating process module 120B is configured to house a plurality of plating baths 39 inside the overflow bath 38, for example. Each plating bath 39 is configured to house one substrate therein, and to perform plating such as copper plating on the substrate surface by immersing the substrate in a plating solution held therein.

The plating apparatus 100 has a conveyor 37 using, for example, a linear motor system, and the conveyor 37 is located laterally of the pretreatment/post-treatment module 120A and the plating treatment module 120B to convey the substrate holder together with the substrate. The conveyor 37 is configured to convey the substrate holders between the fixing station 29, the stocker 30, the prewetting tank 32, the presoaking tank 33, the presoaking tank 34, the blowing tank 35, the flushing tank 36, and the plating tank 39.

An example of a series of plating processes performed by the plating apparatus 100 will be described. First, one substrate is taken out from a cassette 25a mounted on a cassette stage 25 by a robot 24, and the substrate is transferred to a process stage 26 (a process stage 26A for loading). The process stage 26 aligns the position and direction of the transported substrate with a predetermined position and direction. The substrate aligned in position and direction by the process stage 26 is transported to the stationary station 29 by the substrate transport device 27.

On the other hand, the substrate holders accommodated in the stocker 30 are transported to the fixed station 29 by the transport device 37, and are horizontally placed on the fixed station 29. Then, the substrate conveyed by the substrate conveying device 27 is placed on the substrate holder in this state, and the substrate is connected to the substrate holder.

Next, the substrate holder holding the substrate is held by the conveyor 37 and stored in the prewetting tank 32. Next, the substrate holder holding the substrate processed in the pre-wetting tank 32 is transported to the pre-wetting tank 33 by the transport device 37, and the oxide film on the substrate is etched in the pre-wetting tank 33. Next, the substrate holder holding the substrate is transported to the pre-rinse tank 34, and the surface of the substrate is rinsed with pure water stored in the pre-rinse tank 34.

The substrate holder holding the substrate after the completion of the water washing is transported from the pre-rinse tank 34 to the plating processing module 120B by the transport device 37, and is accommodated in the plating tank 39 filled with the plating liquid. The conveyor 37 sequentially repeats the above steps, and sequentially stores the substrate holders holding the substrates in the respective plating tanks 39 of the plating process module 120B.

In each plating tank 39, a plating voltage is applied between an anode (not shown) in the plating tank 39 and the substrate, thereby plating the surface of the substrate.

After the plating is completed, the substrate holder holding the plated substrate is carried to the rinse tank 36 by the transfer device 37, and the surface of the substrate is rinsed with pure water by immersing the substrate in pure water stored in the rinse tank 36. Next, the substrate holder is conveyed to the air blowing groove 35 by the conveyor 37, and water droplets adhering to the substrate holder are removed by blowing air or the like. The substrate holders are then transported to the fixing station 29 by the conveyor 37.

In the fixing station 29, the processed substrate is taken out from the substrate holder by the substrate conveying device 27 and conveyed to the cleaning device 50 of the cleaning module 50a. The cleaning device 50 cleans and dries the substrate after the plating process. The dried substrate is transferred to the process stage 26 (process stage 26B for unloading) by the substrate transfer device 27, and returned to the cassette 25a by the robot 24.

Fig. 2 to 4 are schematic views showing the structure of one plating tank 39 in the plating processing module 120B. Fig. 3 shows the plating tank 39 cut on the AA surface in fig. 2 and viewed from the arrow a direction, and fig. 4 shows the plating tank 39 cut on the BB surface in fig. 2 and viewed from the arrow B direction. Each plating tank 39 in the plating processing module 120B has the same structure as that shown in fig. 2 to 4.

As described above, the substrate holder 30 holding the substrate W is transported by the transport device 37 (see fig. 1) and accommodated in the plating tank 39. In the plating tank 39, the substrate W and the substrate holder 30 are immersed in a plating solution (electrolyte solution) Q. The horizontal line QS shown in fig. 3 and 4 represents the level of the plating solution Q. The inner wall and the inner bottom of the plating tank 39 are provided with partition walls 39a so as to be parallel to the surface of the substrate W and so as to be flush with the substrate W and the substrate holder 30. The partition wall 39a divides the inside of the plating tank 39 into two parts, i.e., a first tank 39-1 and a second tank 39-2, so as to be integrated with the substrate W and the substrate holder 30.

