CN110777412A

CN110777412A - Electroplating device and electroplating method for forming electroplating structure on substrate

Info

Publication number: CN110777412A
Application number: CN201810854001.0A
Authority: CN
Inventors: 王诗男
Original assignee: Shanghai Industrial Utechnology Research Institute
Current assignee: Shanghai Industrial Utechnology Research Institute
Priority date: 2018-07-30
Filing date: 2018-07-30
Publication date: 2020-02-11
Anticipated expiration: 2038-07-30
Also published as: CN110777412B

Abstract

The application provides an electroplating device for forming an electroplating structure on a substrate, comprising: a container for holding an electroplating solution; a substrate holder for holding a substrate to be electroplated within the vessel and having contact electrodes in electrical contact with a plating seed layer of the substrate surface; a metal plate placed in the container in parallel with the substrate; a power supply for supplying a current for plating to the substrate and the metal plate; and an auxiliary electrode disposed within the container and disposed at a periphery of a plating area of the substrate, a plating pattern of the auxiliary electrode being in equipotential electrical communication with a surface of the plating area of the substrate. According to the application, uniform and stable electroplating on the substrate can be realized simply and efficiently.

Description

Electroplating device and electroplating method for forming electroplating structure on substrate

Technical Field

The present disclosure relates to the field of micro-processing technologies, and more particularly, to an electroplating apparatus and an electroplating method for forming an electroplating structure on a substrate.

Background

In the manufacture of semiconductor devices, particularly Micro Electro Mechanical Systems (MEMS) devices, it is often necessary to form various fine structures by electroplating. Particularly, when a fine structure with a thicker thickness and deep holes need to be filled, the electroplating method has better effect, higher speed and lower cost. For example, Through Silicon Vias (TSV), micro-coils, etc., often require the formation of a metal microstructure by electroplating.

In the production of semiconductor devices including MEMS, an electroplating process is generally performed in units of a substrate. That is, it is often necessary to simultaneously plate a plurality of fine structures on each substrate. In the plating, a substrate having a seed layer is usually placed in a plating solution as a cathode in parallel with a metal plate as an anode; by applying a suitable voltage between the cathode and the anode, metal ions in the plating solution are driven to move to the substrate, and the metal ions are reduced to metal atoms on the plating surface of the substrate in contact with the plating solution and deposited, thereby realizing plating. The plating surface referred to herein is a surface of the seed layer which is in contact with the plating solution at the start of plating; when the metal plated on the surface of the seed layer is covered by the plating metal, the plated surface becomes the surface of the plating metal. Because only the plating surface is in contact with the plating solution and is in electrical communication with the anode through the plating solution, an electrical current is generated between the plating surface and the anode during plating.

In order to enable uniform and stable plating of a desired fine structure over the entire substrate, it is necessary that the electric field distribution between the substrate and the anode be uniform and the current density be stable within a range. However, on the one hand, the distribution of the plating pattern over the substrate is often non-uniform, and thus may result in a non-uniform electric field distribution. In order to adjust the electric field distribution between the substrate and the anode, a porous adjusting plate is often interposed between the substrate and the anode, but this tends to enlarge the volume of the plating bath and to impede the flow of the plating solution. On the other hand, in order to realize high-quality plating, it is necessary to control the current density within a certain appropriate range. The plating current is the product of the current density and the plating area; when the plating area on the substrate is small, the plating current must be made small in order to obtain a suitable current density.

It should be noted that the above background description is only for the convenience of clear and complete description of the technical solutions of the present application and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the present application.

Disclosure of Invention

The inventors of the present application have found that, on the one hand, when the distribution of the plating pattern on the substrate is uneven (e.g., asymmetric), the fine structure obtained by plating tends to be uneven in thickness. If a porous adjusting plate is added between the substrate and the anode to adjust the electric field distribution between the substrate and the anode, local disturbance of the electric field may occur due to the blocking of the plating solution flow or current flow, resulting in local variation of the plated microstructure (i.e., structural variation from other normally plated microstructures). On the other hand, when the prior art is used for obtaining a smaller electroplating area, the electroplating current becomes very small, and when the electroplating current is too small, the electroplating process is easily influenced and unstable; in order to adjust the plating area, although redundant plating patterns may be added to the substrate, this approach consumes the effective area of the substrate, limits the integration of the plating patterns, and often increases the difficulty of processing.

