JP7161646B1 - Plating equipment and plating method - Google Patents

Abstract

Provided are a plating apparatus and a plating method that prevent or mitigate electric field intrusion without relying on physical and mechanical structures. According to one embodiment, there is provided a substrate holder configured to hold a substrate, and a plating bath configured to accommodate the substrate holder holding the substrate, wherein a plating bath provided with a first bath and a second bath on the second surface side of the substrate, wherein the first bath and the second bath communicate with each other through a gap; and a plating bath arranged in the first bath of the plating bath. a first anode electrode, 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 tank side of the gap; A plating apparatus is provided, comprising: an auxiliary cathode electrode disposed on the second tank side of the gap; and an auxiliary power source configured to supply an auxiliary current between the auxiliary anode electrode and the auxiliary cathode electrode. be.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus and a plating method, and more specifically to a technique for uniformizing plating film thickness.

Metal plating films such as Cu are formed on the surfaces of substrates for semiconductor devices and electronic devices. For example, a substrate to be plated is held in a substrate holder, and electroplating is performed by immersing the substrate together with the substrate holder in a plating bath containing a plating solution. The substrate holder holds the substrate so that the plated surface of the substrate is exposed. An anode is placed in the plating solution so as to correspond to the exposed surface of the substrate, and a voltage can be applied between the substrate and the anode to form an electroplated film on the exposed surface of the substrate.

There are substrate holders provided with openings on both the front and back sides for plating on both sides of the substrate. For example, there is a substrate holder that holds a single substrate so that both the front and back surfaces of the substrate are exposed.

When plating is performed using a substrate holder having openings on both the front and back sides, a large gap may exist between the substrate holder and the plating tank. If there is a large gap between the substrate holder and the plating bath, wraparound can occur in the electric field from the anode to the substrate. For example, part of the electric field directed from the anode to the front surface of the substrate held by the substrate holder facing the anode may wrap around to the back surface of the substrate held by the substrate holder. When the electric field wraps around, it becomes difficult to form a plated film with a uniform thickness on the substrate. Patent Literature 1 discloses a plating apparatus configured to shield such electric field wraparound using a physical/mechanical structure.

Japanese Patent Application Laid-Open No. 2020-139206

One object of the present disclosure is to provide a plating apparatus and a plating method that prevent or mitigate electric field wraparound without relying on physical and mechanical structures.

According to one embodiment, there is provided a substrate holder configured to hold a substrate, and a plating bath configured to accommodate the substrate holder holding the substrate, wherein a plating bath provided with a first bath and a second bath on the second surface side of the substrate, wherein the first bath and the second bath communicate with each other through a gap; and a plating bath arranged in the first bath of the plating bath. a first anode electrode, a first power source configured to supply a plating current between the substrate and the first anode electrode, an auxiliary anode electrode disposed on the first tank side of the gap; A plating apparatus is provided, comprising: an auxiliary cathode electrode arranged on the second tank side of the gap; and an auxiliary power source configured to supply an auxiliary current between the auxiliary anode electrode and the auxiliary cathode electrode. be.

1 is an overall layout diagram of a plating apparatus according to an embodiment of the present invention; FIG. 1 is a schematic diagram showing the configuration of one plating bath according to one embodiment of the present invention; FIG. 1 is a schematic diagram showing the configuration of one plating bath according to one embodiment of the present invention; FIG. 1 is a schematic diagram showing the configuration of one plating bath according to one embodiment of the present invention; FIG. FIG. 3 is a diagram schematically showing a plating current flowing in a plating bath according to one embodiment of the present invention; FIG. 3 is a diagram schematically showing plating current and auxiliary current flowing in the plating tank according to one embodiment of the present invention; It is a figure showing the equivalent circuit of the plating tank concerning one embodiment of the present invention. It is a figure showing the equivalent circuit of the plating tank concerning one embodiment of the present invention. It is a figure showing the equivalent circuit of the plating tank concerning one embodiment of the present invention. It is a figure showing the equivalent circuit of the plating tank concerning one embodiment of the present invention. It is a figure showing the equivalent circuit of the plating tank concerning one embodiment of the present invention. It is a figure showing the equivalent circuit of the plating tank concerning one embodiment of the present invention. 1 is a diagram showing one configuration example of a portion including a partition wall and a gap in a plating tank according to one embodiment of the present invention; FIG. FIG. 4 is a diagram showing another configuration example of a portion including partition walls and gaps in the plating bath according to one embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION 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 duplicate descriptions are omitted.

