JP2002093834A - Jet flow bump-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jet flow plating apparatus which enables bumps to be formed on a wafer in an uniformized thickness in a plane of the wafer, without reducing the plating deposition efficiency or complicating the structure of anode electrode. SOLUTION: The anode electrode of the jet flow plating apparatus is formed into a spiral shape. With to this structure, a quantity of metal ions in a plating liquid is reduced toward the center of the wafer, while gradually increasing toward the periphery of the wafer, uniformizing the thickness of the metal bumps to be deposited on the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bump formation in a semiconductor device manufacturing process, and more particularly, to a jet type bump forming apparatus for forming bumps having a uniform height.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a gold bump on a wafer, a resist layer is formed on a bump forming surface of the wafer, and the resist layer is exposed and developed to open and expose a metal pad portion. The bumps are formed by depositing metal ions in the plating bath on the metal pad portion.

FIG. 4 shows a schematic configuration diagram of a conventional jet-type plating apparatus using a mesh-shaped anode electrode. In this jet plating apparatus, a cylindrical plating tank 11 and a mesh-shaped anode electrode 22 are provided inside the plating tank 11 as shown in FIG. Further, a cathode pin 33 is provided in a peripheral portion of an upper end opening of the plating tank 11. Then, a plating process is performed by placing the wafer 44 on the cathode pins 33.

The operation of the jet plating apparatus configured as described above will be described below. First, a pump (not shown)
By moving the plating solution, the plating solution is applied to the wafer 44 from the plating solution storage tank through the plating solution jet port 55. Then, a voltage is supplied to the cathode pins 33 and the anode electrode 22, and metal ions in the components of the plating solution are deposited on the wafer 44 in contact with the cathode pins 33, and the wafer 44 is subjected to plating.

Here, since the anode electrode 22 has a mesh shape as shown in FIG. 5, the electric field intensity between the wafer 44 provided on the cathode side and the anode electrode 22 is constant at any place. Therefore, the metal ions are uniformly accelerated by the electric field regardless of the position in the plating tank 11. Further, since the plating solution is supplied from the jet port 55 into the plating tank 11, the flow of the plating solution in the plating tank 11 is such that the flow rate reaching the substantially central portion of the wafer 44 is smaller than the flow rate reaching the peripheral portion of the wafer 44. Also increase. As a result, the bump thickness becomes thicker in the central part of the wafer 44 than in the outer peripheral part by the amount of the plating solution corresponding to the wafer 44, and the in-plane uniformity of the bump thickness of the wafer 44 deteriorates.

A method for solving the above problem is disclosed in Japanese Patent Laid-Open Publication No. Hei 10-321632, and will be described below with reference to FIGS. FIG. 6 shows a plan view of an anode electrode used in a jet plating apparatus constituting the bump forming apparatus. The structure of the jet plating apparatus is basically the same as that of the above-described jet plating apparatus. A plurality of holes 888 are provided in the anode electrode 111 shown in FIG.
11 is formed so as to gradually increase from the central portion toward the outer peripheral portion, so that it is possible to suppress the plating solution that tends to be excessively supplied to the central portion when performing the plating process, and to reduce the flow of the plating solution. A technique has been disclosed in which by making the wafer uniform, the ion supply to the entire inside of the wafer is made uniform and the bump height is adjusted.

FIG. 7 is a schematic structural view of a jet plating apparatus in which a central portion of a mesh-shaped anode electrode is concavely curved. By depressing the central portion of the anode electrode 112 in a curved manner, the distance between the wafer 222 and the anode electrode 112 becomes larger toward the central portion of the wafer 222, so that the anode electrode 112 and the wafer 222
The electric field between them is weaker in the central part, and gradually increases toward the outer peripheral part. The deposition rate of metal ions is faster in the outer peripheral part than in the central part, and the metal ion is deposited on the central part of the wafer 222. A technique for suppressing excess and uniformly adjusting the height of the bump is disclosed.

[0008]

However, in the above-described jet-type plating apparatus, the method of adjusting the flow of the plating solution by utilizing the anode electrode as shown in FIG. In this structure, the amount of metal ions arriving at the wafer is reduced, so that the plating deposition efficiency is reduced, and it takes a long time to obtain a specified bump thickness.

Further, in the method of adjusting the electric field intensity by using the anode electrode as shown in FIG. 7 to adjust the amount of metal ions deposited, the anode electrode is processed into a specified electric field intensity distribution. The problem is that it is very difficult to do so.

Therefore, the present invention solves the above-mentioned problems, and does not reduce the plating deposition efficiency.
It is another object of the present invention to provide a jet plating apparatus capable of making the thickness of bumps formed on a wafer uniform within the plane of the wafer without complicating the structure of the anode electrode.

