JP2980561B2 - Electroplating method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electroplating method and an apparatus for carrying out the method.

[0002]

2. Description of the Related Art Conventionally, electric bumps (B) for mounting precision electronic devices, including, for example, silicon wafer disks,
In the case of performing UMP) plating or other electroplating on a flat plate to be plated, the supply of metal ions (M ⁺⁺ ) to the surface of the plate is required to improve plating quality and increase plating speed. To facilitate this, measures have been taken to constantly stir the plating bath in which the object to be plated as the cathode and the counter electrode are immersed. Specifically, several pipes with many small diameter holes are vertically set in the plating tank, and the plating solution is pumped into these pipes, discharged from the small diameter holes into the plating tank, and overflows from the plating tank. The plating solution thus collected is collected in a spare tank outside the tank, and is pumped again to the above-mentioned pipe so that the plating solution is stirred in the plating tank.

[0003]

However, even if the positive pressure flow generated by the pump agitation generated as described above is simultaneously discharged from a large number of feed small holes toward the surface of the material to be plated, the positive pressure flow is generated on the same surface. In the process of reaching, energy is absorbed by the stress caused by the viscosity of the plating solution, and it becomes a gentle vortex flow, and almost changes on the surface of the plating object into a parallel flow along the surface and becomes a laminar flow. . As a result, the surface of the plating object is covered with a thin layer having a large velocity gradient. There is a thin layer of water hydrated with metal ions on the surface of the plating object, but laminar flow flows outside this thin layer, so kinetic energy is applied to this thin layer and this is applied. The effect of peeling off from the surface of the plating and supplying new hydrated metal ions to the surface of the plating target is weak, and a long plating operation must be performed to obtain a required plating layer.

[0004] In order to shorten the plating time, conventionally, measures have been taken to increase the concentration of metal ions in the plating bath and the temperature of the plating bath. However, when the concentration of metal ions is increased, the uniform electrodeposition property deteriorates. When the bath temperature rises, the movement and vibration of molecules increase, and most liquids between the two poles, which seem to be arbitrary movements such as Brownian motion, and parts near both poles, including the ion gradient layer As a result, the vibration is actively increased, so that the effect appears locally, but a large increase in the effect cannot be obtained.

A first object of the present invention is to provide a method capable of shortening the plating time without increasing the metal ion concentration in the plating bath or the plating bath temperature and obtaining uniform electrodeposition.

A second object of the present invention is to provide an apparatus capable of effectively performing the above method.

[0007] A third object of the present invention is to provide an apparatus capable of performing the above method for a relatively large object to be plated.

[0008]

According to the present invention, the first object is to face a surface of a plating object as a cathode immersed in a plating bath of a plating tank. This problem is solved by a plating method characterized in that a plurality of plating liquid flows having a right angle or a substantially right angle are generated, and each of the plating liquid flows is rapidly changed in direction and inverted on the surface of the material to be plated. By rapidly changing the flow direction of the plating solution on the surface of the plating object, the ion gradient layer generated and adsorbed on the surface of the plating object is removed, and metal ions are supplied to the surface of the plating object without interruption. Therefore, metal ions are continuously reduced on the surface, and a uniform plating film is formed at a high speed.

[0009] The plating liquid flow toward the surface of the plating object is guided between the two flow control plates to near the surface of the plating object, and the plating liquid flow after being reversed on the surface is used as the two flow control plates. By suctioning in the direction away from the surface of the plating object at the outer portion of the substrate, a large kinetic energy for stripping the ion gradient layer from the surface of the plating object is obtained, and the metal ion supply rate to the surface is improved.

[0010] By disposing the generating portion of the plating solution flow toward the surface of the plating object and the suction portion of the reverse flow from the surface of the plating object close to the surface of the plating object, the above-mentioned stripping is achieved. Kinetic energy further increases, and in that case, the current density as a plating condition can be increased by bringing the surface of the plating object as a cathode and the anode facing the plating object close to each other. Can be generated at a high speed.

