JP2001284288A - Fine structure and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fill a recessed part on a base material having recess and projection by forming a thin film in a recessed part only. SOLUTION: The fine structure has base materials (10, 12) with recess and projection, an extremely thin film pattern (18) consisting of organic compound with amino group or thiol group on a recessed part of the base material, and a layer pattern (20) based on the extremely thin film pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstructure and a method of manufacturing the same, and more particularly, to a method of burying and flattening concave portions of a substrate having irregularities.

[0002]

2. Description of the Related Art In recent years, the miniaturization of electronic devices such as semiconductors has been remarkably advanced, and the minimum pattern width has become smaller than 0.1 μm. Photolithography is an indispensable technology in pattern formation,
Patterning on the order of microns has become very restrictive. One of them is the flatness of an object to be processed. When exposing at a high resolution using an exposure device such as a stepper, the depth of focus of the optical system is reduced. Therefore, it is necessary to expose the processing target after making it flat. On the other hand, in forming a semiconductor element, a step on the order of microns is generated in each process. Therefore, it is necessary to perform a planarization process before performing exposure or the like to satisfy a desired shape.

[0003]

The metal wiring used in the semiconductor device includes a wiring for connecting elements in a layer and a wiring for connecting layers. In each case,
First, after forming a bank-shaped pattern using a resist or insulator, a metal film is formed so as to cover the whole, and then unnecessary portions are removed by a technique such as CMP to form a desired wiring pattern. Was.

[0004] As a method of forming a metal film, a sputtering method, a CVD method, or the like is used. However, it is difficult to selectively form a metal film only on the inside of a bank by any of the methods. Since a film is formed, it is necessary to remove an unnecessary metal film by some means. However, it is necessary to perform a process such as CMP in order to remove a part of the thin film such as a metal once formed as described above. An extra process of forming a thin film to an unnecessary area and removing an unnecessary part after that was required. This is because the technique for selectively growing a thin film is not sufficiently established. If a thin film can be formed only in a concave portion in a region where the concave and convex portions are formed, the concave portion can be buried and flattening can be easily realized. Therefore, in order to perform planarization, a thin film may be selectively grown only in the concave portion.

The present invention has been made in view of the above problems, and an object thereof is to provide a fine structure having a flat surface by forming a thin film also in a concave portion of a substrate having irregularities. It is to be.

[0006]

SUMMARY OF THE INVENTION The present invention provides a structure in which a plating film is formed only on a concave region formed on a substrate, and as a result, the concave region is filled with a metal film. It is to be. Another object of the present invention is to provide a structure in which a polymer film is formed only on a concave region formed on a base material and the concave region is filled with the polymer film. Since the plating film or the polymer film is formed only in the concave region, planarization is realized immediately after the film formation, and an unnecessary thin film removing process can be omitted.

In connection with selective thin film formation, the present inventor has proposed a method for manufacturing a fine structure in Japanese Patent Application No. 11-94102. In this method, an ultrathin molecular layer is patterned on a base material, and thereafter, a plating film is selectively grown according to the patterning shape. This makes it possible to form a high-definition plated film structure on the substrate.

Further, in connection with forming a selective thin film,
The present inventor has also proposed a method for producing a polymer microstructure in Japanese Patent Application No. 11-262664. In this method, an ultrathin molecular layer is patterned on a base material, and thereafter, an electrolyte polymer film is selectively grown according to the patterning shape. This makes it possible to form a high-definition polymer film structure on the substrate.

Hereinafter, the contents of the present invention will be specifically described.

According to the present invention, there are provided a substrate having irregularities, an ultra-thin pattern composed of an organic compound having an amino group or a thiol group on the concave portion of the substrate, and a layer pattern based on the ultra-thin pattern. A microstructure is provided.

Here, the "layer pattern based on the ultrathin film pattern" is a layer pattern formed in the shape of the ultrathin film pattern formed at the bottom of the concave portion.

Further, according to the present invention, there is provided a microstructure having a plating layer formed on the surface of a base material based on an extremely thin film pattern.

