JP3212266B2 - Bump forming apparatus and bump forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bump formation in the process of manufacturing semiconductor devices, and more particularly, to a bump formation apparatus and a bump formation method for forming bumps having a uniform height.

[0002]

2. Description of the Related Art Conventionally, as a method of forming bumps on a semiconductor device, a method of plating a semiconductor wafer with gold or the like has been adopted. Hereinafter, a plating apparatus used in the conventional plating method and a plating method using the same will be described.

FIG. 9 is a schematic diagram showing a conventional jet plating apparatus according to the prior art. As shown in FIG. 9, in a conventional jet plating apparatus, a plating cup 8 and a plating solution tank 11 are connected via a power pump 10,
The plating solution 9 is stored in the plating solution tank 11.
The upper and lower ends of the plating cup 8 are open, a plurality of cathodes 13 are provided on the periphery of the upper end opening, and the power pump 10 is connected to the lower end opening. An anode 12 is provided inside the plating cup 8. Then, the plating process is performed by placing the wafer 7 on the cathode 13.

The operation of the jet plating apparatus configured as described above will be described below. First, the plating solution 9 is jetted from the plating solution tank 11 to the plating cup 8 by operating the power pump 10, and the plating solution 9 is applied to the wafer 7. Then, an electric current is supplied to the cathode 13 and the anode 12, and metal ions in the components of the plating solution 9 are precipitated on the wafer 7 in contact with the cathode 13, and the plating process is performed on the wafer 7. If an electroless plating solution is used, plating can be performed without supplying an electric current.

FIG. 10 is a schematic diagram showing a conventional dip plating apparatus. As shown in FIG.
In a conventional dip plating apparatus, a plating solution tank 1
A plating solution 9 is stored in the wafer 1. In the plating solution 9, a wafer 7 connected to a DC power supply and an anode 12 are arranged to face each other.

Hereinafter, the operation of the dip plating apparatus configured as described above will be described. First, a constant current is applied between the anode 12 and the wafer 7. Then, metal ions in the components of the plating solution 9 precipitate on the wafer 7 serving as the cathode portion, and the plating process is performed on the wafer 7.

[0007]

However, when bumps are formed on the wafer 7 by using the above-described jet plating apparatus according to the prior art, the anode 1 constituting the jet plating apparatus is used.
Since a hole having a uniform diameter is formed on the entire surface of the plating liquid 2 (having a uniform mesh shape), the plating solution 9 is formed.
Is excessively supplied to the central portion of the wafer 7. Then, the height of the formed bump is higher at the center of the wafer 7 than at the outer periphery.

Further, when bumps are formed on the wafer 7 by using the above-described conventional dip plating apparatus, the wafer 7 in the plating solution 9 stored in the plating solution tank 11 is used.
The height of the bump formed on the (cathode) becomes lower as it goes deeper into the plating solution 9.

As described above, when bumps are formed using a conventional plating apparatus, the uniformity of the height of the bumps formed in the wafer 7 basically depends on the performance of the plating apparatus. It takes shape. That is, the bump height cannot be adjusted beyond the performance of the plating apparatus.
Therefore, when a plating process is performed on a wafer of a different size or a wafer of a large inch, the height of bumps formed in the wafer varies, and COG (Chip O
For example, it is not possible to sufficiently cope with a device requiring a high-precision bump height such as n Glass).

The present invention has been made to solve such a problem, and an object of the present invention is to provide a bump forming apparatus and a bump forming method capable of adjusting a bump height with high accuracy.

[0011]

According to a first aspect of the present invention, there is provided a bump forming apparatus comprising: a plating cup having upper and lower ends opened; and a plating cup provided inside the plating cup. And a plating solution that jets from the lower end opening of the plating cup toward the upper end opening, and arranges a wafer on the upper end opening of the plating cup, and the anode, the wafer, In a bump forming apparatus for forming a bump by applying plating to the wafer by applying a voltage between the anode and the anode, a means for adjusting the flow of the plating solution to be substantially uniform over the entire surface of the wafer. Prepare. The plating solution flow
As a means for adjusting the distortion, the anode is formed in a curved shape.
The distance between the anode and the center of the wafer
Is larger than the distance between the anode and the outer peripheral portion of the wafer.
Good . According to this bump forming apparatus, the center of the wafer
The distance between the wafer and the anode in
It is possible to adjust the flow of the plating solution that tends to be excessively supplied to the central portion of the substrate, so that the height of the bump can be adjusted with high accuracy.

