WO2003071010A1

WO2003071010A1 - Method for storage of a metal ion supply source in a plating equipment

Info

Publication number: WO2003071010A1
Application number: PCT/EP2003/001588
Authority: WO
Inventors: Yoshihisa Muranushi; Tadashi Saitoh
Original assignee: Atotech Deutschland Gmbh
Priority date: 2002-02-21
Filing date: 2003-02-17
Publication date: 2003-08-28
Also published as: EP1476590A1; KR20040083096A; TW200303937A; TWI263703B; EP1476590B1; JP2003253497A; MY132672A; DE60315422D1; KR100858503B1; DE60315422T2; ATE369446T1; CN1636086B; CN1636086A; CA2473054A1; JP3725083B2; US20050139477A1

Abstract

[Problem] To avoid a change in plating performance, even where operation of the plating equipment is interrupted, the properties of the plating solution need to be preserved.[Means to resolve the problem] For plating equipment having an insoluble anode, add a reservoir (7) for storing a replacement solution to the tank (4) having a metal ion supply source (copper ball (5)) and, upon termination of the plating operation, the entire plating solution is discharged from the tank (4) containing the metal ion supply source, while the solution for replacement is transferred from the reservoir (7) to the empty tank having a metal ion supply source, and immediately prior to the resumption of the plating operation transfer the solution for replacement back to the reservoir (7) and return the plating solution to the tank (4) containing the metal ion supply source.

Description

METHOD FOR STORAGE OF A METAL ION SUPPLY SOURCE IN A PLATING EQUIPMENT .

[Detailed Description of Invention] [0001] [Background to Invention]

The present invention relates to effective storage of

a copper supply source, for example, in a copper plating

equipment . [0002] [Prior Art Technology]

It has been widely known that a brightener, which is

an additive designed to promote a plating reaction and to

provide glossiness to plating, for example, 4,

5-dithiaoctane-l , 8-disulfonic acid [ ( SCH2CH2CH2SO3H) ₂ ]

continues to be decomposed where a copper anode exists even

after the electrical plating operation has ceased (For

example, J. Electroanal. Che ., 338 (1992) , 166-177) . [0003]

Also, as discussed on pages 69-75 of Advanced

Metallization Conference (1999) by A. Thies, H. Meyer, J.

Helneder, M. Schwerd and T. Gebhart, a copper dissolver

(dissolving tank) is to be annexed to plating equipment in order to supply copper ions where an insoluble anode is

used in copper plating. This copper dissolving unit is

designed to allow copper ions to be dissolved from an

inserted copper ball in proportion to the amount of copper

deposition on the substrate, which is a cathode reaction.

Where the cathode reaction is:

Cu²⁺ + 2e^~ → Cu° (1)

The anode reaction is:

Also, copper ions are supplied in the copper dissolver

according to the following reaction:

Cu° + 2Fe²⁺ → Cu²⁺ + 2Fe^{2+ ■ ■}• (3)

[0004]

[Problem to be resolved by Invention]

In a system employing an insoluble anode like this,

copper ions are usually supplied from a copper ball housed

in a copper dissolver. In an actual copper dissolver, the

possibility exists that a brightener is decomposed because

of the existence of a copper ball even while the plating

equipment is deactivated, as discussed in the literature reference mentioned above (J. Electroanal. Che .) .

Therefore, when the plating equipment is activated again,

the solution contained in the copper dissolver enters the

plating reactor (reaction tank), making it impossible to

carry out plating under the same conditions that existed

prior to inactivating the plating equipment.

[0005]

A similar phenomenon also occurs in a system having

a soluble anode. It has been reported that it becomes

difficult to achieve the same plating performance that

existed prior to inactivating the plating equipment when

the operation of the plating equipment is restarted (J.

Electroanal. Chem., 338 (1992), 167-177) . Furthermore,

dissolved substances generated while the plating equipment

remains inactive act as impurities and exert an adverse

effect on the plating surface.

[0006]

Thus, it is an object of the present invention to

prevent deterioration (change in quality) of a plating

solution and changes in plating performance even in those situations where the operation of the plating equipment

is interrupted.

[0007]

[Means to resolve the Problem]

According to the present invention, the

above-described problem is resolved by providing a

reservoir designed to store a solution that does not

deteriorate a metal ion supply source as a "solution for

replacement" and by replacing at least part of the plating

solution for said "solution for replacement" during the

period when the plating operation is interrupted.

