JP2001207288A - Method for electrodeposition into pore and structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of electrodeposition into pores having high uniformity over a large area without being affected by the convection or potential distribution of an electrolyte. SOLUTION: In the method of electrodeposition on the electrode surface on a substrate, the method of electrodeposition into pores has a stage for mounting a porous body 11 having pores 15 on the surface of an electrode 12 on a substrate, a stage for filling an electrolyte 16 and an electrodeposition material into the pores 15, a stage for arranging a counter electrode 13 on the porous body which is closed and a stage for imparting a potential difference between the counter electrode 13 and electrode 12 to electrodeposit the electrodeposition material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a structure for electrodeposition into pores, and more particularly to an electrodeposition method and a structure for uniform electrodeposition with a controlled deposition amount.

[0002]

2. Description of the Related Art Various reports have been made on electrodeposition methods of various materials including metals. Also, a trend of modern technology is to carry out high-precision electrodeposition on finer structures over a large area.

For example, an electrodeposition technique called through-hole plating has been developed. This through-hole plating
This method is often used when manufacturing printed wiring boards. With the rapid development of semiconductor integrated circuits, this printed wiring board has been increasingly densified and multilayered. Pattern width,
The interval is small and narrow, the hole diameter and land diameter of the through hole are small, and the aspect ratio is increased by the multi-layer structure.

[0004] In a manufacturing method using this through-hole plating, it is often manufactured by a subtractive method. The process is (copper clad laminate)-Drilling-Electroless copper plating-
Panel copper plating (primary electrolytic copper)-Photoresist treatment-
Pattern copper plating (secondary electric copper) -surface plating-etching-terminal plating-finish.

[0005] Various methods of electrodepositing the through-hole have also been reported. For example, Japanese Patent Application Laid-Open No. 10-5626
No. 1 publication. In addition, various methods have been reported for electrodepositing a metal in pores prepared in advance. As an example, “J. Electrochem. So
c. Vol. 144, No. 6, page l923 (19)
June 1997).

[0006] Also, various devices have been devised as an electrodeposition method. An example is pulse electrodeposition. The feature of this electrodeposition method is that the change in the concentration of the electrolyte at the cathode interface is smaller than that of the DC method, so that the effect of the composition of the precipitate approaching the electrolyte is expected as compared with the electrodeposition of the DC method. . The feature of electrodeposition obtained by this method is that nucleation is high density and particles are fine. The structural features of pulsed electrodeposition coatings with fine particles and low defect density are:
To increase the tensile strength, elongation, and density of an electrodeposited film, to improve hardness and abrasion resistance, and to reduce its effectiveness.

[0007] Also, there have been reported many methods for performing electrodeposition while applying ultrasonic waves and vibration. As an example thereof, JP-A-5-59594 is cited. In various forms,
It has been developed in various fields for electrodeposition in pores. Applications include microarray electrodes, printed circuit boards, GMR,
Many examples include an electron source and various masks. With further improvement in properties, applications in various fields are also expected.

[0008]

Regarding the electrodeposition method and the electrodeposition technique in the previously extended pores, most of the two-electrode or three-electrode electrodes are immersed in a solution in a plating bath. This is a method in which a desired substance is electrodeposited on the bottom of a pore or the like by applying an electric potential. When such a method is used, at present, the means for controlling the amount of electrodeposition is to calculate from the amount of coulomb or to control by time.

[0009] Further, when performing electrodeposition in the pores, the potential distribution is an important point. The applied voltage has a great effect not only on the amount of electrodeposition in the steady state but also on nucleation, and the amount of electrodeposition on the edge portion where the potential is concentrated generally tends to increase. In order to achieve a uniform potential distribution, a method of installing a frame around the electrodeposit has been developed, but it is very difficult to produce a sufficiently uniform state.