[0012]

[0013]

[0014]

[0015]

Further, a second configuration of the bump forming apparatus according to the present invention for achieving the above object includes a plating solution tank storing a plating solution, and an anode provided in the plating solution tank. A bump forming apparatus for arranging a wafer so as to face the anode and applying a voltage between the anode and the wafer to plate the wafer to form a bump; A distance between the anode and the wafer in a shallow portion of the plating solution tank is larger than a distance between the anode and the wafer in a deep portion of the plating solution tank. According to this bump forming apparatus, the anode is installed such that the distance between the anode and the wafer is longer in a shallow portion of the plating solution and closer in a deep portion. Further, precipitation of metal ions in a shallow portion of the plating solution can be suppressed, and deposition of metal ions in a deep portion of the plating solution can be promoted. Therefore, the height of the bumps can be adjusted with high accuracy over the entire surface of the wafer.

In the second configuration of the bump forming apparatus according to the present invention, it is preferable that the anode is formed in a curved shape. According to this preferred example, the anode is easily connected to the bump forming apparatus such that the distance between the anode and the wafer is longer in a shallow portion of the plating solution and closer in a deep portion. Can be installed in

Further, in a first method of forming a bump according to the present invention, the step of jetting a plating solution onto the wafer and the step of applying a voltage to the wafer form the bump by plating the wafer to form a bump. In the forming method, the wafer on which dummy bumps are formed in advance is used. According to this bump forming method, the ions of plating products (Au, Ag, Cu, etc.) can be concentrated on the dummy bumps, and the ions supplied around the dummy bumps can be reduced. It is possible to supply a suitable ion. Therefore, the height of the bumps can be adjusted with high accuracy over the entire surface of the wafer.

In the first method of forming a bump according to the present invention, a plurality of dummy bumps are formed on the wafer, and the area of the plurality of dummy bumps is gradually increased from a central portion of the wafer to an outer peripheral portion. It is preferable to form them so as to be small. According to this preferred example, it is possible to concentrate plating product ions, which tend to be oversupplied at the central portion of the wafer, on the dummy bumps, and to reduce ions supplied around the dummy bumps. The plating product ions supplied to the wafer can be made uniform over the entire surface of the wafer.

Further, the second method of forming a bump according to the present invention comprises the steps of providing a wafer and an anode in a plating solution so as to face each other, and applying a voltage between the wafer and the anode. In the bump forming method of forming bumps by plating a wafer, the wafer is used in which dummy bumps are formed in advance. According to this bump forming method, plating product ions are concentrated on the dummy bumps (metal ion precipitation is concentrated) and supplied around the dummy bumps (deposition).
Since it is possible to reduce the number of ions to be formed, it is possible to supply the plating product ions uniformly in the wafer.

In a second method of forming bumps according to the present invention, a plurality of dummy bumps are formed on the wafer, and the area of the plurality of dummy bumps is reduced when the wafer is placed in the plating bath. It is preferable that the plating solution be formed so as to gradually increase from a deep portion to a shallow portion in the plating solution tank. According to this preferred example, since the deposition of metal ions in a shallow portion of the plating solution is suppressed, the deposition of metal ions over the entire surface of the wafer is uniform, and the height of the bumps is adjusted with high precision. Can be.

The dummy bumps in the first and second bump forming methods according to the present invention may have a triangular, rectangular, or circular shape.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a plan view of an anode 5 used in a jet plating apparatus constituting a bump forming apparatus according to a first embodiment of the present invention. The structure of the jet plating apparatus according to the present embodiment is basically the same as that of the jet plating apparatus shown in FIG.
Are different from those shown in FIG.