[0008]

In the case of plating equipment having an insoluble

anode, a tank having a metal ion supply source is provided

with said reservoir, upon completion of the plating

operation, the entire plating solution is discharged from

the tank containing a metal ion supply source, the

replacement solution is transferred from the reservoir into

the emptied tank having the metal ion supply source, and

when the plating operation is restarted, the replacement solution is returned into the reservoir and the plating

solution is thereafter returned into the tank containing

the metal ion supply source.

[0009]

For plating equipment having a soluble anode, the

plating tank is provided with the reservoir and a plating

solution storage tank, upon completion of the plating

operation, the plating solution is transferred from the

plating tank into the plating solution storage tank, and

then the replacement solution is transferred from the

reservoir into the emptied plating tank and, when the

plating operation is restarted, the replacement solution

is returned into to the reservoir and the plating solution

is thereafter returned into the plating tank.

[0010]

It is desirable that said replacement solution is a

plating solution containing no brightener that undergoes

a decomposition reaction while the plating operation is

being interrupted. In the case of copper plating,

3- (benzothiazoryl-2-thio) propylsul fonic acid and its sodium salt, 3-mercaptopropane-l-sulfonic acid and its

sodium salt, ethylenedithiodipropylsulfonic acid and its

sodium salt, bis- (p- sul fophenyl ) -disulfide and its

disodium salt, etc. may be used as said brightener.

Specific examples of the replacement solution suitable for

plating with copper include a solution containing copper

sulphate and sulfuric acid, a solution containing copper

sulphate, sulfuric acid and chlorine, and a sulfuric acid

solution .

[0011]

[Preferred Embodiments of Invention]

The present invention will be described below in

greater detail based on representative examples thereof.

[0012]

(Example 1)

Figure 1 shows an embodiment in which this invention

is applied to plating equipment having an insoluble anode.

A copper dissolver 4, which is annexed to a plating tank

(not shown in the figure) which is the main unit of the

plating equipment, is provided with copper balls 5. The copper dissolver 4 and the plating tank, which is not shown

in the figure, are mutually connected via pipes 2, 3 and

each of them is filled with a copper plating solution. The

composition of the copper plating solution comprises, for

example, copper ions at a concentration of 35 g/liter,

sulfuric acid at a concentration of 180 g/liter, iron ions

at a concentration of 12 g/liter and chlorine ions at a

concentration of 50 mg/liter. The copper plating

solution also contains additives, such as brightener,

leveler, etc. This copper plating solution is referred

to hereinbelow as a "real plating solution" in order to

distinguish the copper plating solution from the

replacement plating solution.

[0013]

In addition to the copper dissolver 4, there is also

provided a reservoir for the replacement solution 7.

These two tanks are mutually connected via a pipe equipped

with a pump 6. The pump 6 is so structured to enable a

reversed rotation. The replacement plating solution is

stored in the reservoir 7 for the replacement solution. The replacement plating solution is a solution ("base

plating solution") that does not contain additives, such

as a brightener. The replacement plating solution,

however, may contain additives, provided that they are

substances that undergo no dissolution under the effect of

copper balls and cause no deterioration of the copper

surface. In the event that a base plating solution

containing no additives is used, it is expected to be able

to reduce absorption of the additives onto the copper

surface and to suppress emission from the copper surface

into the plating solution during plating restarting.

Furthermore, it is also possible to use a plating solution

containing neither brightener nor iron ions, or to use a

sulfuric acid solution with a concentration similar to that

of the sulfuric acid in the real plating solution, so no

copper sulphate be contained.

[0014]

In order to operate the plating equipment, valves 15,

16 in the pipes 2, 3 are opened and the real plating solution

circulates between the plating tank and the copper dissolver 4. In this process, the pump 6 must be

inactivated so that the replacement plating solution within

the reservoir 7 is not supplied to the copper dissolver 4.

[0015]

Once the plating operation is completed and the

equipment is stopped, the valves 15, 16 in the pipes 2, 3

are closed, and the real plating solution within the copper

dissolver 4 is discharged to the plating tank or another

tank via the pipe 1 so that only the copper balls are left

in the copper dissolver 4. The pump 6 is thereafter

operated to introduce the replacement plating solution into

the copper dissolver 4 from which the real plating solution

has been discharged. The replacement plating solution is

thus introduced in order to prevent any deterioration to

the copper ball surface, such as dying out or oxidization,

and to preserve the pre-existing properties until

restarting the plating operation.

[0016]

To restart operation of the plating equipment, the

replacement plating solution in the copper dissolver 4 is discharged into the reservoir 7 and only the copper balls

are left in the copper dissolver; then the valves 15, 15

are opened to introduce the real plating solution from the

plating tank via the pipe 3, and plating operation is

started.

