JP2008025000A - Electroplating method and apparatus for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroplating method and an apparatus for the same which is used for plating a substrate for an electronic component, a wafer for IC, a wafer for a thin film magnetic head or the like and by which the thickness of the plated film on the wafer is made uniform. <P>SOLUTION: The electroplating apparatus is provided with an anode electrode 32, a wafer holder 10 provided with a cathode electrode 18 opposed to the anode electrode 32, a cathode holder 3 on which the wafer holder 10 is mounted and a cathode auxiliary electrode 5 provided on the cathode holder 3 and positioned at the outer peripheral part W1 side of the wafer W held by the wafer holder 10 wherein a second cathode auxiliary electrode 6 is provided at the outside of the first cathode auxiliary electrode 5 with a certain interval. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to an electroplating method and apparatus used for plating a substrate for an electronic component, a wafer for an IC, a wafer for a thin film magnetic head, and the like.

    A thin film is attached to the plating surface of the wafer, and this thin film is formed by an electroplating apparatus. In this electroplating apparatus, a conductive base film is provided on a plating surface (also referred to as “front side”) on which a plating film is to be formed, and this base film is used as a cathode to conduct electricity in a plating solution. A plating film is deposited.

  In a conventional electroplating apparatus, an anode electrode is provided on the upper part of the plating tank, and a wafer holder is provided on the lower side thereof so as to be movable up and down. In this apparatus, after placing the wafer on the wafer holder, the cathode holder is inserted into the wafer holder, and the spring contact cathode electrode formed in a dish shape is pressed against the back side of the wafer.

  In the electroplating apparatus, since current concentrates on the outer peripheral portion of the wafer, the film thickness of the outer peripheral portion becomes thicker than other portions. Therefore, a plating film having a uniform thickness cannot be formed on the entire plating surface of the wafer.

In order to solve this problem, an annular cathode auxiliary electrode or an annular cathode auxiliary electrode divided into a plurality of parts is used.
The auxiliary electrode is provided on the cathode holder so as to surround the outer peripheral side of the wafer, and power is supplied to the auxiliary cathode electrode so that current is not concentrated on the outer peripheral portion of the wafer.

  When the cathode auxiliary electrode is provided, the amount of current flowing through the entire wafer can be made uniform to some extent by adjusting the amount of current (current value) supplied to the auxiliary electrode. However, the current tends to concentrate on the outer peripheral portion of the wafer, and a uniform current hardly flows. Therefore, the outer peripheral portion has a different film thickness from other portions. For this reason, since the outer peripheral portion of the wafer must be discarded, the yield of the product wafer is deteriorated. In addition, in the annular cathode auxiliary electrode divided into a plurality, a film thickness portion called a high spot is generated at the outer peripheral portion of the wafer corresponding to the joint (insulation gap) of each divided electrode piece. The film thickness becomes non-uniform.

  In view of the above circumstances, an object of the present invention is to uniformize the thickness of a plating film of an object to be plated, for example, a wafer.

The present invention provides an anode electrode, a wafer holder having a cathode electrode facing the anode electrode, a cathode holder to which the wafer holder is mounted, and provided in the cathode holder, and held by the wafer holder. An electroplating apparatus comprising: a first cathode auxiliary electrode located on the outer peripheral side of the wafer;
A second cathode auxiliary electrode is provided outside the first cathode auxiliary electrode with an interval.

  The cathode electrode, the first cathode auxiliary electrode, and the second cathode auxiliary electrode of the present invention are each connected to an independent power source. The second cathode auxiliary electrode of the present invention is an annular auxiliary electrode formed concentrically with the first cathode auxiliary electrode. The annular auxiliary electrode according to the present invention is divided into a plurality of parts, and the divided arc-shaped electrode pieces are separated from each other. Each of the arc-shaped electrode pieces of the present invention is connected to independent power sources.

The present invention provides an anode electrode, a wafer holder provided with a cathode electrode, a cathode holder to which the wafer holder is mounted, an outer peripheral side of the wafer provided on the cathode holder and held by the wafer holder An electroplating method using an electroplating apparatus, comprising: a first cathode auxiliary electrode positioned at a first cathode auxiliary electrode; and a second cathode auxiliary electrode spaced apart from the first cathode auxiliary electrode;
The process of holding the wafer on the wafer holder, the process of mounting the wafer holder on the cathode holder, and supplying power to each electrode located in the plating solution, and the current amount of the first cathode electrode is in contact with the wafer. And a step of making the current amount of the second cathode auxiliary electrode larger than that of the first cathode electrode.

  The second cathode auxiliary electrode according to the present invention is constituted by arc-shaped electrode pieces divided into a plurality of parts, and each arc-shaped electrode piece is supplied with power from independent power sources. The electrode pieces according to the present invention are supplied with different amounts of current.

