JPH11152600A - Plating apparatus for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plating apparatus for a wafer capable of finely regulating the electric field to be impressed on the wafer when the wafer is subjected to plating thereon and capable of easily forming plating of a uniform thickness. SOLUTION: The wafer 100 and an anode 30 installed to face the surface of the wafer 100 apart a prescribed distance from the wafer 100 are immersed into an electrolytic plating liquid 20. A planar dielectric substance 40 is installed on the front surface of this anode 30 on the side facing the wafer 100. This dielectric substance 40 is formed to the thickness thinner nearer the central part and thickener concentrically nearer the outer peripheral part in such a manner that a shielding effect is concentrically higher nearer the outer peripheral part than the central part of the wafer 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer plating apparatus capable of effectively adjusting an electric field applied when plating a wafer surface.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, a wafer plating apparatus for performing electrolytic plating on the surface of a wafer is installed in an electrolytic plating solution 120 so as to face the wafer 100 and the surface of the wafer 100. The plate-shaped anode 110 is immersed, and a current is applied between the wafer 100 and the anode 110 to perform plating on the surface of the wafer 100.

[0003]

However, in this plating apparatus, when an electric field is applied to perform plating on the wafer 100 due to its structure, as shown in FIG. Therefore, the thickness of the plated film tends to be larger toward the outer peripheral portion than the central portion of the wafer 100.

In order to avoid this and uniformly plate the surface of the wafer 100, it is necessary to adjust the potential of each part near the surface of the wafer 100 to be as uniform as possible. Methods such as installing a shielding plate between the 110 and adjusting the size of the anode 110 have been adopted.

However, these methods make it difficult to finely adjust the potential distribution. In particular, as the diameter of the wafer 100 increases, the difference in potential between the central portion and the outer peripheral portion increases, so that it is difficult to make the potential distribution uniform over a wide range of the entire surface of the wafer 100 to form a uniform plating. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to make it possible to finely adjust a potential distribution applied when plating on a wafer and easily form a plating of uniform thickness on the wafer surface. It is an object of the present invention to provide a wafer plating apparatus that can perform the plating.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of immersing a wafer and an anode, which is placed at a predetermined distance from the wafer and opposed to the wafer surface, in an electrolytic plating solution. Then, in a wafer plating apparatus that performs plating on the wafer surface by energizing between the wafer and the anode, a dielectric is placed on the surface of the anode facing the wafer or between the anode and the wafer, and the dielectric is The wafer is formed so as to have a different shielding effect depending on the portion so that the outer peripheral portion has a greater shielding effect than the central portion in a concentric circle with the wafer. The dielectric was formed in a plate shape such that its thickness became thinner toward the center and thicker toward the outer periphery. Alternatively, the dielectric is a mesh plate or a punching plate, and the size of the opening is larger toward the center and smaller toward the outer periphery.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall schematic view of a plating apparatus used in an embodiment of the present invention. As shown in the figure, the plating apparatus is provided with an electrolytic plating solution 20 in a plating tank 10.
The wafer 100 and the anode 30 are immersed therein at a predetermined distance from each other so that the opposing surfaces thereof are parallel to each other.
0 is attached. Hereinafter, each component will be described.

The plating tank 10 is provided with an overflow tank 13 on the outer periphery thereof, and the plating tank 10 and the overflow tank 13 are connected by a pipe 21 to which a pump 15, a constant temperature unit 17, and a filter 19 are attached.

The wafer 100 has a substantially disk shape, and is configured such that one surface thereof is exposed in the electrolytic plating solution 20 by holding the outer periphery of the wafer 100 with a wafer holding member 101.

The anode 30 is formed in a disk shape having substantially the same dimensions as the wafer 100.

FIG. 2 is a view showing the dielectric 40.
FIG. 1A is a plan view, and FIG. 1B is a side sectional view. As shown in the figure, the dielectric 40 is formed in a disk shape having substantially the same dimensions as the wafer 100, and the thickness of the dielectric 40 is reduced toward the center and increased toward the outer periphery. It is configured so that its thickness is varied concentrically and stepwise.

As a material of the dielectric 40, vinyl chloride is used, but other dielectric materials such as heat-resistant vinyl chloride, polypropylene, polyether sulfone, polyether ether ketone, polycarbonate,
Polyethylene, polystyrene, polyvinylidene fluoride,
Various materials such as a fluororesin may be used.

Next, the operation of the plating apparatus will be described.
First, by driving the pump 15, the electrolytic plating solution 20 passed through the constant temperature unit 17 and the filter 19 is supplied to the plating tank 10.
Is supplied from the lower part thereof, overflows to the overflow tank 13 and circulates.

At this time, the wafer 100 and the anode 3 are simultaneously
Electricity is applied during zero to perform plating on the surface of the wafer 100.