The second problem is that a plating bath containing a plating bath in which a plating object as a cathode is immersed, and a plating object to be immersed in the plating bath in the plating bath. An anode disposed at an interval with respect to the surface, a number of plating solution inflow holes arranged in a row in a row arranged opposite to the surface to be plated, and a row of the plating solution inflow holes; A plurality of plating solution outflow holes arranged in parallel, a plating solution supply chamber communicating with the plating solution inflow hole and communicating with the discharge side of the plating solution pump, A plating solution suction chamber communicating with the holes and communicating with the suction side of the plating solution pump; and further, in the plating bath, from both sides of each column of the plating solution inflow holes toward the surface to be plated. The flow path extends and directs the plating solution flowing into the plating tank from the inflow small hole toward the surface to be plated. A pair of flow control plates is provided, and the above-mentioned row of plating solution outflow holes is provided by a plating apparatus provided on the side of the flow control plate pair forming a plating solution flow path toward the surface to be plated. Will be resolved. With this configuration, the plating solution flow generated and guided between the pair of flow control plates collides with the surface to be plated (cathode surface), and then flows from the plating solution outflow hole adjacent to the flow control plate. By the action of the suction flow provided by the suction, the flow immediately becomes the opposite direction, and this rapid reversal of the flow causes the action of removing the ion gradient layer generated and adsorbed on the surface to be plated, and therefore, the surface to be plated is interrupted. Metal ions are supplied without interruption, and the metal ions are continuously reduced, and a uniform plating film is formed at a high speed.

The above-mentioned columns of plating solution inflow holes and columns of plating solution outflow holes extend in the vertical direction, respectively, and are alternately provided on one tank wall of the plating tank. The generated plating solution flow collides with the surface to be plated, then splits in half and reverses evenly to the left and right, and removes the ion gradient layer from the surface to be plated evenly. Can appear.

[0013] A prismatic anode is disposed in front of the plating solution outflow row of holes between the above-described pair of flow control plates and the pair of flow control plates adjacent thereto, and the anode, the flow control plate and the plating tank opposed thereto are disposed. By providing a plating solution suction passage after being inverted on the plating surface between the wall and the plating surface, after the inversion, a liquid flow in a direction away from the plating surface is generated along the side surface to the flow control plate, A more effective inversion of the plating solution, that is, an inversion flow that effectively removes the ion gradient layer is obtained.

The third problem is that a plating bath containing a plating bath in which a plating object as a cathode is immersed, and a plating object to be immersed in the plating bath in the plating bath. An anode disposed at an interval with respect to the surface, a number of plating solution inflow holes arranged in a row in a row arranged opposite to the surface to be plated, and a row of the plating solution inflow holes; A plurality of plating solution outflow holes arranged in parallel, a plating solution supply chamber communicating with the plating solution inflow hole and communicating with the discharge side of the plating solution pump, A plating solution suction chamber communicating with the hole and communicating with a suction side of the plating solution pump, and extending into the plating bath from both sides of each column of the plating solution inflow holes toward the surface to be plated; Further, a flow path is formed which directs the plating solution flowing into the plating tank from the inflow small hole toward the surface to be plated. A plating apparatus is provided in which a pair of flow control plates are provided, and the row of the plating solution outflow holes is provided on a side of the flow control plate pair forming a plating solution flow path toward the surface to be plated. This is solved by a plating apparatus in which a small plating cell is formed as one unit, a plurality of small plating cells are connected vertically and horizontally, and the plating tanks of each unit are mutually opened to form one large-capacity plating tank as a whole. . According to this plating apparatus, a large-area plating surface (cathode surface) of a plating object immersed in a plating bath of a large-capacity plating tank has a plating surface portion opposed to each small plating cell. Since it can act on the surface and does not significantly affect adjacent portions, uniform removal of the ion gradient layer can be achieved over the entire surface to be plated, and a uniform plating film can be obtained.

