JPH0657497A - Wafer plating device - Google Patents

Abstract

PURPOSE:To avoid contact of a cathode with a plating soln. CONSTITUTION:A cathode 9 is placed on the upper surface of an annular rubber sheet 21 provided on the upper surface of a cup 2 into which a plating soln. 4 is jetted with the end positioned outside at a specified distance from the inner peripheral end of the sheet 21. A plating connecting terminal provided on the surface of a wafer 11 to be plated is brought into contact with the cathode 9, almost all the periphery of the surface to be plated is firmly attached to the upper surface of the sheet 21, hence the clearance is liq.-tightly sealed, the soln. 4 does not flow out of the clearance, and the cathode 9 is completely out of contact with the soln. 4. The soln. 4 in the cup 2 is recovered in a plating tank 1 through many plating soln. outlet holes 22 radially furnished in the upper wall of the cup 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer plating apparatus for plating a semiconductor wafer.

[0002]

2. Description of the Related Art For example, when a bump electrode is formed on a semiconductor wafer (hereinafter simply referred to as a wafer), a plating resist layer is formed on the bump electrode forming surface (surface to be plated) of the wafer, and the plating resist layer is etched. By forming an opening by exposing the pad portion through the opening, the exposed pad portion is plated with gold or the like by using a wafer plating device, and the bump electrode is formed by the plating. There is.

2A and 2B show a conventional wafer plating apparatus used in such a case. In this wafer plating apparatus, a cup 2 is provided in the plating tank 1. The plating tank 1 and the cup 2 are connected by a liquid path 3. The plating tank 1 is provided in the liquid passage 3.
A jet pump 5 for jetting a plating liquid (including ionized gold) 4 contained therein into the cup 2 is interposed. A net-shaped anode electrode 6 is provided on the bottom of the cup 2. Anode electrode 6 is lead wire 7
Is connected to the anode of a power supply device not shown.
Plating solution blocking members 8 having a substantially rectangular shape in a plane having plating solution blocking walls 8a on predetermined three sides are provided at predetermined three locations on the upper surface of the cup 2 that are spaced at equal intervals. Inside the plating liquid blocking member 8, a cathode electrode 9 having a substantially U-shaped side surface and having a wafer mounting wall 9a inside is provided. The wafer mounting wall 9 a of the cathode electrode 9 has a plating liquid blocking member 8
Of the plating liquid blocking wall 8a. The cathode electrode 9 is connected to the cathode of the power supply device via the lead wire 10. A wafer 11 is mounted on the wafer mounting walls 9 a of the three cathode electrodes 9. Wafer 1
1 is not shown in detail, but as described above, the opening is formed in the plating resist layer (not shown) formed on the bump electrode formation surface (the lower surface in FIG. 2A), The pad portion is exposed through this opening, and a plating connection terminal (not shown) is provided at the portion of the cathode electrode 9 that contacts the wafer mounting wall 9a. The wafer 11 is pressed by a leaf spring 13 provided on the lower surface of an upper lid 12 attached to the plating tank 1.

When the jet pump 5 of the wafer plating apparatus is driven, the plating solution 4 contained in the plating tank 1 passes through the anode electrode 6 and is jetted into the cup 2 to reach the lower surface of the wafer 11. Be sprayed. At this time,
When a plating current is passed between the anode electrode 6 and the cathode electrode 9, the pad portion exposed on the lower surface of the wafer 11 is gold-plated, and the bump electrode is formed by this gold plating. The plating liquid 4 sprayed on the lower surface of the wafer 11 is, as shown by an arrow in FIG.
It overflows from the upper end of the cup 2 excluding the three plating liquid blocking members 8 to the outside, flows down, and is collected in the plating tank 1. In this case, the plating liquid 4 is made to flow outward from the upper end of the cup 2 excluding the three plating liquid blocking members 8 is that the new plating liquid 4 is always supplied to the lower surface of the wafer 11. This is to remove bubbles in the plating solution 4 contacting the lower surface of the wafer 11 to prevent defective plating. The other is to prevent the plating solution 4 from flowing into the plating solution blocking member 8 by the plating solution blocking wall 8a of the plating solution blocking member 8, and thereby to prevent the cathode electrode 9 provided in the plating solution blocking member 8.
Is to prevent the cathode electrode 9 from being plated by coming into contact with the plating solution 4, and thus to prevent the expensive gold (plating metal) in the plating solution 4 from being wasted.

[0005]

However, in such a conventional wafer plating apparatus, the wafer 11 is mounted on the wafer mounting wall 9a of the cathode electrode 9 provided in the plating liquid blocking member 8 and the wafer 11 is mounted on the wafer mounting wall 9a. Since the plating connection terminal 11 and the cathode electrode 9 are electrically connected to each other, in order to avoid contact between the upper surface of the plating solution blocking wall 8a of the plating solution blocking member 8 and the lower surface of the wafer 11, a small amount of, for example, 0 .2-
It is necessary to provide a gap of about 0.3 mm, while the liquid surface of the plating liquid 4 jetted in the cup 2 is in contact with the lower surface of the wafer 11, and therefore the plating liquid 4 is plated through the gap described above. There is a problem in that it is impossible to completely prevent the liquid from flowing into the liquid blocking member 8, and the cathode electrode 9 may be plated by the plating liquid 4 that has flowed into the plating liquid blocking member 8. An object of the present invention is to provide a wafer plating apparatus capable of preventing the cathode electrode from coming into contact with the plating solution at all.

