JPH08100292A - Method and apparatus for forming plating film - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for forming a plating film by making the current density distribution uniform in the plating region and making the film thickness of the plating film uniform, and a plating apparatus necessary for the method. [Configuration] Current flowing between the anode electrode 3 and the object 9 to be plated
All 14 passes through the opening 13 of the film thickness control plate 6. The path of the plating current 14 from the anode electrode 3 to the object 9 to be plated is
The outer peripheral portion of the object to be plated becomes longer than the central portion, and the electric resistance of the plating solution also increases. [Effect] By installing the film thickness correction plate 6, it is possible to suppress the concentration of current in the outer peripheral portion of the object to be plated. By optimizing the area S1 of the opening 13 of the film thickness control plate and the distance h between the film thickness control plate 6 and the object 9 to be plated, it is possible to achieve uniform plating film thickness distribution within the plating region. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is suitable for electroplating thin film magnetic head substrates, semiconductor substrates, various electronic component substrates and the like.

[0002]

2. Description of the Related Art In electroplating a thin film magnetic head substrate, a semiconductor substrate, various electronic component substrates, etc., it is an important subject to make the plating film thickness distribution uniform. In the conventional plating apparatus that does not take any measures for uniforming the film thickness distribution, for example, in the plating apparatus as shown in FIG.
The current density becomes extremely high in the outer peripheral part of the film, and the film thickness distribution deteriorates to a level that cannot be practically used. Several methods are known as means for making the film thickness uniform. For example, the method disclosed in JP-A-53-84830 is
As shown in FIG. 2, the object to be plated 9 having conductivity is arranged in the center of the cathode 2 having a much larger area than the object to be plated, and the anode electrode 3 having the same area as the cathode is installed facing the cathode. Is the way to do it. In general, the outer periphery of the cathode has a high current density and a thicker plating film, which causes a so-called edge effect. However, since the plating film tends to have a relatively uniform thickness in the center, this method By arranging the object to be plated on the object to be plated, it is intended to make the plating film thickness deposited on the object to be plated uniform. However, in this method, since plating is also performed on a portion that does not require plating, the plating solution deteriorates quickly and is uneconomical. Furthermore, the plating film in the non-plating part may partly float up from the underlying surface when the film thickness becomes thicker, and if it rises, deposition of the plating film will start on the back side of the plating film and the area to be plated will increase substantially. It will be. Since it is practically impossible to calculate the area to be plated after the increase, it is impossible to set the amount of current necessary to obtain the target film thickness, and as a result, it becomes impossible to secure the necessary plating film thickness. To make matters worse, it is difficult to determine in advance whether or not the plating film floating in the unnecessary plating area will start. Therefore, in consideration of safety, it is necessary to carry out the plating film peeling work every plating. And the manufacturing cost is increased. As another example, according to Japanese Patent Application Laid-Open No. 5-44076, the shape and size of the anode are optimized, and specifically, the area of the anode is made smaller than the area of the cathode.
A method of making the plating film thickness on the object to be plated uniform has been proposed. However, this method is presumed to change the anode area with the plating time when a soluble anode is used, and deteriorate the plating film thickness distribution deposited on the substrate. Furthermore, as another method, Patent Application Publication No. 4-43
As disclosed in Japanese Patent Publication No. 990, a method has been proposed in which a tubular body for controlling current distribution is provided, the inner diameter of the tubular body is changed to make the current distribution uniform, and as a result, the plating film thickness distribution is made uniform. However, this method is based on the assumption that the surface of the object to be plated is vertically arranged and plated, and the problem has not been solved when the object to be plated is horizontally arranged and plated. Further, in this method, all of the current flowing between the anode and the cathode does not flow through the cylinder, and the current near the plating solution surface passes through the parts other than the cylinder and flows between the anode and the cathode. It is one of the causes of worsening.

