JPH08199389A - Electroplating and fine pattern formation - Google Patents

Abstract

PURPOSE: To prevent the contamination of an electrolyte or the breaking of a resist pattern by using the main components common both to a base conductive layer and an electroplated film, and using the other components common both to an electropolishing solution and an electroplating solution, at the time of forming a fine pattern by electroplating method. CONSTITUTION: The base conductive layer 2 composed of Ni, a resist layer 4 and an SiO2 film as an intermediate layer 5 are formed on an Si wafer as a substrate 1 and finally an upper resist layer 6 is formed. The upper resist layer 6 is exposed, developed and baked to form the resist pattern 6a, the pattern is transferred to the intermediate layer 5 by using the resist pattern 6a as a mask by dry etching method and, after that, the pattern is transferred to the under resist layer 4 by using the intermediate layer 5a as a mask by dry etching method using gaseous O2 to form an under layer resist pattern 4a. Next, a plasma electrode is connected to the base conductive layer 2 to electropolish and, after an electroplated layer 3 is deposited by using the under layer resist pattern 4a as a mask, the upper resist pattern 6a is stripped and further the intermediate layer pattern 5a and the under layer resist pattern 4a are removed by dry etching method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic plating method and a fine pattern forming method using electrolytic plating.

[0002]

2. Description of the Related Art At present, as a fine processing technique, a dry process such as an ion milling method or an RIE (reactive ion etching) method performed in a vacuum is mainly used. However, in recent years, the electrolytic plating technique has been applied to the production of microfabrication patterns such as micromachines, LSI patterns, X-ray mask patterns, and zone plates. Since the electroplating method is generally performed under atmospheric pressure, a vacuum system is not required, and a microfabrication pattern can be produced at a lower cost than a dry process.

Recently, the manufacturing process has been improved so that a finer pattern and a pattern with a high aspect ratio can be formed by using such an electrolytic plating method. For example, a method disclosed in Japanese Patent Application No. 6-216133 is disclosed as a method for forming a fine pattern.

3 to 4 are process diagrams showing the steps of the above method. First, the base conductive layer 22 is formed on the substrate 21 (FIG. 3A), and then the lower resist layer 24 and the intermediate layer 2 are formed.
5, each layer is formed in order of the upper resist layer 26 (FIG. 3).
(B)). Next, after a resist pattern 26a having a desired pattern is formed by exposure and development (FIG. 3C), the intermediate layer 25 is patterned by the dry etching method using this resist pattern 26a as a mask (FIG. 3).
(D)). Further, etching is performed to pattern the lower resist layer 24, which is the state shown in FIG. After this, the underlying conductive layer 2 partially exposed
An electrolytic plating film is attached to the exposed portion 22a of 2 (see FIG. 4).
(B)) Further, by removing the resist, a desired fine pattern is formed (FIG. 4 (c)).

However, there are the following problems in performing electrolytic plating on the exposed portion of the underlying conductive layer. First, the dry etching used when patterning the intermediate layer 25 and the lower resist layer changes the exposed portion 22a of the surface of the underlying conductive layer, which makes electrolytic plating difficult. This is because the dry etching method uses a highly reactive gas such as oxygen, and the exposed portion 22a of the exposed underlying conductive layer surface is damaged. For example, if the surface of the underlying conductive layer is oxidized to lose its conductivity, electrolytic plating cannot be deposited.

Even when a manufacturing process which does not use the dry etching method is selected, or when the surface of the underlying conductive layer is not damaged by the dry etching, the resist residue adheres to the surface of the conductive layer, which is excellent. The plating film may not be obtained. Even after a process such as wet development or dry etching, unnecessary resist may not be completely removed and may remain, which may cause defects such as disconnection.

By the way, in general, a process by electrolytic polishing is performed as a pre-process of electrolytic plating. Electrolytic polishing is a step of modifying the surface to be plated by treating the object to be plated in a mixed solution (electrolytic polishing solution) containing sulfuric acid, phosphoric acid, chromic acid, etc. as the main components. By electrolytic polishing, the deteriorated layer and the resist residue are removed, and at the same time, the plated surface is flattened.

[0008]

However, there are the following problems in the conventional electrolytic plating method in which electrolytic polishing is performed using electrolytic polishing liquid and then electrolytic plating is performed.
First, it is difficult to completely remove the electrolytic polishing solution before electrolytic plating, and there is a problem that the remaining electrolytic polishing solution is carried into the electrolytic plating solution and contaminates the electrolytic plating solution. Further, when a conventional electropolishing liquid is used in the above-described fine pattern forming method, there is a problem that the resist pattern is destroyed by electropolishing because the resist has low resistance to the electropolishing liquid.