The present application provides a plating apparatus and a plating method for forming a plating structure on a substrate, wherein an auxiliary electrode is provided on the periphery of a plating region of a substrate to be plated, and the auxiliary electrode contributes to adjustment of electric field distribution between the substrate and an anode and adjustment of plating current, thereby enabling uniform and stable plating on the substrate to be simply and efficiently achieved.

According to an aspect of an embodiment of the present application, there is provided an electroplating apparatus for forming an electroplating structure on a substrate, including:

a container for holding an electroplating solution; a substrate holder for holding a substrate to be electroplated within the vessel and having contact electrodes in electrical contact with a plating seed layer of the substrate surface; a metal plate placed in the container in parallel with the substrate; a power supply for supplying a current for plating to the substrate and the metal plate; and an auxiliary electrode positioned within the container and disposed at a periphery of a plating area of the substrate, a plating pattern of the auxiliary electrode being in equipotential electrical communication with a surface of the plating area of the substrate.

According to another aspect of the embodiment of the present application, a perpendicular distance between the plating pattern of the auxiliary electrode and the surface of the plating area of the substrate is smaller than a perpendicular distance between the plating pattern of the auxiliary electrode and the surface of the flat metal plate.

According to another aspect of the embodiment of the present application, wherein a perpendicular distance between the plating pattern of the auxiliary electrode and the surface of the plating area of the substrate is less than 1/5 of a perpendicular distance between the plating pattern of the auxiliary electrode and the surface of the flat metal plate.

According to another aspect of the embodiments of the present application, wherein an area of the plating pattern of the auxiliary electrode is larger than an area of the plating pattern in the plating region of the substrate.

According to another aspect of the embodiments of the present application, wherein the plating pattern of the auxiliary electrode is a symmetrical pattern.

According to another aspect of the embodiments of the present application, wherein the plating pattern of the auxiliary electrode is a center symmetrical pattern.

According to another aspect of the embodiments of the present application, wherein the plating pattern of the auxiliary electrode includes:

at least two sub-patterns of equal area separated by an insulating layer of the auxiliary electrode surface in a circumferential direction of a plating region of the substrate; or a pattern continuous in the circumferential direction of the plating region of the substrate.

According to another aspect of the embodiments of the present application, there is provided an electroplating method for forming an electroplating structure on a substrate by using the electroplating apparatus of any one of the above aspects, including:

holding the substrate on which the plating seed layer is formed in a container containing a plating solution by a substrate holder; and

and supplying a current for plating to the substrate and the metal flat plate using a power supply, wherein a plating pattern of the auxiliary electrode is in electrical contact with the plating solution and is in equipotential electrical communication with a surface of the plating region of the substrate.

The beneficial effect of this application lies in: uniform and stable plating can be easily and efficiently performed on a substrate.

Specific embodiments of the present application are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the application may be employed. It should be understood that the embodiments of the present application are not so limited in scope. The embodiments of the application include many variations, modifications and equivalents within the spirit and scope of the appended claims.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the application, are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

FIG. 1 is a schematic view of a plating apparatus according to example 1 of the present application;

FIG. 2 is a schematic view showing a positional relationship among a substrate, a substrate holder and an auxiliary electrode according to example 1 of the present application;

FIG. 3 is a schematic view of an auxiliary electrode in example 1 of the present application;

FIG. 4 is a schematic view of an electroplating method according to example 2 of the present application.

Detailed Description

The foregoing and other features of the present application will become apparent from the following description, taken in conjunction with the accompanying drawings. In the description and drawings, particular embodiments of the application are disclosed in detail as being indicative of some of the embodiments in which the principles of the application may be employed, it being understood that the application is not limited to the described embodiments, but, on the contrary, is intended to cover all modifications, variations, and equivalents falling within the scope of the appended claims.

Example 1

Example 1 of the present application provides a plating apparatus for forming a fine structure on a substrate. Fig. 1-3 are schematic diagrams of the present embodiment. In the present embodiment, the schematic diagram of fig. 1 includes only the simplest elements in order to highlight the main idea of the present application.