According to the method of the present invention, the electroless plating film is stably formed in the region where the organic compound ultra-thin film having an amino group or a thiol group is selectively formed. In a region where an organic compound ultrathin film having a chemical structure having an amino group or a thiol group is selectively formed, a mechanism for forming a stable electroless plating film is considered to be as follows. It is considered that palladium, which is the nucleus of electroless plating, has a coordination bond or an ionic bond with an amino group or a thiol group. Palladium is adsorbed on the amino group or thiol group formed at the terminal of the molecular chain of the organic compound thin film on the surface of the substrate. Since this bond is stronger than ordinary physical adsorption, stable selective adsorption of palladium becomes possible, and it is considered that the electroless plating film having this as a nucleus is formed stably. In consideration of such a mechanism, it is desirable that the amino group or the thiol group is formed at the terminal of the molecular chain of the organic compound. An ultra-thin pattern serving as a growth nucleus of the electroless plating film is formed only at the bottom of the recess, and the electroless plating film grows so as to fill the recess.

Further, according to the present invention, there is provided an ultra-thin film pattern made of an organic compound having a functional group exhibiting a positive or negative charge in a solution on a concave portion of the substrate,
A microstructure having a layer pattern based on the ultrathin film pattern is provided.

According to the method of the present invention, an electrolyte polymer film is formed stably in a region where an organic compound ultrathin film having a functional group showing a positive or negative charge is selectively formed in a solution. . In a region where an organic compound ultrathin film having a functional group showing a positive or negative charge in a solution is selectively formed, the mechanism for forming a stable electrolyte polymer film is considered to be as follows. . After forming an organic compound ultra-thin film pattern having a functional group showing a positive or negative charge in the solution at the bottom of the concave portion, and immersing the substrate in the solution, a positive or negative Takes charge. For example, a very thin film pattern having an amino group has a positive charge, while a carboxyl group has a negative charge. When an electrolyte polymer having a charge of the opposite polarity is present in the solution, the electrolyte polymer is selectively adsorbed on the ultrathin film pattern by electrostatic force, and an ultrathin polymer film is formed. After washing the substrate on which the ultra-thin polymer film is formed, the substrate is further immersed in an electrolyte polymer solution having a charge of the opposite polarity, whereby the electrolyte polymer film can be further grown. A polymer film having a desired film thickness can be obtained by repeating alternate immersion in an electrolyte polymer solution having an opposite charge. An extremely thin film pattern serving as a growth nucleus is formed only at the bottom of the concave portion, and the electrolyte polymer film grows so as to fill the concave portion.

The raw material of the compound having an amino group, a thiol group, or a functional group showing a positive or negative charge in a solution, which constitutes the ultra-thin film pattern used in the present invention, may be an amino group, a thiol group, or a A methoxysilane compound, an ethoxysilane compound, or a chlorosilane compound having a functional group exhibiting a positive or negative charge is desirable, and it is more desirable to use either aminopropyltriethoxysilane or mercaptopropyltriethoxysilane.

It is known that any one of a methoxysilane compound, an ethoxysilane compound and a chlorosilane compound reacts with a silicon substrate to form a self-assembled molecular film on the substrate surface. By using a material having an amino group, a thiol group or a functional group having a positive or negative charge in a solution at the terminal of the molecular chain of these compounds as a raw material, an amino group, a thiol group or a It becomes possible to form a self-assembled film having a functional group exhibiting a positive or negative charge.

Aminopropyltriethoxysilane or mercaptopropyltriethoxysilane can be uniformly formed on a substrate in a uniform film thickness, and an amino group is added to a part of the chemical structure in the formed organic electrode film pattern. Alternatively, it has a thiol group as a functional group.

In the method of the present invention, when an electroless plating film is prepared, an amino group or a thiol group is added to a region other than the thin film portion of the ultra-thin film pattern comprising an organic compound having an amino group or a thiol group. It is preferable to provide an ultrathin organic compound film that does not contain any of the groups.

In the case of preparing an electrolyte polymer film, a region other than the thin film portion of the ultra-thin film pattern made of an organic compound having a functional group exhibiting a positive or negative charge in a solution may be positive or negative in the solution. It is preferable to provide an organic compound ultra-thin film having only a functional group that does not exhibit a negative charge.

Further, in the method of the present invention, the region other than the thin film portion of the ultra-thin film pattern of the ultra-thin film pattern comprising an organic compound having an amino group, a thiol group or a functional group exhibiting a positive or negative charge in a solution, It is preferable to provide an organic compound ultra-thin film having a group or a fluoroalkyl group.