An object of the present invention is to provide an electrolytic plating method which does not contaminate the electrolytic plating solution even when the remaining electrolytic polishing solution is mixed in the electrolytic plating solution. Another object of the present invention is to provide a method for producing a fine pattern that does not destroy the resist pattern and does not contaminate the electrolytic plating solution even when the remaining electrolytic polishing solution is mixed into the electrolytic plating solution.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIGS. 1 and 2 showing an embodiment.
Applied to an electrolytic polishing solution and a step of forming an electrolytic plating film 3 on the upper layer of the underlying conductive layer 2 with an electrolytic plating solution. Then, the above-mentioned object is achieved by making the main component of the underlying conductive layer 2 and the main component of the electrolytic plating film 3 the same, and the electrolytic polishing liquid and the electrolytic plating liquid the same. In addition, the present invention provides a resist pattern (4a,
5a, 6a) and the resist pattern (4
a, 5a, 6a), the step of treating the surface of the underlying conductive layer 2 exposed by the electrolytic polishing solution, and the step of forming the electrolytic plating film 3 on the electrolytically polished underlying conductive layer 2 by the electrolytic plating solution. It is applied to a fine pattern forming method including and. The above-mentioned object is achieved by making the main component of the underlying conductive layer 2 and the main component of the electrolytic plating film 3 the same, and the electrolytic polishing liquid and the electrolytic plating liquid being the same component.

[0011]

Since the main component of the underlying conductive layer 2 is the same as the main component of the electrolytic plating liquid film, and a mixed solution of the same components as the electrolytic plating liquid is used as the electrolytic polishing liquid, it dissolves in the electrolytic polishing liquid during the electrolytic polishing treatment. The components of the underlying conductive layer 2 to be ejected are the same as the main components of the electrolytic plating film 3, and the electrolytic polishing liquid does not contain an impurity component contaminating the electrolytic plating liquid. Therefore, even if the electrolytic polishing liquid remains during electrolytic plating, there is no risk of contaminating the electrolytic plating liquid. In addition, the resist pattern (4
a), 5a, 6a)
Since the above electrolytic polishing liquid is used, there is no risk of contaminating the electrolytic plating liquid, and if a resist material that withstands the electrolytic plating liquid is used, there is no risk of destroying the resist patterns (4a, 5a, 6a).

In the means and means for solving the above problems which explain the constitution of the present invention, the drawings of the embodiments are used for easy understanding of the present invention. However, the present invention is not limited to this.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 (a)-(d) and FIG.
(A)-(d) is a board | substrate sectional drawing which shows the process of a present Example.

First, a 12 nm thick nickel film was formed as a base conductive layer 2 on a 200 mm square silicon wafer 1 by magnetron sputtering (FIG. 1A). Subsequently, a diazonaphthoquinone-novolak resin-based resist (trade name: AZ-1350, manufactured by Hoechst) is spin-coated on the underlying conductive layer 2 and then baked to form a lower resist layer 4 having a thickness of 0.3 μm. did. As the intermediate layer 5, a 50 nm-thick silicon oxide film was formed thereon by a sputtering method. Finally, PMMA positive resist (trade name: OEBR-1000, manufactured by Tokyo Ohka)
Spin coat and then bake to 0.2μ
An upper resist layer 6 having a thickness of m was formed (FIG. 1 (b)).

In FIG. 1C, the above-mentioned upper resist layer 6 is exposed by an electron beam drawing method, and then developed and baked,
It shows a state in which a resist pattern 6a having a line & space of 0.1 to 1 μm is formed. Next, using the resist pattern 6a as a mask, a line & space pattern of 0.1 to 1 μm was transferred to the intermediate layer 5 by a dry etching method using CHF ₃ gas (FIG. 1 (d)). Further, using the patterned intermediate layer 5a as a mask,
A similar pattern was transferred to the lower resist layer 4 by a dry etching method using O ₂ gas to form a lower resist pattern 4a (FIG. 2 (a)). In the portion where the lower layer resist is removed by the dry etching method, the underlying conductive layer is exposed and the altered portion 2a is generated in the surface region thereof. Further, the resist residue 7 is attached to the surface of the conductive layer.

