JP3606795B2 - Jet type bump forming equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to bump formation in the manufacturing process of a semiconductor device, and more particularly to a jet-type bump forming apparatus for forming bumps having a uniform height.
[0002]
[Prior art]
Conventionally, as a method for forming gold bumps on a wafer, a resist layer is formed on the bump forming surface of the wafer, and the resist layer is exposed and developed to open and expose the metal pad portion. The bumps are formed by depositing metal ions in the plating tank.
[0003]
FIG. 4 shows a schematic configuration diagram of a conventional jet type plating apparatus using a mesh-like anode electrode. In the jet plating apparatus, a cylindrical plating tank 11 and a mesh-like anode electrode 22 are provided inside the plating tank 11 as shown in FIG. A cathode pin 33 is provided around the upper end opening of the plating tank 11. Then, the wafer 44 is placed on the cathode pins 33 and plating is performed.
[0004]
Below, operation | movement of the jet-type plating apparatus comprised as mentioned above is demonstrated. First, by moving a pump (not shown), the plating solution is applied to the wafer 44 from the plating solution storage tank through the plating solution jet 55. Then, a voltage is supplied to the cathode pin 33 and the anode electrode 22, and metal ions in the component of the plating solution are deposited on the wafer 44 in contact with the cathode pin 33, so that the plating process is performed on the wafer 44.
[0005]
Here, since the anode electrode 22 has a mesh shape as shown in FIG. 5, the electric field strength between the wafer 44 placed on the cathode side and the anode electrode 22 is constant everywhere. The metal ions are uniformly accelerated by the electric field regardless of the position in the plating tank 11. In addition, since the plating solution is supplied into the plating tank 11 from the jet port 55, the flow rate of the plating solution in the plating tank 11 is higher than the flow rate at which the wafer 44 reaches the central portion of the wafer 44. Will also increase. As a result, the bump thickness is thicker in the central portion of the wafer 44 than in the outer peripheral portion as much as the amount of the plating solution that hits the wafer 44, and the in-plane uniformity of the bump thickness of the wafer 44 becomes worse.
[0006]
Therefore, a method for solving the above problem is disclosed in Japanese Patent Laid-Open No. 10-321632, and will be described below with reference to FIGS. FIG. 6 shows a plan view of the anode electrode used in the jet plating apparatus constituting the bump forming apparatus. The structure of the jet plating apparatus is basically the same as the above-described jet plating apparatus. A plurality of holes 888 are provided in the anode electrode 111 shown in FIG. 6, and the plating process is performed by forming the holes 888 so as to gradually increase from the central portion toward the outer peripheral portion of the anode electrode 111. At the same time, it is possible to suppress the plating solution that tends to be excessively supplied to the central part, and by making the flow of the plating solution uniform, the ion supply to the entire inside of the wafer is made uniform, and the technology for adjusting the bump height is disclosed. Has been.
[0007]
Further, FIG. 7 shows a schematic configuration diagram of a jet plating apparatus in which a mesh-shaped anode electrode central portion is concavely curved. By indenting the central portion of the anode electrode 112 in a curved shape, the distance between the wafer 222 and the anode electrode 112 increases as the distance from the central portion of the wafer 222 increases. Therefore, the electric field between the anode electrode 112 and the wafer 222 is weak at the central portion. In this case, the metal ions gradually increase in strength toward the outer peripheral portion, the deposition rate of metal ions at the outer peripheral portion is higher than that at the central portion, the excessive precipitation of metal ions on the central portion of the wafer 222 is suppressed, and the bump height is increased. A technique for uniformly adjusting the above is disclosed.
[0008]
[Problems to be solved by the invention]
However, in the above-described jet type plating apparatus, in the method of adjusting the flow of the plating solution by using the anode electrode as shown in FIG. 6, the structure of the anode electrode itself is a structure that inhibits the flow of the plating solution. Since the amount of metal ions reaching the wafer is reduced, the plating deposition efficiency is lowered, and it takes a long time to obtain a prescribed bump thickness.
[0009]
Further, in the method of adjusting the electric field intensity by using the anode electrode as shown in FIG. 7 and adjusting the amount of deposited metal ions, processing into the shape of the anode electrode having a prescribed electric field intensity distribution is performed. The problem is that it is very difficult.
[0010]
