JPS6020477B2 - Jet plating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a jet plating apparatus for plating a thin plate such as a semiconductor wafer by spraying a plating solution onto one side of the same.

In general, when forming an electrode film on a semiconductor wafer (hereinafter simply referred to as a wafer) such as a diode, a metal deposition method, a jet plating method, an immersion plating method, etc. are applied.

Metal vapor deposition is effective when the electrode film is relatively thin, but
For example, it is inappropriate to form bump electrodes that are raised to about five capes, and these bump electrodes are formed by jet plating or immersion plating. This latter immersion plating method involves coating one side of the wafer with wax to protect it, immersing it in a plating solution, applying a negative electrode to the wafer, and inserting a positive electrode plate into the plating solution. This is a plating method. However, this method requires a lot of work such as applying wax before plating and removing wax after plating, resulting in poor workability and further problems such as disposal of wax waste liquid. Therefore, a jet plating method is an improvement on the above-mentioned plating method. For example, when plating bump electrodes 3 on the front surface of a wafer 2 having a flat back electrode 1 on the back surface with a protrusion of about 5 capes, as in the case of a diode shown in FIG. I used plating equipment. In this FIG. 2, 4 is a cylindrical head that insulates and supports the wafer 2, 5 is a cylindrical cover placed in the center of the head 4, and 1 is placed at the bottom of the head 4 and the bottom of the cover 5. They are connected by a regular circulation pipe 6, and a pump 7 is installed in the middle of this circulation pipe 6. Further, 8 is a lower electrode for plating such as platinum installed in the head 4, and 9 is the head 4.
An upper electrode 10 for plating appropriately presses the upper surface of the upper wafer 2, and 10 is a plating solution such as silver. The head 4 has a stepped surface 11 cut along the upper end of the inner peripheral surface.
The periphery of the wafer 2 is brought together, and the wafer 2 is held on the head 4 in such a manner as to cover the head 4. Further, a plurality of windows 12 are provided at fixed positions below the stepped surface 11 at the upper end of the head 4 to allow the plating liquid 10 spouted up within the head 4 to flow out of the head 4. Bump electrode 3 by the above device
The plating is performed in the following manner. A wafer 2, on which a back electrode 1 has been formed in advance, is placed on a step surface on a head 4 with the back electrode 1 facing upward, and held horizontally. Next, the upper electrode 9 is lightly pressed against the center of the upper surface of the wafer 2, and a negative voltage is applied to the upper electrode 9, a positive fin pressure is applied to the lower electrode 8, and the pump 7 is activated. , the plating solution 10 is spouted upward from inside the head 4 and sprayed onto the lower surface of the wafer 2. Then, back electrode 1 of wafer 2
Since a negative voltage (forward direction) is applied to , bump electrodes 3 grow on the lower surface of wafer 2. Then, the plating solution flows horizontally along the bottom surface of the wafer 2, and
2 and flows out of the head 4. The plating solution 10 flowing out from the head 4 falls between the head 4 and the cover 5, is sent to the circulation pipe 6, and is again blown up by the pump 7.
By the way, the above-mentioned follower device had the following drawbacks.

That is, since the wafer 2 is competitively supported on the step surface 11 on the head 4, the plating solution 10 creeps up due to capillary action between the wafer 2 and the step surface 11, and spreads onto the upper surface of the wafer, that is, on the cylindrical surface of the back electrode 1. The problem is that the particles creep up to the surface and corrode a part of the back electrode 1, resulting in a large number of defective products. Furthermore, when the wafer 2 is removed after one plating process is completed, the plating solution 10 remains attached to the step surface 11 and silver precipitates out, or when the next wafer 2 is ironed, the plating solution 10 remains on the step surface 11. Since the plating solution 10 creeps up onto the wafer 2, it is necessary to remove the plating solution 10 adhering to the stepped surface 11 every time plating is performed, which requires a lot of work. In addition, in order to reduce such creeping up of the plating solution 10, the amount of the plating solution 10 spouted out is reduced; There are times when there is no
Therefore, there was a drawback that variations occurred in the plating. In view of the above-mentioned conventional drawbacks, the present invention improves and eliminates these problems and provides a jet plating apparatus with an improved supporting mechanism for plating objects such as wafers. The configuration of the present invention will be explained below with reference to embodiments of the drawings. An example in which the present invention is applied to an apparatus for plating the bump electrodes 3 of the wafer 2 is shown in FIGS. 15 is a tapered surface formed by chamfering the outer circumferential edge of the upper end surface of the head 13; 15 is a support pin having a plurality (three in the drawing) protruding from the flat upper end surface of the head 13 at equal intervals; and 16 is a support pin of the head 13. A side pin is provided with a plurality of pins (three in the drawing) protruding from the tapered surface 14 at equal intervals, and each of these pins 15 and 16 is attached to the head 1.
3, or an insulating plate is formed as a shield on the head 13. Further, 17 is an adjustment tube screwed into the lower part of the head 14, and 18 is a head body into which the adjustment tube 17 is screwed into the upper end.The height of the head 13 can be freely adjusted by this adjustment tube 17. Also, 19 is a lower magnetic pole, 20 is an upper electrode,
Reference numeral 21 represents a cover, and 22 represents a plating solution, which may be the same as conventional ones. Support pin 15 on the upper end surface of the head 13
supports the lower peripheral edge of the wafer 2 with its upper end surface, and at this time, a gap g determined by the height of the support pin 15 is formed between the head 13 and the wafer 2, and the plating solution passes through this gap g. 22 flows out of the head 13.

