JP3046967B1 - Cup type plating equipment and partition - Google Patents

Abstract

A technique is provided that enables the use of a diaphragm for a cup-type plating apparatus without a problem of cost. SOLUTION: The present invention supplies a plating solution to a wafer placed in an opening of a plating tank from a solution supply pipe provided at a central bottom portion of the plating tank, and supplies an anode and a wafer provided in the plating tank to a wafer. The present invention is applied to a plating apparatus that performs plating on a wafer by forming a potential difference between the cathode and a connected cathode. A partition is formed inside the plating tank and has a shape capable of separating the anode and the wafer from each other, and is provided with a plurality of openings covered with a conductive diaphragm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus for plating a semiconductor wafer,
In particular, it relates to a cup-type plating apparatus.

[0002]

2. Description of the Related Art A cup-type plating apparatus is known as an apparatus for plating a semiconductor wafer. This cup-type plating apparatus generally supplies a plating solution to a wafer placed in a plating tank opening from a solution supply pipe provided at a central bottom portion of the plating tank, and an anode provided in the plating tank. It is designed to plate a wafer by forming a potential difference between it and the cathode connected to the wafer, suitable for small lot production, and widely used because the plating process can be automated. Has been reached.

[0003] However, this cup-type plating apparatus also has points to be improved. For example, when plating is performed,
A film such as a black film is formed on the anode surface, peels off and mixes as impurities in the plating solution, and the impurities reaching the plating target surface of the wafer may cause uneven plating properties. .

Further, when an insoluble anode is used in a plating apparatus, control of plating properties and the like is performed by decomposing additives present around the insoluble anode instead of dissolving the anode metal during the plating process. It may not work and may cause problems in management and cost.

In consideration of such a point, Japanese Patent Laid-Open Publication No. Sho 62-36529 discloses that an anode and a wafer are separated from each other by disposing a conductive diaphragm in a plating tank.
A technique as disclosed in Japanese Patent Application Laid-Open No. 242797 or the like has been proposed. This technology separates the plating solution on the anode side from the plating solution on the wafer side by a conductive diaphragm to prevent mixing of both plating solutions, thereby preventing impurities from coming into contact with the wafer and preventing the plating solution from coming into contact with the wafer. It is excellent in preventing overall deterioration.

By the way, the diaphragm used in this case is:
For the purpose of isolating the anode and the wafer from each other, one having an area substantially corresponding to the cross-sectional area of the plating tank is required. However, there are technical difficulties in producing a large-area diaphragm, and the production cost when the area of the diaphragm increases is geometrically increased. Thus, although there are many advantages, the use of the diaphragm is practical. It is very difficult to convert.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not provide a technology that enables the use of a diaphragm for a cup-type plating apparatus without a problem of cost. It is assumed that.

[0008]

According to the present invention, there is provided a cup-type plating apparatus as described above, that is, a plating solution is supplied to a wafer placed in an opening of a plating tank through a liquid supply pipe provided at the center bottom of the plating tank. Is applied to a plating apparatus that performs plating on a wafer by forming a potential difference between an anode provided in a plating tank and a cathode connected to the wafer. By arranging a partition formed inside the plating tank in a shape capable of separating the anode and the wafer from each other and having a plurality of openings covered with an electrically conductive diaphragm, Is to solve the problems that existed in.

In this technique, a partition wall having a plurality of openings formed by a conductive diaphragm is used in place of a single diaphragm in the prior art. Therefore, according to the present invention, since it is not necessary to use a large-area diaphragm, it is possible to realize plating in a good state using the diaphragm without technical and cost problems.

The above-mentioned partition wall may be formed in a shape capable of separating the anode and the wafer from each other, and there is no particular restriction on the shape. However, when the plating solution is supplied from the liquid supply pipe to the lower surface of the wafer, If it is necessary not to obstruct the flow of the plating solution,
It is possible to provide a liquid supply pipe insertion port into which the liquid supply pipe is inserted. The openings covered by the diaphragm can be formed at equal intervals on a plurality of concentric circles centered on the liquid supply pipe insertion port if it is necessary to ensure uniformity of current supply.

