JPH0874088A - Cup type plating machine - Google Patents

Abstract

(57) [Abstract] [Purpose] For a cup-type plating apparatus used for bump plating, etc., eliminates unevenness in the flow rate and current density of the plating solution that causes uneven plating. [Composition] A damper body 4 for diffusing a jet flow of a plating solution L from a supply port 3 into a plating tank 2 is provided above the supply port, and a current flows along an outlet 7 of the plating solution in an upper opening 1. The shield 8 is provided so as to project inward of the plating tank. The current shield is characterized by having a current density guide surface 8f having a shape in which the distance between the plating target U and the plating target surface gradually increases from the end on the outlet side toward the protruding tip. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cup type plating apparatus used for bump plating of wafers, for example.

[0002]

2. Description of the Related Art A typical basic structure of a cup type plating apparatus is shown in FIG. That is, the cup-shaped plating tank 20 is provided, and the upper opening 21 of the plating tank 20 is provided.
An object to be plated, for example, a wafer U is placed on the surface of the wafer U to be plated, and the plating solution L jetted from the supply port 22 at the bottom of the plating tank 20 is contacted while flowing out from the upper opening to the surroundings. It is designed to be plated. Reference numeral 23 in the figure is an anode electrode, while the wafer U is connected to a cathode electrode (not shown).

One of the problems in such a cup type plating apparatus is that the flow velocity of the plating solution at the portion in contact with the surface to be plated is uneven and the current density is uneven on the surface to be plated. This is due to non-uniformity in plating.

Many measures have already been taken to eliminate such non-uniformity of plating. For example, the technique disclosed in Japanese Utility Model Publication No. 58-8774 is one of them.
In this technique, it is assumed that the non-uniformity is caused by the fact that the outer peripheral part of the surface to be plated is in contact with the plating solution more than other parts and the current density is likely to increase in the outer peripheral part. The ridges are provided on the peripheral surface, the flow of the plating solution is deflected inward by the ridges, and the current density on the surface to be plated is made uniform, thereby improving the uniformity of plating. According to this technique, the uniformity can be improved to some extent, but the degree is not always sufficient.

Then, when further pursuing the cause,
First, since the flow velocity in the central portion, which is directly affected by the jet flow from the supply port, is faster than other portions, a donut-shaped stagnation portion S (FIG. 3) is formed around the central portion, and the plating thickness at this stagnation portion. Second, it is easy to become thin.
It was found that the ridge structure used in No. 4 cannot sufficiently make the current density in the outer peripheral portion uniform.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cup type plating apparatus capable of eliminating the above-mentioned causes of non-uniformity.

[0007]

According to the cup type plating apparatus of the present invention, the object to be plated placed on the upper opening of the cup-shaped plating tank is jetted from the supply port at the bottom of the plating tank. Based on the structure in which the plating solution to be flowed from the upper opening to the surroundings is contacted and plated, a damper body is provided above the supply port, and this damper body allows the jet flow of the plating solution from the supply port to be stored in the plating tank. It has a structure to diffuse into.

According to this structure, the jet flow from the supply port is uniformly diffused by the damper body throughout the plating tank, so that the flow velocity is increased only in the central portion to cause a stagnation portion around it. It can be effectively prevented.

The cup type plating apparatus according to the present invention is
Plating is performed by bringing the plating solution jetted from the supply port at the bottom of the plating tank into contact with the surface to be plated of the plating object placed in the upper opening of the cup-shaped plating tank while allowing it to flow from the upper opening to the surroundings. Based on the structure, the current shield is provided so as to protrude inward of the plating tank along the outlet of the plating solution at the upper opening, and the current shield is provided from the end on the outlet side toward the protruding tip. It has a structure in which a current density guide surface having a shape in which the distance between the object to be plated and the surface to be plated gradually widens is provided.

According to this structure, since the current shield is interposed between the outer peripheral portion of the surface to be plated and the anode electrode, it is possible to roughly prevent the current from concentrating on the outer peripheral portion. By adjusting the layer thickness of the plating solution corresponding to the outer peripheral portion by the shape of the current density guide surface, the current density can be made more uniform and the uniformity of the current density in the outer peripheral portion can be greatly increased. You can

Further, in the cup type plating apparatus according to the present invention, the plating solution jetted from the supply port at the bottom of the plating tank is applied to the surface to be plated of the object to be plated placed in the upper opening of the cup-shaped plating tank. Basically, the structure is such that plating is performed while allowing it to flow out from the upper opening to the surroundings, and a damper body for diffusing the jet flow of the plating solution from the supply port into the plating tank is provided on the upper side of the supply port and A current shield is provided so as to project inward of the plating tank along the outlet of the plating solution, and the current shield is provided with a surface to be plated of the object to be plated from the end on the outlet side toward the protruding tip. Has a structure in which a current density guide surface having a shape in which the interval of gradually increases is provided.