Further, the side pins 16 are arranged at positions slightly apart from the side surfaces of the wafer 2 supported by the support pins 15, and
prevent horizontal displacement. Further, this side pin 16 is provided so as to protrude from the center of the bottom surface of the recess 23, which is a part of the tapered surface 14 cut out. Furthermore, the upper surface edge 1 of the tapered surface 14
4' is provided with a size that is located slightly inside the support pin 15. Next, the wafer plating operation using the apparatus shown in FIG. Position it using pin 16.

Then, the upper electrode 20 is pressed against the center of the upper surface of the wafer 2 to completely fix the wafer 2. After that, upper electrode 2
0 is negative and the lower electrode 19 is positive, a plating voltage is applied, and the plating liquid 22 is spouted from inside the head 13 toward the lower surface of the wafer 2, thereby growing bump electrodes 3 on the lower surface of the wafer 2. During this plating, plating solution 22
flows out from the gap g between the head 13 and the wafer 2. The plating liquid 22 first flows to the upper end surface of the head 13 and flows down the tapered surface 14.
The outflow is encouraged by the upper edge 14 of the tapered surface 14.
Since the plating liquid 22 is located inside the side surface of the wafer 2, the plating liquid 22 flows on the tapered surface 14 and gradually moves away from the wafer 2 until it reaches below the edge of the wafer 2. Therefore, the rate at which the plating solution 22 adheres to the edge of the bottom surface of the wafer 2 and flows out is not small, and the rate at which the plating solution 22 creeps up to the top surface of the wafer 2 is correspondingly reduced. It is also possible that the plating solution 22 creeps up onto the wafer 2 along the side pins 16, but the fixing position of the side pins 16 is below the upper end surface of the head 13, and the concave part cut out in the tapered surface 14 is 23, the creepage distance on the head from the upper end surface 16 of the head 13 to the side pin 16 is shortened.
Therefore, there is almost no creeping up of the plating solution 22 from the side pins 16. Furthermore, since the support pins 15 rest against the green portion of the lower surface of the wafer 2, there is no problem of the plating solution 22 creeping up. As a means to more reliably prevent the plating solution 22 from creeping up onto the wafer 2, for example, nitrogen gas may be continuously sprayed from above onto the green area of the upper surface of the wafer 2.
It is also possible to devise a way to blow off the plating solution 22 that has climbed up. Furthermore, the present invention is not limited to the above embodiments,
For example, it is also possible to integrate the support pin and the side pin without separating them.

Furthermore, although the example of plating bump electrodes on a wafer has been described, the present invention can also be applied to plating a simple flat hair surface electrode, and the object to be plated is not limited to semiconductor wafers. Although the support pin is preferably made of an insulator, it is also possible to use a good conductor as a plating electrode depending on the object to be plated. As explained above, according to the present invention, since the object to be plated is only point-supported at about three points by the support pins, the rate at which the plating solution creeps up onto the top surface of the wafer is extremely reduced.
Therefore, jet plating can be performed stably at all times, and the amount of plating solution ejected can be increased, so that variations in plating are reduced and defects are eliminated by plating the object to be plated.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a diode semiconductor wafer, which is an example of the object to be plated, Fig. 2 is a side cross-sectional view of the main part of a secondary jet plating apparatus, and Fig. 3 is an embodiment of the plating apparatus according to the present invention. FIG. 4 is a side sectional view of the main part, and FIG. 4 is a perspective view of the head portion shown in FIG. 3. 2...Object to be plated (wafer), 13...Head,
15...Support pin, 16...Side pin, 22...Plating solution, g...Gap. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In a plating device that holds an object to be plated to which a plating voltage is applied on a cylindrical head and jets plating liquid onto one side of the object, the head has an upper end surface of the object to be plated. A plurality of support pins for supporting the peripheral edge and a plurality of side pins for positioning the circumferential surface are protrudingly provided, and from the gap formed by the plurality of pins between the end surface of the cylindrical head and one surface of the object to be plated. A jet plating device characterized by flowing out plating liquid.