[0003]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the object of the present invention is to prevent the unnecessary portion from being plated at all and to contribute the applied total electric energy to the plating of the object to be plated. , Reduce the factors of film thickness variation,
It is intended to make the plating film thickness deposited on the object to be plated uniform. Also, the plating film thickness distribution and film quality are not affected by the shape and area of the anode electrode,
It is an object of the present invention to provide a plating apparatus equipped with a squeegee for stirring a plating solution in order to make the plating film thickness and film quality uniform.

[0004]

In order to solve the above problems, the present invention is a plating apparatus including a plating tank, a cathode electrode, an anode electrode, a squeegee, an anode electrode storage box and a film thickness control plate. A film thickness control plate is installed at the bottom of the anode electrode storage box. The film thickness control plate has an opening and opens toward the cathode electrode. The upper edge of the anode electrode storage box is higher than the plating liquid surface. Therefore, it is characterized in that the current flowing between the anode electrode and the cathode electrode always passes through the opening of the film thickness control plate.

[0005]

The film thickness control plate is installed between the anode and the cathode and has an opening area smaller than that of the object to be plated. The center of the film thickness control plate opening and the center of the object to be plated coincide with each other, and all the current flowing between the anode and the cathode is configured to pass through the film thickness control plate opening. Since the area of the film thickness control plate opening is smaller than the area of the plating target part of the plating target, the general tendency that the current density between the anode and the cathode is higher than the center of the plating peripheral part is suppressed. The action acts to make the current density uniform in the surface of the object to be plated. The effect of suppressing the concentration of current density on the outer periphery of the object to be plated increases as the area of the opening of the film thickness control plate becomes smaller and as the distance between the film thickness control plate and the object to be plated gets closer. The area of the plate opening is large, and decreases as the distance between the film thickness control plate and the object to be plated increases. Therefore, if the area and shape of the film thickness control plate opening and the distance between the film thickness control plate and the object to be plated are controlled according to the shape and area of the area to be plated of the object to be plated, the object to be plated will be optimal. The current density in the object plane can be made extremely highly uniform, and as a result, the plating film thickness formed on the object to be plated can be made uniform to a level that satisfies practical requirements.

[0006]

EXAMPLE FIG. 1 is a schematic view of a plating apparatus according to the present invention. The cathode electrode 2 has an opening 12. The opening 12 opens in the plating tank 1 and its peripheral edge makes surface contact with the outer peripheral portion of the object to be plated 9 to make the potential of the object to be plated the same as that of the cathode electrode and to define the plating region of the object to be plated. The object 9 to be plated is placed on the substrate holder 11 and plated. The substrate holder moves up and down by a vertical drive device (not shown). An O-ring for sealing the plating solution is provided between the substrate holder 11 and the cathode electrode 2 in order to prevent the plating solution from leaking. The cathode electrode 2 is covered with an insulating film except for the contact portion with the object 9 to be plated, and the plated film is not deposited. The side surface of the anode electrode 3 is surrounded by the anode electrode storage box 5, and the upper edge of the anode storage box 5 is higher than the plating liquid surface. Further, a film thickness control plate 6 is installed on the bottom of the anode electrode storage box 5. The film thickness control plate 6 is installed between the anode electrode 3 and the object 9 to be plated, and horizontally faces both the anode electrode 3 and the object 9 to be plated. The film thickness control plate 6 has an opening 13, and a plating solution flowing between the anode electrode 3 and the object 9 to be plated.
8 and the plating current 14 are all in the opening 13 of the film thickness control plate 6.
It is configured to go through. Opening 13 of film thickness control plate 6
Since the area S1 of the anode electrode 3 is made smaller than the plating area S2 of the object 9 to be plated,
The path of the plating current 14 leading to is longer in the vicinity of the outer peripheral portion of the object to be plated than in the vicinity of the central portion of the object to be plated, and the electrical resistance of the plating solution also increases. Therefore, by providing the film thickness correction plate 6, it is possible to suppress the phenomenon that the current density becomes high in the outer peripheral portion of the object to be plated. The suppression effect is as the area S1 of the opening 13 of the film thickness control plate is made smaller,
Further, the smaller the distance h between the film thickness control plate 6 and the object 9 to be plated, the larger the film thickness. Therefore, the area S of the opening 13 of the film thickness control plate
If the distance h between 1, the film thickness control plate 6 and the object 9 to be plated is properly selected, it becomes possible to make the current density in the surface of the object to be plated uniform. The distance h between the film thickness control plate 6 and the object 9 to be plated is determined by exchanging the thickness of the spacer 15 with an appropriate thickness. By making the current density uniform, it is possible to make the plating film thickness distribution uniform in the plating region of the object to be plated. Using the plating device shown in Fig. 1, the opening of the film thickness control plate has a diameter of 100 m on the substrate with a diameter of 120 mm.
m, the distance h between the film thickness control plate 6 and the object 9 to be plated is set to 20 mm to form a magnetic alloy plating film with an average film thickness of about 3 μm, and plating is performed at 25 points within the substrate surface so as to cover the entire surface of the substrate. The film thickness was measured. When the average value of the obtained measurement results is A and the maximum film thickness-the minimum film thickness is R, the film thickness distribution = ± (R / A)
The film thickness distribution was determined as / 2 x 100%. As a result, the film thickness distribution = ± 4.5% could be achieved. For comparison, the film thickness control plate was removed, plating was performed, and the same measurement was performed. As a result, the film thickness distribution was ± 80%.