As shown in FIG. 1, the plating apparatus 1 of the present embodiment includes a container 2, a substrate 4, a metal plate 5, a substrate holder 6, an auxiliary electrode 7, and a power source 11. The container 2 is filled with a plating liquid 3. The substrate 4 is placed in the plating liquid 3 in parallel with the metal flat plate 5. Parallel, as used herein, means that two opposing surfaces are disposed approximately parallel, with an included angle of no more than 10 °. The surface of the substrate 4 facing the metal flat plate 5 has a plating seed layer 8. The auxiliary electrode 7 has a conductive material 7a inside. The plating seed layer 8 and the conductive substance 7a are electrically connected to each other through a wire 11a having an insulating sheath and a wire 11b having an insulating sheath, respectively, and are connected to the negative electrode of the power supply 11 through a wire 11c having an insulating sheath. Therefore, the plating seed layer 8 and the conductive material 7a are almost equipotential, and the substrate 4 and the auxiliary electrode 7 are cathodes for plating. On the other hand, the flat metal plate 5 is connected to the positive electrode of the power supply 11 through a wire 11d having an insulating sheath. The metal plate 5 is thus an anode for electroplating.

The plating portion B of the substrate 4 (the portion circled by the broken line B in fig. 1), and the portion C of the flat metal plate 5 corresponding thereto (the portion circled by the broken line C in fig. 1) are completely immersed in the plating liquid 3. For example, in fig. 1, the substrate 4 is placed upright on the flat metal plate 5, and the plating portion B of the substrate 4 and the corresponding portion C of the flat metal plate 5 are completely submerged below the liquid surface 3a of the plating liquid 3.

The positional relationship among the substrate 4, the substrate holder 6, and the auxiliary electrode 7 will be further described with reference to fig. 1 and 2. Fig. 2 is an enlarged view of a portion encircled by a broken line a in fig. 1. As shown in fig. 1 and 2, the substrate 4 is fixed inside the substrate holder 6, and the plating part B of the substrate 4 is located within the opening 6a of the substrate holder 6. The auxiliary electrode 7 is provided at the periphery of the plating part B of the substrate 4 without obstructing the flow of the plating liquid 3 and ions therein between the plating part B and the metal flat plate 5 as an anode. Thus, the flow of the plating liquid 3 and the ions in the plating liquid between the plating section B and the flat metal plate 5 is not hindered during the plating, and the electric field therebetween is not disturbed by the shielding as in the case of the shielding.

The auxiliary electrode 7 may have a plating pattern 7 d. The surface of the plating pattern 7d and the opposite surface 5a of the flat metal plate 5 as the anode are parallel to each other. In order to achieve a relatively uniform electric field distribution at the plating section B of the substrate 4 and thus a uniform plating rate, the vertical distance of the surface of the plating pattern 7d from the surface of the plating section B needs to be smaller than the vertical distance of the surface of the plating pattern 7d from the surface 5a of the flat metal plate 5. For example, a specific example is that the surface of the plating pattern 7d is located in the middle between the surface of the plated portion B and the surface 5a of the flat metal plate 5, and the perpendicular distance between the surface of the plating pattern 7d and the surface of the plated portion B is smaller than 1/5 of the perpendicular distance between the surface of the plating pattern 7d and the surface 5a of the flat metal plate 5.

In the present embodiment, the auxiliary electrode 7 is fixed on the surface of the outer portion of the substrate holder 6 facing the flat metal plate 5.

The following describes the state of electrical connection between the lower substrate 4, the substrate holder 6 and the auxiliary electrode 7 in conjunction with fig. 1 and 2. As shown in fig. 1 and 2, the surface of the plating seed layer 8 of the substrate 4 has an insulating film 12. In the plating portion B of the substrate 4, the insulating film 12 is opened with corresponding windows 12a corresponding to the pattern of the fine structure 13 (refer to fig. 4) to be formed by plating. At the window 12a, the surface 8a of the plating seed layer 8 is exposed, and can be contacted with the plating solution 3 so that a desired fine structure 13 can be formed on the surface 8a by plating. On the other hand, the surface of the substrate holder 6 which is in contact with the plating liquid 3 is insulated and thus is not plated. The substrate holder 6 is provided with a contact electrode 9 inside. The contact electrode 9 is in contact with the plating seed layer 8 at the periphery of the substrate 4 to be in electrical communication. Thus, the plating seed layer 8 is connected to the outside of the substrate holder 6 by the wire 11a via the contact electrode 9. As for the auxiliary electrode 7, the inside thereof is composed of a conductive substance 7a, the surface thereof is provided with an insulating layer 7b, and the insulating layer 7b is provided with an opening 7c so that the conductive substance 7a is exposed at the opening 7c, thereby forming a plating pattern 7 d. The plating pattern 7d is connected to the outside of the auxiliary electrode 7 through the inside of the conductive substance 7a of the auxiliary electrode 7 (refer to fig. 3) via the wire 11b, and is electrically connected to the plating seed layer 8 through the wire 11 a. This connection makes the plating seed layer 8 nearly equipotential with the plating pattern 7 d. Since the plating pattern 7d can contact the plating liquid 3, a current can be generated between the metal plate 5 during the plating process.