The arrangement of the plating solution inflow holes and the plating outflow holes in each of the small plating cells is arranged vertically and alternately. After the plating solution flow hits the surface to be plated,
It is possible to remove the ion gradient layer from the surface to be plated evenly on the large-area surface to be plated.

Further, a prismatic anode is arranged at a distance in front of the plating solution outflow small hole row between the flow control plate pair of each small plating cell and the adjacent flow control plate pair, A passage for guiding the plating solution, which has been inverted on the surface to be plated, to the plating solution outflow hole along the flow control plate located in the closest position is provided between the flow control plate and the opposing control plate. , After inversion,
A liquid flow in a direction away from the surface to be plated is generated along the flow control plate, and a more effective reversal of the plating solution, that is, a reverse flow for effectively removing the ion gradient layer, is generated even on the large area plated surface. can get.

[0017]

1 to 3 schematically show a plating apparatus for carrying out the method of the present invention. FIG. 1 is a front view of the plating apparatus, FIG. 2 is a side view thereof, and FIG. FIG.

In the figure, 1 is a plating tank, 2 is an anode disposed in this tank, 3 is a cathode plate, for example, a silicon wafer disk or the like, which is disposed in the plating bath in the tank so as to face the anode 2. It is an object to be plated. The plating tank 1 has four walls 1a, 1
b, 1c, 1d and a bottom wall 1e. A wall portion 1a having a flat inner wall surface has a large number of plating solution inflow holes 5 arranged in tandem and a large number of plating solution outflow holes also arranged in tandem. 6 are provided. The columns of the inflow holes 5 and the outflow holes 6 respectively extend in the vertical direction and are arranged alternately.

Each of the inflow small hole 5 and the outflow small hole 6 is open in the plating tank 1 on one side. On the other hand, the inlet hole 5 opens into a plating solution supply chamber 8 communicating with the discharge side of a plating solution pump (not shown) via a discharge pipe 7, and the outlet hole 6 opens the plating solution pump. It opens to a plating solution suction chamber 10 which communicates with the suction side via a suction pipe 9.

The plating solution supply chamber 8 and the plating solution suction chamber 10 are provided over the bottom wall 1e and the front wall 1a of the plating tank 1 so as to be overlapped on the outside thereof. The small outflow hole 6 communicating with the inside of the inside 1 is formed by a short tube 6 a extending across the plating solution supply chamber 8.

The discharge pipe 7 and the suction pipe 9 extend below the bottom wall 1e of the plating tank 1 across the plating solution supply chamber 8 and the plating solution suction chamber 10, respectively. The small holes 7a, 9a (FIG. 1) communicate with the corresponding chambers 8, 10.

In the plating tank 1, on both sides of an inflow small hole 5 arranged in a vertical cascade which is opened on a flat wall inside the front wall 1a, a flow control extending substantially perpendicularly from the inner wall is provided. A plate 11 is provided. The pair of flow control plates 11 guide the plating solution fed from the row of inflow small holes 5 straightly toward the surface of the plating object 3.

A pair of prismatic anodes (baskets) are provided between the adjacent flow control plate pairs and outside the flow control plate pairs at both ends, at intervals from the openings of the outflow small holes 6 in each row in the vertical column arrangement. )
12 are arranged.

As shown in the partial views of FIGS. 4 to 6, the anode 12 is spaced from the side surface of the flow control plate 11, and is also spaced from the inner surface of the plating tank front wall 1a. . Therefore, a suction passage 13 is formed between the anode 12 and the flow control plate 11 and between the anode 12 and the inner surface of the front wall.

