JP2935448B2 - Plating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

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

FIG. 2 shows a conventional substrate plating apparatus used for forming a bump electrode on such a substrate. In this substrate plating apparatus, a cup 22 is provided in a plating tank 21 as shown in FIG.
The plating tank 21 and the cup 22 are connected by a liquid path 23. A jet pump (not shown) for jetting a plating solution (including ionized gold) 24 contained in the plating tank 21 into the cup 22 is interposed in the liquid passage 23.

[0004] A mesh-shaped anode electrode 25 is provided at the bottom in the cup 22, and the anode electrode 25 is connected to an anode 27 of a power supply device (not shown) via a lead wire 26. Cathode electrodes 28, 28, 28 are provided at predetermined three places on the upper surface of the cup 22, respectively, at equal intervals, and the cathode electrodes 28 are connected to cathodes 30 of a power supply device via lead wires 29. ing.

The above three cathode electrodes 28, 28, 2
A substrate 31 is placed on 8. Although not shown in detail, the substrate 31 has an opening formed in a plating resist layer (not shown) formed on the bump electrode formation surface (the lower surface in the drawing) as described above.
A pad portion is exposed from the opening, and further, a plating connection terminal (not shown) is provided at a portion in contact with the cathode electrodes 28, 28, 28. The substrate 31 is pressed by a plate spring (not shown) provided on the lower surface of an upper cover (not shown) attached to the plating tank 21.

When the jet pump of the substrate plating apparatus is driven, the plating solution 24 contained in the plating tank 21 passes through the anode electrode 25 and is jetted into the cup 22, so that the lower surface of the substrate 31 is exposed. Sprayed on. At this time, when a plating current is caused to flow between the anode electrode 25 and the cathode electrode 28, the pad portion exposed on the lower surface of the substrate 31 is plated with gold, and a bump electrode is formed by the plated gold. The plating solution 24 sprayed onto the lower surface of the substrate 31 overflows from the cup 22 to the outside, flows down, and is collected in the plating tank 21.
In this case, the plating solution 24 overflows outward from the cup 22 and flows down.
This is because a new plating solution 24 is always supplied to the lower surface of the substrate 1.

[0007]

However, in the conventional plating apparatus for a substrate as described above, since the substrate 31 is set with its surface on which bump electrodes are formed facing downward, the plating solution 24 is blown up. In this case, there is a disadvantage that bubbles (air) in the plating solution 24 are accumulated on the surface of the substrate 31 and on the resist opening, so that bump plating cannot be performed stably. In addition, gas generated in the electrochemical reaction during the electrolytic deposition of the plating metal also accumulates in the resist opening and the surface of the substrate 31, which has a disadvantage that the formation of bump plating is hindered.

As a method for removing air bubbles accumulated on the downward surface of the substrate 31, while the plating current is stopped during plating, the flow rate of the plating solution 24 is increased, and the air bubbles (air, Although there is a method for removing gas), there is still a disadvantage that gas and air cannot be completely removed. At this time, unless the plating current is stopped during plating and the flow rate of the plating solution 24 is not increased, the plating abnormally grows in the flow direction.

Accordingly, the plating time becomes longer than the original plating time (time obtained by dividing the thickness by the deposition rate) by executing the bubble removal sequence, and there is a disadvantage that the efficiency is poor. Furthermore, in solder bump plating and the like, there is a disadvantage that the current density must be extremely reduced in order to suppress the generation of bubbles.

Therefore, an object of the present invention is to easily remove bubbles on the surface of a substrate and a resist opening during plating, that is, air in a plating solution at an initial stage of plating and gas generated during an electrochemical reaction, An object of the present invention is to provide a plating apparatus capable of improving the efficiency of plating and reducing the total amount of liquid.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention has a downward opening surface through which a plating solution flows.
In a plating apparatus that provides an anode electrode and a cathode electrode to a cup, and in which the cathode electrode is in contact with a plating connection terminal provided on the surface to be plated of the substrate, plating is performed on the surface to be plated of the substrate. A lower part of the cup with an opening surface facing down, a substrate supporting part for supporting the substrate with the plating surface facing upward, and a contact with the plating connection terminal of the substrate supported by the substrate supporting part. From the inner peripheral end of the cup
Is also provided outside by a predetermined distance . The present invention is characterized in that the anode electrode is provided above the substrate in the cup, and a plating solution supply means for flowing the plating solution is provided.

[0012]

According to the present invention, in the lower part of the cup, such as with a downward open surface, before the substrate with its surface to be plated facing upward plating connection terminals provided on the plating surface
A predetermined distance outside the inner circumference of the cup.
The cathode electrode is contacted and supported, and the plating solution is supplied by flowing the plating solution above the substrate in the cup by the plating solution supply means. Bubbles easily escape upward from the resist opening. That is, the air in the plating solution at the initial stage of plating easily escapes upward from the substrate, and the gas generated during the electrochemical reaction easily escapes upward.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a plating apparatus according to the present invention will be described below with reference to FIG.