[0011]

In order to solve the above-mentioned problems, in order to solve the above-mentioned problems, a jet port for jetting a plating solution into a plating tank, a semiconductor substrate provided so as to face the jet port, the jet port, and In a jet-type bump forming apparatus including an electrode provided between a semiconductor substrate and a predetermined voltage applied between the electrode and the semiconductor substrate, a region where the flow rate of a plating solution in the plating tank is the highest. Is a jet-type bump forming apparatus, characterized in that it has an electrode having a structure in which the electric field strength of the electrode becomes weakest and gradually increases toward a region where the flow rate of the plating solution is small.

Further, in the above-mentioned electrode, a jet-type bump forming apparatus is characterized in that a conductive wire has a spiral shape, and an interval between the conductive wires is gradually reduced from a center portion to an outer peripheral portion.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing the shape of a spiral anode electrode 1 used in a jet plating apparatus constituting a bump forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic structural view of a jet plating apparatus using the spiral anode electrode 1 of the present invention. In FIG. 1, the shape of the anode electrode 1 is a spiral shape, and the distance between the lines becomes gradually smaller from the center to the outer periphery. Here, as the material of the anode electrode 1, platinum or an alloy of platinum is used, and the wire diameter is 0.5 mm to 1.5 mm. For example, the distance between platinum lines at the center of the spiral anode electrode is 7.5.
It is processed relatively sparsely from 15 mm to 15 mm, and the distance between platinum lines on the outermost periphery is densely processed to about 5 mm to 10 mm. In FIG. 2, the plating tank 2 and the plating liquid storage tank 3 are connected via a pump 4, and the plating liquid is stored in the plating liquid storage tank 3. The upper and lower ends of the plating tank 2 are open, a plurality of cathode pins 5 are provided on the periphery of the upper end opening, and a pump 4 is connected to the lower end opening. An anode electrode 1 is provided inside the plating tank 2. Then, a plating process is performed by placing the wafer 6 on the cathode pins 5.

The operation of the above-mentioned jet plating apparatus will be described below. First, by operating the pump 4, the plating solution is jetted from the plating solution storage tank 3 to the plating tank 2 through the plating solution jet hole 7, and the plating solution is applied to the wafer 6. Then, a voltage is supplied to the cathode pins 5 and the anode electrode 1, and metal ions in a plating solution component are deposited on the wafer 6 in contact with the cathode pins 5, and the wafer 6 is subjected to a plating process. The wiring method is the anode electrode 1
Are connected to the positive potential side of the constant voltage source 8 to keep the anode electrode 1 at a constant potential, and the cathode pin 5 on the wafer 6 side is connected to the negative potential side.

For example, when the constant voltage source is set to 0.4 to 0.5 volt, a current of 3 to 6 mA is made to flow.

Further, as shown in FIG. 3, the shape of the anode electrode 1 may be a plurality of concentric circles, and the distance between the lines may be gradually reduced from the center to the outer periphery.

The plating solution used in this embodiment includes Au, Ag, and solder, which are the main components,
A plating solution in which sulfurous acid, sulfuric acid, thallium or the like is dissolved or a plating solution in which cyan is dissolved is used. When an electroless plating solution is used, plating can be performed without supplying an electric current.

[0018]

By using the anode electrode of the present invention, the electric field intensity is weak at the center of the plating tank, gradually increases toward the outer periphery, and becomes the highest at the outer periphery. By reducing the amount of metal ions in the plating solution toward the center of the wafer, and gradually increasing the amount of metal ions in the plating solution toward the outer periphery of the wafer, without changing the flow of the plating solution It is possible to make the thickness of the metal bump deposited thereon constant.

[Brief description of the drawings]

FIG. 1 is a plan view of an anode electrode according to the present invention.

FIG. 2 is a schematic configuration diagram of a jet plating apparatus according to the present invention.

FIG. 3 is a plan view of another anode electrode according to the present invention.

FIG. 4 is a schematic configuration diagram of a conventional jet plating apparatus.

FIG. 5 is a plan view of a conventional mesh-shaped anode electrode.

FIG. 6 is a plan view of a conventional anode electrode.

FIG. 7 is a schematic configuration diagram of a conventional jet plating apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode electrode 2 Plating tank 3 Plating solution storage tank 4 Pump 5 Cathode pin 6 Wafer 7 Plating solution jet hole 8 Constant voltage source

Claims (2)

[Claims] 1. A jet port for jetting a plating solution into a plating tank, a semiconductor substrate provided to face the jet port, and an electrode provided between the jet port and the semiconductor substrate. In the jet-type bump forming apparatus, when a predetermined voltage is applied between the electrode and the semiconductor substrate, the electric field intensity in a region where the flow rate of the plating solution in the plating tank is highest becomes the weakest, and the flow rate of the plating solution is reduced. A jet flow type bump forming apparatus, comprising: an electrode having a structure in which an electric field intensity gradually increases toward a region having a small number of bumps. 2. The jet bump forming method according to claim 1, wherein the electrode has a spiral shape of a conductive wire, and a distance between the conductive wires is gradually reduced from a central portion toward an outer peripheral portion. apparatus.