In the microstructure according to the present invention, the growth nucleus of the electroless plating film or the electrolyte polymer film is formed only on the concave portion, and the thin film grows sequentially from there. By appropriately selecting the film forming time, it is possible to adopt a configuration in which only the concave portion is buried with the electroless plating film or the electrolyte polymer film. Therefore, planarization can be performed without using a process such as CMP.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on examples.

(Embodiment 1) First, the microfabrication process used in this embodiment will be described with reference to FIG. The Si wafer 10 was washed with a mixed solution of sulfuric acid and hydrogen peroxide solution.
The liquid temperature is 80 ° C. for 10 minutes. Next, a resist pattern 12 was formed on the Si wafer (FIG. 1a). The resist used was a novolak-based resin as a base, and the pattern had a simple line-and-space shape, a line / space ratio of 1: 1 and a line width of 1.0 micron. The resist thickness was 2.0 microns. A Si wafer having a resist pattern formed thereon and (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane [CF ₃ (C
F ₂ ) ₇ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ ] in a closed container, and heating the entire container to form a fluoroalkylsilane (FAS) unit on the surface of the resist-patterned Si wafer. A molecular layer 14 was formed (FIG. 1b). The heating condition is 70 ° C. for 3 hours. The thickness of the monolayer 14 was about 1 nm. In order to confirm that the FAS film 14 is formed on the resist pattern 12 (line portion) and on the Si wafer (corresponding to the space portion 16), the same conditions were applied to two types of samples, that is, the entire resist film and the Si wafer. When a FAS film was prepared and the contact angle with water was measured, each sample showed a contact angle of 105 ° or more, and it was confirmed that a water-repellent film was formed on the surface.

Next, a part of the FAS film on the patterned Si wafer was removed by UV light. Using the photomask used for forming the resist pattern, the substrate was irradiated with UV light through the photomask. The wavelength of the UV light is 172 nm. The substrate of the photomask used here was made of quartz, and the transmittance of 172 nm UV light was about 60%. The photomask and the resist pattern were aligned so that UV light was applied to the space 16 of the resist pattern. The irradiation intensity of the UV light was about 5 mW / cm2 on the sample, and the irradiation time was 40 minutes. By performing the above processing,
The FAS film on the space 16 was removed.

Further, the patterned Si wafer was washed with pure water and ethanol in this order, and immersed in a solution obtained by mixing 1 vol% aminopropyltriethoxysilane in ethanol for 5 minutes. Further, the substrate was washed in the order of ethanol and pure water. By this process, only in the space region where the FAS film 14 has been removed,
An organic ultra-thin film containing an amino group as a part of the structure was formed, and an ultra-thin film pattern 18 having an amino group was obtained (FIG. 1D). FAS film 1 on the part other than the space
4 will be provided. In this case, the amino group is formed at the terminal of the molecular chain of the organic compound thin film. Here, the FAS film 14 does not contain an amino group.

Next, a process of performing electroless nickel plating is performed. When performing electroless nickel plating, a pretreatment called activation, in which palladium serving as a nucleus of plating is formed on the substrate surface, is performed. Thereafter, by immersing the substrate in an electroless nickel plating solution, a nickel thin film can be obtained on the substrate.

Electroless nickel plating was performed on the sample on which the organic ultra-thin film pattern was formed as described above. First, as an activator, a mixture obtained by adding 30 mL of a mixed solution containing a palladium salt compound and hydrogen chloride (4% of hydrogen chloride, 0.2% of a palladium salt compound, and the balance of water) to 1 L of water was used. An aqueous sodium hydroxide solution was added to adjust the pH to 5.8 at room temperature. In this liquid, about 2
By submerging, palladium was attached to the substrate surface. After removing the sample from the aqueous sodium hydroxide solution, the sample was washed in running water for 3 minutes. Apply electroless nickel plating solution to 7
The sample was maintained at 0 ° C. and pH 4.6, and the washed sample was immersed for about 1 minute.

The electroless nickel plating solution used here contained a nickel salt compound and hypophosphorous acid in a composition of a nickel salt compound: 30 g / L and sodium hypophosphite: 10 g / L. Then, after taking out from the liquid, it was washed in running water and dried. Observation of this sample by SEM confirmed that a structure in which the nickel film 20 was pattern-formed only in the space portion 16 was obtained (FIG. 1E). The nickel film thickness was about 2 microns. In addition, the concave portion of the resist pattern was buried with a nickel film, and planarization was achieved.

