JPH11181590A - Electroplating method and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the variation on the film thickness of a plating film to a wafer. SOLUTION: An anode electrode holder 20 disposed to face the wafer 1 held on a cathode electrode plate 13 of the electroplating apparatus 10 by which the wafer 1 is immersed in a plating liquid 12 and the gold plating film 3 is deposited on the surface of the wafer 1 by energizing the liquid is provided with a current rectifier plate 26 and the current rectifier plate 26 is so constituted that the flow of the plating liquid 12 forms the axial flow coming into uniform contact with the entire surface of the wafer 1. An anode electrode 36 is laid in the holder 20 in the state of covering the current rectifier plate 26, openings 27 and the through-holes 22 of a main body 21. Since gold plating ions are evenly adhered over the entire surface of the wafer, the formation of the gold plating film to the uniform thickness distribution is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electrolytic plating technique,
In particular, the present invention relates to a technique for uniformly depositing a plating film on the surface of a plate-like object. Effective technology.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device, a gold plating film is applied to a wafer to project a gold (Au) bump on a semiconductor pellet cut from the wafer, and the gold bump is formed by the gold plating film. In some cases. Generally, when a gold plating film is deposited on the surface of a wafer,
The following electrolytic plating apparatus is used.

[0003] That is, an electrolytic plating apparatus for depositing a gold plating film on the surface of a wafer is a plating tank in which a plating solution (electrolytic solution) containing gold ions is stored, and the wafer is held and immersed in the plating solution. Along with, a cathode electrode for making the wafer a cathode, an anode electrode for making the plating solution an anodized,
The apparatus is provided with an energizing device for energizing between both electrodes, and a circulating device for circulating the gold plating solution in which the wafer is immersed.
The plating solution is circulated and a current is applied between the wafer and the plating solution while the plating solution is circulated, so that the gold plating film is deposited on the surface of the wafer.

[0004] Japanese Patent Application Laid-Open No. Hei 4 (1999) discloses an example of an electrolytic plating technique for depositing a gold plating film on the surface of a wafer.
No. 41698.

[0005]

However, in the above-described electrolytic plating apparatus, the flow of the gold plating solution is not uniform with respect to the wafer. The inventor has found that there is a problem that the thickness of the film becomes non-uniform in the plane of the wafer. If the thickness of the gold plating film varies within the wafer surface, the height of the gold bumps formed from the gold plating film varies between semiconductor pellets.

An object of the present invention is to provide an electrolytic plating technique capable of suppressing variations in plating film thickness when a plating film is applied to a plate-like object.

[0007] The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0008]

The outline of a typical invention among the inventions disclosed in the present application is as follows.

That is, in the electrolytic plating method, wherein the plate-like material is immersed in a plating solution, and a current is applied between the plate-like material and the plating solution to deposit a plating film on the surface of the plate-like material. The flow of the plating solution is rectified by the rectifying plate so as to uniformly contact the entire surface of the plate-like object.

According to the above-mentioned means, since the flow of the plating solution is rectified uniformly on the entire surface of the plate-like material by the rectifying plate, the plating ions can be uniformly attached to the entire surface of the wafer. The thickness distribution of the film can be formed uniformly over the entire surface corresponding to the uniformity of the flow of the plating solution.

[0011]

FIG. 1 is a front sectional view showing an electrolytic plating apparatus according to an embodiment of the present invention. 2A and 2B show an anode electrode holder, and FIG.
(B) is a side view. FIG. 3 shows a current plate,
(A) is a partially cut side view, (b) is a cross-sectional view along line bb of (a), and (c) is an enlarged partial cross-sectional view along line cc of (a). FIG. 4 is an explanatory diagram for explaining the operation.

In this embodiment, an electroplating apparatus according to the present invention applies a gold plating film for a gold bump on a main surface (hereinafter, referred to as a first main surface) on an active area side of a wafer. Is configured as The electrolytic plating apparatus 10 includes a plating tank 11, and a plating solution (electrolytic solution) 12 containing gold ions is stored in the plating tank 11 to form a gold plating film.

A cathode electrode plate 13 is provided at the center of the plating tank 11 so as to be movable up and down.
Holders 14 for holding the wafers 1 that are in contact with the main surfaces are attached to the main surfaces on both sides of 3, respectively. That is, the cathode electrode plate 13 is configured to also serve as a holding jig for holding the wafer 1. Cathode electrode plate 1
Numeral 3 is made of an insoluble conductive material and has a main surface formed in a rectangular plate shape capable of holding two wafers 1 side by side.

