JP2003268599A - Method and equipment for electroplating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for electroplating by which film composition and film thickness can be held constant nearly perfectly and equipment therefor. <P>SOLUTION: In the electroplating method, an anode electrode is constituted of an array of a plurality of two-dimensional microelectrodes; a potential measuring electrode is moved on the surface of a plating film during energization to measure potential distribution on the film surface, and an electrode current is individually controlled on the basis of the results to control the surface potential of the plating film of a cathode electrode to an arbitrary value constantly. The electroplating equipment is provided with the anode electrode in which the plurality of microelectrodes are two-dimensionally arranged and an electric current is supplied independently to the respective microelectrodes; a reference electrode for measuring the potential distribution on the surface of the plating film of the cathode electrode during energization; and a control means for exerting control in such a way that the electric current can be supplied independently to the respective microelectrodes of the anode electrode on the basis of the potential distribution obtained by the reference electrode so that the surface potential of the plating film of the cathode electrode can be held constant. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electroplating method and an electroplating apparatus using a two-dimensional microelectrode.

[0002]

2. Description of the Related Art The deposition of metal by electroplating is greatly affected by the surface potential of the cathode electrode, that is, the plating region. For example, in electroplating, the flow density differs between the center and the end of the plating region, but the surface potential is lower at the end of the plating region where the current density is higher than at the center of the plating region. In alloy plating, the plating film composition is affected by the difference in surface potential, so there is a problem that the film composition differs between the center and the end of the plating region.

[0003]

As a method for controlling the current density on the surface of the plating region, a method of installing a shield plate between the anode electrode and the cathode electrode has been used so far. However, this method cannot control the local surface potential, so
There is a problem that the film composition cannot be made completely constant and the film thickness cannot be made constant.

Therefore, an object of the present invention is to provide an electroplating method and an electroplating apparatus which can make the film composition and film thickness almost completely constant.

[0005]

In the electroplating method of the present invention for solving the above problems, the anode electrode is composed of an array of a plurality of minute electrodes, and the potential measuring electrode (reference electrode) is moved on the surface of the plating film. Therefore, the potential distribution on the entire surface of the film is measured, and the microelectrode currents are individually controlled based on the result, so that the surface potential of the cathode electrode is controlled to a constant value.

According to the present invention, since the surface potential is continuously measured during plating to control the value of the current flowing through each microelectrode, the surface potential of the plating film can always be kept constant. Thereby, the composition of the plating film can be kept uniform. Further, since the current density becomes constant when the surface potential is constant, the film thickness can be controlled uniformly.

Further, the electroplating apparatus of the present invention which solves the above-mentioned problems, has an anode electrode in which a plurality of microelectrodes are two-dimensionally arranged and an electric current is independently supplied to each of the microelectrodes.
A reference electrode for measuring the potential distribution on the surface of the plating film of the cathode electrode during energization, and a small amount of the anode electrode so as to make the surface potential of the plating film of the cathode electrode constant based on the potential distribution obtained on the reference electrode. And a control unit that controls so that an electric current is independently supplied to each of the electrodes.

According to the present invention, the anode electrode comprises a plurality of anode electrodes.
It is configured such that the current is independently supplied to the microelectrodes of the dimensional array, the reference electrode provided in the present invention measures the potential distribution on the coating surface of the cathode electrode, and the control means is based on the measurement result. An electric current is independently supplied to each of the minute electrodes of the anode electrode so that the surface potential of the plating film of the cathode electrode is kept constant. Thereby, the composition of the plating film can be kept uniform. Further, since the current density becomes constant when the surface potential is constant, the film thickness can be controlled uniformly.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The plating solution used in the present invention is
The combination of metal elements that can be electroplated is not particularly limited. The anode electrode used in the present invention is also not particularly limited, but a soluble anode electrode requires replacement of the electrode material, so an insoluble anode is preferable.

[0010]

Example The surface of a 5 × 5 cm copper foil was smoothed by electrolytic polishing to obtain a plated sample. On this copper foil, a plating solution described in Table 1 below was used to form a 20 μm thick Fe—Ni alloy plating film under the plating conditions shown in Table 2 below.

[0011]

[Table 1]

[Table 2]

FIG. 1 shows a schematic view of the anode electrode used, and FIG. 2 shows a schematic view of the entire plating apparatus. In FIG. 1, an anode electrode 10 is a point electrode 10 having a diameter of 500 μm.
100a of 100a are arranged, the point electrodes 10a are insulated from each other by the insulating material 10b, and the current value is individually applied to each point electrode 10a.
Configured to be (independently) controllable. Further, as shown in FIG. 2, ten reference electrodes 12 arranged in the vertical direction are moved left and right on the surface of the plated sample 14 (see the arrow in the right diagram of FIG. 2) to conduct electricity, and the measured surface potential is used as the basis. In addition, the surface potential of the plated sample was fixed at -0.5 V by controlling the amount of current to each point electrode. Specifically, the upper and lower potential values are sampled at predetermined intervals in the left-right direction, and the difference between these values and the potential of the plating sample 14 is detected by the potentiometer 16 (after A / D conversion).
Typed in 8. After that, by using the rectifier 22 and distributing the current by, for example, a resistor (not shown), the current is individually supplied to each microelectrode 10a of the anode electrode 10 to set the plating sample surface potential to −0.5V. Fixed to. In this embodiment, ten reference electrodes were used, but the number of electrodes is not limited to this, and may be one as long as the structure can measure the potential of the entire surface.

When the composition ratio in the obtained Fe-Ni plating film was measured, the iron content was 61 ± 0.3 wt% regardless of the center and end of the plating film. It was possible to obtain a plating film having a uniform composition. Further, it was possible to obtain a uniform plating film having a film thickness of 20 ± μm.

On the other hand, when plating was performed using the plating solution composition shown in Table 1 and the plating conditions shown in Table 2 without measuring the surface potential, the film composition was 55.3 wt at the center.
%, The edge portion was 70.1 wt%, and the film thickness was 15 μm at the center portion of the film and 30 μm at the edge portion.

[0015]

By using the present invention, the surface potential of the plated surface can be kept constant, so that the film composition during alloy plating can be controlled uniformly. Further, since the current distribution on the plated surface becomes constant, it becomes possible to control the film thickness evenly.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an array of microelectrodes of an anode electrode used in the present invention.

FIG. 2 is a schematic view of the entire plating tank of the present invention.

[Explanation of symbols]

10 Anode electrode 12 Reference electrode 14 Cathode electrode

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C25D 17/12 C25D 17/12 Z

Claims (2)

[Claims] 1. An anode electrode is composed of an array of a plurality of two-dimensional micro electrodes, and the potential distribution electrode on the coating surface is measured by moving the potential measuring electrode on the surface of the coating film during energization, and based on the result. An electroplating method characterized in that the surface potential of the plating film of the cathode electrode is controlled to an arbitrary value by controlling the electrode current individually. 2. An anode electrode in which a plurality of microelectrodes are two-dimensionally arranged, and an electric current is independently supplied to each of the microelectrodes,
A reference electrode for measuring the potential distribution on the surface of the plating film of the cathode electrode during energization, and a small amount of the anode electrode so as to make the surface potential of the plating film of the cathode electrode constant based on the potential distribution obtained on the reference electrode. An electroplating apparatus comprising: a control unit that controls so that an electric current is independently supplied to each of the electrodes.