FIG. 1 is an overall layout diagram of a plating apparatus 100 according to one embodiment of the present invention. The plating apparatus 100 is roughly divided into a load/unload module 110 that loads a substrate onto or unloads a substrate from a substrate holder (not shown), a processing module 120 that processes the substrate, and a cleaning module 50a. be done. The processing module 120 further includes a pre-processing/post-processing module 120A that performs pre-processing and post-processing of the substrate, and a plating processing module 120B that performs plating processing on the substrate.

The load/unload module 110 has a handling stage 26 , a substrate transport device 27 and a fixing station 29 . As an example, in this embodiment, the load/unload module 110 has two handling stages, a handling stage 26A for loading a substrate before processing and a handling stage 26B for unloading a substrate after processing. 26. In the present embodiment, the handling stage 26A for loading and the handling stage 26B for unloading have the same configuration, and are arranged with 180° orientations different from each other. In addition, the handling stage 26 is not limited to the one provided with the handling stages 26A and 26B for loading and unloading, and may be used without distinguishing between the handling stages 26A and 26B for loading and unloading. Also, in this embodiment, the load/unload module 110 has two fixing stations 29 . The two fixing stations 29 have the same mechanism, and the free one (the one not handling substrates) is used. One handling stage 26 and one fixing station 29 or three or more fixing stations 29 may be provided depending on the space in the plating apparatus 100 .

Substrates are transported from a plurality of cassette tables 25 (three in FIG. 1 as an example) to the handling stage 26 (handling stage 26A for loading) through the robot 24 . The cassette table 25 includes a cassette 25a in which substrates are accommodated. A cassette is, for example, a hoop. The handling stage 26 is configured to adjust (align) the position and orientation of the mounted substrate. Between the handling stage 26 and the fixing station 29, a substrate transfer device 27 is arranged for transferring the substrate therebetween. The substrate transport apparatus 27 is configured to transport substrates between the handling stage 26, the fixing station 29 and the cleaning module 50a. A stocker 30 for storing substrate holders is provided near the fixing station 29 .

The cleaning module 50a has a cleaning device 50 that cleans and dries the plated substrate. The substrate transfer device 27 is configured to transfer the plated substrate to the cleaning device 50 and take out the cleaned substrate from the cleaning device 50 . The substrate after cleaning is transferred to the handling stage 26 (handling stage 26B for unloading) by the substrate transfer device 27 and returned to the cassette 25a through the robot 24. FIG.

The pretreatment/posttreatment module 120</b>A has a pre-wet tank 32 , a pre-soak tank 33 , a pre-rinse tank 34 , a blow tank 35 and a rinse tank 36 . In the pre-wet tank 32, the substrate is immersed in pure water. In the presoak tank 33, the oxide film on the surface of the conductive layer such as the seed layer formed on the surface of the substrate is removed by etching. In the pre-rinse tank 34, the pre-soaked substrate is washed with a cleaning liquid (pure water or the like) together with the substrate holder. In the blow tank 35, liquid draining from the substrate after cleaning is performed. In the rinsing tank 36, the substrate after plating is washed with a washing liquid together with the substrate holder. The configuration of the pretreatment/posttreatment module 120A of the plating apparatus 100 is an example, and the configuration of the pretreatment/posttreatment module 120A of the plating apparatus 100 is not limited, and other configurations can be adopted. .

The plating processing module 120B is configured, for example, by housing a plurality of plating baths 39 inside an overflow bath 38 . Each plating bath 39 accommodates one substrate therein and is configured to immerse the substrate in the plating solution held therein to apply plating such as copper plating to the surface of the substrate.

The plating apparatus 100 has a transporter 37 employing, for example, a linear motor system, which is positioned to the side of the pretreatment/posttreatment module 120A and the plating module 120B and transports the substrate holder together with the substrate. The transporter 37 is configured to transport substrate holders between the fixing station 29 , the stocker 30 , the pre-wet bath 32 , the pre-soak bath 33 , the pre-rinse bath 34 , the blow bath 35 , the rinse bath 36 and the plating bath 39 . be.