A pair of left and right anode electrode holders (hereinafter, referred to as holders) 2 are provided at both left and right ends in the plating tank 11.
0 and 20 are provided respectively. As shown in FIG. 2, the holder 20 has a main body 21 and the main body 2
Reference numeral 1 denotes a wafer 1 made of an insulating material such as resin.
Is formed in a rectangular flat plate shape having a height larger than the diameter of the wafer 1 and a width twice or more the diameter of the wafer 1. A pair of through holes 22 having an inner diameter substantially equal to the diameter of the wafer 1 are opened in the main body 21 side by side.

An inner ring 23 and an outer ring 24 are formed on the main surface of the main body 21 facing the wafer side.
The inner ring 23 is formed in a circular ring shape having an outer diameter smaller than the inner diameter of the through hole 22 by using an insulating material such as resin, and the outer ring 24 has the same inner diameter as the through hole 22. Is formed in a circular ring shape having a diameter larger than the inner diameter of the ring. A gap 25 is formed concentrically between the outer circumference of the inner ring 23 and the inner circumference of the outer ring 24, and the inner peripheral edge of the through hole 22 is located substantially at the center of the gap 25.

A rectifying plate 26 shown in FIG. 3 is concentrically abutted on the main surface of the main body 21 facing away from the wafer and is fixed by means such as welding. The rectifying plate 26 is made of an insulating material such as resin and has an outer shape of the main body 2.
The current plate 26 is formed in a substantially rectangular shape that is similar to that of the first through hole. Has been established.

The contact surface of the current plate 26 with the main body 21 is substantially C
A pair of U-shaped annular flow paths 28 are concentrically disposed outside the openings 27, 27. Annular channel 2
Partition wall 29 formed in a substantially C-shape between the opening 8 and the opening 27
A plurality of jet ports 30 are formed radially so as to communicate the inner spaces between the annular flow path 28 and the opening 27. As shown in FIG. 3 (c), the ejection port 30 is inclined such that the end on the opening 27 side is closer to the contact surface side than the end on the annular flow path 28 side. 2
It is set to be 6.5 degrees.

At the center of the lower end portion of the contact surface of the current plate 26 with the main body 21, a substantially square hole-shaped communication flow path 31 is submerged, and the communication flow path 31 is formed in both annular flow paths 28, 28. Are in communication. A substantially rectangular communication hole 32 is opened at the lower end of the communication channel 31 so as to communicate with the inner space of the communication channel 31. An inlet pipe 33 is vertically fixed at a position facing the communication hole 32 on the main surface of the current plate 26 opposite to the contact surface with the main body 21, and the inlet pipe 33 communicates with the communication hole 32. I have.

As shown in FIG. 2, mounting rings 34, 34 each having a female screw portion formed on the inner periphery are fixed concentrically to both openings 27, 27 of the current plate 26. Each of the retaining rings 35, 3
5 is attached by screwing a male screw portion formed on the outer periphery to a female screw portion. The holding ring 35 is formed in a circular ring shape having an L-shaped cross section, and the inner diameter is set equal to the inner diameter of the through hole 22 and the opening 27.
On the rectifying plate 26 side of the holding ring 35, an anode electrode 36 is sandwiched so as to cover the opening 27. The anode electrode 36 is formed in a shape of a disk in which an elongated conductor is woven in a net shape and has an outer diameter larger than the inner diameter of the holding ring 35.

The holder 20 constructed as described above is shown in FIG.
As shown in the figure, both inlet pipes 33, 33
Is inserted into an insertion hole 15 formed in the bottom wall of the plating tank 11 and is vertically erected. A circulation path 17 is provided between the drainage port 16 formed on the bottom wall of the plating tank 11 and each inlet pipe 33, and a circulation pump 18 is provided in the circulation path 17 via an inlet from the drainage port 16 side. The plating solution 12 is interposed so as to circulate to the pipe 33 side.

An energizing circuit 37 is connected between the cathode electrode plate 13 and the anode electrode 36.
Is provided with a DC power supply 38.

Next, the operation of the electrolytic plating apparatus according to the above configuration will be described, and an electrolytic plating method according to an embodiment of the present invention will be described for a case where the electrolytic plating apparatus is used.

Outside the plating tank 11, the wafer 1 as a plate-like object to be plated is brought into contact with the cathode electrode plate 13 with the surface to be plated 2 exposed, and is held by a holder 14. By the way, the wafer 1 is the cathode electrode plate 1
On the both sides, two sheets are held on both sides, and a total of four sheets are held at once. The cathode electrode plate 13 on which the wafer 1 is mounted is vertically lowered and immersed in the plating solution 12 of the plating tank 11.

