JP3532065B2 - Plating method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroplating method and apparatus capable of improving in-plane uniformity of plating film thickness and current efficiency of a plate-shaped or disk-shaped object to be plated and improving plating particles. .

[0002]

2. Description of the Related Art In the semiconductor industry, a method has been adopted in which a large number of elements formed on a silicon wafer are provided with protruding electrodes called bumps by an electroplating method and used as electrodes for connection. There is. In the plating of the bumps, since it is necessary to keep the height and shape of the bumps as constant as possible, the plating solution is made to flow at high speed over the surface of the object to be plated.

For this purpose, a method of irradiating the bumps on the surface of the object to be plated with a jet is often adopted as shown in the schematic view of FIG. As a result, there was a drawback in that the equipment became complicated in terms of piping, etc.

On the other hand, there is an improved method of plating by immersing an object to be plated in a plating bath, as has been conventionally done for an ordinary object to be plated. This method has the advantage that the device is relatively simple. For example, in Japanese Patent Laid-Open No. 7-243097,
As shown in the schematic diagram of FIG. 2, a method of suspending the wafer 1 on a rack held vertically and rotating the rack is disclosed. This method also has the advantage of working efficiency that two sheets can be processed while rotating at the same time, but the rotation speed is limited because the rotation direction is not horizontal to the plate-shaped surface to be plated, and a satisfactory solution There was a limit that the flow, and eventually, the bump height and shape could not have satisfactory uniformity.

On the other hand, as shown in the schematic view of FIG. 3, there is a method of holding the object to be plated 1 horizontally on a jig arranged vertically and rotating the jig. This method has the advantage that the plating of the object to be plated can be rotated horizontally with respect to the plating surface and the rotation speed can be increased, but the object to be plated is arranged at a position facing the anode. Therefore, it was possible to plate only one object at a time, and the work efficiency was poor.

[0006]

In view of such a situation, the inventors of the present invention have used a dipping method capable of plating with a simple apparatus to achieve satisfactory plating thickness and shape uniformity or high current. It is an object of the present invention to develop a plating method and apparatus that can achieve efficiency, improve plating particles, and process two wafers at the same time.

[0007]

In order to achieve the above object, the present invention provides a disk-shaped mounting plate that rotates like two wheels of a vehicle in an immersion plating method that can use a simple device. By supporting the object to be plated with the support fittings attached to the mounting plate, the two objects to be plated can be plated at the same time, and the object to be plated can be rotated horizontally with respect to the plated surface. Therefore, the method of electroplating a plate-shaped or disk-shaped object to be plated, which enables high-speed rotation and can achieve satisfactory liquid flow, and thus satisfactory uniformity in bump height, shape, and particle shape, and high current efficiency. And a device.

That is, according to the first aspect of the present invention, when a flat plate-shaped or disk-shaped object to be plated is immersed in a plating solution for electroplating, a pair of opposed disk-shaped members that can be rotated in a vertical plane by a rotating shaft are used. the object to be plated supported so as to face an anode in the mounting plate, rotate the該被plated with mounting plate, moreover
A method of electroplating a plate-shaped or disk-shaped object to be plated, which comprises plating the mounting plate while swinging the mounting plate horizontally and / or vertically .

A second aspect of the present invention is to mount two plate-like or disk-shaped objects to be plated and vertically arranged to rotate the surfaces of the objects to be plated in a vertical orientation. A plate, a metal fitting (chuck) for holding and energizing the object to be plated on the mounting plate, and holding the mounting plate at each end to become the center of rotation of the mounting plate and to energize the object to be plated Rotation shaft, an auxiliary structure for rotatably supporting the rotation shaft and energizing the rotation shaft, an anode facing the object to be plated, and a mounting plate in a horizontal direction and / or a vertical direction.
An apparatus for carrying out the above method, which is provided with a means for moving the plating tank.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a pair of opposed disc-shaped mounting plates which can be rotated in a vertical plane by a rotating shaft when a plate-shaped or disc-shaped object to be plated is immersed in a plating solution for electroplating. It is a method of electroplating a plate-shaped or disk-shaped object to be plated, which is characterized by supporting the object to be plated and rotating the object to be plated, and a plating apparatus capable of embodying this method. An example is shown in FIG.
The present invention will be described based on this. Referring to FIG. 4,
In the plating apparatus according to the present invention, in the plating tank 8,
Two mounting plates 2 vertically arranged to hold the disk-shaped object 1 to be plated and to rotate horizontally with respect to the surface of the object to be plated. A metal fitting (chuck) 3 for holding the mounting plate 2, a rotating shaft 4 for holding the mounting plate 2 as a center of rotation of the mounting plate and for energizing the object to be plated, a motor 5 for driving the rotating shaft 4, and A main component holding housing 9 for rotatably supporting the rotating shaft 4 and energizing the rotating shaft 4, including a rotation transmission shaft 6, and an anode 7 are arranged.