One end of the partition wall 39a is connected to the inner wall and the inner bottom of the plating tank 39 (for example, the partition wall 39a is connected to the inner wall and the inner bottom of the plating tank 39 without any gap). On the other hand, a gap GP exists between the end of the partition 39a on the opposite side and the outer periphery of the substrate holder 30. For example, the substrate holder 30 may be supported or suspended by a supporting mechanism, not shown, so as not to contact the partition wall 39a, thereby forming a gap GP shown in fig. 3 and 4 over the entire outer periphery of the substrate holder 30. Alternatively, the partition wall 39a may have a shape in which a part thereof contacts the substrate holder 30, and in this case, the gap GP may be formed locally on the outer periphery of the substrate holder 30.

Such a gap GP exists between the substrate holder 30 and the partition wall 39a in the plating tank 39, and thus the first tank 39-1 and the second tank 39-2 of the plating tank 39 are not completely isolated from each other. In other words, the first bath 39-1 of the plating bath 39 communicates with the second bath 39-2 through the gap GP, whereby the plating solution Q and ions contained in the plating solution Q can move between the first bath 39-1 and the second bath 39-2 through the gap GP.

A first anode electrode 221 held by an anode holder, not shown, is disposed in the first groove 39-1 of the plating groove 39. The first anode 221 is electrically connected to the positive electrode of the first power supply 231, and the negative electrode of the first power supply 231 is electrically connected to a surface of the substrate W facing the first groove 39-1 (hereinafter referred to as a first surface W1). A conductive material such as a seed layer may be formed on the first surface W1 of the substrate W. The first power supply 231 is configured to supply a plating current between the first anode electrode 221 and the first surface W1 of the substrate W.

Similarly, a second anode electrode 222 held by an anode holder, not shown, is disposed in the second groove 39-2 of the plating groove 39. The second anode electrode 222 is electrically connected to the positive electrode of the second power supply 232, and the negative electrode of the second power supply 232 is electrically connected to the surface of the substrate W facing the second groove 39-2 (hereinafter referred to as a second surface W2). A conductive material such as a seed layer may be formed on the second surface W2 of the substrate W. The second power supply 232 is configured to supply a plating current between the second anode electrode 222 and the second surface W2 of the substrate W.

Fig. 5 is a schematic view showing plating currents flowing in the plating solution Q in the first and second grooves 39-1 and 39-2 of the plating tank 39. In the first groove 39-1, the plating current flows from the first anode electrode 221 toward the first surface W1 of the substrate W as indicated by arrow IQ1, and in the second groove 39-2, the plating current flows from the second anode electrode 222 toward the second surface W2 of the substrate W as indicated by arrow IQ 2. Here, when the first surface W1 and the second surface W2 of the substrate W are electrically connected inside the substrate (for example, the first surface W1 and the second surface W2 of the substrate W are connected by the via hole), a current path through which a current flows through the gap GP between the substrate holder 30 and the partition wall 39a of the plating tank 39 may be formed in the plating tank 39. For example, if the current density in the plating solution Q in the first tank 39-1 is larger than the current density in the plating solution Q in the second tank 39-2, a current is generated which passes through the gap GP from the first tank 39-1 side to the second tank 39-2 side as shown by an arrow IQ12 in FIG. 5. If the magnitude relation of the current density is reversed, the current leaks from the second groove 39-2 to the first groove 39-1 in contrast to fig. 5, but the following description will be given by assuming the situation as shown in fig. 5.