The plating solution 12 in the plating tank 11 is circulated by a circulation pump 18. That is, the circulation pump 1
8, the plating solution 12 drained from the drain port 16 is sent from each inlet pipe 33 attached to the straightening plate 26 of the holder 20 to the annular flow path 28 via the communication hole 32 and the communication flow path 31, Radiation is ejected from the group of ejection openings 30 formed in the annular flow passage 28 to the opening 27. The plating solution 12 jetted to the opening 27 passes through the through hole 22, the inner peripheral space of the inner ring 23, and the gap 25 between the inner ring 23 and the outer ring 24, as shown by the dashed arrow in FIG. 1. The flow is then rectified as an axial flow, flows in the direction of the wafer 1 facing the rectifying plate 26, and uniformly contacts the entire surface of the wafer 1. Incidentally, the plating solution 12 is heated to a predetermined processing temperature by a heater (not shown).

When the rectification of the plating solution 12 with respect to the wafer 1 and the temperature are stabilized, a DC power is supplied between the anode electrode 36 and the cathode electrode plate 13 by the DC power supply 38 so that the wafer 1 and the plating solution 12 Is energized. By this energization and heating, the gold plating film 3 is deposited on the plating surface 2 of the wafer 1 to a uniform thickness over the entire surface as shown in FIG.

At this time, since the flow of the plating solution 12 rectified by the rectifying plate 26 uniformly contacts the entire surface of the wafer 1, the gold plating film 3 caused by the uneven flow of the plating solution 12 is formed.
Of the film thickness distribution (described later) is prevented.

In addition, since the anode electrode 36 is laid so as to cover the opening 27 and the through hole 22 in the holder 20, the gold plating ions are
7 and the through hole 22, the flow of the plating solution 12 rectified so as to flow axially so as to uniformly contact the entire surface of the wafer 1, so that the variation in the film thickness distribution of the gold plating film 3 is further reduced. It is surely prevented.

Then, after a predetermined electrolytic plating time has elapsed, the energization is stopped. Next, the cathode electrode plate 13 serving as a holding jig holding the wafer 1 is taken out of the plating tank 11. The wafer 1 on which the gold plating film 3 is applied is removed from the cathode electrode plate 13 outside the plating tank 11. Thereafter, the gold plating film 3 is applied to the wafer 1 by repeating the above operation.

By the way, due to the uneven flow of the plating solution 12 in the plating tank, the plating solution 12
4A becomes non-uniform as shown in FIG. 4A, the adhesion of gold plating ions becomes non-uniform over the entire surface of the wafer 1, and the thickness distribution of the gold plating film 3 becomes The flow becomes uneven in response to the unevenness of the flow.

However, in the present embodiment, the current plate 2
6, the flow of the plating solution 12 is evenly rectified over the entire surface of the wafer 1, so that the adhesion of the gold plating ions becomes uniform over the entire surface of the wafer 1, so that the thickness distribution of the gold plating film 3 is reduced. The flow becomes uniform over the entire surface in accordance with the uniformity of the flow of No. 12.

As described above, gold bumps (not shown) are formed on the wafer 1 on which the gold plating film 3 has been adhered to the plating surface 2 by means such as lithography and etching in a later step. Is done.

According to the present embodiment, when forming the gold bumps, the thickness of the gold plating film 3 is uniformly formed over the entire wafer 1, so that the gold bumps having uniform electric characteristics are formed. Become.

Further, since the variation in the thickness of the gold plating film 3 between the wafers 1, 1,... Is small, uniform electric characteristics can be obtained between the wafers 1, 1,. The resulting gold bumps are obtained.

According to the above embodiment, the following effects can be obtained. By rectifying the flow of the plating solution uniformly over the entire surface of the wafer by the rectifying plate, gold plating ions can be uniformly attached to the entire surface of the wafer.
The thickness distribution of the gold plating film can be formed uniformly over the entire surface corresponding to the uniformity of the flow of the plating solution.

By laying the anode electrode in a state of being stretched so as to cover the opening and the through-hole in the holder, the gold plating ions can be uniformly carried on the plating solution uniformly formed in the opening and the through-hole. Therefore, the gold plating ions can be brought into uniform contact with the entire surface of the wafer, and the variation in the film thickness distribution of the plating film can be more reliably prevented.

When a gold bump is formed by a gold plating film adhered to a wafer, the gold plating film having uniform electric characteristics can be formed by uniformly forming the gold plating film over the entire wafer. As a result, product quality and reliability can be improved.

By minimizing the variation in the thickness of the gold plating film between the wafers, it is possible to obtain gold bumps exhibiting uniform electric characteristics between the wafers, ie, between the chips.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say.

For example, the rectifying plate is not limited to being provided on the anode electrode holder, but may be provided independently.

The specifications such as the diameter, the number, and the inclination angle of the ejection ports for ejecting the plating solution radially, the ejection speed of the plating solution, the distance between the holder and the wafer, and the like are determined by the size of the wafer, the thickness of the plating film, the plating processing time, and the like. It is desirable to select the optimum value according to various conditions such as the material of the plating film.

The structure of the holding jig / cathode electrode plate is not limited to the structure of the above-described embodiment, but can be appropriately changed in consideration of the convenience of attaching / detaching the wafer.