According to the method of the present invention, as shown in FIG. 4, the disk-shaped object to be plated 1 can be rotated horizontally with respect to the disk surface and two objects can be plated at the same time. Moreover, so that it can rotate around the horizontal axis 4,
By mounting the mounting plate 2 vertically and holding the object to be plated 1 on the mounting plate so that the object to be plated 1 can rotate at a high speed on a vertical surface, the surface of the object to be plated 1 is plated. The liquid can be made to flow at high speed.

Further, by providing a mechanism capable of freely changing the rotation speed and the rotation direction of the mounting plate, it is possible to select the optimum rotation conditions for the objects to be plated having different sizes and shapes. became.

The rotation of the motor 5 causes the mounting plate 2 to rotate via the transmission shaft 6 and the rotary shaft 4. By using a motor with a variable rotation direction and rotation speed, it is possible to electrically change the rotation speed and forward / reverse of the mounting plate 2, and thus the most appropriate rotation condition can be set according to the type of the object to be plated. Can be given. The rotation speed is usually 5
Approximately 100 rpm is preferable, but it is preferable to find the most suitable condition by changing the range of approximately 3 to 200 rpm depending on the type of the object to be plated.

Usually, the object 1 to be plated is the object 1 to be plated.
The center of the mounting plate 2 and the center of the mounting plate 2 are aligned and held by the mounting plate 2 by a current-carrying metal fitting (chuck) 3. The object to be plated 1 is held eccentrically from the rotation center of the mounting plate 2. It was found that it is possible to eliminate a portion where the relative velocity of the plating surface and the plating solution becomes small, and it is possible to further improve the in-plane uniformity of the plating thickness. That is, the relative velocity between the rotating object and the plating solution is faster in the circumferential portion and slower in the central portion. Therefore, when the object to be plated is placed at the center of the mounting plate, the plating thickness or the plating shape is likely to change because the stirring conditions are different between the central portion and the circumferential portion. As a result of diligent research, it was found that if the object to be plated is held eccentrically from the center of the mounting plate and the center of rotation is offset from the center of the object to be plated, it is possible to eliminate locations where the relative speed between the surface to be plated and the plating solution decreases. I found it. Geometrically, even if it is eccentrically held, there is a center of rotation, so it is expected that the flow velocity will be slow in that part, but since the rotation is not symmetrical, the flow of the plating solution becomes irregular, The result is that the uniformity of the film thickness is greatly improved.

The size of the eccentricity may be about 2% or more of the diameter of the mounting plate, but in the case of a mounting plate of 200 mm or less, the eccentricity becomes very small at 2%, so about 5 mm from the center of the object to be plated 1. It is preferable that the above-mentioned abnormality or eccentricity is 2% or more of the diameter of the mounting plate.

In the plating apparatus of the present invention, the flow of the plating solution is further provided by providing a mechanism, for example, a crankshaft, for swinging the casing 9 holding the entire main constituent parts including the constituent elements 1 to 6 in the left-right direction. Could be further promoted. Since the surface of the plating solution moves up and down due to such swinging of the mounting plate in the left-right direction, the plating tank should be configured to allow overflow, and plating should be performed in the preliminary tank and the main tank for holding the overflowing plating solution. More favorable results were obtained by providing a pump for returning the liquid.

The swinging of the main component holding casing 9 to the left and right as described above, specifically, changes the rotation of the motor 10 into a horizontal movement by the crank 11 to guide the entire main component. It is performed by sliding the rail 12 right and left. Further, the main component holding casing 9 may be swung by setting the sliding direction to be the vertical direction.

In the plating apparatus of the present invention, in order to further promote the stirring of the plating solution, the surface to be plated is irradiated with a jet stream,
It is also possible to perform plating by using ultrasonic irradiation or using squeegee together. Especially in the combined use of ultrasonic waves,
Generally, when plating while irradiating ultrasonic waves in a stationary state, the ultrasonic waves directly irradiated and the waves reflected on the wall resonate, causing strong and weak sound waves, which causes uneven plating. On the other hand, in the plating apparatus of the present invention, the position of the surface to be plated is constantly changed by rotation, so that the above-mentioned inconvenience does not occur, and therefore it is advantageous for stirring the plating interface. There is a feature that you can safely perform various ultrasonic irradiation.

In the plating apparatus of the present invention, an anode which is convexly curved with respect to the center of rotation of the object to be plated can be used, and the distribution of current density can be further improved.

Further, in the plating apparatus of the present invention, auxiliary equipment that can be added to a normal plating apparatus, that is, a stirrer, a filter, a temperature controller, a pH controller and the like can be added and used. Further, when plating is performed using the apparatus, not only a general direct current but also a pulse current, a reversal current, a current in which an alternating current is superimposed, or the like can be used.

[0021]

EXAMPLES The present invention will now be described in more detail with reference to examples. In these tests, the results of plating the disk-shaped object to be plated using the plating apparatus shown in FIG. 4 and achieving improvement in the in-plane uniformity of the plating thickness will be described.