FIG. 1 shows a plating apparatus for a substrate as an example to which the present invention is applied. 1 is a substrate support, 2 is a cup, 3 is a suction path, 4 is an anode electrode, 5 is an anode, and 6 is an anode. Sealing sheet, 7 is a cathode electrode, 8 is a cathode, 9 is a guide ring, 10 is an O-ring, 11 is a substrate, 12 is a plating solution, 13 is a tank, 14 is a pump, 15 is a supply path, 16
Is a discharge path, 17 is a relief valve, and 18 is a return path.

In the plating apparatus for a substrate, a cup 2 is provided on a substrate support table 1 as shown in the figure, and the opening of the cup 2 faces downward. Substrate support 1
Is movable up and down, and the cup 2 is fixed to a plating apparatus body (not shown).

A suction path 3 is formed in the substrate support table 1. The suction path 3 is connected to a suction source (not shown), for example, a vacuum pump via a lower pipe 3a. On the upper surface of the substrate support 1, a large number of suction ports 3 opening upward are provided.
, 3b, 3b,... are formed.
The periphery of the substrate supporting surface where b, 3b, 3b,... are opened is a male tapered inclined engaging surface 1a for alignment when the unit is combined with the cup 2.

A reticulated anode electrode 4 is provided in the upper part of the cup 2 with the opening surface facing downward, and the anode electrode 4 is connected to an anode 5 of a power supply device (not shown). An annular plate-shaped sealing sheet 6 made of elastic viton rubber is provided around the downward opening surface of the cup 2. Plate-shaped cathode electrodes 7, 7, 7 are provided at predetermined three places on the lower surface of the sealing sheet 6 at regular intervals (center angle 120 °). This cathode electrode 7 is connected to the cathode 8 of the power supply.

Further, a guide ring 9 is integrated on the lower surface of the sealing sheet 6 in an overlapping manner. That is, for example, around the downward opening surface of the cup 2 at equal intervals (central angle 1
20 [deg.]), Three positioning projections 2a,
2a, 2a are formed.
a, 2a, 2a, positioning holes 6a, 6a, 6a in sealing sheet 6, positioning holes 7a, 7a, 7a in cathode electrodes 7, 7, 7 and guide ring 9 corresponding to a, 2a, 2a.
Alignment recesses 9a, 9a, 9a are formed on the upper surface, respectively.

These positioning projections 2a, 2a, 2a
Through the positioning through holes 6a, 6a, 6a and the positioning through holes 7a, 7a, 7a, respectively.
The sealing sheet 6 and the cathode electrodes 7, 7, 7 are fixed to the cup 2 using the guide ring 9 by engaging with the positioning recesses 9a, 9a, 9a, respectively. The inner peripheral side of the guide ring 9 is female-tapered for centering during the mating with the substrate support table 1 so as to engage with the male taper-shaped inclined engaging surface 1a formed on the cup 2. Is formed as the inclined engagement surface 9b.

In such a state that the cathode electrodes 7, 7, 7 are integrated into the cup 2 side, only about 3 to 4 mm is exposed inside the guide ring 9, and other parts are not exposed. It is completely covered by the sealing sheet 6 and the guide ring 9, so that no plating metal is deposited on this portion. That is, since the tips of the cathode electrodes 7, 7, 7 are located outside the inner peripheral edge of the sealing sheet 6 by a predetermined distance, the inner peripheral edge of the sealing sheet 6 is , 7, 7 are blocked from flowing in the direction where they are located, so that the cathode electrodes 7, 7, 7 do not come into contact with the plating solution 12 at all. An O-ring 10 is provided between the lower surface of the guide ring 9 and the substrate support 1.

Here, the substrate 11 has a large number of openings 11c, 11c, 11c,... Formed in a plating resist layer 11b formed on a metal layer 11a formed on the bump electrode formation surface. Openings 11c, 11c, 1
1c,..., A pad portion is exposed, and a portion of the metal layer 11a is provided with a plating connection terminal (not shown) at a portion in contact with the tips of the three cathode electrodes 7, 7, 7, respectively. Has become.

A tank 13 for storing the plating solution 12 flowing into the cup 2 is provided, and the tank 13 is disposed below the cup 2. Further, a pump 14 for pumping the plating solution 12 from the tank 13 is provided. A supply path 15 through which the plating solution 12 discharged from the pump 14 flows is connected to a lower portion of the cup 2 and opens into the cup 2. ing.

In the upper part of the cup 2 and almost in the center,
A discharge path 16 is provided. The discharge path 16 is provided with a relief valve 17 outside the cup 2, and is connected to a return path 18 branching from the near side of the relief valve 17. This return path 18
It is connected inside the tank 2.

When bump electrodes are formed on the substrate 11 using the substrate plating apparatus having the above-described configuration, the substrate support 1 is first lowered from the cup 2 to a separated state. The substrate 11 is set on the substrate supporting surface with the surface to be plated, which is the surface of the substrate 11, facing upward. Then, by operation of a vacuum pump constituting the substrate suction means, the suction ports 3b, 3b, 3
b,.. to apply a suction force to the substrate
Is fixed by suction on the substrate supporting surface of the substrate.

