JPS6241320B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plating apparatus, and particularly to a plating apparatus for plating wafers.

Protruding electrodes such as solder electrodes and copper electrodes of semiconductor devices are generally formed by the method shown in FIGS. 1a to 1d. That is, as shown in FIG. 1A, an aluminum wiring 1 and a protective film 2 made of silicon nitride or the like are formed on the base 3, and these are covered by an electrode base film 4 made of copper or the like by vapor deposition. Next, as shown in FIG. 1B, a photoresist 5 is applied onto the electrode base film 4, and a predetermined protruding electrode pattern is formed by exposure and development. Next, using a plating device as shown in FIG. 1c, solder, copper, or the like is plated to a predetermined thickness to form the protruding electrodes 6. Finally, as shown in FIG. 1d, the photoresist 5 is removed, and the unnecessary electrode base film 4 other than the area below the protruding electrode 6 is removed by etching. When the plating described above is carried out using a rectangular parallelepiped type immersion plating apparatus that has been commonly used in the past, the electric current is concentrated near the outer periphery of the wafer due to the edge effect peculiar to electroplating. The tightening layer is thicker in some parts than in other parts, resulting in a tendency for the height of the protruding electrode to become higher. Second
In the figure, the horizontal axis shows the distance (m/m) from the wafer center C, and the vertical axis shows the plating thickness (μm).
It shows. That is, in the case of the conventional immersion plating apparatus, as shown in a in FIG. 2, the plating thickness increases as the distance from the wafer center C increases, and when the average plating thickness is 80 μm, C
There is a difference in plating thickness of about 32 μm between the wafer edge E and the wafer edge E. In this way, if the plating thickness varies within a single wafer, when the wafer is divided into individual chips, the height of the protruding electrodes will vary from chip to chip and between electrodes within a chip. It turns out. When chips with different electrode heights are bonded to a substrate, the bonding strength will differ for each chip, and if the electrode heights within the chip differ, the bonding strength of the high electrode will be high, but the bonding strength of the low electrode will be small. In extreme cases, they will not bond. The difference in electrode height as described above gives rise to extremely unfavorable results in terms of bonding strength and bonding reliability.

The present invention was proposed in order to eliminate the above-mentioned drawbacks, and its purpose is to provide a plating device for wafers that is of good quality, has no abnormal protrusions, and can provide a uniform plating thickness. There is a particular thing.

In order to achieve the above object, the present invention has a method in which a wafer and an anode, which are arranged facing each other in a cylindrical sealed space, are separated by a porous partition wall, and plating is performed with the partition wall interposed. This device is characterized by a pinning device having a configuration.

Embodiments of the present invention will be described below based on the drawings. In FIGS. 3 and 4, the plating tank body 7
is made of acrylic and is divided into two parts 7a and 7b. In the center of the plating tank body 7, in the case of a 3-inch wafer, an insulating wall 8 consisting of a cylindrical hole with a diameter of about 76.2 m/m is formed. The plating tank bodies 7a and 7b are polymerized with porous partition walls 14 made of polypropylene cloth in between. The open ends of the plating tank bodies 7a and 7b are connected to a wafer mounting plate 10 on which the wafer 9 is attached and an anode 11.
It is sealed by the anode mounting plate 12 to which the anode mounting plate 12 is attached, forming a sealed space chamber 13. Plating liquid supply pipes 15a, 15b and Discharge pipes 16a, 16
b is connected.

The operation of the final plating device based on the above configuration will be explained next. The wafer 9 and the anode 11 are arranged parallel to each other and are surrounded by an insulating wall 8 consisting of a cylindrical hole having approximately the same diameter as the wafer and the anode, so that the current flows from the anode 11 to the wafer 9. It will flow uniformly and in a straight line towards. Therefore, it becomes possible to form a uniform plating thickness. On the other hand, when plating solder, copper, etc. in the above-mentioned cylindrical plating tank, insoluble substances such as lead oxide and copper oxide formed at the anode are carried to the cathode side, and the plating Co-fraction occurs within the film, reducing the mechanical properties and other qualities of the plated film, and
It can also cause abnormal protrusions. Therefore, by interposing the porous partition wall 14, it is possible to prevent these insoluble substances from flowing from the anode side to the cathode side. As described above, the partition wall 14 is formed with holes through which ions contained in the plating solution can pass, and therefore can prevent the insoluble substances from passing through, but does not impair the plating effect. . On the other hand, the plating liquid is supplied to each chamber 13a and 1 of the closed space chamber 13 as described above.
3b, the plating liquid flows smoothly in the closed space chamber 13, which helps in forming a good plating film.

Next, a specific example of forming a plating film using the plating apparatus based on this embodiment will be described. As a plating liquid,
A copper sulfate plating solution consisting of 200 g of copper sulfate and 50 g of sulfuric acid is used. Current density 2A/dm ² , liquid temperature 30
Plating was carried out at a temperature of 0.degree. C. and a plating solution flow rate of about 2 cm/sec. The results are shown in FIG. 2b above. That is, a substantially uniform plating thickness of 80 μm was obtained, and there was no co-refraction of copper oxide generated at the anode and no abnormal protrusions caused thereby, making it possible to obtain an extremely good plating film. Naho, the plating liquid discharged from the plating tank is placed outside with a 5μm
Filtration was carried out continuously through a polypropylene filter (not shown).

The porous partition walls in the above embodiments are made of polypropylene cloth, but are not limited to this, and may be made of porous glass filters, cloth with excellent chemical resistance, ion exchange membranes, etc. I don't mind. Furthermore, it goes without saying that the size of the plating tank is not limited to the size of a 3-inch wafer.

As is clear from the above explanation, the present invention makes it possible to form a uniform plated film, and also to form a high-quality plated film that is free from co-refraction of insoluble substances and free from abnormal protrusions. It was also possible to improve the plating yield.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the process of forming protruding electrodes of semiconductor elements, FIG. 2 is a diagram showing the plating thickness distribution of wafers according to the conventional method and the embodiment of the present invention, and FIG.
FIG. 4 is a sectional view showing the structure of a plating apparatus according to an embodiment of the present invention. FIG. 4 is a front view thereof. 1... Aluminum wiring, 2... Protective film, 3... Base, 4... Electrode base film, 6... Protruding electrode, 7, 7
a, 7b... plating tank body, 8... cylindrical insulating wall, 9... wafer, 10... wafer mounting plate, 11
... Anode, 12 ... Anode mounting plate, 13, 13a,
13b... Closed space chamber, 14... Partition wall, 15,1
5a, 15b...plating liquid supply pipe, 16,
16a, 16b... Plating liquid discharge pipe.

Claims (1)

[Scope of Claims] 1. A cylindrical sealed space chamber having an inner diameter substantially the same as that of the wafer, and a cylindrical sealed space chamber located on the cathode end side of the sealed space chamber, facing the wafer, and located on the anode side at the other end of the sealed space chamber. In the plating apparatus, the plating apparatus is provided with an anode that is connected to the wafer, and an inlet/discharge section for supplying and discharging a plating solution into and out of the sealed space chamber, wherein the plating apparatus includes a porous partition wall interposed between the wafer and the anode in the closed space chamber; , each of the closed space chambers separated by the partition wall,
A plating device characterized by comprising an inlet and a discharge section for supplying and discharging a plating solution. 2. A plating apparatus, wherein the partition wall according to claim 1 has a porous portion through which ions contained in the plating liquid flowing into and out of the closed space chamber can pass.