In the present application, the surface of the plating part B may be, for example, the surface 8a of the plating seed layer 8.

Next, the constituent materials of the plating apparatus 1 will be described by way of example.

The container 2 may be made of an insulating material such as quartz, plastic, or teflon. The material of the container 2 is resistant to corrosion by the plating liquid 3 and does not release impurities such as ions into the plating liquid enough to affect the quality of plating.

The plating solution 3 is an aqueous solution containing copper sulfate as a main component when a fine pattern of Cu is to be plated, for example.

The substrate 4 may be a wafer commonly used in the field of semiconductor manufacturing, such as a Silicon wafer, a Silicon On Insulator (SOI) wafer, a Silicon germanium wafer, a gallium nitride wafer, or a SiC wafer, or may be an insulating wafer such as quartz, sapphire, or glass. The substrate 4 may be a wafer commonly used in the field of semiconductor manufacturing, and the surface of the wafer may further include various films and various structures required for semiconductor devices and MEMS devices. The substrate 4 may be ceramic, metal, Printed Circuit Board (PCB), or the like. In a specific embodiment, the substrate 4 may be a semiconductor substrate.

The plating seed layer 8 on the substrate 4 may be a metal thin film. The plating seed layer 8 may be a single metal film or a composite film formed by stacking two or more metal films. The insulating film 12 may be a photoresist suitable for plating, and the window 12a of the insulating film 12 corresponds to the fine structure 13 to be formed by plating (refer to fig. 4).

The metal flat plate 5 may be a metal plate of the same or different material as the plating material of the microstructure to be plated, depending on the actual plating requirement. For example, the metal flat plate 5 is a flat plate of a metal such as Pt or Cu. If necessary, the metal plate 5 may be placed in a filter to prevent the surface deposits from falling into the plating solution and causing contamination.

The substrate holder 6 has a surface made of an insulating material except for a portion contacting the electrode 9 (fig. 2). The insulating material is required to have sufficient corrosion resistance to the plating solution and not to release impurities such as ions into the plating solution enough to affect the plating quality. In a specific example, the substrate holder 6 is made of a conductive material except for the portion contacting the electrode 9 (fig. 2), and the surface thereof contacting the plating solution is covered with an insulating material.

The conductive substance 7a inside the auxiliary electrode 7 may be metal. For example, the conductive material 7a is a metal such as aluminum (Al) or stainless steel, and the insulating layer 7b on the surface thereof is a teflon (PTFE) coating.

The auxiliary electrode 7 can be used to adjust the electric field distribution and the current magnitude between the substrate 4 and the metal plate 5. This adjustment is achieved by adjusting the pattern distribution and pattern area Sa of the plating pattern 7d on the auxiliary electrode 7. Namely: on the one hand, the total surface area Sa of the desired plating pattern 7d can be calculated from the total surface area Sw of the contact plating solution of the fine pattern to be plated of the substrate 4, the optimum plating current density Dm, and the comparatively ideal plating current Im; on the other hand, the pattern distribution of the plating pattern 7d for making the electric field distribution uniform can be calculated from the distribution of the fine pattern of the substrate 4 to be plated.

In one embodiment, the pattern area Sa of the plating pattern 7d may be set based on the following method. That is, assuming that the auxiliary electrode 7 is not provided, the plating current I ═ Sw × Dm is obtained. When Sw is small, I is small and is easy to influence and fluctuate, so that the electroplating process is unstable; by introducing the auxiliary electrode, the total plating area S becomes Sw + Sa, so that the total plating current can be set to a current value Im that is sufficiently large to ensure stable plating, and Im becomes S × Dm, that is, (Sw + Sa) × Dm. Here, Im and Dm are set values, and since Sw is known, Sa can be calculated. Therefore, by introducing the auxiliary electrode 7, the plating area is increased, and the total plating current Im is increased, so that even if the total surface area Sw of the fine pattern of the substrate 4 to be plated contacting the plating liquid is small, the plating current can be made to reach a relatively desired value Im under the condition of the optimum plating current density Dm, and the plating process is stabilized and is not easily influenced to fluctuate. In a specific example, when the total surface area of the fine pattern of the substrate 4 to be plated is small, for example, much smaller than the total surface area of the plating pattern 7d, the magnitude of the plating current and the electric field distribution are mainly determined by the plating pattern 7 d. In this case, the total surface area of the plating patterns 7d can be adjusted so that the plating patterns 7d are symmetrically distributed around the center of the substrate 8. Thus, a uniform and symmetrical electric field distribution can be obtained, and a relatively ideal plating current Im can be realized. In addition, the total surface area of the fine pattern of the substrate 4 to be plated may be not less than the total surface area of the plating pattern 7d, and in this case, the auxiliary electrode may be used to adjust the symmetry of the electric field.