(Embodiment 2) Next, another embodiment will be described along with an embodiment. The same plating embedding as in Example 1 was performed by changing the monomolecular film material in the line portion and the space portion.
Processes other than the formation of the monomolecular film are exactly the same as those in the first embodiment. As an alternative to the FAS film 14, an organic molecular film having an alkyl group was formed. Resist-patterned Si wafer and hexamethyldisilazane (HMD
S) was placed in a closed container, and the entire container was heated to form a trimethylsilyl (TMS) monomolecular layer on the substrate surface. The heating condition is 70 ° C. for 3 hours. Also,
An organic molecular film having a thiol group was formed instead of the organic molecular film having an amino group. The organic molecular film was formed in the liquid phase in the same manner as the amino group organic molecular film, and the film was formed under the same manufacturing conditions as in Example 1 except that mercaptopropyltriethoxysilane was used as the organic molecular film material. went. Electroless plating was performed in the same manner as in Example 1, and the sample was observed by SEM. As a result, it was confirmed that a substrate having a nickel film pattern formed only in the space region was obtained. The nickel film thickness was about 2 microns. Further, the concave portion of the resist pattern was buried with a nickel film, and in this case, flattening was achieved. The thiol group-containing monolayer is placed in the space (recess).
In this case, it was confirmed that a good embedding of the electroless plating film in the concave portions was observed even when only the first electroless plating film was formed.

As described above, in the present embodiment, the organic molecular film containing no amino group or thiol group is formed in the convex portion (line portion), but the present invention is limited to such an embodiment. It is needless to say that there is no need to dare to form an organic molecular film unless a functional group such as an amino group or a thiol group to which a growth nucleus of electroless plating is bonded is present on the surface of the convex portion. Further, the present invention is not limited to the electroless nickel plating film, but is also effective when using cobalt, copper, palladium, gold, or the like.

Embodiment 3 Next, an example of embedding an electrolyte polymer film in a concave portion will be described with reference to FIG.

As in the first embodiment, the FAS film 14 is formed on the resist pattern 12 and the amino group organic molecular film 18
Formed a sample formed in the space 16 (FIG. 2).
(A) to (d)). In this embodiment, the resist thickness was set to 0.2 μm.

As a method for producing an electrolyte polymer membrane, an alternate adsorption method of an electrolyte polymer was used. This is a polycation,
In this method, an organic ultrathin film controlled in atomic order is formed on a substrate by alternately immersing the substrate in a solution containing both polyanions. In this embodiment, the cationic polymer is polyallylamine (Poly (allyla)
mine hydrochloride): PA
H), polyacrylic acid (Po) as an anionic polymer
ly (acrylic acid): PAA) was used. In each case, the solutions were adjusted to a concentration of 10 ^-2 M. Also,
Both solutions were prepared using 1N hydrochloric acid to obtain a hydrogen ion concentration p.
H was adjusted to 5.5. The polymer adsorption time was set to 10 minutes for both the anionic polymer and the cationic polymer, and the polymer was adsorbed and washed with ultrapure water for a total of 5 minutes for three times.

In this embodiment, since the amino group organic molecular film 18 having a positive charge is locally formed in the space portion 16 of the substrate, first, it is immersed in a PAA solution, washed,
Further, immersion washing was performed in a PAH solution. Further, these steps were successively repeated 50 times in total. Observation of this sample by SEM confirmed that a substrate in which the electrolyte polymer films (22a, 22b) were pattern-formed only in the space portion 16 was obtained (FIG. 2E).
The polymer film thickness was about 0.2 microns. The concave portions of the resist pattern were buried with the electrolyte polymer film, and almost flattening was achieved. SEM could not confirm a fine laminated structure of the order of angstroms, but since a polymer film with a total thickness of about 0.2 micron was formed, the anionic polymer and the cationic polymer were alternately adsorbed. It is thought that it is. In Examples 1 and 2, embedding of the metal film was confirmed by using a technique called electroless plating. In this example, embedding of the polymer film in the concave portion was confirmed.