The anode 5 shown in FIG. 1 is formed using a material which is difficult to be plated, such as platinum, and a plurality of holes (hereinafter referred to as “mesh holes”) 6 are formed in the anode 5 according to the present embodiment. ing. That is, the mesh formed on the anode 5 is partially coarsely formed (the coarsely formed portion is the mesh hole 6). This mesh hole 6 is formed over the entire surface of the anode 5,
The size (area) is small at the center and gradually increases from the center to the outer periphery.

In this embodiment, a jet plating apparatus (see FIG. 9) using the anode 5 formed as described above.
Since the central portion of the mesh hole 6 is formed small, the plating solution 9 that tends to be excessively supplied to the central portion during plating can be suppressed. Can be made uniform. Accordingly, the supply of ions to the entire inside of the wafer becomes uniform, so that the bump height can be easily adjusted.

In the present embodiment, the case where the mesh holes 6 are formed in a circular shape has been described. However, the present invention is not limited to this. The flow of the liquid 9 may be adjusted (see FIGS. 7 and 8). Further, in the present embodiment, the case where the area of the mesh holes 6 formed in the anode 5 gradually increases from the center to the outer periphery has been described, but the present invention is not limited to this. The mesh holes 6 having an appropriate size and distribution may be formed in the anode 5 so that the flow of the plating solution 9 can be appropriately adjusted according to the characteristics of the jet plating apparatus to be used.

(Second Embodiment) FIG. 2 is a schematic diagram showing a jet plating apparatus constituting a bump forming apparatus according to a second embodiment of the present invention. The structure of the jet plating apparatus according to the present embodiment is basically the same as that of the jet plating apparatus shown in FIG. 9, except for the structure of the anode.

The anode 15 constituting the jet plating apparatus shown in FIG. 2 is formed so as to be curved so that the central portion is depressed. The anode 15 is mounted on the jet plating apparatus so that the distance between the wafer 7 and the anode 15 is longer at the center and shorter at the outer periphery. That is, in the present embodiment, the anode 15
The anode 15 is mounted on the jet plating apparatus such that the distance between the anode 15 and the central portion of the wafer 7 is larger than the distance between the anode 15 and the outer peripheral portion of the wafer 7.

In this embodiment, since the jet plating apparatus is constituted by using the anode 15 formed as described above, the deposition rate of metal ions is higher at the outer peripheral portion than at the central portion, and the 7, it is possible to suppress the excessive precipitation of metal ions at the central portion, and it is possible to uniformly adjust the height of the bumps.

(Third Embodiment) FIG. 3 is a schematic configuration diagram showing a dip plating apparatus constituting a bump forming apparatus according to a third embodiment of the present invention. The structure of the dip plating apparatus according to the present embodiment is basically the same as the dip plating apparatus shown in FIG. 10, except for the structure of the anode.

In the dip plating apparatus according to the prior art shown in FIG. 10, the wafer 7 (cathode) provided in the plating solution 9 stored in the plating solution tank 11 enters the plating solution 9 deeply. It is known that the more you go, the lower the bump height. Therefore, in the present embodiment, an anode 15 having a shape as shown in FIG. 3 is used.

The anode 25 constituting the dip type plating apparatus shown in FIG. Then, the distance between the wafer 7 and the anode 25 is longer in a shallow portion of the plating solution 9.
In the deep part of the plating solution 9,
An anode 25 is mounted on a dip plating apparatus. That is, in the present embodiment, the distance between the anode 25 and the wafer 7 in a shallow portion of the plating solution 9 is larger than the distance between the anode 25 and the wafer 7 in a deep portion of the plating solution 9. , Anode 25
Is mounted on the dip plating apparatus.

In the present embodiment, since the dip plating apparatus is constituted by using the anode 25 formed as described above, the deep portion of the plating solution 9 is more likely to deposit metal ions than the shallow portion. The speed is increased, and the height of the bump can be adjusted uniformly.