[0010] Diffusion in a solution also plays a significant role. Usually, when performing electrodeposition, vibration application by ultrasonic waves,
It is necessary to uniformly generate convection such as stirring by a stirrer and vibration of the electrodeposited substrate in and around the solution.
However, it is difficult to control this convection, and there is a problem in that the amount of electrodeposition is different.

An object of the present invention is to provide a method for electrodeposition into pores having high uniformity over a large area without being affected by convection and potential distribution of an electrolytic solution. It is another object of the present invention to provide an electrodeposition method having excellent controllability of an extremely minute amount of electrodeposition into a pore or lamination electrodeposition. Another object of the present invention is to provide an electrodeposition method that uses a small amount of electrolyte solution, is easy to manage the electrolyte solution, and can reduce the cost. Another object of the present invention is to provide an electrodeposition method capable of easily electrodepositing desired pores.
Further, it is another object of the present invention to provide a nanostructure having an electrodeposition part manufactured by applying these electrodeposition techniques.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned technical requirements, and one of its objects is to solve these problems. In the electrodeposition method, a step of providing a pore body having pores on the surface of the electrode on the substrate, a step of filling the pores with an electrolytic solution and an electrodeposition material, and sealing an opposing electrode on the pore body. Providing a method for electrodeposition into pores, comprising a step of disposing, and a step of electrodepositing an electrodeposition material by applying a potential difference between the counter electrode and the electrode on the substrate via an electrolytic solution. It is.

Here, the electrodeposition material can be supplied by a solid in contact with the counter electrode or by a solute in the electrolytic solution. Further, the present invention is particularly effective in the case of a structure having a diameter of the pores of 1000 μm or less, and an example thereof is that the pores are anodized alumina nanoholes. When a larger amount of electrodeposition is required or when it is desired to sequentially deposit different materials, it is effective to have a step of replacing the electrolytic solution or the electrodeposition material.

When electrodeposition is performed on a specific area, it is effective to supply the electrolytic solution or the electrodeposition material only to the specific area in the pores. This can be performed by a droplet discharging method. As another method of electrodepositing a specific region, there is a method in which the counter electrode is patterned on a conductive portion and an insulating portion.

Further, there is a structure produced by the electrodeposition method according to the present invention.

That is, a metal,
By embedding a functional material such as a semiconductor, there is a possibility that it can be applied to a new electronic device. The structural porous body of the present invention includes a quantum wire, an MIM element, a molecular sensor, coloring,
Application in various forms including magnetic recording media, EL elements, electrochromic elements, optical elements such as photonic bands, electron-emitting devices, solar cells, gas sensors, abrasion-resistant and insulating films, filters This greatly expands its application range.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The method for electrodeposition into pores according to the present invention comprises:
In the method of electrodeposition on the electrode surface on the substrate, a pore body is provided on the electrode surface on the substrate, an electrolytic solution and an electrodeposition material are arranged in the pores of the pore body, and the counter electrode and the electrode on the substrate are finely arranged. It is characterized in that it is arranged in a closed manner with a hole interposed therebetween, and electrodeposition is performed by applying a potential difference between the electrode on the substrate and the counter electrode via an electrolytic solution.

Next, the concept and specific method of the present invention will be described below with reference to FIGS. 1, 2 and 10. Here, FIG. 1 is a cross-sectional view showing one embodiment of the process of the method for electrodeposition into pores of the present invention, and FIG. 2 is a plan view taken along the line AA ′ in FIG. FIGS. 1 (a) to 1 (c) show B in FIG.
2 (a) to 2 (c) are cross-sectional views taken along the line B ', and FIGS. FIG. 10 is a schematic view showing a conventional electrodeposition method.

(A) Step before electrodeposition First, as shown in FIGS. 1 (a) and 2 (a), a pore body 11 having pores 15 on a substrate 15 on which a working electrode 12 is provided.
Is installed. The porous body 11 may be a material on a film separate from the substrate, or may be a structure formed on the substrate. Here, it is desirable that the surface of the porous body 11 be flat enough to be sealed with the counter electrode.