Here, the cup-type plating apparatus according to the present invention may be provided with a non-conductive lid formed in a shape to fit into the opening and detachable from the opening. And preferably also. When plating is performed by a plating apparatus, uneven plating may occur due to the properties of the cathode electrode connected to the wafer and the unevenness of the flow of the plating solution supplied upward.
In such a case, it is of course possible to reduce the plating unevenness by adjusting the cathode electrode and the plating solution flow, but the operation is very complicated. Therefore, if a lid made of a non-conductor capable of closing the opening formed in the partition is used and this can be fitted into any of the openings, the current density in the plating tank cross-sectional direction can be improved. Can be freely changed, so that uneven plating can be eliminated without complicated work. Here, in the case where a configuration in which openings are formed at equal intervals on a plurality of concentric circles centering on the liquid supply pipe insertion port is adopted, not only is it easy to produce a uniform current density, but also for each part. The change in the current density can be easily obtained by calculation, and as a result, the current density can be arbitrarily changed for each portion, so that the plating unevenness can be further eliminated.

Further, the partition according to the present invention is preferably formed in a flat shape. This is because three-dimensional cutting of the diaphragm becomes unnecessary, and processing of the diaphragm can be facilitated.
By the way, when such a planar partition is employed, gas generated from the anode tends to stay in a portion directly below the partition. The presence of this gas is undesirable because it affects the current density. In order to solve such a problem, it is possible to provide a gas outlet for discharging gas generated from the anode at a position directly below the partition in the plating tank. In this way, more precise control of the current density can be performed.

Further, a cup type plating apparatus according to the present invention.
Then, inside the plating tank on the anode side, which is partitioned by the partition
To supply to wafer and supply from liquid supply pipe to wafer
With separate liquid circulation paths that do not mix with liquid
It is preferable that In this way, the wafer
The solution supplied to the anode, that is, the plating solution, is directly
Contact with the plating solution.
Is no longer decomposed by the
This makes it easier to adjust the plating solution. In addition, the emission from the anode
Impurities such as black film generated on the wafer
The plating solution is not mixed with the supplied plating solution.
It will also be easier.

The partition described above supplies the plating solution to the cup-type plating apparatus as described above, that is, the plating solution supplied from the solution supply pipe provided at the center bottom of the plating tank to the wafer placed in the opening of the plating tank. In addition, for any cup-type plating apparatus that performs plating on the wafer by forming a potential difference between the anode provided in the plating tank and the cathode connected to the wafer, Can be applied. In other words, the partition wall according to the present invention, which is formed in a shape capable of separating the anode and the wafer from each other and has a plurality of openings covered with a conductive diaphragm, involves a change in the specifications of the plating tank. Without being used, a conventional cup-type plating apparatus can be used afterwards, and by doing so, a simple cup-type plating apparatus can be changed to a cup-type plating apparatus using a diaphragm.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a partition wall according to the present invention and a cup-type plating apparatus including the same will be described.

FIG. 1 schematically shows a section of a plating tank of a cup-type plating apparatus according to the present embodiment. As shown in FIG. 1, the cup-type plating apparatus according to the present embodiment places a wafer 2 along an opening of a plating tank 1, and in this state, performs plating on a plating target surface on a lower surface of the wafer 2. It has become. A cathode (not shown) is provided in the opening of the plating tank 1, and the wafer 2 placed in the opening comes into contact with the cathode. At the center of the bottom of the plating tank 1, a liquid supply pipe 3 connected to an external supply means is provided. Also,
At the upper end of the plating tank 1, there is provided a solution discharge port 4 for allowing an excess plating solution to overflow to the outside. The solution discharge port 4 is connected to the solution supply pipe 3 via a path (not shown), thereby forming a first path for plating solution circulation. In addition, around the liquid supply pipe 3 inside the plating tank 1,
Disc-shaped anode 5 formed insoluble with Pt / Ti 5
Is provided.

The partition wall 6 in the present invention is formed in a shape capable of separating the anode 5 and the wafer 2, more specifically, in a disk shape corresponding to the cross-sectional shape of the plating tank 1, and is formed at the center thereof. The liquid supply pipe 3 is fixed inside the plating tank 1 in a state where the liquid supply pipe 3 is inserted into the liquid supply pipe insertion port 7. A large number of openings 8, 8 are formed in the partition 6.
Each of the openings 8, 8,... Is provided with a conductive diaphragm 9, 9,... So as to cover each of the openings 8, 8,.
The openings 8, 8,... Are arranged at equal intervals on concentric circles C1, C2, C3 around the liquid supply insertion port 7. The partition 6 is formed in a shape that fits into the opening and is detachable from the opening.
., And arbitrary openings are covered with the lids 10, 10,... By fitting the lids 10, 10,. Although not shown, the openings 8, 8
... on the inner surface and on the outer surface of the lids 10, 10 ...
Each is threaded, and the lids 10, 10,... Can be fixed to the openings 8, 8,. The structure of the partition 6 is shown in FIG.
3 and FIG.