Subsequently, the substrate support 1 on which the substrate 11 is fixed as described above is raised, and the male taper-shaped inclined engagement surface 1a provided for centering the substrate support 1 is integrated with the cup 1. The O-ring 10 is interposed between the lower surface of the guide ring 9 and the substrate support 1 while being engaged with the female taper-shaped inclined engagement surface 9 b provided for centering the guide ring 9. At this time, the inside of the cup 2 contains the sealing sheet 6 and the O-ring 1
0, completely sealed. Further, substantially the periphery of the substrate 11 is in close contact with the lower surface of the sealing sheet 6, and the connection terminals for plating by a part of the metal layer 11a of the substrate 11 are connected to the cathode electrodes 7, 7, 7, respectively.

Next, by driving the pump 14 constituting the plating solution supply means, the plating solution 12 is supplied into the cup 2 from the supply path 15. The plating solution 12 flows above the substrate 11 and its level gradually rises, and the relief valve 17 is closed.
The air inside the tank 1 passes through the return path 18 from the discharge path 16
It is sent into 3 and opened to the outside, and there is no air in the piping system. Also, the resist openings 11c, 11
With respect to the gas generated at c, 11c,..., since the surface (plated surface) of the substrate 11 faces upward, the gas is easily released above the resist openings 11c, 11c, 11c,.

In the above state, when a plating current is applied between the anode electrode 4 and the cathode electrodes 7, 7, 7, the substrate 11
Are plated on the exposed portions of the resist openings 11c, 11c, 11c,... On the upper surface of the substrate, and bump electrodes are formed by the plated metal. As described above, since the plating can be performed by setting the substrate 11 with the surface to be plated facing upward, bubbles in the plating solution 12 can be removed by floating so that plating failure can be prevented.

After completion of the plating, the relief valve 17 is opened, and the discharge path 16 and the return path 18 are opened to the atmosphere, so that the plating path 12 in the return path 18 is collected in the tank 13 and the tank 13 is removed. The plating solution 1 in the cup 2
2 is collected in the tank 13 via the supply path 15 and the pump 14. Thereafter, the substrate support 1 is lowered to release the substrate 11 from being attracted and fixed on the substrate support surface, thereby taking out the substrate 11 after plating.

In the above embodiment, the tank is disposed below the cup, and after the plating is completed, the plating solution is recovered to the tank by opening the inside of the cup to the atmosphere. However, the present invention is not limited to this. The present invention is not limited to this, and the plating solution in the cup may be collected in the tank by suction. In the embodiment, the cup is fixed and the substrate support is movable up and down.However, the substrate support is fixed and the cup may be movable up and down, or both the substrate support and the cup may be moved up and down. It may be movable. Further, the number of the cathode electrodes and the like are also arbitrary, and it goes without saying that the specific detailed structure and the like can be appropriately changed.

[0030]

As described above, according to the plating apparatus of the present invention, the base having the plating connection electrode provided on the surface to be plated is provided.
The board can be plated with the surface to be plated facing upward, and the board can be set up for plating. Bubbles can easily escape upward from the surface of the board and the resist opening, so it occurs during the air in the plating solution during the initial plating and during the electrochemical reaction Gas can be easily removed. For this reason, as in the past, for example, in solder bump plating, the current density had to be extremely reduced in order to suppress the generation of bubbles,
Even at a high current density, the bump electrodes can be formed without concern for bubble generation, so that plating efficiency can be improved. In addition, the cathode electrode is set at a predetermined distance from the inner peripheral end of the cup.
A cathode electrode and a cathode electrode
Do not allow the plating connection electrodes to come into contact with the plating solution.
And plating the cathode electrode and the connection terminal for plating
Since no plating occurs, the efficiency of plating can be improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a plating apparatus for a substrate as an example to which the present invention is applied, and is a schematic configuration diagram also showing the configuration of a piping, a plating solution tank, and the like.

FIG. 2 is a vertical sectional side view showing a main part of a conventional substrate plating apparatus used for forming a bump electrode on a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate support stand 2 Cup 3 Suction path 4 Anode electrode 6 Sealing sheet 7 Cathode electrode 9 Guide ring 10 O-ring 11 Substrate 12 Plating solution 13 Tank 14 Pump 15 Supply path 16 Discharge path 17 Relief valve 18 Return path

Claims (1)

(57) [Claims] 1. A downward opening surface into which a plating solution flows.
An anode electrode and a cathode electrode provided on the cup with the cathode electrode in a state in contact with the connection terminal plating provided on plating surface of the substrate, the plating apparatus for performing a plating to the plating surface of the substrate, A lower part of the cup, a substrate supporting part for supporting the substrate with the surface to be plated facing upward, and the force source electrode for contacting the plating connection terminal of the substrate supported by the substrate supporting part, the cup being A predetermined distance outside the inner peripheral edge of
To provided above the substrate in the cup, provided with the anode electrode, a plating apparatus characterized by having a plating solution supply means for flowing the plating solution.