The plating apparatus 100 according to the present embodiment includes an auxiliary anode electrode 241 and an auxiliary cathode electrode 242 in the plating tank 39 in order to reduce or prevent the aforementioned current from bypassing. As shown in fig. 2 and 3, the auxiliary anode electrode 241 is provided in the vicinity of the gap GP, that is, on the surface of the partition wall 39a on the first groove 39-1 side. As shown in fig. 2 and 4, the auxiliary cathode electrode 242 is provided near the gap GP, that is, on the surface of the partition wall 39a on the second groove 39-2 side. As shown in fig. 3 and 4, the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 may be disposed along the entire circumference of the gap GP formed between the substrate holder 30 and the partition 39a. However, such an arrangement is not essential, and one or both of the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 may be arranged along only a part of the gap GP, or may be divided into a plurality of pieces along the gap GP, for example.

The auxiliary anode electrode 241 is electrically connected to the positive electrode of the auxiliary power supply 243, and the auxiliary cathode electrode 242 is electrically connected to the negative electrode of the auxiliary power supply 243. The auxiliary power supply 243 is configured to supply an auxiliary current between the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 via the gap GP. Fig. 6 is a diagram schematically showing a plating current (see fig. 5) flowing in the plating tank 39 and an auxiliary current, and as shown in the diagram, the auxiliary current flows from the first tank 39-1 side toward the second tank 39-2 side at the gap GP between the substrate holder 30 and the partition wall 39a (arrow IQ 3). The auxiliary current also flows from the auxiliary anode electrode 241 toward the first surface W1 (arrow IQ 31) of the substrate W and from the second anode electrode 222 toward the auxiliary cathode electrode 242 (arrow IQ 32) outside the gap GP. Since the directions of the components IQ31 and IQ32 of the auxiliary current are opposite to the direction of the detour component IQ12 of the plating current, the two mutually weaken or cancel each other, whereby the net current flowing from the first tank 39-1 to the second tank 39-2 (i.e., detour of the plating current) can be reduced or prevented. The magnitude of the optimum auxiliary current that can cancel the plating current that passes from the first groove 39-1 of the plating groove 39 to the second groove 39-2 through the gap GP will be described below.

Fig. 7 and 8 are diagrams showing equivalent circuits of the plating tank 39 in the plating apparatus 100 according to the present embodiment. The equivalent circuit shows a relationship of how the elements shown in fig. 2 are electrically connected to each other. For convenience of explanation and understanding, fig. 7 is an equivalent circuit drawn with a part of elements related to the auxiliary current omitted, and fig. 8 is a complete equivalent circuit including elements related to the auxiliary current.

Referring to fig. 7, the polarization resistance of the first anode electrode 221 is set to R _A1 The resistance of the plating solution Q between the first anode 221 and the first surface W1 of the substrate W is R _E1 The polarization resistance of the first surface W1 (i.e., cathode) of the substrate W is R _C1 The resistance (of the seed layer, for example) of the first surface W1 of the substrate W is R _S1 The resistance of the plating solution Q from the opening of the gap GP on the side of the first groove 39-1 to the opening of the second groove 39-2 is R _IC The internal connection resistance (e.g., of via hole) connecting the first surface W1 and the second surface W2 of the substrate W is R _IS The polarization resistance of the second anode electrode 222 is set to R _A2 The resistance of the plating solution Q between the second anode 222 and the second surface W2 of the substrate W is R _E2 The polarization resistance of the second surface W2 (i.e., cathode) of the substrate W is R _C2 Resistance of the second surface W2 (e.g. of seed layer) of the substrate WLet R be _S2 . In addition, the output current from the first power supply 231 is set to I ₁ Will I ₁ The current flowing to the first surface W1 of the substrate W is I _1-1 Will I ₁ The current flowing to the second groove 39-2 side through the gap GP is defined as I _1-2 The output current from the second power supply 232 is set to I ₂ Will I ₂ The current flowing to the second surface W2 of the substrate W is I _2-1 Will I ₂ The current flowing to the first groove 39-1 side through the gap GP is defined as I _2-2 . Wherein I is ₁ ＝I _1-1 +I _1-2 ，I ₂ ＝I _2-1 +I _2-2 。

At this time, in the closed circuit C shown in fig. 7, the following expression holds according to Kirchhoff's law.