  In the present invention, since the second cathode auxiliary electrode is provided outside the first cathode auxiliary electrode with a space therebetween, the first cathode auxiliary electrode functions as a conventional cathode auxiliary electrode. That is, the outer peripheral portion of the wafer that is difficult to uniformly plate is the outer peripheral portion of the first cathode auxiliary electrode. Therefore, a plating film having a uniform film thickness can be formed on the wafer and the first cathode auxiliary electrode except for the outer peripheral portion of the cathode auxiliary electrode, so that the yield of the product is greatly improved as compared with the conventional example. be able to.

A first embodiment of the present invention will be described with reference to FIGS.
A cathode holder 3 having a fitting hole 3 a is provided at the bottom 1 a of the plating tank 1. An annular first cathode auxiliary electrode 5 is provided at the upper end of the fitting hole 3a.
The inner peripheral portion 5a of the auxiliary electrode 5 protrudes into the fitting hole 3a, and the inner peripheral portion 5a also functions as a wafer holder when the wafer holder 10 is inserted into the fitting hole 3a. To do.

A second auxiliary cathode electrode 6 is provided outside the first cathode electrode 5 with an interval w ₀ . The electrode 6 is an annular electrode formed concentrically with the auxiliary electrode 5, and the power source 49 is provided separately from the power source 31 of the auxiliary electrode 5. The auxiliary electrode 6 is wider than the auxiliary electrode 5 (difference between the inner diameter and the outer shape), and the width, shape, and the like are appropriately selected as necessary.

  A wafer holder 10 is provided below the cathode holder 3. A circular pad storage recess 12 is provided at the center of the upper surface of the wafer holder 10, and an annular electrode storage recess 14 is provided outside thereof.

  A suction pad such as a rubber vacuum pad 16 is fixed to the pad housing recess 12. A spring contact type cathode electrode 18 is fixed to the electrode housing recess 14.

  The wafer holder 10 is provided with a suction passage 22 communicating with the suction pad 16, and the suction passage 22 is connected to a vacuum line 24. The wafer holder 10 is provided with a cathode wafer electrode 26, and the cathode wafer electrode 26 is connected to a cathode wafer power supply 28. A vertical movement means, for example, an elevating cylinder 30 is connected to the wafer holder 10.

  In the figure, 32 is an anode electrode (plus electrode) disposed in the plating tank 1, 34 is a paddle that slides in the plating tank 1, 36 is a paddle sliding arm, and 38 is a reservoir for overflowing plating solution. An overflow section for returning to the circulation tank (not shown), 40 is a plating supply pipe for supplying the plating solution from the circulation tank to the plating solution circulation supply section 42, 44 is a magnet, 46 is returned to the circulation tank, and 47 is an automatic valve. , Respectively.

Next, the operation of the present embodiment will be described.
When an object to be plated, for example, an IC wafer W is placed on the wafer holder 10 and a suction drive device (not shown) is started, vacuuming is performed via the vacuum line 24 and the suction passage 22, and the suction is performed. Since the pad 16 is attracted to the wafer W, the wafer W is securely fixed and held.

  In this state, the elevating cylinder 30 is driven to insert the wafer holder 10 into the fitting hole 3a of the cathode holder 3 and press the front side of the wafer W against the first cathode auxiliary electrode 5 as shown in FIG.

  Then, the suction pad 17 is deformed, and the upper end surface thereof is flush with the upper surface of the wafer holder 10, and the tip of the cathode electrode 18 is bent and descends to the upper surface position of the wafer holder 10. Press the back side.

  In this state, the plating tank 1 is filled with the plating solution M, and power is supplied to the electrodes 5, 6, 18, and 32. At this time, the current value of the first cathode auxiliary electrode 5 (referred to as “current amount”) is the same as or substantially the same as the current amount of the cathode electrode 26 (for example, 700 milliamperes). The amount of current is made larger than the amount of current of the first cathode auxiliary electrode 5 (for example, 980 mA).

  By doing so, the amount of current flowing from the anode electrode 32 to the wafer W and the first and second cathode auxiliary electrodes 5 and 6 is increased on the second cathode auxiliary electrode 6 side, so that the positive polarity of the metal in the plating solution M is increased. A plating film is formed while a large amount of ions are attracted to the second cathode auxiliary electrode 6 side.

  At this time, the second cathode auxiliary electrode 5 serves as a conventional cathode auxiliary electrode. That is, the outer peripheral portion W1 of the wafer W which is difficult to uniformly plate is substantially replaced by the outer peripheral portion 5b of the first cathode auxiliary electrode 5, so that the plating surface of the wafer W and the first cathode auxiliary electrode 5 A plating film F having a substantially uniform film thickness t is formed on the upper surface except for the outer peripheral portion 5b of the first cathode auxiliary electrode 5. Accordingly, since all the plated portions of the wafer W can be used as products, the yield of products is greatly improved as compared with the conventional example.

Next, a second embodiment of the present invention will be described with reference to FIG. 5. The same reference numerals as those in FIGS. 1 to 4 have the same names and functions.
The difference between this embodiment and the first embodiment is that the second cathode auxiliary electrode 6 is divided into a plurality of parts.