A gas discharge port 11 for removing bubbles generated from the anode 5 and collected on the lower surface side of the partition 6 is formed in the wall surface of the plating tank 1 facing directly below the partition 6. This gas discharge port 11 is connected at its tip to a liquid storage chamber 12. The liquid storage chamber 12 has a gas vent 13
Is provided, so that the gas extracted in the liquid storage chamber 12 can be discharged to the outside. Below the solution storage chamber 12, there is provided a discharge path 14 for sending the accumulated plating solution to a path (not shown). Further, an auxiliary solution supply pipe 15 for supplying a plating solution to a portion on the anode side with respect to the partition wall of the plating tank 1 is provided from outside the bottom of the plating tank 1. The auxiliary liquid supply pipe 15 is connected to the liquid storage chamber 1 described above.
2 through a discharge path 14 and a path (not shown), which forms a second path for plating solution circulation. This second path for plating solution circulation and the first
Are provided independently of each other, and the wafer 2
The plating solution in the second path containing impurities is prevented from being mixed with the plating solution in the first path provided for plating. When two independent plating solution paths are formed, the presence of the plating solution flowing through the second plating solution path requires that an appropriate electric field be formed between the anode and the cathode. In addition, there are sufficient conditions. Therefore, the plating solution flowing through the second path may not contain metal ions required for plating, and a mere electrolytic solution satisfying the above conditions can be used for this. Therefore, the cup-type plating apparatus according to this embodiment can further reduce costs.

[0019]

According to the cup-type plating apparatus of the present invention, a partition having a plurality of openings covered with a conductive diaphragm is used to change to a general diaphragm. Therefore, a cup-type plating apparatus using a diaphragm, which has many advantages, can be put to practical use. In addition, by using a non-conductive lid that is shaped to fit the opening and is detachable from the opening in combination with the above-described partition, by allowing electricity to flow only through an arbitrary diaphragm, The current density in the cross section can be freely adjusted, and uneven plating on the wafer can be prevented. Furthermore, since the partition wall in the present invention can be retrofitted to an existing cup-type plating apparatus, it is excellent in that the existing cup-type plating apparatus can be easily used as a plating apparatus using a diaphragm. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a preferred embodiment of a cup-type plating apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view showing a partition used in the cup-type plating apparatus shown in FIG.

FIG. 3 is a plan view showing a partition used in the cup plating apparatus shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plating tank 2 Wafer 3 Liquid supply pipe 4 Liquid discharge port 5 Anode 6 Partition wall 7 Liquid supply pipe insertion port 8 Opening 9 Diaphragm 10 Cover 11 Gas discharge port 12 Liquid storage chamber 13 Gas vent path 14 Discharge path 15 Auxiliary liquid supply tube

Claims (6)

(57) [Claims] 1. A plating solution is supplied to a wafer placed in an opening of a plating tank from a liquid supply pipe provided at a central bottom of the plating tank, and an anode provided in the plating tank and a cathode connected to the wafer. Is to be plated on the wafer by forming a potential difference between
And in a cup-type plating apparatus in which an anode and a wafer are separated from each other by an electrically conductive diaphragm provided in a plating tank, the anode and the wafer are formed in a shape that can separate the anode and the wafer from each other. A cup-type plating apparatus comprising: a partition wall provided with a plurality of openings covered by a conductive diaphragm; 2. A liquid supply pipe insertion port into which a liquid supply pipe is inserted is provided at the center of the partition, and the openings are formed on a plurality of concentric circles centered on the liquid supply pipe insertion port. The cup-type plating apparatus according to claim 1, wherein the cup-type plating apparatus is provided at intervals. 3. The cup-type plating according to claim 1, further comprising a non-conductive lid formed in a shape to fit into the opening and detachable from the opening. apparatus. 4. The cup-type plating apparatus according to claim 1, wherein a gas discharge port for discharging gas generated from the anode is provided at a position directly below the partition in the plating tank. . 5. An anode-side plating defined by partition walls.
The liquid to be supplied into the tank and the liquid supply pipe to the wafer
Separate liquid circulation paths to prevent mixing with the supplied liquid
The cup-type dressing according to any one of claims 1 to 4.
Equipment. 6. A plating solution is supplied to a wafer placed in an opening of a plating tank from a liquid supply pipe provided at a central bottom of the plating tank, and an anode provided in the plating tank and a cathode connected to the wafer. And a partition used inside a plating tank of a cup-type plating apparatus configured to perform plating on a wafer by forming a potential difference between the anode and the wafer. In addition, a partition wall having a plurality of openings covered with a conductive diaphragm.