An example of a series of plating processes by this plating apparatus 100 will be described. First, one substrate is taken out by the robot 24 from the cassette 25a mounted on the cassette table 25, and the substrate is transferred to the handling stage 26 (handling stage 26A for loading). The handling stage 26 adjusts the position and orientation of the transported substrate to a predetermined position and orientation. The substrate whose position and orientation are adjusted by the handling stage 26 is transported to the fixing station 29 by the substrate transport device 27 .

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

Next, the substrate holder holding the substrate is gripped by the transporter 37 and stored in the pre-wet bath 32 . Next, the substrate holder holding the substrate processed in the pre-wet bath 32 is transported to the pre-soak bath 33 by the transporter 37, and the oxide film on the substrate is etched in the pre-soak bath 33. FIG. Subsequently, the substrate holder holding this substrate is transferred to the pre-rinse tank 34, and the surface of the substrate is washed with pure water stored in this pre-rinse tank 34. FIG.

The substrate holder holding the washed substrate is transported from the pre-rinse bath 34 to the plating processing module 120B by the transporter 37 and stored in the plating bath 39 filled with the plating solution. The transporter 37 sequentially repeats the above-described procedure, and sequentially stores the substrate holders holding the substrates in the plating tanks 39 of the plating processing modules 120B.

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

After the plating is completed, the substrate holder holding the plated substrate is gripped by the transporter 37, transported to the rinsing tank 36, and immersed in the pure water contained in the rinsing tank 36 to wash the surface of the substrate with pure water. do. Next, the substrate holder is transported to the blow tank 35 by the transporter 37, and water droplets adhering to the substrate holder are removed by blowing air or the like. The substrate holder is then transported to fixing station 29 by transporter 37 .

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

2 to 4 are schematic diagrams showing the configuration of one plating tank 39 in the plating module 120B. 3 shows the plating bath 39 cut along the plane AA in FIG. 2 and viewed from the direction of the arrow A, and FIG. 4 shows the plating bath 39 cut along the plane BB in FIG. 2 and viewed from the direction of the arrow B. showing the situation. Each plating bath 39 in the plating module 120B has the same configuration as shown in FIGS. 2-4.

As described above, the substrate holder 30 holding the substrate W is transported by the transporter 37 (see FIG. 1) and accommodated in the plating bath 39 . In the plating tank 39, the substrate W and the substrate holder 30 are immersed in a plating solution (electrolytic solution) Q. As shown in FIG. A horizontal line QS shown in FIGS. 3 and 4 represents the liquid level of the plating solution Q. As shown in FIG. A partition wall 39 a is provided on the inner wall and inner bottom of the plating bath 39 so as to be parallel to the surface of the substrate W and to form the same plane as the substrate W and the substrate holder 30 . The partition wall 39a is integral with the substrate W and the substrate holder 30, and partitions the inside of the plating bath 39 into two parts, ie, a first bath 39-1 and a second bath 39-2.

One end of the partition 39a is connected to the inner wall and inner bottom of the plating tank 39 (for example, the partition 39a and the inner wall and inner bottom of the plating tank 39 are connected without any gap). On the other hand, a gap GP exists between the opposite end of the partition wall 39 a and the outer periphery of the substrate holder 30 . For example, the substrate holder 30 is supported or suspended by a support mechanism (not shown) so as not to come into contact with the partition wall 39a, thereby forming a gap GP across the entire circumference of the substrate holder 30 as shown in FIGS. It may be because there is Alternatively, the partition wall 39a may have a shape that partially contacts the substrate holder 30, in which case the gap GP is partially formed around the outer periphery of the substrate holder 30. FIG.

Due to the presence of such a gap GP between the substrate holder 30 and the partition wall 39a in the plating bath 39, the first bath 39-1 and the second bath 39-2 of the plating bath 39 are not completely isolated from each other. do not have. 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 the ions contained in the plating solution Q flow through the gap GP. It can move between the first tank 39-1 and the second tank 39-2 through the GP.

A first anode electrode 221 held by an anode holder (not shown) is arranged in the first bath 39-1 of the plating bath 39. As shown in FIG. The first anode electrode 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 connected to the surface of the substrate W facing the first tank 39-1 (hereinafter referred to as the first surface W1). ) are electrically connected. A conductive material such as a seed layer may be formed on the first surface W1 of the substrate W. As shown in FIG. 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. As shown in FIG.