  That is, the annular second cathode auxiliary electrode 6 is composed of four divided arc-shaped electrode pieces 6a, 6b, 6c, and 6d, and the electrode pieces 6a to 6d are formed in the same shape and have a gap d between them. It is arranged with a gap. This interval d is for insulation, and for example, 3 mm is adopted as the gap d. Each of the electrode pieces 6a to 6d is connected to a separate and independent power source. The number of divisions of the electrode 6, the shape of each auxiliary electrode piece, the gap d, and the like are appropriately selected as necessary.

In this embodiment, as in the previous embodiment, the current amount of the first cathode auxiliary electrode 5 is made the same as or substantially the same as the current amount of the cathode electrode, and the current amount of the second cathode auxiliary electrode 6 is changed to the first cathode. The current amount of the auxiliary electrode 5 is made larger.
The current amount of each electrode piece 6a to 6d of the second cathode auxiliary electrode 6 is adjusted as necessary, for example, the current amount of each of the electrode pieces 6a to 6d is all different, or The current amount of the electrode pieces 6a and 6b is made larger than the current amount of the electrode pieces 6c and 6d.

  In this embodiment, since the current concentrates in the gap d (joint portion) between the auxiliary electrode pieces 6a to 6d, the film thickness called the high spot 50 is formed in the portion corresponding to the joint portion of the first cathode auxiliary electrode 5. Parts are generated. However, even if the high spot 50 is generated, the first cathode electrode 5 is not a product, so that there is no particular problem.

The embodiment of the present invention is not limited to the above, and may be as follows, for example.
(1) Although the charge amount supplied to the cathode electrode and the first and second cathode auxiliary electrodes is controlled by the current amount, it can also be controlled by the voltage value (voltage amount). Therefore, “control by current amount” in the present invention includes a case of “control by voltage value (voltage value)”.
(2) Instead of providing the first cathode auxiliary electrode so as to be in contact with the upper surface of the outer peripheral portion of the wafer, the first cathode auxiliary electrode may be provided apart from the outer peripheral portion of the wafer.
(3) Although an IC wafer was used as an object to be plated, the object to be plated of the present invention is not only an IC wafer, but also an electronic component substrate, a thin film magnetic head wafer, and the like. However, the “wafer” here includes all of the objects to be plated.
(4) An anode electrode is provided on the lower surface side of the wafer, instead of forming an anode electrode on the upper surface side of the wafer and forming a plating film on the upper surface of the wafer by contacting the lower surface side with the cathode electrode. A plating film may be formed on the lower surface of the wafer with the side in contact with the cathode electrode.

It is a top view which shows 1st Embodiment of this invention. It is a front view which shows a use condition. It is a principal part expanded longitudinal cross-sectional view of FIG. It is a longitudinal cross-sectional view which shows an electroplating apparatus. It is a top view which shows 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating tank 3 Cathode holder 5 1st cathode auxiliary electrode 6 2nd cathode auxiliary electrode 10 Wafer holder 18 Spring contact type cathode electrode 26 Cathode wafer electrode 26
32 Anode electrode

Claims (8)

A wafer holder having an anode electrode, a cathode electrode facing the anode electrode, a cathode holder to which the wafer holder is mounted, and an outer periphery of the wafer provided in the cathode holder and held by the wafer holder An electroplating apparatus comprising: a first cathode auxiliary electrode located on the part side;
2. An electroplating apparatus, wherein a second cathode auxiliary electrode is provided outside the first cathode auxiliary electrode with an interval. 2. The electroplating apparatus according to claim 1, wherein the cathode electrode, the first cathode auxiliary electrode, and the second cathode auxiliary electrode are connected to independent power sources, respectively. The electroplating apparatus according to claim 1, wherein the second cathode auxiliary electrode is an annular auxiliary electrode formed concentrically with the first cathode auxiliary electrode. 4. The electroplating apparatus according to claim 3, wherein the annular auxiliary electrode is divided into a plurality of pieces, and the divided arc-shaped electrode pieces are separated from each other. 5. The electroplating apparatus according to claim 4, wherein each of the arc-shaped electrode pieces is connected to an independent power source. An electroplating method using the electroplating apparatus according to claim 1;
The process of holding the wafer in the wafer holder;
Attaching the wafer holder to the cathode holder;
While supplying power to each electrode located in the plating solution,
The current amount of the first cathode electrode is equal to or substantially equal to the current amount of the cathode electrode in contact with the wafer, and the current amount of the second cathode auxiliary electrode is larger than the current amount of the first cathode electrode. The process of making it bigger,
An electroplating method comprising: 7. The electricity according to claim 6, wherein the second cathode auxiliary electrode is composed of arc-shaped electrode pieces divided into a plurality of parts, and each arc-shaped electrode piece is supplied with power from mutually independent power sources. Plating method. The electroplating method according to claim 7, wherein different amounts of current are supplied to the electrode pieces.

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