(B) Electrodeposition Step I Next, as shown in FIGS. 1B and 2B, a plating solution or an electrolytic solution 16 is injected into the pores. At this time, when the electrodeposition material is dissolved in the electrolytic solution, the plating solution is supplied, and when the electrodepositing material is supplied as a solid, the electrolytic solution is injected. Thereafter, the counter electrode 13 is hermetically arranged on the porous body 11.

Here, the electrolytic solution refers to a solution in which a solute such as a supporting electrolyte is present to cause an electrochemical reaction and electricity is flowing, and a plating solution is a solution to the solute in the electrolytic solution. Means a solution containing what is to be deposited.

FIG. 5 shows an example of a method for supplying raw materials in detail. FIG. 5A shows a case where the raw material is supplied as a solution, and a general plating solution can be used. However, it is preferable to use a plating solution that does not react with the material of the pores. In this case, the amount of electrodeposition can be controlled by the concentration and amount of the plating solution injected into the pores. This is made possible in the present invention by using the electrodeposition raw material in the plating solution. In other words, uniform electrodeposition can be performed almost independently of the potential distribution, electrodeposition time, and applied voltage. Of course, the applied voltage needs to be a potential at which the electrodeposition material is deposited.

FIGS. 5 (b) and 5 (c) show a method of supplying a solid. In FIG. 5B, the solid raw material 34 is provided on the counter electrode 31, and in FIG. 5C, the solid raw material 36 is provided on the pore body in contact with the counter electrode 31. Since it is necessary to apply the potential of the counter electrode as this solid raw material, a certain degree of electrical conductivity is required. In this electrodeposition process, the generation of bubbles in the pores may interfere with the electrodeposition process, so that application of ultrasonic waves or addition of a surfactant to the electrolyte is also an effective means.

As shown in FIG. 10, which is a conventional example, a substrate (working electrode) 81 which is an object to be deposited on a plating solution 83 in a solution,
In the method of immersing the counter electrode 82, the convection is inevitable, so that the electrodeposition amount can be easily distributed. In addition, a non-uniform potential distribution is formed between the counter electrode and the electrode on the substrate due to the presence of the edge portion, which has a large effect on the amount of electrodeposition.

(C) Electrodeposition step II When electrodeposition is performed in the state of the above-mentioned electrodeposition step I (B), the electrodeposition raw material is electrodeposited on the electrode, and FIG. 1 (c) and FIG. As a result, a structure on which the electrodeposit 14 is formed is obtained. Of course, it is also possible to remove the pores after electrodeposition before use.

By repeating the above electrodeposition steps I (B) and II (C) several times while changing the electrolyte, FIG.
A laminated film as shown in (b) can be obtained. Especially G
When a film having a thickness of about 1 nm is laminated like an MR film, control of the amount of electrodeposition is an important factor, and the present invention is effective. Further, since a very small amount of electrodeposition can be performed according to the present invention, ultrafine particles of several nanometers can be produced if the nucleation generating portion of the electrodeposition is limited as shown in FIG.

In the present invention, the pores are not limited to the straight and uniform diameters described above, but may be electrodeposited on the pores 17a having different diameters as shown in FIG. The present invention can also be used for the fine pores 17b whose diameter changes as shown in FIG. 9 (b), and the fine pores 17c where the fine pores are not linear as shown in FIG. 9 (c).

In order to pattern the electrodeposition into the pores, a method of injecting an electrolytic solution or a plating solution 51 into a specific region as shown in FIG. 7A or a method shown in FIG. As described above, there is a method of patterning the counter electrode 52 into an electrode portion and an insulating portion.