Comparative Example 1 A commercially available solder plating bath was used to hold a φ8-inch disk-shaped workpiece on a disk-shaped mounting plate having a diameter of 300 mm at the center of the mounting plate, and the mounting plate was not rotated and was stationary. The plating was performed while stirring the pump. 10m from the circumference of the object to be plated
Within 4 m, the plating film thicknesses at four points (A to D) where the circumference was divided into four equal parts and the center point (E) of the object to be plated were compared. The plating conditions are 2.5 A / dm ² , plating time 40 minutes, and 20 ° C.

Example 1 As in Comparative Example 1, the disk-shaped object to be plated was held at the center of the mounting plate, and the mounting plate was rotated at 60 rpm for plating. The plating conditions are the same as in Comparative Example 1.

Example 2 A disk-shaped object to be plated was eccentrically held by 15 mm from the center of the mounting plate and held to perform plating. In addition to the measurement points of Comparative Example 1 and Example 1, the plating thickness of the portion (F) that serves as the rotation center of the disk-shaped object to be plated was also measured.

Example 3 In addition to the conditions of Example 2, plating was performed by reversing the rotation every 1 minute.

Example 4 In addition to the conditions of Example 3, plating was performed by swinging the main component holding casing to the left and right to swing the mounting plate of the object to be plated. The swing distance was 50 mm and the swing speed was 50 mm / sec.

The results obtained in Comparative Example 1 and Examples 1 to 4 are shown in Table 1.
It was shown to.

[Table 1]

[0028]

As described above, according to the present invention, it is possible to treat two plate-shaped objects at the same time in the plating method for a plate-shaped or disk-shaped object to be plated in an immersion method using a simple device. In addition, the in-plane uniformity of the plating thickness and plating shape and the current efficiency can be greatly improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a conventional jet-type plating apparatus.

FIG. 2 is a conceptual diagram (two-plate simultaneous plating type) showing a conventional immersion type plating apparatus.

FIG. 3 is a conceptual diagram (horizontal rotation type) showing a conventional immersion type plating apparatus.

FIG. 4 is an explanatory diagram showing an example of an apparatus that can embody the method of the present invention.

[Explanation of symbols]

1 ... Disk-shaped object to be plated 2 ... Mounting plate 3 ... Energization and mounting bracket (chuck) 4 ... Axis 5 ... Motor 6 ... Rotation transmission shaft 7 ... Anode 8 ... Plating tank 9 ... Main component holding housing 10 ... Motor 11. Crank 12 ... Guide rails

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keigo Obata 21-8 Minami Futami, Futami-cho, Akashi-shi, Hyogo Daiwa Kasei Research Institute Co., Ltd. (56) Reference JP-A-5-33196 (JP, A) Japanese Patent Laid-Open No. 7-243097 (JP, A) Japanese Patent Laid-Open No. 4-131395 (JP, A) Japanese Patent Laid-Open No. 5-230688 (JP, A) Japanese Patent Laid-Open No. 8-311689 (JP, A) Japanese Patent Laid-Open No. 50-104730 (JP , A) Japanese Patent Laid-Open No. 50-95138 (JP, A) Actual Development No. 57-65968 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) C25D 5/00-7/12 C25D 17/00-17/08

Claims (4)

(57) [Claims] 1. When a flat plate-shaped or disk-shaped object to be plated is immersed in a plating solution for electroplating, the object to be plated is used as an anode on a pair of opposed disk-shaped mounting plates that can be rotated in a vertical plane by a rotating shaft. It is supported face-to-face, the object to be plated is rotated together with the mounting plate , and the mounting plate is moved in the horizontal direction (
A) A method for electroplating a plate-shaped or disk-shaped object to be plated, which comprises oscillating vertically . 2. The center of the plate-shaped or disk-shaped object to be plated is 2% or more of the diameter of the mounting plate or 5 mm from the center of rotation of the mounting plate.
2. The method according to claim 1, wherein the plating is eccentrically held on the mounting plate and plated. 3. The rotation speed of the mounting plate is variable, and
The method according to claim 1 or 2, wherein the plating is performed by reversing the rotation direction of the mounting plate with a timer and freely changing the time of the normal rotation. 4. Two mounting plates arranged vertically for holding a plate-shaped or disk-shaped object to be plated and rotating so that the surface of the object to be plated has a vertical orientation, and the mounting plate. A metal fitting (chuck) for holding and energizing the object to be plated, and a rotary shaft for holding the mounting plate at each end to serve as a center of rotation of the mounting plate and for energizing the object to be plated,
An auxiliary structure for rotatably supporting the rotating shaft connected to the drive source and energizing the rotating shaft, an anode facing the object to be plated, and a mounting plate shaken in the horizontal direction and / or the vertical direction.
Apparatus for performing the method of claim 1, wherein the plating bath is provided with means for moving .