The overall shape of the auxiliary electrode 7, the shape and distribution of the plating pattern 7d will be described below with reference to fig. 3.

As shown in fig. 3, the overall shape of the auxiliary electrode 7 depends on the shape of the plated portion B of the substrate 4. When the plated portion B is circular, the overall shape of the auxiliary electrode 7 may be mainly circular, for example, a combined pattern of a circle and other images. Wherein the inner diameter D of the circular portion of the auxiliary electrode 7 is slightly larger than the diameter of the plated portion B. The auxiliary electrode 7 may have a fixing portion 7e, and the surface of the auxiliary electrode 7 may have an insulating layer 7 b. A part 7f of the fixing portion 7e exposes the conductive substance 7a inside as an electrical contact portion 7 f. If necessary, a conductive layer for reducing contact resistance may be further formed on the surface of the electrical contact portion 7 f. As shown in a) and b) of fig. 3, the plating pattern 7d of the auxiliary electrode 7 may be composed of a plurality of separate patterns. Such a configuration is suitable for a case where the total area of the plating patterns 7d to be formed is relatively small and a case where the distribution of the fine structures 13 to be formed by plating on the substrate 4 is relatively uneven. When the magnitude of the plating current and the electric field distribution are mainly determined by the plating pattern 7d, or when the distribution of the fine structure 13 is relatively uniform, the areas of the plurality of separated patterns 7d may be substantially equal, and the plurality of patterns 7d may be symmetrically distributed about the center of the substrate 4. As shown in c) of fig. 3, the plating pattern 7d of the auxiliary electrode 7 may be formed of a continuous pattern having a symmetrical shape with respect to the center of the substrate 4, and the pattern shown in c) of fig. 3 may make the total area of the plating pattern 7d large.

Further, the plating pattern 7d may not be limited to the center symmetry, and for example, the plating pattern 7d may be an axisymmetric pattern or the like. Further, the plating pattern 7d may also be asymmetrical.

The power source 11 may be a dc power source, a power source capable of providing a pulse current, or a composite power source formed by combining a plurality of power sources.

If necessary, mechanisms such as circulation of the plating liquid, stirring, temperature control, concentration control, and liquid level control may be added to the plating apparatus 1 shown in FIG. 1.

In the plating apparatus 1 shown in fig. 1, a voltage is applied between the substrate 4 as a cathode and the metal flat plate 5 as an anode by the power supply 11, so that a plating current is generated between the substrate 4 and the metal flat plate 5 by the plating liquid 3, and metal ions are continuously transported to the surface 8a of the plating seed layer 8 and deposited, thereby forming a microstructure 13 (see fig. 4) by plating.

As described above, in the present embodiment, there is provided a plating apparatus in which an auxiliary electrode is provided at the periphery of a plating region of a substrate, and by setting the distribution and area of a plating pattern of the auxiliary electrode, it is possible to adjust the electric field distribution between the substrate and an anode uniformly, and at the same time, adjust the plating current to a large value which is less susceptible to disturbance within an optimum plating current density range, thereby achieving uniform and stable plating on the substrate easily and efficiently and obtaining a uniform microstructure.

Example 2

Embodiment 2 of the present application provides a method of electroplating a substrate. In this example, the plating apparatus of example 1 was used to perform plating.

Fig. 4 is a schematic view of the plating method of the present embodiment. Similar parts in this embodiment to those in embodiment 1 will not be described in detail. For simplicity, the present embodiment will be described with reference to copper (Cu) plating as an example.

As shown in a) of fig. 4, the substrate 4 is fixed to the substrate holder 6. In one embodiment, the substrate 4 is a silicon (Si) wafer, which is 20cm in diameter.