V _C1 ＝V _C2 +(R _IC +R _IS )·(I _1-2 －I _2-2 )……(1)

Wherein V is _C1 V (V) _C2 The overvoltage of the cathode reaction (reduction reaction) in the first surface W1 and the second surface W2 of the substrate W has V _C1 ＞V _C2 Is a relationship of (3). In addition, in the case of small overvoltage, the overvoltage is proportional to the current, and is thus denoted as V _C1 ＝R _C1 ·(I _1-1 +I _2-2 )，V _C2 ＝R _C2 ·(I _2-1 +I _1-2 )。

Next, as shown in fig. 8, an auxiliary current I is supplied from an auxiliary power supply 243 via an auxiliary anode electrode 241 and an auxiliary cathode electrode 242 _aux . Will I _aux The current from the auxiliary anode electrode 241 toward the first surface W1 of the substrate W is I _aux－1 The current flowing from the auxiliary anode electrode 241 to the second groove 39-2 through the gap GP is set as I _aux－2 . Wherein I is _aux ＝I _aux－1 +I _aux－2 . At this time, the current flowing from the first groove 39-1 into the gap GP (and the current flowing from the gap GP into the second groove 39-2) can be represented as I _1-2 －I _2-2 －I _aux－1 If this current is zero, no net current flow from the first slot 39-1 to the second slot 39-2 occurs. That is to say,can use the auxiliary current I _aux The condition for canceling the plating current that passes from the first groove 39-1 side to the second groove 39-2 side through the gap GP is as follows.

I _1-2 －I _2-2 ＝I _aux－1 ……(2)

When the above condition is satisfied, the current flow in each part of the equivalent circuit of fig. 8 is represented as the equivalent circuit shown in fig. 9. In the closed circuit C of fig. 9, the following expression is obtained according to kirchhoff's law, as in the expression (1) described above.

V _C1 －V _C2 ＝R _IC ·I _aux ……(3)

Thus, by supplying the auxiliary current I _aux Is set to satisfy the equation (3), i.e., by setting the auxiliary current I _aux Is set to set the overvoltage V in the first surface W1 of the substrate W _C1 And an overvoltage V in the second face W2 _C2 Divided by the resistance value R between the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 _IC The obtained value prevents the plating current from passing through the gap GP from the first groove 39-1 side to the second groove 39-2 side. In other words, the auxiliary current I capable of preventing the detour of the plating current _aux The optimum value of (c) is expressed as (V _C1 －V _C2 )/R _IC . Equation (3) represents the auxiliary current I _aux But even if the auxiliary current is slightly deviated from the optimum value, the detour of the plating current can be reduced to some extent.

In equation (3), the overvoltage V on the first surface W1 of the substrate W _C1 And an overvoltage V in the second face W2 _C2 The value of (2) can be obtained by measuring the potential in the reaction between the equilibrium potential when no plating current flows and the potential when the plating current flows, using reference electrodes (potential measurement probes) provided near the first surface W1 and the second surface W2 of the substrate W, respectively. Overvoltage V _C1 V (V) _C2 The value obtained by measuring the potential of the test substrate in advance may be used continuously after that, or the overvoltage V at the time point may be calculated by measuring the potential of the actual product substrate in real time _C1 V (V) _C2 And use them to regulate auxiliary current in real timeI _aux 。

In addition, the resistance value R between the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 in the formula (3) _IC For example, the size of the gap GP and the conductivity of the plating solution Q can be used for calculation.

At an overvoltage V _C1 V (V) _C2 In the smaller case, since the overvoltage is proportional to the current, the equation (3) can be deformed as follows. Wherein R is _p1 、R _p2 Is the polarization resistance per unit area, I ₁ 、I ₂ Is the current density.

I _aux ＝(R _C1 ·I ₁ －R _C2 ·I ₂ )/R _IC ……(4)

＝(R _p1 ·I ₁ －R _p2 ·I ₂ )/R _IC ……(4’)

In addition, in the polarization resistance R per unit area _p1 、R _p2 In the case of equality, if R _p ＝R _p1 ＝R _p2 Then formula (4') is as follows.