[0017]

(Example 2)

Figure 2 shows an embodiment in which this invention

is applied to plating equipment having a soluble anode.

The shown structure basically comprises a plating tank 10

equipped with a cathode (substrate) 11 and a soluble anode

(phosphorous copper anode) 12, a reservoir 14 for

replacement plating solution and a plating solution storage

tank (not shown in the figure) . The plating tank 10 and

the reservoir 14 for replacement plating solution are

mutually connected via a pipe equipped with a pump 13, and

the plating tank 10 and the storage tank can be connected

to each other via a pipe 15. The pump 13 is also structured

in such a way to enable reversed rotation. The

composition of the copper plating solution contained in the plating tank 10 is the same plating solution as that shown

in Example 1 above, except that it does not contain iron

ions, and the content of additives is also the same. A

printed circuit board or semiconductor wafer can be used

as a substrate of the cathode 11; however, it is not limited

to them.

[0018]

When the plating equipment is to be operated, the pump

13 is stopped so that the base replacement plating solution

in the reservoir 14 is not transferred to the plating tank

10. When the equipment is stopped for completion of the

plating operation, the real copper plating solution in the

plating tank 10 is discharged into the storage tank via the

pipe 15 so that the plating tank 10 is emptied. The pump

13 is then operated and the base replacement plating

solution is introduced into the emptied plating tank 10,

from which the real plating solution has been discharged.

Through the introduction of the base replacement plating

solution, it become possible to prevent the deterioration

of surface conditions, including drying out of the black film formed on the anode surface, thereby preserving the

properties until restarting the plating operation.

[0019]

To restart operation of the plating equipment, the

base replacement plating solution within the plating tank

10 is discharged into the reservoir 14 to empty the plating

tank 10, then the real plating solution is then introduced

from the storage tank via the pipe 1.

[0020]

In either of said examples, objects to be plated are

not limited to printed circuit boards or semiconductor

wafers .

[0021]

[Effect of Invention]

In accordance with the present invention, it is

possible to prevent a change in plating performance after

interruption to the plating operation, as a reservoir for

storing a replacement plating solution that does not

deteriorate a metal ion supply source is installed and at

least part of the plating solution is replaced for said replacement plating solution during the interruption of

the plating operation. ^•

[0022]

By installing a reservoir to the tank having a metal

ion supply source, in the case of plating equipment having

an insoluble anode, or by installing a reservoir and a

plating solution storage tank to the plating tank, in the

case of plating equipment having a soluble anode, it becomes

possible to prevent the surface of the anode or other metal

ion supply source from deteriorating during the plating

operation and also to prevent a possible change in plating

properties caused by decomposition of a brightener

contained in the plating solution.

[Brief Description of Drawings]

[Figure 1]

This figure outlines the major components when this

invention is applied to plating equipment having an

insoluble anode.

[Figure 2]

This figure outlines the major components when this invention is applied to plating equipment having a soluble

anode .

[Key to Drawings]

4: copper dissolver

5: copper ball

6, 13: pump with ability for reserved rotation.

7, 14: reservoir for replacement solution

10: plating tank

11 : cathode

12: anode

Claims

Cl a ims

1. A method for effective storage of a metal ion supply

source in a plating equipment, comprising the steps of

providing a reservoir containing a solution causing no

deterioration of the metal ion supply source as a

replacement solution, and replacing at least part of the

plating solution with said replacement solution when the

plating operation is stopped.

2. The storage method according to claim 1, wherein in

the plating equipment having an insoluble anode, a tank

containing the metal ion supply source is provided with said

reservoir, upon completion of the plating operation the

entire plating solution is discharged from the tank

containing the metal ion supply source, the replacement

solution is transferred from the reservoir into the emptied

tank containing the metal ion supply source, and when the

plating operation is restarted, the replacement solution

is returned into the reservoir and the plating solution is thereafter returned into the tank containing the metal ion

supply source .

3. The storage method according to claim 1, wherein in

the plating equipment having a soluble anode, a plating tank

is provided with said reservoir and a plating solution

storage tank, upon completion of the plating operation the

plating solution is transferred from the plating tank into

the plating solution storage tank and the replacement

solution is transferred from the reservoir into the emptied

plating tank, and when the plating operation is restarted,

the replacement solution is returned into the reservoir and

the plating solution is thereafter returned into the

plating tank.

4. The storage method according to any of claims 1-3,

wherein said replacement solution is a plating solution

containing no brightener that undergoes a decomposing

reaction when the plating operation is stopped.

5. The storage method according to any of claims 1-4,

wherein said plating is copper plating.

The storage method according to claim 4, wherein said

replacement solution is a sulfuric acid solution