Similarly, in the second bath 39-2 of the plating bath 39, a second anode electrode 222 held by an anode holder (not shown) is arranged. The second anode electrode 222 is electrically connected to the positive electrode of the second power source 232, and the negative electrode of the second power source 232 is connected to the surface of the substrate W facing the second tank 39-2 (hereinafter referred to as the second surface W2). ) are electrically connected. A conductive material such as a seed layer may be formed on the second surface W2 of the substrate W. As shown in FIG. 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. As shown in FIG.

FIG. 5 is a diagram schematically showing the plating current flowing in the plating solution Q in the first bath 39-1 and the second bath 39-2 of the plating bath 39. As shown in FIG. In the first tank 39-1, a plating current flows from the first anode electrode 221 toward the first surface W1 of the substrate W as indicated by the arrow IQ1. A plating current flows toward the second surface W2 of the substrate W as indicated by an arrow IQ2. 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 vias), A current path may be formed in the plating bath 39 through which current flows through the gap GP between the substrate holder 30 and the partition wall 39 a of the plating bath 39 . For example, if the current density in the plating solution Q in the first tank 39-1 is higher than the current density in the plating solution Q in the second tank 39-2, the first tank 39 A current is generated that flows from the -1 side to the second tank 39-2 side through the gap GP. If the magnitude relationship of the current densities is reversed, the current will leak from the second tank 39-2 to the first tank 39-1, contrary to FIG. will be explained.

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 above-described current from entering. As shown in FIGS. 2 and 3, the auxiliary anode electrode 241 is provided in the vicinity of the gap GP and on the surface of the partition wall 39a on the first tank 39-1 side. 2 and 4, the auxiliary cathode electrode 242 is provided near the gap GP on the surface of the partition wall 39a on the second tank 39-2 side. As shown in FIGS. 3 and 4, the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 may be arranged along the entire circumference of the gap GP formed between the substrate holder 30 and the partition wall 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, for example, along only a portion of the gap GP, or may be arranged in multiple positions along the gap GP. It may be divided and arranged.

The auxiliary anode electrode 241 is electrically connected to the positive electrode of the auxiliary power source 243 , and the auxiliary cathode electrode 242 is electrically connected to the negative electrode of the auxiliary power source 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 the plating current (see FIG. 5) flowing in the plating tank 39 and the auxiliary current. At the gap GP portion of , it flows from the first tank 39-1 side toward the second tank 39-2 side (arrow IQ3). Outside the gap GP, the auxiliary current also flows from the auxiliary anode electrode 241 toward the first surface W1 of the substrate W (arrow IQ31) and from the second anode electrode 222 toward the auxiliary cathode electrode 242 (arrow IQ32). flow. Since the directions of the components IQ31 and IQ32 of the auxiliary current are opposite to the direction of the wraparound component IQ12 of the plating current, they weaken or cancel each other, so that the current flows from the first tank 39-1 to the second tank 39-2. net current flow (ie, plating current wraparound) can be reduced or prevented. The optimum magnitude of the auxiliary current capable of canceling the plating current flowing through the gap GP from the first bath 39-1 to the second bath 39-2 of the plating bath 39 will be described below.

7 and 8 are diagrams showing equivalent circuits of the plating bath 39 in the plating apparatus 100 according to this embodiment. This equivalent circuit shows the relationship of how the elements shown in FIG. 2 are electrically connected together. Of these, FIG. 7 is an equivalent circuit drawn by omitting some elements involved in the auxiliary current for convenience of explanation and understanding, while FIG. Equivalent circuit.