I _aux ＝R _p /R _IC ·(I ₁ －I ₂ )……(5)

Therefore, by using the formula (4) or the formula (5), it is possible to respond to the current I ₁ 、I ₂ Or current density I ₁ 、I ₂ To determine the auxiliary current I _aux Is set to the optimum value of (2). In the formulae (4) and (5), the polarization resistance R _C1 、R _C2 、R _p For example, the value of (c) is derived from an IV curve obtained by measurement using a reference electrode in advance.

In the above description, the current I is output from the first power supply 231 ₁ Output current I from the second power supply 232 ₂ But the output current from the second power supply 232 may also be zero (i.e., I ₂ ＝I _2-1 ＝I _2-2 =0). For example, the output of the second power supply 232 may be stopped alone, or the second power supply 232 and the second anode electrode 222 themselves may be omitted from the plating tank 39. The plating apparatus 100 according to the present embodiment can be applied to the above-described plating apparatus that advances only one surface (first surface W1) of the substrate WAnd (3) a case of a line plating process.

Fig. 10 to 12 are diagrams showing equivalent circuits of the plating tank 39 in the case where the output current from the second power supply 232 is zero, and correspond to fig. 7 to 9 described above, respectively. In this case, the above-described formulas (1), (2), (3), (4), (5) are respectively formulas (6), (7), (8), (9), (10) below.

V _C1 ＝V _C2 +(R _IC +R _IS )·I _1-2 ……(6)

I _1-2 ＝I _aux－1 ……(7)

V _C1 ＝R _IC ·I _aux ……(8)

I _aux ＝R _C1 ·I ₁ /R _IC ……(9)

I _aux ＝R _p1 /R _IC ·I ₁ ……(10)

Therefore, when the output current from the second power supply 232 is zero, the assist current I is set by the above-described expression (8), (9) or (10) _aux It is possible to prevent the plating current from passing from the first groove 39-1 side to the second groove 39-2 side through the gap GP.

Fig. 13 is a diagram showing an example of the structure of a portion including the partition wall 39a and the gap GP in the plating tank 39 of the plating apparatus 100 according to the present embodiment. In the example of fig. 13, the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 are disposed so as to be accommodated in the recess of the partition 39a and are fixed to the bus bar 245. A diaphragm 246 is provided in the recess of the partition wall 39a, and the inner side of the recess for accommodating the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 is separated from the first groove 39-1 and the second groove 39-2 of the plating groove 39 by the diaphragm 246. The membrane 246 is a membrane having a function of selectively allowing permeation of only specific ions.

By isolating the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 from the first groove 39-1 and the second groove 39-2 by the separator 246, when the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 are electrodes having solubility, diffusion of metal ions or fine particles eluted from the electrodes into the first groove 39-1 and the second groove 39-2 can be suppressed. In the case where the auxiliary anode electrode 241 is an insoluble electrode, diffusion of active oxygen generated in the auxiliary anode electrode 241 into the first groove 39-1 can be suppressed.

The liquid filling the inside of the recess may be an electrolyte different from the plating liquid Q. In this case, the deposition of metal to the auxiliary cathode electrode 242 can be suppressed or prevented. In addition, when the additive is contained in the plating liquid Q, the additive can be prevented from moving to the auxiliary anode electrode 241 or the auxiliary cathode electrode 242 and being decomposed on the electrode surface.

Fig. 14 is a diagram showing another configuration example of a portion including the partition wall 39a and the gap GP in the plating tank 39 of the plating apparatus 100 according to the present embodiment. In the example of fig. 14, the substrate holder 30 has a convex shape on the surface facing the partition wall 39a, and the partition wall 39a of the plating tank 39 has a concave shape on the surface facing the substrate holder 30. The gap GP between the substrate holder 30 and the partition wall 39a is formed as a curved passage between the first groove 39-1 and the second groove 39-2 of the plating groove 39 by combining the convex portion of the substrate holder 30 with the concave portion of the partition wall 39a.

By this curved passage, the distance of movement of ions between the first groove 39-1 and the second groove 39-2 becomes longer, and thus the resistance value R of the plating solution Q in the gap GP becomes larger _IC Increasing. Here, according to the above-described formulas (3) to (5) and (8) to (10), the auxiliary current I can be prevented from bypassing the plating current _aux And R _IC In inverse proportion, the auxiliary current I can be reduced by forming the gap GP into the above-described curved path structure _aux Thereby enabling to reduce the power required to prevent the detour of the plating current.