On the plating surface of the substrate 4, a plating seed layer 8 is formed. The plating seed layer 8 is formed by stacking a Ti thin film and a Cu thin film in this order on the plating surface of the substrate 4. The thicknesses of the Ti thin film and the Cu thin film were 5nm and 100nm, respectively.

A pattern of a photoresist film 12 is formed on the surface of the plating seed layer 8. The photoresist film 12 has a plurality of openings 12a substantially uniformly distributed in the plating region B (region B in fig. 1). At the opening 12a of the photoresist film 12, the surface 8a of the plating seed layer 8 is exposed, and can contact the plating solution 3 (refer to fig. 1) to serve as a starting point of plating. In one embodiment, the total area of the exposed surfaces 8a of the plating seed layer is Sw 0.1cm ²Approximately uniformly distributed at about 250cm ²In the plating region B. Assuming that the optimum plating current density Dm is 20mA/cm ²In order to obtain high-quality and stable plating, the plating current density is set to Dm of 20mA/cm ². If the auxiliary electrode is not added, the electroplating current I is equal to Iw and is equal to Dm and Sw is equal to 2 mA. Experiments prove thatThe plating current of 2mA is distributed at about 250cm ²The plating area (B) of the substrate (A) is unstable, and the repeatability of the plating result per time is poor, and the uniformity of the plating film thickness at different positions in the plating area (B) of the same substrate is also poor. One of the main reasons for this is that when the plating current I is small, the electric field intensity E between the substrate 4 and the surface 5a (see fig. 1) of the flat metal plate 5, which is proportional to the plating current, is small, and thus disturbance easily occurs with little disturbance. Specifically, E ═ ir/d, where R and d are the resistance and distance, respectively, between the plated surface 8a of the substrate 4 and the metal flat plate 5.

In the plating, the distance d between the plating surface 8a of the substrate 4 and the surface 5a of the flat metal plate 5 is substantially fixed. A special case is that d ═ 5 cm. On the other hand, R is mainly determined by the components of the plating liquid, the state of the plating surface 8a, and the state of the surface 5a of the flat metal plate 5, and is maintained stable during plating. Therefore, R is also substantially constant in electroplating. Therefore, if the plating current I is small, the electric field intensity E at the time of plating is directly caused to be small.

In order to increase the plating current I and thereby enhance the electric field intensity E and realize stable and uniform plating, as shown in FIG. 1, an auxiliary electrode 7 is provided on the periphery of the plated portion B of the substrate 4. This auxiliary electrode 7 does not obstruct the flow of the plating liquid 3 between the plating section B and the metal plate 5 and the ions therein. Thus, the flow of the plating liquid 3 and the ions therein between the plated portion B and the flat metal plate 5 is not hindered during plating, and the electric field therebetween is not disturbed by the presence of a barrier as in the case of a barrier. On the auxiliary electrode 7, a plating pattern 7d composed of a plurality of separate patterns is provided. The shape and distribution of the plating pattern 7d are, for example, as shown in a) of fig. 3. In fig. 3 a), the plurality of separated patterns 7d have substantially the same area and are symmetrical about the center of the substrate 4. The total area of the plating patterns 7d is Sa.

Since the plating surface 8a of the substrate 4 and the plating pattern 7d of the auxiliary electrode 7 are electrically connected in parallel, the total plating current I flows into the plating surface 8aThe sum of the current Iw and the current Ia flowing into the plating pattern 7 d. I.e., I ═ Iw + Ia. That is, in holding I _wIn the same case, the overall plating current I can be increased to a desired value Im by adjusting Ia. In one embodiment, Im is 100 mA; setting Iw + Ia-Im-100 mA at I _wWhen Ia is 2mA, Ia is 98 mA. In this way, the total area Sa of the plating patterns 7d of the auxiliary electrode 7 required can be calculated from the relationship of Im ═ (Sw + Sa) × Dm. Namely, Sa is Im/Dm-Sw. Alternatively, Sa is Ia/Dm. In the above specific example, Sa is 4.9cm ². In a) of fig. 3, the plating pattern 7d is composed of 8 circular openings 7c of the same area, and the diameter of each circular opening 7c is about 0.88 cm. This is the plating pattern 7d which can be obtained by a general machining.

The plating solution 3 (see fig. 1) is an aqueous solution containing copper sulfate as a main component. An appropriate amount of sulfuric acid, hydrochloric acid, and plating additives may be added to the plating solution 3 as needed. The plating additives may include a plating accelerator, a plating inhibitor, and a leveler.