7, R _A1 is the polarization resistance of the first anode electrode 221, R _E1 is the resistance of the plating solution Q between the first anode electrode 221 and the first surface W1 of the substrate W, R _C1 is the polarization resistance on the surface W1 (that is, the cathode), R _S1 is the resistance of the first surface W1 of the substrate W (for example, of the seed layer), and the gap GP from the opening on the side of the first tank 39-1 to the second tank 39-2. R _IC is the resistance of the plating solution Q up to the side opening, R _IS is the internal connection resistance (for example, via via) connecting the first surface W1 and the second surface W2 of the substrate W, and R _A2 is the polarization resistance at the second anode electrode 222. , the resistance of the plating solution Q between the second anode electrode 222 and the second surface W2 of the substrate W is R _E2 , the polarization resistance at the second surface W2 (that is, the cathode) of the substrate W is R _C2 , the second Let R _S2 be the resistance of surface W2 (eg, of the seed layer). Further, the output current from the first power supply 231 is I ₁ and I ₁ , the current flowing to the first surface W1 of the substrate W is I _1-1 , and the current flowing to the first surface W1 of I ₁ is the second tank 39-2 side through the gap GP. I _1-2 is the current flowing to the second power supply 232, I ₂ is the output current from the second power supply 232, I _2-1 is the current flowing to the second surface W2 of the substrate W in I ₂ , and I ₂ is the gap GP through the gap GP. The current flowing to the first tank 39-1 is assumed to be _I2-2 . However, I ₁ =I _1-1 +I _1-2 and I ₂ =I _2-1 +I _2-2 .

At this time, in the closed circuit C shown in FIG. 7, the following equation holds according to Kirchhoff's law.
V _C1 =V _C2 +(R _IC +R _IS )·(I _1-2 -I _2-2 ) (1)

However, V _C1 and V _C2 are the overvoltages of the cathodic reaction (reduction reaction) on the first surface W1 and the second surface W2 of the substrate W, respectively, and the relationship V _C1 >V _C2 is assumed. _When the _{overvoltage is small} , the _{overvoltage is proportional} to the _current . can express

Next, as shown in FIG. 8, the auxiliary current I _aux is supplied from the auxiliary power supply 243 through the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 . Among I _aux , the current flowing from the auxiliary anode electrode 241 to the first surface W1 of the substrate W is I _aux-1 , and the current flowing from the auxiliary anode electrode 241 to the second tank 39-2 through the gap GP is I _aux-2 . and where I _aux =I _aux-1 +I _aux-2 . At this time, the current flowing from the first tank 39-1 to the gap GP (and the current flowing from the gap GP to the second tank 39-2) can be expressed as I _1-2 -I _2-2 -I _aux-1 . , if this current is zero, there will be no net current flow from the first cell 39-1 to the second cell 39-2. In other words, the conditions under which the plating current flowing from the first tank 39-1 side to the second tank 39-2 side via the gap GP can be canceled using the auxiliary current I _aux are as follows.
I _1-2 -I _2-2 =I _aux-1 (2)

When the above conditions are satisfied, the current at each point of the equivalent circuit in FIG. 8 is expressed as in the equivalent circuit shown in FIG. Similar to the above equation (1), the following equation is obtained from Kirchhoff's law in the closed circuit C of FIG.
V _C1 −V _C2 =R _IC ·I _aux (3)

Therefore, by setting the auxiliary current I _aux such that equation (3) is satisfied, i.e., the difference between the overvoltage V _C1 on the first surface W1 of the substrate W and the overvoltage V _C2 on the second surface W2 of the substrate W, the auxiliary anode By setting the auxiliary current I _aux to a value obtained by dividing the resistance value R _IC between the electrode 241 and the auxiliary cathode electrode 242, the plating current passes through the gap GP from the first tank 39-1 side to the second tank 39-2. You can prevent it from going around. In other words, the optimum value of the auxiliary current I _aux that can prevent the plating current from leaking is expressed as (V _C1 -V _C2 )/R _IC . Formula (3) indicates the optimum value of the auxiliary current I _aux , but even if the auxiliary current deviates slightly from this optimum value, it is possible to reduce the wraparound of the plating current to a certain extent.

In equation (3), the values of the overvoltage V _C1 on the first surface W1 and the overvoltage V _C2 on the second surface W2 of the substrate W are set near the first surface W1 and the second surface W2 of the substrate W, respectively. Using a reference electrode (potential measurement probe), the equilibrium potential when no plating current is applied and the potential during the reaction when plating current is applied are measured, and the potential difference can be obtained. For the overvoltages V _C1 and V _C2 , the values obtained by measuring the potential on the test board in advance may be permanently used thereafter, or the potential may be applied to the actual product board in real time. The measurements may be used to calculate the momentary overvoltages V _C1 and V _C2 and use them to adjust the auxiliary current I _aux in real time.