In addition to the arrangement of the pores and the electrodes on the substrate, as shown in FIG. 1A and FIG. 6A, for example, as shown in FIG. And a configuration in which the pores are insulated from the electrode on the substrate, the counter electrode, and the insulating layer. As another example, as shown in FIG. 6C, a configuration having an electrode portion inside a fine hole is also possible.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 In this example, an example in which anodized alumina nanoholes were formed using Pt as a base layer and Co was electrodeposited in the pores will be described with reference to the steps shown in FIGS. . Ti and P having a thickness of 100 nm on a quartz substrate by RF sputtering
After the formation of t, an Al film having a thickness of 500 nm was formed.
At this time, the gas was Ar, the gas pressure was 30 mTorr, and the RF was
The power was 300 W.

The above was subjected to anodizing treatment using an anodizing apparatus. A 0.3 mol / l (0.3 M) aqueous solution of oxalic acid was used as the electrolytic solution, and the electrolyte was placed in a constant-temperature water bath to remove
C. was maintained. Here, the anodic oxidation voltage was DC 40 V, and the current value was displayed on a monitor, and it was confirmed that the current penetrated into the underlayer when the current value became small.

After the anodic oxidation treatment, cleaning with pure and isopropyl alcohol was performed. Thereafter, by performing a pore widening process of dipping in a 5 wt% phosphoric acid solution for 40 minutes,
By expanding the diameter of the nanohole, a nanostructure shown in FIG. 3A was produced.

A plating solution 23 of 1 mol / l (1 M) of cobalt sulfate was dropped into the nanoholes 27 of the nanostructure (alumina) 21 (FIG. 3B), and the upper part of the nanoholes was sealed with a counter electrode 24 (FIG. 3B). FIG. 3 (c)). Then, the on-substrate electrode 22 is set to −2 V with respect to the counter electrode 24 to 10
Electrodeposition was performed for 2 seconds (FIG. 4D). And the counter electrode 2
4 was peeled off (FIG. 4 (e)), and after washing, alumina was dissolved with an acid to produce the nanostructure shown in FIG. (FIG. 4F) The nanostructure produced by the above method was observed by FE-SEM. It was confirmed that Cos regularly arranged in a honeycomb shape were uniformly formed over the entire surface of the substrate.

Example 2 In this example, anodized alumina nanoholes were produced in the same manner as in Example 1. However, the underlying layer was made of n-Si, and the anodic oxidation was terminated when the anodic oxidation became smaller. Then, in the same manner as in Example 1, the pore widening treatment was performed using phosphoric acid at 20 ° C. for 40 minutes.

On the above sample, Cu was deposited by oblique incidence resistance heating evaporation of about 50 nm to form a nanostructure shown in FIG. 5C. And 1m of sulfuric acid in the nanohole
ol / l (1M) of the electrolytic solution was dropped, and the upper portion of the nanohole was sealed with a counter electrode. Then, the electrode on the substrate was set to -2 V with respect to the counter electrode, and electrodeposition was performed for 10 seconds.

The nanostructure produced by the above method was converted to FE-
Observed by SEM. It was confirmed that Cu arranged regularly in a honeycomb shape was uniformly formed over the entire surface of the substrate.

Example 3 In this example, the results of forming regular pores by a semiconductor process using SiO ₂ as pores and electrodepositing Co in the pores will be described.

The surface-oxidized Si substrate on which the oxide layer was formed to a thickness of about 500 nm was washed with acetone and IPA, dried, and then spin-coated to form a resist film (200 nm thick).
m) was applied and dried (90 ° C., 20 minutes).

Next, using a stepper exposure apparatus, a concave / convex pattern made of a resist having a honeycomb-shaped periodic structure (interval of 230 nm) was prepared. 1: 1 developer in pure water
And developed for about 30 seconds to form a honeycomb-shaped regular uneven pattern penetrating to the SiO ₂ surface. Then, the sample was dry-etched using CF ₄ gas, and penetrated to the Si substrate. Dry etching conditions are 150 W, 5 Pa, and 2 minutes.