In the third embodiment, the organic molecular film 18 having an amino group is formed in the space portion 16, but the organic polymer film having a carboxyl group is formed to alternately form the electrolyte polymer films (22a, 22b). You can also. In this case, since the organic molecular film 18 having a carboxyl group having a negative charge is formed in the space 16, the order of stacking the alternately adsorbing films is to start with immersion of a PAH solution having a positive charge first. I do.

In Example 3, only PAA and PAH are described as electrolyte polymer materials. However, the present invention is not limited to only these electrolyte polymer materials, and the present invention is not limited to these electrolyte polymer materials. Needless to say, a polymer having the following formula can be embedded in the concave portion.

[0038]

As described in detail above, according to the present invention,
The electroless plating film or the electrolyte polymer film can be formed only in the concave portions of the substrate on which the concaves and convexes are formed. As a result, the concave portions can be embedded with the metal film or the polymer film.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method according to an embodiment of the present invention along its steps.

FIG. 2 is a sectional view showing a method of another embodiment of the present invention along the steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Si substrate 12 Resist pattern 14 FAS film 16 Space part (resist removal area, concave part) 18 Ultra-thin pattern of organic molecular film 20 Electroless plating film (nickel film) 22 a, b Electrolyte polymer layer

Claims (12)

[Claims] 1. A substrate having irregularities, an ultrathin film pattern comprising an organic compound having an amino group or a thiol group on a concave portion of the substrate, and a layer pattern based on the ultrathin film pattern. Fine structure. 2. The microstructure according to claim 1, wherein the layer pattern based on the ultrathin film pattern is a plating layer. 3. An ultra-thin film pattern comprising a substrate having irregularities, an organic compound having a functional group exhibiting a positive or negative charge in a solution on a concave portion of the substrate, and A microstructure having a layer pattern. 4. The microstructure according to claim 3, wherein the layer pattern based on the ultra-thin film pattern comprises an electrolyte polymer layer. 5. The organic compound having an amino group, a thiol group, or a functional group exhibiting a positive or negative charge in a solution, the amino group, the thiol group, or a positive or negative The fine particle according to claim 2, wherein the fine particle is formed from any one of a methoxysilane compound, an ethoxysilane compound, and a chlorosilane compound, which has any one of a functional group exhibiting a negative charge. Structure. 6. An organic compound having the amino group, the thiol group, or a functional group showing a positive charge in a solution,
The microstructure according to claim 2, wherein the microstructure is formed from one of aminopropyltriethoxysilane and mercaptopropyltriethoxysilane. 7. A first step of forming an ultrathin film pattern made of an organic compound having an amino group or a thiol group on a concave portion of a substrate having irregularities, and forming an ultrathin film on the surface of the substrate based on the ultrathin film pattern. A second step of forming a plating layer by using an electrolytic plating method. A method for producing a microstructure having a plating layer pattern, the method comprising: 8. A first step of forming an ultrathin film pattern made of an organic compound having a functional group showing a positive or negative charge in a solution on a concave portion of a substrate having irregularities, and A second step of forming a polymer layer on the surface of the base material by immersing the polymer layer in an electrolyte polymer solution. 9. An organic compound having an amino group, a thiol group, or a functional group exhibiting a positive or negative charge in a solution, wherein the organic compound has an amino group, a thiol group, or a positive or negative The microstructure according to claim 7, wherein the microstructure is formed from any one of a methoxysilane compound, an ethoxysilane compound, and a chlorosilane compound having a functional group having a charge of: How to make the body. 10. An ultrathin organic compound film containing neither an amino group nor a thiol group is provided in a region other than the thin film portion of the ultrathin film pattern made of an organic compound having an amino group or a thiol group. The method for producing a microstructure according to claim 7, wherein 11. A region other than the thin film portion of the ultra-thin film pattern made of an organic compound having a functional group showing a positive or negative charge in the solution, a functional group showing no positive or negative charge in the solution. 9. The method for producing a microstructure according to claim 8, wherein an organic compound ultra-thin film having only one is provided. 12. A region other than the thin film portion of the ultra-thin film pattern comprising an organic compound having any of the amino group, thiol group, or functional group showing a positive or negative charge in a solution, an alkyl group 9. The method for producing a microstructure according to claim 7, wherein an organic compound ultra-thin film having any one of a fluoroalkyl group is provided.