Also, the resistance value _RIC between the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 in Equation (3) can be calculated using the dimension of the gap GP and the conductivity of the plating solution Q, for example.

If the overvoltages V _C1 and V _C2 are small, the overvoltage is proportional to the current, so equation (3) can be transformed as follows. However, R _p1 and R _p2 are polarization resistances per unit area, and i ₁ and i ₂ are current densities.
I _aux =(R _C1 ·I ₁ -R _C2 ·I ₂ )/R _IC (4)
=(R _p1 ·i ₁ -R _p2 ·i ₂ )/R _IC (4')

Further, when the polarization resistances R _p1 and R _p2 per unit area are equal, setting R _p =R _p1 =R _p2 , Equation (4′) becomes as follows.
I _aux =R _p /R _IC ·(i ₁ -i ₂ ) (5)

Therefore, by using equation (4) or equation (5), the optimum value of the auxiliary current I _aux can be determined from the measured values of the currents I ₁ , I ₂ or the current densities i ₁ , i ₂ . In equations (4) and (5), the values of the polarization resistances R _C1 , R _C2 , and R _p can be derived, for example, from an IV curve previously obtained by measurement using a reference electrode.

In the above description, the current I1 is output from the _first power supply 231 and the current _I2 is output from the second power supply 232, but the output current from the second power supply 232 may be zero ( That is, I ₂ =I _2-1 =I _2-2 =0). For example, the output of the second power supply 232 may simply be stopped, or the second power supply 232 and the second anode electrode 222 themselves may be omitted from the plating bath 39 . The plating apparatus 100 according to this embodiment can also be applied to plating only one surface (first surface W1) of the substrate W in this way.

10 to 12 are diagrams showing equivalent circuits of the plating bath 39 when the output current from the second power supply 232 is zero, and correspond to FIGS. 7 to 9, respectively. In this case, the above equations (1), (2), (3), (4), and (5) become the following equations (6), (7), (8), (9), and (10), respectively.
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, if the output current from the second power supply 232 is zero, setting the auxiliary current I _aux according to equations (8), (9), or (10) above will cause the plating current to flow through the gap GP. can be prevented from going around from the side of the first tank 39-1 to the side of the second tank 39-2.

FIG. 13 is a diagram showing a 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 this embodiment. In the example of FIG. 13, the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 are housed in the recess of the partition wall 39a and fixed to the bus bar 245. As shown in FIG. A diaphragm 246 is provided in the recess of the partition wall 39a, and the diaphragm 246 separates the inside of the recess accommodating the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 from the first tank 39-1 and the second tank of the plating tank 39. 39-2 is partitioned off. The diaphragm 246 is a membrane having a function of selectively allowing specific ions to pass therethrough.

Since the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 are separated from the first tank 39-1 and the second tank 39-2 by the diaphragm 246, the auxiliary anode electrode 241 and the auxiliary cathode electrode 242 are soluble electrodes. In this case, metal ions or fine particles eluted from the electrodes can be prevented from diffusing into the first tank 39-1 and the second tank 39-2. When the auxiliary anode electrode 241 is an insoluble electrode, active oxygen generated in the auxiliary anode electrode 241 can be suppressed from diffusing into the first tank 39-1.

The liquid that fills the inside of the recess may be an electrolytic solution different from the plating solution Q. FIG. In this case, metal deposition on the auxiliary cathode electrode 242 can be suppressed or prevented. Moreover, when the plating solution Q contains an additive, it is possible to prevent the additive from moving toward the auxiliary anode electrode 241 or the auxiliary cathode electrode 242 and decomposing on the electrode surface.

FIG. 14 is a diagram showing another configuration example of the portion including the partition wall 39a and the gap GP in the plating bath 39 of the plating apparatus 100 according to this embodiment. In the example of FIG. 14, the substrate holder 30 is configured to have a convex portion on the surface facing the partition wall 39a, and the partition wall 39a of the plating tank 39 is configured to have a concave portion on the surface facing the substrate holder 30. ing. A gap GP between the substrate holder 30 and the partition wall 39a is bent between the first tank 39-1 and the second tank 39-2 of the plating bath 39 by combining the convex portion of the substrate holder 30 and the concave portion of the partition wall 39a. It forms a passageway.