A plating solution of 1 mol / l (1M) of cobalt sulfate was injected into the above-mentioned sample only at a predetermined position by using a droplet discharging method to produce a nanostructure shown in FIG. . Then, the upper portion of the nanohole was densely opened with a counter electrode, and the electrode on the substrate was set to −2 V with respect to the counter electrode, and electrodeposition was performed for 10 seconds.

The nanostructure produced by the above method was converted to FE-
Observed by SEM. It was confirmed that the regularly electrodeposited Co was uniformly formed in the region 51.

Embodiment 4 In this embodiment, an SiO ₂ substrate is used as a base layer,
An example in which regular pores are formed by FIB (focused ion beam) and Co is electrodeposited in the pores will be described.

The SiO ₂ substrate was washed with acetone and IPA and dried. Then, a laminated film was formed by successively sputtering 100 nm of Ti and 500 nm of SiO ₂ . Then, the workpiece is irradiated with a focused ion beam using a focused ion beam processing apparatus, and the surface SiO ₂ layer is etched and T
i was penetrated to the underlayer. The ion type of the focused ion beam processing apparatus is Ga, and the acceleration voltage is 30 kV. Then, a structure as shown in FIG. 9B was manufactured.

To the above sample, 1 mol / l of cobalt sulfate was added.
The plating solution of (1M) was dropped. Then, the upper portion of the nanohole was sealed with the counter electrode of FIG. 7B in which Pt52 was deposited and patterned on the insulator, and the electrode on the substrate was set to −2 V with respect to the counter electrode, and electrodeposition was performed for 10 seconds. .

The nanostructure produced by the above-described method was
Observed by SEM. It was confirmed that the regularly electrodeposited Co was uniformly formed only in the region where the Pt electrode was present on the surface.

Example 5 In this example, anodized alumina nanoholes were produced in the same manner as in Example 1. However, the substrate was a quartz substrate, and Ti and Cu were sequentially formed on the substrate by sputtering to a thickness of 10 nm and anodized. Anodizing is oxalic acid 0.3mol / l
(0.3 M), DC 40 V, bath temperature 10 ° C., and ended when the anodic oxidation current became small. And Example 1
In the same manner as in the above, bore widening treatment was performed at 20 ° C. for 40 minutes with phosphoric acid.

To the above sample, cobalt sulfate 1 mol / l
The plating solution of (1M) was dropped, and the upper portion of the nanohole was sealed with a counter electrode. And the electrode on the substrate is-
Electrodeposition was performed at 2 V for 10 seconds. After removing the counter electrode and cleaning the substrate, copper sulfate 1 mol / l (1
The plating solution composed of M) was dropped, and the upper portion of the nanohole was sealed with a counter electrode. Then, the electrode on the substrate was set to -2 V with respect to the counter electrode, and electrodeposition was performed for 10 seconds. This work 1
After repeating 0 times, Cu was finally electrodeposited to the upper portion of the nanohole to produce a nanostructure shown in FIG. 8B.

Observation of the cross section of this sample showed that Co and C
u were each laminated with a thickness of about 1 nm. Then, an electrode was attached to the upper part of the nanostructure of this example, and the magnetic field dependency of the resistance between the underlying substrate electrode and the upper electrode was examined.
It showed a negative magnetoresistance change. From the above, the present invention provides G
It turns out that it can be used as an MR magnetic sensor.

[0050]

As described above, the present invention has the following effects. (1) The electrodeposition method of the present invention enables electrodeposition with high uniformity over a large area easily without being affected by convection and potential distribution of the electrolytic solution. (2) According to the electrodeposition method of the present invention, the electrodeposition amount can be controlled by the initial supply amount of the electrodeposition material into the pores. The controllability of electrodeposition is facilitated. (3) In the electrodeposition method of the present invention, since a required amount of the electrolytic solution may be supplied to the inside of the pores, the amount of the electrolytic solution used is small, and the cost of the electrolytic solution can be easily controlled and the cost can be reduced. (4) In the method of forming an electrodeposition structure according to the present invention, a desired electrolytic solution is injected into each pore, or the counter electrode is patterned to easily electrodeposit the desired pore. it can. The present invention can be widely applied to electrodeposition using pores, and the electrodeposition structure produced by this method has a wide range of application.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the steps of the method for electrodeposition into pores according to the present invention.

