JPH03148133A - Plating method for bump electrode of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent occurrence of an improper chip by forming a conductive film on the entire surface of a wafer, electrically conducting the film with an electrode pin on the rear surface of the wafer, and plating a bump electrode. CONSTITUTION:A conductive film 22 of aluminum, etc., is formed on the entire surface of a wafer 21 to be formed with a bump electrode by vacuum depositing, etc., the front surface of the wafer 21 is coated with a mask material 23 such as resist, and so patterned as to open only at a part to be desired to be formed with the bump electrode. Then, it is so set in a rack 25 that the rear surface of the wafer 21 is brought into contact with an electrode pin 24, an O-ring 26 is mounted at the peripheral edge to seal the space of the rear surface of the wafer 21 against the atmosphere, the wafer 21 is sucked and held by vacuum evacuating, then dipped in a plating solution 27, and plated by supplying a plating current. Thus, an improper chip is eliminated to be stably plated with the bump electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plating method for forming bump electrodes on a semiconductor device.

(Prior art) Conventionally, as a technology in this field, for example,
There was one described in No. 1-182031.

FIG. 2 is an explanatory diagram of a conventional plating method for bump electrodes of a semiconductor device.

As shown in this figure, when forming bump electrodes on a wafer 1 by plating, a conductive film 2 is applied by a method such as vacuum evaporation to allow the plating current to flow, and then a mask material 3 such as a resist is applied. Using this method, pattern the holes so that only the areas where you want to plate them are drilled. In this state, by sticking the electrode pin 4 into the surface of the wafer 1 from above the mask material 3 and applying pressure from the back side of the wafer 1, the pin 4 breaks through the mask material 3 and extends directly below the mask material 3. Make sure that it reaches the applied conductive coating 2. In this manner, the plating current was made to flow from the electrode pins 4 to the conductive coating 2 on the wafer l, and then the wafer was immersed in the plating solution 5 to perform plating.

In addition to the above plating method, there is also a method as shown in FIG. That is, as in FIG. 2, a conductive film 12 is applied to the surface of the wafer 11 by a method such as vacuum deposition, and then a mask material 13 such as resist is used to open holes only in the areas where plating is desired. Butter it. Furthermore,
A vacuum is drawn from the back surface of the wafer 11, and the electrode pins 14 are brought into contact with the front surface of the wafer 11 to conduct plating current. In addition, here, 15 is mask rubber.

(Problem to be Solved by the Invention) However, in the first plating method described above, if the electrode pins 4 break through to the conductive coating 2 and reach the wafer 1, the semiconductor chip becomes defective. The number and shape of the pins 4 are strictly limited. In addition, electrode pin 4
The plating current penetrates through the mask material 3 and conducts the plating current, but there is a problem in that if the mask material 3 cannot be penetrated successfully, the conduction tends to become unstable.

Further, according to the second plating method, the problems in the first plating method are solved, but since the electrode binder 4 is in direct contact with the silicon on the back surface of the wafer 11, the semiconductor chips inside the wafer 11 are Depending on the structure and the state of contact between the conductive film 12 applied to the surface of the wafer 11 and silicon, a phenomenon occurs in which there is no conduction at all. Further, there are many problems such as the need to set the plating current value in consideration of differences in electrical resistance on the surface and inside of the wafer 11, and it has been difficult to perform stable plating.

Furthermore, if the contact between the electrode pin and the conductive film is unstable, there is a problem in that the process must be repeated many times in order to break through the mask material and bring about good contact.

The present invention eliminates the above-mentioned problems of the occurrence of defective chips, unstable conduction of plating current, and deterioration of workability, and enables stable plating of bump electrodes without the occurrence of defective chips. An object of the present invention is to provide a method for plating bump electrodes of a semiconductor device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for plating bump electrodes of semiconductor devices, in which a conductive film is applied to the entire surface of a wafer, and the conductive film is removed from the back surface of the wafer. The bump electrode is plated by electrically connecting with the electrode pin.

(Function) According to the present invention, as described above, a conductive film is applied to the entire surface of the wafer on which bump electrodes are to be formed by a method such as vacuum deposition, and then a mask material is applied to the wafer surface, and the bump electrodes are formed on the wafer. A hole is opened only in the part where an electrode is to be formed, an electrode pin is brought into contact with the back side of the wafer, and a plating current is conducted to form a bump electrode.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram of a method of plating bump electrodes of a semiconductor device showing an embodiment of the present invention.

As shown in this figure, a conductive film 22 made of aluminum or the like is applied to the entire surface of the wafer 21 on which bump electrodes are to be formed, that is, the front, back, and side surfaces, by vacuum evaporation or the like.
Make sure that there is electrical continuity between the front and back sides.

After that, a mask material 2 such as a resist is placed on the front side of the wafer 21.
3 and leave it in a patterned state so that holes are formed only in the areas where bump electrodes are to be formed.

Therefore, the wafer 21 is set on the rack 25 so that the back surface thereof is in contact with the electrode pins 24. This rack 25 holds and fixes the wafer 21 and can be energized. That is, by installing the O-ring 26 around the periphery of the back surface of the wafer 21, the space on the back surface of the wafer 21 is sealed from the outside air, the wafer 2 is attracted by vacuum, and the wafer 21 is held. The wafer 21 is energized.

In this way, after holding the wafer 21 and immersing it in the plating solution 27, plating is performed by applying a plating current.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, a conductive film is applied to the entire surface of the wafer, and the plating current is conducted from the back surface of the wafer, so that the following effects can be achieved. This effect can be achieved.

(1) Since the electrode pins are not pushed up from above the mask material, the occurrence of defective chips is eliminated.

(2) Since the entire surface of the wafer is covered with a conductive film, electrical conductivity is good, and stable plating can be performed regardless of the element structure and manufacturing method of the semiconductor device. For example, the PN junction may be reverse biased,
Further, an insulating film may remain on the back surface of the wafer.

(3) Since the electrode pins do not come into direct contact with the plating solution, they are not plated and maintenance is unnecessary.

(4) Since there is no need to break through the mask material with electrode pins, the shape of the pins can be changed freely.

(5) There is no obstruction to the flow of the plating solution,
Uniform plating is possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a method of plating bump electrodes of a semiconductor device showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of a method of plating bump electrodes of a conventional semiconductor device, and FIG. 3 is an explanatory diagram of a method of plating bump electrodes of a conventional semiconductor device. FIG. 3 is an explanatory diagram of a method of plating bump electrodes of the device. 21... Wafer, 22... Conductive film, 23...
Mask material, 24... Electrode pin, 25... Rack,
26...O ring, 27...Plating liquid.

Claims (1)

[Claims] A method for plating bump electrodes of a semiconductor device, comprising applying a conductive film to the entire surface of a wafer, establishing electrical continuity between the conductive film and electrode pins on the back side of the wafer, and plating the bump electrodes.