Therefore, the present invention solves the above-mentioned problems, and the bump thickness formed on the wafer is reduced without reducing the plating deposition efficiency and without complicating the structure of the anode electrode. It is an object of the present invention to provide a jet type plating apparatus that can be made uniform in the plane.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, a jet port through which a plating solution is jetted in a plating tank, a semiconductor substrate installed so as to face the jet port, and the jet port and the semiconductor substrate are provided. In a jet type bump forming apparatus comprising an electrode, when a predetermined voltage is applied between the electrode and the semiconductor substrate, the electric field strength in the region where the flow rate of the plating solution in the plating tank is the highest is the weakest. A jet-type bump forming apparatus having an electrode having a structure that gradually increases toward a region where a liquid flow rate is small.
[0012]
Further, the electrode is a jet type bump forming apparatus characterized in that the conducting wire has a spiral shape, and the interval between the conducting wires gradually decreases from the central portion toward the outer peripheral portion.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
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 diagram 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 gradually decreases from the center to the outer periphery. Here, the material of the anode electrode 1 is platinum or a platinum alloy, and the wire diameter is 0.5 mm to 1.5 mm. For example, the distance between the lines of platinum at the center of the spiral anode electrode is processed relatively sparsely from 7.5 mm to 15 mm, and the distance between the lines of the outermost platinum is densely processed to about 5 mm to 10 mm. Yes. In FIG. 2, a plating tank 2 and a plating solution storage tank 3 are connected via a pump 4, and the plating solution is stored in the plating solution storage tank 3. The upper and lower ends of the plating tank 2 are open, a plurality of cathode pins 5 are provided at the peripheral edge 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, the wafer 6 is placed on the cathode pins 5 and plating is performed.
[0014]
Below, operation | movement of said jet-type plating apparatus is demonstrated. First, by moving the pump 4, the plating liquid is jetted from the plating liquid storage tank 3 to the plating tank 2 through the plating liquid jet hole 7, and the plating liquid is applied to the wafer 6. Then, a voltage is supplied to the cathode pin 5 and the anode electrode 1, metal ions in the plating solution component are deposited on the wafer 6 in contact with the cathode pin 5, and the wafer 6 is plated. In the wiring method, the outermost peripheral portion and the central portion of the anode electrode 1 are connected to the positive potential side of the constant voltage source 8 so that the anode electrode 1 is at a constant potential, and the negative potential side is connected to the cathode pin 5 on the wafer 6 side. Connecting.
[0015]
For example, when the constant voltage source is 0.4 to 0.5 volts, a current of 3 to 6 milliamperes flows.
[0016]
Moreover, the shape of the anode electrode 1 may be a plurality of concentric circles as shown in FIG. 3, and the distance between the lines may be gradually reduced from the center to the outer periphery.
[0017]
As the plating solution used in the present embodiment, a plating solution in which sulfurous acid, sulfuric acid, thallium and the like are dissolved or a plating solution in which cyan is dissolved is used in addition to Au, Ag and solder as main components. Further, when an electroless plating solution is used, plating can be performed without supplying current.
[0018]
【The invention's effect】
By using the anode electrode of the present invention, the electric field strength is weak at the central portion of the plating tank, the electric field strength gradually increases toward the outer peripheral portion, and the electric field strength becomes strongest at the outer peripheral portion, Metal that deposits on the wafer without changing the flow of the plating solution by decreasing 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 The bump thickness can be made 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 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 liquid storage tank 4 Pump 5 Cathode pin 6 Wafer 7 Plating liquid jet hole 8 Constant voltage source

Claims (2)

Jet-type bump formation comprising a jet port through which a plating solution is jetted into a plating tank, a semiconductor substrate installed so as to face the jet port, and an electrode provided between the jet port and the semiconductor substrate In the device
When a predetermined voltage is applied between the electrode and the semiconductor substrate, the electric field strength in the region where the flow rate of the plating solution in the plating tank is the highest is weakest, and the electric field strength is directed toward the region where the flow rate of the plating solution is low. have a electrode increasing structures, electrode has a spiral and concentric one shape, and nozzle-type characterized by gradually small and Rukoto as the distance between lines leading to the outer peripheral portion from the central portion Bump forming device. 2. The jet type bump forming apparatus according to claim 1, wherein the electrode has a spiral conductor, and the interval between the conductors gradually decreases from the center toward the outer periphery.

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