In this embodiment, the plating solution 9
Wafer 7 and anode 2 at shallow and deep portions inside
The case where the anode 25 is curved in order to change the distance from the anode 5 has been described, but the present invention is not limited to this. For example, using a flat anode,
Attach the anode at an angle.
The anode may be mounted on the dip plating apparatus such that the distance between the anode and the wafer 7 in the shallow portion of the plating solution 9 is greater than the distance between the anode and the wafer 7 in the deep portion of the plating solution 9.

(Fourth Embodiment) FIG. 4 is a plan view of a wafer used when performing a bump forming method (plating method) according to a fourth embodiment of the present invention. In the plating method according to this embodiment, the dummy bumps 4 as shown in FIG. 4 are formed on the wafer 17 using the jet plating apparatus shown in FIG. The wafer 17 shown in FIG.
A plurality of dummy bumps 4 are formed over the entire surface of the wafer 17. The area of the dummy bump 4 is formed such that the area of the dummy bump 4 is large at the center and gradually decreases from the center to the outer periphery.

In the plating method according to the present embodiment,
The wafer 17 formed as described above is set in a jet plating apparatus (see FIG. 9), and plating for forming bumps is performed. By doing so, it is possible to suppress the height of the bump formed at the center of the wafer 17 (adjust the height of the bump formed on the wafer 17). That is, the large dummy bumps 4 are formed in the center of the wafer 17 according to the present embodiment, and the plating solution 9 concentrates on the dummy bumps 4.
The height of the bumps formed at the center of the wafer 7 (around the dummy bumps 4 at the center) can be suppressed, and the height of the bumps formed over the entire surface of the wafer 17 can be appropriately adjusted.

In this embodiment, the case where the dummy bumps 4 are formed in a rectangular shape has been described. However, the present invention is not limited to this. For example, the plating solution may be formed in another shape such as a circle or a triangle. 9 may be suppressed (adjusted) and the bump height may be adjusted. Further, in the present embodiment, the case where the area of the dummy bumps 4 gradually decreases from the central portion to the outer peripheral portion has been described, but the present invention is not limited to this, and the characteristics of the jet plating apparatus used are The dummy bumps 4 having an appropriate size and distribution may be formed on the wafer 17 so that the flow of the plating solution 9 can be appropriately adjusted according to the conditions.

(Fifth Embodiment) FIG. 5 is a plan view of a wafer used when performing a bump forming method (plating method) according to a fifth embodiment of the present invention. In the plating method according to this embodiment, the dummy bumps 4 as shown in FIG. 5 are formed on the wafer 27 using the dip plating apparatus shown in FIG. Wafer 2 shown in FIG.
The area of the dummy bumps 4 formed on the plating solution 7 is small in a region that enters a deep portion of the plating solution 9 when the wafer 27 is placed in the plating solution 9 of the plating solution tank 11, and increases from a deep portion to a shallow portion. It is formed so as to gradually increase.
The reason why the dummy bumps 4 having such a shape are formed on the wafer 27 is that the dummy bumps 4 are formed on the wafer 7 (cathode portion) provided in the plating solution 9 in the conventional dip plating apparatus shown in FIG. This is because it is known that the deeper the bumps go into the plating solution 9, the lower the height of the bumps becomes.

That is, in the plating method according to the present embodiment, since the dummy bumps 4 are formed on the wafer 27 as described above, the plating solution 9 concentrates on the dummy bumps 4 in the shallow portion of the plating solution 9 and the plating solution 9 Since the plating solution 9 is less concentrated on the dummy bumps 4 in the deep portion 9 than in the shallow portion, the height of the bump formed in the shallow portion of the plating solution 9 of the wafer 27 is suppressed, and the bump 9 is formed over the entire surface of the wafer 27. The height of the bumps can be adjusted appropriately.

In the present embodiment, the case where the dummy bumps 4 are formed in a rectangular shape has been described. However, the present invention is not limited to this. For example, other shapes such as a circle and a triangle may be used.