Due to this curved path, the migration distance of ions between the first tank 39-1 and the second tank 39-2 is increased, so that the resistance value _RIC of the plating solution Q within the gap GP is increased. Here, according to the above equations (3) to (5) and (8) to (10), the optimal value of the auxiliary current I _aux that can prevent the plating current from sneaking around is inversely proportional to R _IC . With such a curved path structure, the optimum value of the auxiliary current _Iaux can be reduced, and the power required to prevent the plating current from leaking can be reduced.

Although the embodiments of the present invention have been described above based on several examples, the above-described embodiments of the present invention are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. . The present invention can be modified and improved without departing from the spirit thereof, and the present invention naturally includes equivalents thereof. In addition, any combination or omission of each component described in the claims and the specification is possible within the range that at least part of the above problems can be solved or at least part of the effect is achieved. is.

Claims (11)

a substrate holder configured to hold a substrate;
A plating bath configured to accommodate the substrate holder holding the substrate, the plating bath comprising a first bath on the side of the first surface of the substrate and a second bath on the side of the second surface of the substrate; a plating tank in which the first tank and the second tank communicate with each other through a gap;
a first anode electrode arranged in the first tank of the plating tank;
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 tank side of the gap;
an auxiliary cathode electrode disposed on the second tank side of the gap;
an auxiliary power supply configured to supply a direct current auxiliary current between the auxiliary anode electrode and the auxiliary cathode electrode;
plating equipment. 2. The plating according to claim 1, wherein the auxiliary current is set to a current value obtained by dividing the overvoltage on the first surface of the substrate by the resistance value of the electrolytic solution between the auxiliary anode electrode and the auxiliary cathode electrode. Device. a second anode electrode arranged in the second tank of the plating tank;
a second power supply configured to supply a plating current between the substrate and the second anode electrode, wherein the current from the second power supply is such that an overvoltage at the second surface of the substrate causes an overvoltage of the substrate; a second power supply set to be less than the overvoltage on the first surface;
The plating apparatus of claim 1, further comprising: The auxiliary current is a current obtained by dividing the difference between the overvoltage on the first surface of the substrate and the overvoltage on the second surface of the substrate by the resistance value of the electrolyte between the auxiliary anode electrode and the auxiliary cathode electrode. 4. The plating apparatus of claim 3, set to a value. a first reference electrode for measuring an overvoltage on the first surface of the substrate, the first reference electrode being disposed near the first surface of the substrate;
a second reference electrode for measuring an overvoltage on the second surface of the substrate, the second reference electrode being disposed near the second surface of the substrate;
wherein the auxiliary current is controlled based on the overvoltage measured using the first reference electrode and the overvoltage measured using the second reference electrode;
The plating apparatus according to claim 4. 5. The plating apparatus according to claim 4, wherein said auxiliary current is controlled based on a measured current supplied from said first power supply and a measured current supplied from said second power supply. 7. The plating apparatus according to claim 6, wherein said auxiliary current is controlled based on a difference between a current density on said first surface of said substrate and a current density on said second surface of said substrate. Between the auxiliary anode electrode and the first tank of the plating tank and between the auxiliary cathode electrode and the second tank of the plating tank, a diaphragm configured to selectively allow ions to pass therethrough is provided. Item 8. The plating apparatus according to any one of Items 1 to 7. 9. The plating apparatus according to any one of claims 1 to 8, wherein said gap communicates said first tank and said second tank with a curved path. 10. The plating apparatus according to claim 1, wherein said substrate is a substrate in which said first surface and said second surface are electrically connected. A method for plating a substrate in a plating apparatus comprising:
The plating apparatus is
a substrate holder configured to hold the substrate;
A plating bath configured to accommodate the substrate holder holding the substrate, the plating bath comprising a first bath on the side of the first surface of the substrate and a second bath on the side of the second surface of the substrate; a plating tank in which the first tank and the second tank communicate with each other through a gap;
wherein the method comprises:
supplying a plating current from a first power supply between a first anode electrode arranged in the first tank of the plating bath and the substrate; and an auxiliary anode arranged on the first tank side of the gap. supplying a direct current auxiliary current from an auxiliary power supply between an electrode and an auxiliary cathode electrode positioned on the second tank side of the gap.

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