The operation of the plating apparatus will be described. The plating solution discharged from the plating solution pump and sent into the discharge pipe 7 enters the plating solution supply chamber 8 through the small hole 7a (FIG. 1), and then flows into the plating solution supply chamber 8. It flows into the plating bath in the plating tank 1 from the hole 5. At this time, the flowing plating solution is guided straight toward the plating object 3 by a pair of flow control plates 11 corresponding to the vertical columns of the respective inflow holes 5.

The plating flow guided by the flow control plate 11 collides with the surface to be plated and is changed in direction. At this time, a small amount flows out into the plating solution suction chamber 8 communicating with the suction side of the plating solution pump. The above-described direction change is rapidly performed by the plating liquid flow generated in the suction passage 13 by suction of the plating liquid from the hole 6 in the direction away from the surface to be plated. Reversal causes a large kinetic energy to remove the ion gradient layer generated and adsorbed on the surface of the plating object.

As described above, the ion gradient layer is effectively removed, and the plating film is formed at a high speed by supplying a large amount of metal ions to the surface of the material to be plated. 6, if the distance to the surface of the plating object is shortened, the effect of removing the ion gradient layer and supplying metal ions increases, and if the supply rate of the metal ions is high, the distance between the surface of the plating object and the anode is increased. The plating speed is further increased because the distance between them can be reduced and the cathode current density (Dk) can be increased.

After the plating solution flow guided by the flow control plate 11 collides with the surface of the plating object, it is separated in both the left and right directions, and is reversed to remove the ion gradient layer. Since it is generated continuously in the horizontal direction every time,
A plating film is formed substantially uniformly over the entire surface. At this time, the uniformity of the formed film is further enhanced by swinging the plating object 3 right and left in a direction perpendicular to the flow control plate 11.

7 to 9 show an embodiment of a plating apparatus corresponding to a relatively large object to be plated. FIG. 7 is a front view of the plating apparatus, FIG. 8 is a side view thereof, and FIG. FIG.
This plating apparatus is basically constructed by using the plating apparatus shown in FIGS. 1 to 6 as a small plating cell as one unit and connecting the small plating cells vertically and horizontally. In the illustrated embodiment, four small plating cells 20 </ b> A to 20 </ b> D are combined, two vertically and two horizontally. However, the plating tank 21 is open to all the small plating cells 20A to 20D and is configured as a room without partitions.

The plating solution supply chamber 28 and the plating solution suction chamber 30 of the small plating cells 20A to 20D are independent for each cell, and one plating solution pump (not shown) is provided to each plating solution supply chamber 28. The plating solution is supplied through a discharge tube 27 connected to the discharge side of the plating solution, and the plating solution is supplied from each plating solution suction chamber 30 through a suction tube 29 connected to the suction side of another plating solution pump. Is sucked.

As shown in FIG. 7, the flow control plates 31 of the small plating cells 20A and 20B and the small plating cells 20C and 20D connected vertically are connected.
Are linearly aligned, and the left and right small plating cells 20
At the connection between A and 20C, and 20B and 20D,
One anode 32 is shared.

The function of each plating cell is substantially the same as that of the plating apparatus shown in FIGS. According to the plating apparatus formed by combining and synthesizing these small plating cells, only the surface of the plating object facing each small plating cell is stirred,
That is, the ion gradient layer removing operation is performed, and the adjacent portion is not affected, and the uniform plating operation is performed over the entire plating area of the large plating object 23.

In the above-described embodiment, a case has been described in which two small plating cells are connected to each other in the upper, lower, left, and right directions to form a plating apparatus for a large plating object. The numbers can be changed and combined.

[0034]

As described above, according to the present invention, the plating time can be shortened even when working at a normal temperature without increasing the metal ions (M ⁺⁺ ) in the plating bath. Even if the cathode current density (Dk) is increased at an average M ⁺⁺ concentration, uniform electrodeposition can be obtained, and as a result, high quality plating can be obtained in a relatively short time.

[Brief description of the drawings]

FIG. 1 is a front view of a plating apparatus according to the present invention.