The plating solution used in each of the above embodiments may be a plating solution in which sulfurous acid, sulfuric acid, thallium or the like is dissolved, or a plating solution in which cyan is dissolved, in addition to Au, Ag, and solder which are main components. Is used. According to the above embodiments, for example, as shown in FIG. 6, the bumps 3 having a uniform height formed of Au, Ag, solder, and the like are deposited on the product chips 2 of the wafer 1. Be composed. Further, if a product chip 2 having a uniform bump height can be provided as described above, the ILB (In
Processing of products such as ner lead bonding is simplified, and the number of manufacturing steps and cost can be reduced.

[0042]

As described above, according to the present invention,
A bump forming apparatus and a bump forming method capable of adjusting the bump height with high accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing an anode included in a bump forming apparatus (jet plating apparatus) according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a bump forming apparatus (jet plating apparatus) according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a bump forming apparatus (dip plating apparatus) according to a third embodiment of the present invention.

FIG. 4 is a plan view showing a wafer used when performing a bump forming method (plating method) according to a fourth embodiment of the present invention.

FIG. 5 is a plan view showing a wafer used when performing a bump forming method (plating method) according to a fifth embodiment of the present invention.

FIG. 6 is a plan view showing an example of a wafer having bumps obtained by implementing the present invention.

FIG. 7 is a plan view showing another shape of the anode constituting the bump forming apparatus (jet plating apparatus) according to the first embodiment of the present invention.

FIG. 8 is a plan view showing another shape of the anode constituting the bump forming apparatus (jet plating apparatus) according to the first embodiment of the present invention.

FIG. 9 is a schematic configuration diagram showing a jet plating apparatus according to a conventional technique.

FIG. 10 is a schematic configuration diagram showing a dip plating apparatus according to a conventional technique.

[Explanation of symbols]

 1, 7, 17, 27 Wafer 4 Dummy bump 5, 12, 15, 25 Anode 6 Mesh hole 8 Plating cup 9 Plating solution 10 Power pump 11 Plating solution tank 13 Cathode

Claims (8)

(57) [Claims] 1. A plating cup having open upper and lower ends, an anode provided inside the plating cup, and a plating solution jetted from a lower end opening to an upper end opening of the plating cup. A bump forming apparatus that arranges a wafer on an upper end opening of the plating cup and applies a voltage between the anode and the wafer to perform plating on the wafer to form a bump. The anode includes means for adjusting the flow of the plating solution to be substantially uniform over the entire surface of the wafer, and the means for adjusting the flow of the plating solution includes:
A node is formed in a curved shape, the anode and the wafer
Distance between the anode and the wafer
A bump forming apparatus characterized by being larger than a distance from a peripheral part . 2. A plating solution tank in which a plating solution is stored, and an anode provided in the plating solution tank, wherein a wafer is disposed so as to face the anode, and between the anode and the wafer. In a bump forming apparatus for forming a bump by plating the wafer by applying a voltage to the wafer, a distance between the anode and the wafer in a shallow part of the plating solution tank is greater than the distance between the anode and the plating solution. A pump forming apparatus which is larger than a distance from the wafer in a deep part in a tank. 3. The anode is formed in a curved shape.
The bump forming apparatus according to claim 2 . 4. A step of jetting a plating solution onto the wafer;
A bump forming method, wherein a bump is formed by plating the wafer by applying a voltage to the wafer, wherein the wafer has dummy bumps formed thereon in advance. 5. The bump formation according to claim 4 , wherein a plurality of dummy bumps are formed on the wafer, and the areas of the plurality of dummy bumps are formed so as to gradually decrease from a central portion to an outer peripheral portion of the wafer. Method. 6. A bump forming step of plating a wafer to form a bump by a step of providing a wafer and an anode facing each other in a plating solution and a step of applying a voltage between the wafer and the anode. A method of forming a bump, comprising using the wafer on which a dummy pump is formed in advance. 7. A plurality of dummy bumps are formed on the wafer, and the area of the plurality of dummy bumps is increased from a deep portion to a shallow portion in the plating solution tank when the wafer is put in the plating solution tank. 7. The bump forming method according to claim 6 , wherein the bump is formed so as to gradually increase. 8. The shape of the dummy bump, triangular, bump forming method according to any one of claims 4 to 7, one rectangular and circular.