Next, 450 g of nickel sulfamate /
1, boric acid 30 g / l, sodium lauryl sulfate 0.5
Electrolytic polishing was performed using a mixed aqueous solution of g / l as an electrolytic polishing liquid. A positive electrode was connected to the underlying conductive layer 2 and subjected to electrolytic polishing conditions of 0.5 to ² mA / cm ² , ph ³ to 4, and a temperature of 50 ° C. for several to several tens of seconds. As a result, the altered portion 2a of the underlying conductive layer 2 and the resist residue 7 were removed. By electropolishing, the underlying conductive layer 2 is about 2n
The thickness of the underlying conductive layer 2 before polishing (12n
m) and the pattern line width were sufficiently small. Therefore, there was no portion under the underlying conductive layer 2 where the silicon wafer was exposed. In addition, the resist patterns (4a, 5
a, 6a) was not peeled off or damaged (FIG. 2 (b)).

FIG. 2C shows a state in which the electrolytic plating film 3 is deposited on the underlying conductive layer using the lower layer resist pattern 4a as a stencil mask. As the electrolytic plating solution, a mixed solution having the same composition as the above electrolytic polishing solution was used, and a negative electrode was connected to the underlying conductive layer. 1-4
Electrolytic plating was performed under the conditions of mA / cm ² , pH ³ to 4, and temperature of 50 ° C. As a result, electrolytic nickel having a thickness of about 0.2 μm was deposited.

Next, the substrate was washed with pure water and dried, and then the upper resist pattern 6a was peeled off using acetone. Further, the intermediate layer pattern 5a and the lower resist layer pattern 4a were removed by a dry etching method to obtain a nickel film having a predetermined pattern (FIG. 2 (d)).

The nickel film produced as described above has good film quality and good film thickness reproducibility. This is the electrolytic plating film 3
This is because the main component and the material of the underlying conductive layer 2 are the same metal (nickel), and the electrolytic polishing liquid and the electrolytic plating liquid are the same component. That is, by the former, the metal ions eluted in the electrolytic polishing solution in the electrolytic polishing step and the metal ions contained in the electrolytic plating solution become the same. Therefore,
This is because even if the electrolytic polishing solution is mixed in the electrolytic plating solution in the electrolytic plating step, both solutions do not contaminate the electrolytic plating solution because they have the same components.

Although the case of using a multilayer resist pattern has been described in the present embodiment, the method for producing the resist pattern is not limited to this. Further, although the case of nickel plating has been described in the present embodiment, it can be applied to all other metals that can be deposited by electrolytic plating. When another metal is used, the optimum electropolishing conditions and electroplating conditions for the metal can be freely selected, and the type of metal is not particularly limited.
Furthermore, the present invention can be applied to the case of performing electroless plating instead of electrolytic plating.

[0021]

As described above, according to the present invention,
Since the electrolytic plating solution component and the electrolytic polishing solution component are the same and the main component of the underlying conductive layer and the electrolytic plating film are the same, even if the electrolytic polishing liquid remains, the electrolytic plating liquid is contaminated. Never. Further, in the case of producing a fine pattern, if only the resistance to the electrolytic plating solution composition is taken into consideration when selecting the resist material, the resist pattern is not destroyed by the electrolytic polishing treatment.

[Brief description of drawings]

FIG. 1 is a process drawing showing the method for producing a fine pattern of the present embodiment.

FIG. 2 is a process drawing showing a process that follows FIG.

FIG. 3 is a process drawing showing a conventional fine pattern manufacturing method.

FIG. 4 is a process drawing showing a process that follows FIG.

[Explanation of symbols]

 2 Underlayer conductive layer 3 Electroplating film

Claims (4)

[Claims] 1. An electrolytic plating method comprising: a step of treating an underlying conductive layer with an electrolytic polishing solution; and a step of forming an electrolytic plating film on the underlying conductive layer with an electrolytic plating solution, the main component of the underlying conductive layer. And the main component of the electrolytic plating film is the same, and the electrolytic polishing liquid and the electrolytic plating liquid are the same component. 2. The main component of the underlying conductive layer and the main component of the electrolytic plating film are nickel, and the electrolytic polishing liquid and the plating liquid contain nickel sulfamate. Item 1 is an electrolytic plating method. 3. A step of forming a resist pattern on the underlying conductive layer, a step of treating the surface of the underlying conductive layer exposed in the gaps of the resist pattern with an electrolytic polishing liquid, and the electrolytically polished underlying conductive layer. In the method for producing a fine pattern, which comprises a step of forming an electrolytic plating film on the above with an electrolytic plating liquid, the main component of the underlying conductive layer and the main component of the electrolytic plating film are the same, and the electrolytic polishing liquid. And a method for producing a fine pattern, wherein the electrolytic plating solution and the electrolytic plating solution have the same components. 4. The main component of the underlying conductive layer and the main component of the electrolytic plating film are nickel, and the electrolytic polishing liquid and the plating liquid contain nickel sulfamate. Item 3. A method for producing a fine pattern according to item 3.