FIG. 2 is a plan view taken along the line AA ′ of FIG. 1;

FIG. 3 is a plan view showing the first half of another embodiment of the steps of the method for electrodeposition into pores according to the present invention.

FIG. 4 is a plan view showing the latter half of another embodiment of the process of the method for electrodeposition into pores of the present invention.

FIG. 5 is a cross-sectional view illustrating a method for supplying a solid raw material according to the present invention.

FIG. 6 is a sectional view showing an electrode configuration according to the present invention.

FIG. 7 is a plan view showing a patterning electrodeposition method of the present invention.

FIG. 8 is a sectional view showing an electrodeposited state in the present invention.

FIG. 9 is a cross-sectional view showing pores according to the present invention.

FIG. 10 is a schematic view showing a conventional electrodeposition method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Porous body 12 Working electrode 13 Counter electrode 14 Electrodeposit 15 Pores 16 Electrolyte 21 Alumina 22 Electrode 23 Co plating solution 24 Counter electrode 25 Electrolyte 26 Co 27 Nanohole 31 Counter electrode 32 On-substrate electrode 33 Plating solution 34 Counter electrode Solid raw material on top 35 Electrolyte solution 36 Solid raw material on pores; Cu 37 Electrode on substrate; n-Si 38 Porous body 41 Electrode 42 Insulating layer 43 Conductive material 44 Insulating material 51 Co plating solution 52 On insulating material Pt counter electrode 61: alumina 62 Co 63 Cu / Ti / quartz substrate 64 Cu 65 nucleus generator 71 a, 71 b, 71 c pore 81 working electrode 82 counter electrode 83 plating solution

Continued on the front page F term (reference) 4K024 AA03 AB02 AB08 BA06 BA09 BB09 BC02 CA01 CB01 CB08 CB11 DA02 DA04 DA10 DB05 GA01 5E317 AA24 BB04 CC25 CC31 GG16

Claims (11)

[Claims] 1. A method for electrodeposition on an electrode surface on a substrate, comprising:
Providing a pore body having pores on the electrode surface on the substrate,
A step of filling the pores with an electrolytic solution and an electrodeposition material, a step of sealingly arranging a counter electrode on the pore body, and applying a potential difference between the counter electrode and the electrode on the substrate via an electrolytic solution. A method for electrodepositing pores, comprising the step of electrodepositing an electrodeposition material. 2. The electrodeposition method according to claim 1, wherein the electrodeposition material is a solid. 3. The electrodeposition method according to claim 1, wherein the electrodeposition material is a solute in an electrolytic solution. 4. The electrodeposition method according to claim 1, wherein the diameter of the fine pore is 1000 μm or less. 5. The electrodeposition method according to claim 4, wherein said pores are anodized alumina nanoholes. 6. The electrodeposition method according to claim 1, further comprising a step of replacing the electrolytic solution or the electrodeposition material and performing electrodeposition. 7. The method according to claim 6, further comprising the step of replacing said at least two kinds of electrolytes or said electrodeposition material and performing electrodeposition.
Electrodeposition method described in 1. 8. The electrodeposition method according to claim 1, wherein the electrolytic solution or the electrodeposition material is supplied only to a specific region in the pore. 9. The electrodeposition method according to claim 8, wherein the electrolyte is injected by a droplet discharging method. 10. The electrodeposition method according to claim 1, wherein the counter electrode is patterned on a conductive portion and an insulating portion. 11. A structure produced by the electrodeposition method according to claim 1.