[0006]

According to the present invention, a cup into which a plating solution is jetted, a large number of plating solution outflow holes radially provided on an upper wall portion of the cup, and an upper surface of the cup are provided. A ring-shaped rubber sheet and a cathode electrode provided on the upper surface of the rubber sheet in a state where the end portion is located outside the inner peripheral edge of the rubber sheet by a predetermined distance. With the connection terminal for plating provided on the surface being in contact with the cathode electrode, almost the periphery of the surface to be plated is brought into close contact with the upper surface of the rubber sheet.

[0007]

According to the present invention, substantially the periphery of the surface to be plated of the wafer is in close contact with the upper surface of the rubber sheet, and the space between them is liquid-tight, so that the plating solution does not flow out from this area.
Therefore, the cathode electrode can be prevented from coming into contact with the plating solution at all.

[0008]

1 (A) and 1 (B) show a wafer plating apparatus in an embodiment of the present invention. In these figures, parts having the same names as those in FIGS. 2A and 2B are designated by the same reference numerals, and the description thereof will be omitted as appropriate. In this wafer plating apparatus, a ring-shaped rubber sheet 21 is provided on the upper surface of the cup 2. The thickness of the rubber sheet 21 is uniform over the whole in an unloaded state,
It is about 1.5 mm. Cathode electrodes 9 each having a substantially L-shaped side surface are disposed at predetermined three positions on the upper surface of the rubber sheet 21 that are spaced apart from each other by a predetermined distance from the inner peripheral end of the rubber sheet 21. It is provided in a closed state. The cathode electrode 9 has a thickness of 0.1 to 0.3 mm
It consists of a platinum plate. Although a part of the illustration is omitted in FIG. 2 (B), the plating solution outflow holes 22 are radially provided at a large number of places on the upper wall of the cup 2 that are equally spaced apart. The plating solution outflow hole 22 is inclined obliquely downward from the inside to the outside at an angle of about 30 to 60 °. The distance between the inner end opening of the plating solution outflow hole 22 and the upper surface of the cup 2 is preferably 0, but in terms of strength,
It is about 0.5 to 1.0 mm.

When forming bump electrodes made of gold plating on the wafer 11 using this wafer plating apparatus, first, the upper lid 12 is removed and the wafer 11 is positioned with its bump electrode forming surface facing downward. In this state, it is placed on the three cathode electrodes 9 on the rubber sheet 21. Next, the upper lid 12 is attached to the plating tank 1, and the upper lid 12
The wafer 11 is pressed by the leaf spring 13 provided on the lower surface of the wafer. Then, the wafer 11 presses the cathode electrode 9 so that the cathode electrode 9 bites into the rubber sheet 21 while elastically deforming it, and the lower surface of the wafer 11 is in close contact with the upper surface of the rubber sheet 21. Therefore, in this state, the plating connection terminal provided on the lower surface of the wafer 11 is surely brought into contact with the cathode electrode 9, and a reliable electrical connection is obtained. Also, the wafer 1
The lower surface of 1 is brought into close contact with the upper surface of the rubber sheet 21 so that a liquid-tight state is provided between them.

When the jet pump 5 is driven in this state,
The plating solution 4 contained in the plating tank 1 passes through the anode electrode 6 and is jetted into the cup 2 to be jetted onto the lower surface of the wafer 11. At this time, when a plating current is passed between the anode electrode 6 and the cathode electrode 9, the pad portion exposed on the lower surface of the wafer 11 is gold-plated, and the bump electrode is formed by this gold plating. The plating solution 4 sprayed on the lower surface of the wafer 11 is collected in the plating tank 1 through the numerous plating solution outflow holes 22. In this case, since the plating solution 4 flows out from a large number of the plating solution outflow holes 22, the same effect as the conventional overflow can be obtained, and the new plating solution 4 can always be supplied to the lower surface of the wafer 11 and the wafer 11 can be supplied. The bubbles in the plating solution 4 contacting the lower surface of the plate can be removed to prevent defective plating. Further, since the periphery of the lower surface of the wafer 11 is in close contact with the upper surface of the rubber sheet 21 and the space between them is in a liquid-tight state, the plating solution 4 does not flow out during this period, and the end portion of the cathode electrode 9 is Since the rubber sheet 21 is positioned outside by a predetermined distance from the inner peripheral edge of the rubber sheet 21, the cathode electrode 9 can be prevented from coming into contact with the plating solution 4 at all.

[0011]

As described above, according to the present invention, the periphery of the surface to be plated of the wafer is brought into close contact with the upper surface of the rubber sheet, and the space between them is kept liquid-tight, so that the plating liquid flows out from this interval. Therefore, it is possible to prevent the cathode electrode from coming into contact with the plating solution at all, and it is possible to eliminate unnecessary consumption of the plating metal.

[Brief description of drawings]

FIG. 1A is a sectional view of a wafer plating apparatus according to an embodiment of the present invention, and FIG. 1B is a plan view of a part thereof.

FIG. 2A is a cross-sectional view of a conventional wafer plating apparatus,
(B) is a plan view of a part thereof.

[Explanation of symbols]

 1 Plating Tank 2 Cup 4 Plating Liquid 5 Jet Pump 6 Anode Electrode 9 Cathode Electrode 11 Wafer 21 Rubber Sheet 22 Plating Liquid Outflow Hole

Claims (1)

[Claims] 1. A cup into which a plating solution is jetted, a large number of plating solution outflow holes radially provided on an upper wall portion of the cup, a ring-shaped rubber sheet provided on an upper surface of the cup, and an end. And a cathode electrode provided on the upper surface of the rubber sheet in a state in which the portion is located outside the inner peripheral edge of the rubber sheet by a predetermined distance, and a plating connection provided on the surface to be plated of the wafer. A wafer plating apparatus, wherein substantially the periphery of the surface to be plated is brought into close contact with the upper surface of the rubber sheet while the terminal is in contact with the cathode electrode.