[0007]

As described above, in the plating method and plating apparatus according to the present invention, the film thickness control plate is installed between the anode electrode and the object to be plated, and the opening area of the film thickness control plate is adjusted to the object to be plated. By setting the area smaller than the plating area and optimizing the distance between the anode and the object to be plated, it is possible to suppress the concentration of current density on the outer periphery of the object to be plated, and as a result, the plating on the object to be plated. It is possible to make the film thickness distribution uniform.

[Brief description of drawings]

FIG. 1 is a schematic view of a plating apparatus according to the present invention.

FIG. 2 is a diagram illustrating a problem of a conventional plating apparatus.

FIG. 3 is a conventional plating apparatus.

[Explanation of symbols]

1 ... Plating tank, 2 ... Cathode electrode, 3 ... Anode electrode, 4 ... Squeegee, 5 ... Anode electrode storage box, 6 ... Film thickness control plate, 7 ... Plating power supply, 8 ... Plating solution, 9 ... Plated object, 10 … Plating solution seal O-ring, 11… Substrate holder, 12…
Cathode electrode opening, 13 ... Film thickness control plate opening, 14 ...
Plating current.

Claims (4)

[Claims] 1. A film thickness correcting plate having an opening area and an opening shape according to the shape of an object to be plated when the plating film is electroplated on a substrate, the anode electrode is horizontally opposed to the upper side and the cathode electrode is horizontally opposed to the lower side. Installed between the anode and cathode,
A method for forming a plating film, wherein all the current flowing between the anode electrode and the cathode electrode during electroplating passes through the opening of the film thickness adjusting plate, and plating is performed while stirring the vicinity of the cathode with a squeegee. 2. A plating apparatus including a plating tank, a cathode electrode, an anode electrode, a squeegee, an anode electrode storage box and a film thickness control plate, wherein the film thickness control plate is installed at the bottom of the anode electrode storage box. Has been done. The film thickness control plate has an opening and opens toward the anode and cathode electrodes. The upper edge of the anode electrode storage box is higher than the plating liquid surface. Therefore, the plating apparatus is characterized in that the current flowing between the anode electrode and the cathode electrode always passes through the opening of the film thickness control plate. 3. The opening area and opening shape of the film thickness control plate are optimized according to the substrate shape. The opening area and opening shape of the film thickness control plate can be easily changed by replacing the film thickness control plate. Further, the distance between the film thickness control plate and the cathode can be easily adjusted by sandwiching the spacer. Further, a squeegee for stirring the plating solution is installed between the film thickness control plate and the cathode, which is a plating apparatus. 4. A plating film thickness distribution deposited on an object to be plated can be made uniform by adjusting the opening area and opening shape of the film thickness controlling plate and the distance between the film thickness control plate and the object to be plated. Plating equipment characterized by being possible.