The embodiments of the present invention have been described above based on several examples, but the embodiments of the present invention described above are for easy understanding of the present invention, and are not limited to the present invention. The present invention is of course capable of modification and improvement without departing from its gist, and equivalents thereof are also encompassed in the present invention. Any combination or omission of the respective constituent elements described in the claims and the description may be made within a range in which at least a part of the above-described problems can be solved or at least a part of the effects can be achieved.

Claims

1. A plating apparatus is characterized by comprising:

a substrate holder configured to hold a substrate;

a plating tank configured to house the substrate holder holding the substrate, the plating tank including a first tank on a first surface side of the substrate and a second tank on a second surface side of the substrate, the first tank and the second tank communicating with each other via a gap;

a first anode electrode disposed in the first groove of the plating groove;

a first power supply configured to supply a plating current between the substrate and the first anode electrode;

an auxiliary anode electrode disposed on the first groove side of the gap;

an auxiliary cathode electrode disposed on the second groove side of the gap; and

and an auxiliary power supply configured to supply an auxiliary current between the auxiliary anode electrode and the auxiliary cathode electrode.

2. A plating apparatus as recited in claim 1, wherein,

the auxiliary current is set to a current value obtained by dividing an overvoltage on the first surface of the substrate by a resistance value of an electrolyte between the auxiliary anode electrode and the auxiliary cathode electrode.

3. The plating apparatus according to claim 1, further comprising:

a second anode electrode disposed in the second groove of the plating groove; and

and a second power supply configured to supply a plating current between the substrate and the second anode electrode, the current from the second power supply being set such that an overvoltage in the second surface of the substrate is smaller than an overvoltage in the first surface of the substrate.

4. A plating apparatus according to claim 3, wherein,

the auxiliary current is set to a current value obtained by dividing a difference between an overvoltage in the first surface of the substrate and an overvoltage in the second surface of the substrate by a resistance value of an electrolyte between the auxiliary anode electrode and the auxiliary cathode electrode.

5. The plating apparatus according to claim 4, further comprising:

a first reference electrode disposed near the first surface of the substrate and configured to measure an overvoltage in the first surface of the substrate; and

a second reference electrode disposed near the second surface of the substrate and used for measuring an overvoltage in the second surface of the substrate,

the auxiliary current is controlled based on an overvoltage measured using the first reference electrode and an overvoltage measured using the second reference electrode.

6. A plating apparatus as recited in claim 4, wherein,

the auxiliary current is controlled based on a measured value of the current supplied from the first power source and a measured value of the current supplied from the second power source.

7. A plating apparatus according to claim 6, wherein,

the auxiliary current is controlled based on a difference in current density in the first side of the substrate and current density in the second side of the substrate.

8. The plating apparatus as recited in any of claims 1 to 7, wherein,

a separator is provided between the auxiliary anode electrode and the first bath of the plating bath and between the auxiliary cathode electrode and the second bath of the plating bath, the separator being configured to selectively allow ions to pass therethrough.

9. Plating device according to one of the claims 1 to 8, characterized in that,

the gap communicates the first slot with the second slot through a curved passage.

10. Plating device according to one of the claims 1 to 9, characterized in that,

the substrate is a substrate with the first surface and the second surface being conducted.

11. A method for plating a substrate in a plating apparatus,

the method is characterized in that,

the plating apparatus includes:

a substrate holder configured to hold the substrate; and

a plating tank configured to house the substrate holder holding the substrate, the plating tank including a first tank on a first surface side of the substrate and a second tank on a second surface side of the substrate, the first tank and the second tank being in communication with each other via a gap,

the method comprises the following steps:

supplying a plating current from a first power source between a first anode electrode of the first bath arranged in the plating bath and the substrate; and

an auxiliary current is supplied from an auxiliary power source to an auxiliary anode electrode disposed on the first groove side of the gap and an auxiliary cathode electrode disposed on the second groove side of the gap.