FIG. 3 shows the wafer 10 during plating.
FIG. 3 is an equipotential diagram showing a state of an electric field around 0 and an anode 30. As shown in the figure, in the present embodiment, the thickness of the dielectric 40 attached to the surface of the anode 30 is concentrically varied stepwise so as to be thinner toward the center and thicker toward the outer periphery. That is, since the thickness of the outer peripheral portion is made different from that of the central portion of the wafer 100 concentrically so that the shielding effect is greater than that of the central portion of the wafer 100, the potential of the wafer 100 becomes lower from the outer peripheral portion of the wafer 100 where the potential tends to increase. A uniform potential distribution to the parts was achieved. Therefore, the plating film thickness of each part of the wafer 100 could be finely adjusted and made uniform.

FIGS. 4, 5, and 6 are diagrams showing dielectrics 40-2, 3, and 4 having other structures used in the present invention. FIG. 4A is a plan view, and FIG. Is a side sectional view.

That is, the dielectric 40- shown in FIGS.
The wafers 2, 3, and 4 are also formed in a disk shape having substantially the same dimensions as the wafer 100.

The dielectric 40-2 shown in FIG. 4 is a disk made of a dielectric material and has a spherical surface on its surface so that its thickness is thinner toward the center and thicker concentrically toward the outer periphery. It is constituted by providing a concave portion 41 of a shape.

In the case of the dielectric 40-3 shown in FIG. 5, a large number of circular openings 43 are provided in a circular plate made of a dielectric material to form a so-called punching plate. The larger the portion, the smaller the size concentrically toward the outer periphery.

In the case of the dielectric 40-4 shown in FIG. 6, a wire made of a dielectric material is knitted into a mesh-like plate. In this case, the size of the opening 45 of the mesh becomes larger toward the center. It is formed concentrically so as to become smaller toward the outer periphery.

In the case of these dielectrics 40-2, 3, and 4, as in the case of the dielectric 40, the outer periphery is concentric with the opposed wafer 100 so that the outer peripheral portion has a greater shielding effect than the central portion. Thus, since the shielding effect is formed differently, the potential of each part of the wafer 100 can be made uniform, and the plating film thickness of each part of the wafer 100 can be finely adjusted and made uniform.

The above dielectrics 40, 40-2, 3, 4
Is not necessarily required to be attached to the surface of the anode 30 so that the wafer 10 is separated from the surface of the anode 30.
It may be arranged between 0 and the anode 30.

[0024]

As described above in detail, according to the present invention, a dielectric having a structure in which the shielding effect is different depending on the portion is provided on the surface of the anode or between the anode and the wafer. Over the entire surface of the wafer by finely adjusting the electric field, resulting in a uniform plating film thickness. Have.

[Brief description of the drawings]

FIG. 1 is an overall schematic view of a wafer plating apparatus used in an embodiment of the present invention.

FIGS. 2A and 2B are views showing a dielectric 40, wherein FIG. 2A is a plan view and FIG. 2B is a side sectional view.

3 is an equipotential diagram showing a state of an electric field around a wafer 100 and an anode 30. FIG.

4A and 4B are diagrams showing a dielectric body 40-2 having another structure, wherein FIG. 4A is a plan view and FIG. 4B is a side sectional view.

5A and 5B are diagrams showing a dielectric 40-3 having another structure, wherein FIG. 5A is a plan view and FIG. 5B is a side sectional view.

6A and 6B are diagrams showing a dielectric 40-4 having another structure, wherein FIG. 6A is a plan view and FIG. 6B is a side sectional view.

FIG. 7 is an overall schematic view of a conventional wafer plating apparatus.

FIG. 8 is an equipotential diagram showing a state of an electric field around the wafer 100 and the anode 110.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Plating tank 20 Electrolytic plating solution 30 Anode 40 Dielectric 40-2 Dielectric 40-3 Dielectric 40-4 Dielectric 43 Opening 45 Opening 100 Wafer

Claims (3)

[Claims] 1. A wafer and an anode provided at a predetermined distance from the wafer and opposed to the wafer surface are immersed in an electrolytic plating solution, and a current is applied between the wafer and the anode to plate the wafer surface. In the wafer plating apparatus, a dielectric is provided on the surface of the anode facing the wafer or between the anode and the wafer, and the dielectric is arranged concentrically with the wafer toward an outer peripheral portion than a central portion thereof. Is formed in a structure having different shielding effects depending on portions so as to increase the shielding effect. 2. A wafer plating apparatus according to claim 1, wherein said dielectric has a plate shape, and is configured such that its thickness becomes thinner toward a central portion and becomes thicker toward an outer peripheral portion. . 3. The dielectric according to claim 1, wherein the dielectric is a mesh plate or a punching plate, and the size of the opening is larger toward the center and smaller toward the outer periphery. Item 2. A wafer plating apparatus according to Item 1.