This structure is a combination of the above structures,
Both flow velocity and current density can be made uniform, and more uniform plating can be achieved.

[0013]

EXAMPLES An example of the present invention will be described below.
The cup type plating apparatus of the present embodiment is an example for bump plating of a wafer, and as shown in FIG. 1 and FIG.
It has a cup-shaped plating tank 2 having a circular upper opening 1 corresponding to the above shape. The bottom of the plating tank 2 is provided with a supply port 3 for supplying the plating solution, which is supplied via a circulation mechanism (not shown), into the tank by jetting. A damper body 4 is provided on the upper side of the supply port 3 slightly apart from the upper end of the supply port 3, and an anode electrode 5 is provided in a state of being superposed on the damper body 4. Reference numeral 6 in the drawing denotes a cathode electrode whose tip is in contact with the wafer U.

The damper body 4 is formed in a disk shape, and diffuses the plating solution ejected from the supply port 3 to the surroundings. That is, the damper body 4 functions so as to moderate the flow of the plating solution L ejected from the supply port 3 and to give a flow as shown by the arrow to this so that the plating solution L gradually spreads and rises over the entire plating tank 2. To do.

A current shield 8 is provided along the outlet 7 of the plating solution in the upper opening 1 of the plating tank 2 so as to project inward. The current shield 8 is formed in a ring shape having a fan-shaped cross section, and has a current density guide surface 8f in a state of diagonally facing the wafer U placed in the upper opening 1. The current density guide surface 8f is formed into an arcuate curved surface, and the distance between the current U and the surface to be plated of the wafer U gradually increases from the end portion side in contact with the outlet 7 toward the protruding tip.

The current shield 8 is provided between the outer peripheral portion of the wafer U and the anode electrode 5 to function to roughly prevent the concentration of the electric current on the outer peripheral portion. Further, in the current shield 8, the layer thickness of the plating solution corresponding to the outer peripheral portion of the wafer U is gradually reduced toward the outer peripheral edge due to the shape of the current density guide surface 8f, and the current density is accordingly reduced. Works as well. As a result, the decrease in the current density and the tendency for the current density to increase toward the outer peripheral edge are offset, and the current density in the outer peripheral portion can be made high and uniform.

As can be seen from the function of such a current shield, the shape of the current density guide surface varies depending on the type of plating solution, the flow state of plating, etc., depending on the degree of current concentration at the outer peripheral edge. Will be selected. Therefore, the above-mentioned arc curved surface shape is an example, and if the type of plating solution is different, other shapes will be given in a shape range satisfying the above-mentioned offsetting function.

[0018]

As described above, according to the cup type plating apparatus of the present invention, the factors that cause non-uniformity of plating can be effectively eliminated, and plating with high uniformity can be performed.

[Brief description of drawings]

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

FIG. 2 is a plan view seen from the direction of the arrow DA in FIG.

FIG. 3 is a sectional view showing an internal structure of a conventional cup-type plating apparatus.

[Explanation of symbols]

 1 Upper opening 2 Plating tank 3 Supply port 4 Damper body 7 Outlet 8 Current shield 8f Current density guide surface L Plating liquid U Wafer (plating target)

Claims (3)

[Claims] 1. A plating solution jetted from a supply port at the bottom of a plating tank to the surface to be plated of an object to be plated placed in the upper opening of a cup-shaped plating tank while flowing out to the surroundings from the upper opening. In a cup-type plating device that is configured to contact and plate, a damper body is provided above the supply port, and this damper body is used to diffuse the jet flow of the plating solution from the supply port into the plating tank. A cup-type plating device. 2. The plating solution jetted from the supply port at the bottom of the plating tank onto the surface of the object to be plated placed in the upper opening of the cup-shaped plating tank while flowing out from the upper opening to the surroundings. In a cup-type plating apparatus that is configured to contact and plate, a current shield is provided so as to protrude inward of the plating tank along the outlet of the plating solution at the upper opening, and A cup-type plating apparatus characterized in that a current density guide surface having a shape in which a space between a plating target object and a plating target surface gradually widens from an end on the outlet side toward a protruding tip is provided. 3. The plating solution jetted from the supply port at the bottom of the plating tank to the surface of the object to be plated placed in the upper opening of the cup-shaped plating tank while flowing out to the surroundings from the upper opening. In a cup-type plating apparatus that is adapted to contact and plate, a damper body for diffusing the jet flow of the plating solution from the supply port into the plating tank is provided above the supply port, and the plating solution at the upper opening is provided. The current shield is provided so as to project inward of the plating tank along the outlet of the plate, and the gap between the current shield and the surface to be plated of the object to be plated from the end on the outlet side toward the protruding tip. The cup-type plating device is characterized in that a current density guide surface having a shape that gradually expands is provided.