As shown in fig. 1, plating can be performed by applying a nearly constant current Im between the cathode composed of the substrate 4 and the auxiliary electrode 7 and the flat metal plate 5 so that Im becomes 100 mA. At the beginning of plating, Cu2+ ions in the plating solution are driven to the plating surface 8a in contact with the plating solution, and after getting electrons, they are reduced to Cu atoms to be deposited on the plating surface 8 a. At the same time, plating also occurs on the surface of the plating pattern 7d of the auxiliary electrode 7.

As shown in b) of fig. 4, a plating material (copper (Cu) in this embodiment) 13 is gradually deposited starting from the plating seed layer 8. After covering the exposed surface of the plating seed layer 8, the surface 13a of the plating material 13 becomes a new plating surface 8 a. This plating is continued for an appropriate time to obtain a plated material pattern 13 of a desired thickness.

Then, as shown in c) of fig. 4, the plated substrate 4 is taken out, and the photoresist 12 shown in b) of fig. 4 is removed. The removal of the photoresist 12 can be performed, for example, by a general organic solvent dissolution method.

Then, as shown in d) of fig. 4, the plating material of the seed layer 8 is removed at portions other than the pattern 13. For example, the removal process may be performed by wet etching using an appropriate etchant or by dry etching using plasma or ions of an appropriate gas. After the removal, the fine structure 13 formed by electroplating can be obtained. Such a fine structure is, for example, a micro coil and/or a micro antenna.

As for the metal plated on the plating pattern 7d of the auxiliary electrode 7, it can be removed by an appropriate method. Thus, the auxiliary electrode 7 can be reused.

As described above, with the plating method of the present embodiment, by setting the distribution and area of the plating pattern of the auxiliary electrode, it is possible to adjust the electric field distribution between the substrate and the anode uniformly, and at the same time, adjust the plating current to a large value which is less susceptible to disturbance within the optimum plating current density range, thereby achieving uniform and stable plating on the substrate simply and efficiently and obtaining a uniform fine structure.

The present application has been described in conjunction with specific embodiments, but it should be understood by those skilled in the art that these descriptions are intended to be illustrative, and not limiting. Various modifications and adaptations of the present application may occur to those skilled in the art based on the spirit and principles of the application and are within the scope of the application.

Claims

1. An electroplating apparatus for forming an electroplated structure on a substrate, comprising:

a container for holding an electroplating solution;

a substrate holder for holding a substrate to be electroplated within the vessel and having contact electrodes in electrical contact with a plating seed layer of the substrate surface;

a metal plate placed in the container in parallel with the substrate;

a power supply for supplying a current for plating to the substrate and the metal plate; and

and an auxiliary electrode positioned within the container and disposed at a periphery of a plating area of the substrate, a plating pattern of the auxiliary electrode being in equipotential electrical communication with a surface of the plating area of the substrate.

2. The plating apparatus as recited in claim 1,

the vertical distance between the electroplating pattern of the auxiliary electrode and the surface of the electroplating area of the substrate is smaller than the vertical distance between the electroplating pattern of the auxiliary electrode and the surface of the metal flat plate.

3. The plating apparatus as recited in claim 2,

the perpendicular distance between the plating pattern of the auxiliary electrode and the surface of the plating area of the substrate is less than 1/5 of the perpendicular distance between the plating pattern of the auxiliary electrode and the surface of the metal flat plate.

4. The plating apparatus as recited in claim 1,

the area of the electroplating pattern of the auxiliary electrode is larger than that of the electroplating pattern in the electroplating area of the substrate.

5. The plating apparatus as recited in claim 1,

the electroplating pattern of the auxiliary electrode is a symmetrical pattern.

6. The plating apparatus as recited in claim 5,

the electroplating pattern of the auxiliary electrode is a centrosymmetric pattern.

7. The plating apparatus as recited in claim 5,

the plating pattern of the auxiliary electrode includes:

8. An electroplating method for forming an electroplated structure on a substrate by using the electroplating device as claimed in any one of claims 1-7, comprising:

a power supply is used for supplying current for electroplating to the substrate and the metal flat plate,

wherein the plating pattern of the auxiliary electrode is in electrical contact with the plating solution and is in equipotential electrical communication with the surface of the plating region of the substrate.

9. The plating method according to claim 8,

10. The plating method according to claim 9,