FIG. 2 is a side view of the plating apparatus of FIG.

FIG. 3 is a plan view of the plating apparatus of FIG. 1;

FIG. 4 is a partially enlarged view of the plating apparatus of FIG. 1;

FIG. 5 is a view of FIG. 4 as viewed in the direction of the arrow along line 5-5.

FIG. 6 is a view of FIG. 4 as viewed in the direction of the arrow along line 6-6.

FIG. 7 is a front view of a plating apparatus for a large-area plating object according to the present invention.

FIG. 8 is a side view of the plating apparatus of FIG. 7;

FIG. 9 is a plan view of the plating apparatus of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ‥‥ Plating tank 1 a 壁 Wall having flat inner wall surface 2 陽極 Anode 3 ‥‥ Plated object (cathode) 5 小 Plating solution inflow hole 6 ‥‥ Plating solution outflow hole 7 ‥‥ Discharge tube 8 ‥ ‥ Plating solution supply chamber 9 ‥‥ Suction pipe 10 ‥‥ Plating solution suction pipe 11 流 Flow control plate 13 Suction passage 20A-20D ‥‥ Small plating cell 21 ‥‥ Plating tank 23 ‥‥ Plated material 27 ‥‥ Discharge pipe 28 鍍 Plating solution supply chamber 29 吸入 Suction pipe 30 ‥‥ Plating solution suction chamber 31 ‥‥ Flow control plate 32 ‥‥ Anode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-322599 (JP, A) JP-A-56-136977 (JP, A) JP-A-2-185999 (JP, A) JP-A-60-1985 67689 (JP, A) JP-A-62-297493 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C25D 21/10

Claims (4)

(57) [Claims] 1. A plating bath containing a plating bath in which a plating object as a cathode is immersed, and an interval between a plating surface of the plating object immersed in the plating bath in the plating bath. And a plurality of plating solution inflow holes arranged in a row in a row and opposed to the surface to be plated, and a plurality of plating solution inflow holes arranged in parallel with the row of the plating solution inflow holes. A plurality of plating solution outflow holes arranged in tandem, a plating solution supply chamber communicating with the plating solution inflow hole and communicating with the discharge side of the plating solution pump, and a plating solution communicating with the plating solution outflow hole and plating. A plating solution suction chamber communicating with the suction side of the solution pump, and further extending into the plating tank from both sides of each of the plating solution inflow holes toward the surface to be plated; A pair of flow control plates are provided that form a flow path that directs the plating solution flowing from the plating tank into the plating tank toward the surface to be plated. In addition, a plating cell as one unit is a plating apparatus provided on a side of a flow control plate pair in which the above-mentioned row of plating solution outflow holes forms a plating solution flow path toward a surface to be plated. and then, a plurality of small plating cells connected in a matrix, the plating bath generally one of the large-capacity plating bath open to each other for each unit, plating the plating solution supply chamber above the small plating cells
The liquid suction chamber is independent for each cell ,
Plating equipment. 2. One plating solution pump is provided for each plating solution supply chamber.
The plating solution is supplied via a discharge pipe connected to the discharge side of the pump.
The plating solution is supplied from each plating solution suction chamber.
The plating solution is sucked through the suction pipe connected to the inlet side.
The plating apparatus according to claim 1, wherein: 3. The method according to claim 1, wherein the columns of plating solution inflow holes and the columns of plating solution outflow holes of each small plating cell extend in the vertical direction and are alternately provided. Plating equipment. 4. A prism-shaped anode is arranged at a distance in front of a plating solution outflow small hole row between a flow control plate pair of each small plating cell and a flow control plate pair adjacent to the flow control plate pair. A passage for guiding the plating solution, which has been inverted on the surface to be plated, to the plating solution outflow hole along the flow control plate located at a close position is provided between the opposing control plate and the plating plate. Claims 1 to 3
The plating apparatus according to any one of the above.