The above-described electrolytic plating apparatus and electrolytic plating method are not limited to use for forming a gold plating film, but may be used for forming a solder plating film or other metal films.

In the above description, the case where the invention made by the present inventor is mainly applied to the electroplating technique of depositing a gold plating film on a semiconductor wafer, which is the background of application, has been described. In the case where a gold plating film having a trimetal structure or a PHS structure is applied instead, the present invention can be applied to a technique of embedding gold plating in a via hole, and further to a technique of electroplating other metals and alloys in general. In particular, the present invention can be applied to a plate-like object having a large surface to be plated to obtain excellent effects.

[0044]

The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.

By rectifying the flow of the plating solution uniformly over the entire surface of the plate-like material by the rectifying plate, plating ions can be uniformly attached to the entire surface of the wafer. It can be formed uniformly over the entire surface corresponding to the uniformity of the liquid flow.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an electrolytic plating apparatus according to an embodiment of the present invention.

2A and 2B show an anode electrode holder, wherein FIG. 2A is a partially cut front view, and FIG. 2B is a side view.

3A and 3B show a current plate, wherein FIG. 3A is a partially cut-away side view, FIG. 3B is a sectional view taken along line bb of FIG. 3A, and FIG. 3C is line cc of FIG. FIG.

FIG. 4 is an explanatory diagram for explaining an operation, and FIG.
Shows a comparative example, and (b) shows this embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer (plate-like material), 2 ... Plated surface, 3 ... Gold plating film, 10 ... Electroplating apparatus, 11 ... Plating tank, 12 ... Plating solution (electrolyte solution), 13 ... Cathode electrode plate, 14 ... Holding Tool, 15: insertion hole, 16: drain port, 17: circulation path, 18
... circulation pump, 20 ... anode electrode holder, 21 ... body, 22 ... through hole, 23 ... inner ring, 24 ... outer ring, 25 ... clearance, 26 ... rectifier plate, 27 ... opening, 28 ...
Annular flow path, 29 ... partition wall, 30 ... jet port, 31 ... communication flow path, 32 ... communication hole, 33 ... inlet pipe, 34 ... mounting ring, 35 ... holding ring, 36 ... anode electrode, 3
7 ... energizing circuit, 38 ... DC power supply.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Akira Miyota, Inventor 5-2-1, Josuihonmachi, Kodaira-shi, Tokyo Inside Semiconductor Division, Hitachi, Ltd. No. 22-1, Hitachi Microcomputer System Co., Ltd. (72) Inventor Masahiko Gomi 3-3-2, Fujibashi, Ome-shi, Tokyo Hitachi Tokyo Electronics Co., Ltd.

Claims (10)

[Claims] 1. An electrolytic plating method in which a plate is immersed in a plating solution and a plating film is deposited on a surface of the plate by energizing between the plate and the plating solution. An electrolytic plating method, wherein a flow of a plating solution is rectified by a rectifying plate so as to uniformly contact the entire surface of the plate-like object. 2. The rectifying plate radially ejects the plating solution toward a center of an opening formed to face the plate-like object, and causes a flow of the plating solution along a center line of the opening. The electrolytic plating method according to claim 1, wherein the flow is rectified as axial flow. 3. An electrolytic plating apparatus wherein a plate is immersed in a plating solution, and a current is applied between the plate and the plating solution to deposit a plating film on a surface of the plate. An electrolytic plating apparatus, wherein a flow of a plating solution is rectified by a rectifying plate so that the flow of the plating solution uniformly contacts the entire surface of the plate. 4. The rectifying plate radially ejects the plating solution toward a center of an opening formed to face the plate-like object, and causes a flow of the plating solution along a center line of the opening. The electrolytic plating apparatus according to claim 3, wherein the flow is rectified as axial flow. 5. The rectifying plate has an opening formed so as to face the plate-like object, and a plurality of jets for jetting the plating solution radially toward the center of the opening. 5. The service has been established.
An electroplating apparatus according to item 1. 6. An inner ring having an outer diameter smaller than the inner diameter of the opening and an outer ring having an inner diameter larger than the inner diameter of the opening are concentrically arranged on the plate-like object side of the opening. The electrolytic plating apparatus according to claim 4, wherein the plating is performed. 7. The electrolytic plating apparatus according to claim 3, wherein the rectifying plate is attached to an anode electrode holder to which an anode electrode is attached. 8. The electrolytic plating apparatus according to claim 7, wherein the anode electrode is formed in a mesh, and the anode electrode is laid so as to cover an opening of the rectifying plate. 9. The electrolytic plating apparatus according to claim 7, wherein the anode electrode is laid so as to be exchangeable. 10. The electrolytic plating apparatus according to claim 6, wherein the inner ring and the outer ring are provided on a main body of the anode electrode holder.