JP5146866B2 - Multilayer thin film and manufacturing method thereof - Google Patents

Description

  The invention of this application relates to a nanometer-precision multilayer thin film used in fields such as spintronics, actuators, MEMS, gas and ion separation membranes, and more particularly to a self-supporting multilayer thin film.

  Nanometer-precision multilayer thin films are used in various technical fields. The formation of a multilayer thin film on a silicon substrate is a manufacturing technique that is the backbone of the electronics field. Multi-layered thin films consisting of magnetic and non-magnetic layers are creating new phenomena such as the giant magnetoresistive effect and support the technical field of spintronics.

  A nano-thick multilayer thin film may have significantly improved mechanical strength compared to a thin film material having a uniform composition.

  A conventional multilayer thin film is produced on a smooth substrate such as silicon and does not have a self-supporting property enough to remove the silicon substrate. However, when the multilayer thin film has a self-supporting property and has a flaky shape, in addition to the above properties, the potential as a new functional material is expanded. For example, a multilayer thin film having an asymmetric structure is an important element for manufacturing a material accompanied by a structural change such as an actuator or MEMS. Further, when such a multilayer thin film is obtained with a nanometer thickness, it can also be used as a light energy conversion material or a catalyst.

  Furthermore, when a multi-layered thin film having self-supporting properties is formed on a porous film (support), the mechanical stability increases and a high pressure can be applied. Can be used for various purposes. The separation of hydrogen and carbon dioxide is said to be an important science and technology that will support the society of the 21st century. In order to efficiently separate such gases, it is important not only to produce a nanometer-scale dense membrane but also to give affinity for a specific gas (Non-patent Document 1).

  At present, the technique for producing a flaky multilayer thin film with nanometer precision is limited to a technique using lithography or the like (Non-Patent Document 2). On the other hand, the inventors have already developed a technique for producing a nano-thickness thin film by a vapor deposition method on a support having fine pores of several micrometers (Japanese Patent Application No. 2004-176314). In this technique, a dry foam film is formed in the micropores of the support, and a vapor deposition film is formed on the entire surface including the pores. For example, when platinum is deposited to a thickness greater than 10 nm, There was a problem that it was broken (Non-Patent Document 3).

For this reason, it has been considered that it is impossible to make the deposited film multi-layered because the thickness is increased.
2003 carbon dioxide fixation / effective utilization technology countermeasures program system carbon dioxide fixation / effective utilization technology development "Development of CO2 separation technology using polymer membrane" result report (Global Environment Industrial Technology Research Organization) 2004 March. E. Kwak, et al. , NanoLetters, Vol. 5, p1963-1967, 2005. J. et al. Jin, et al. , Angelwandte Chemie International Edition, Vol. 44, p4532-4535, 2005. Japanese Patent Application No. 2004-176314

In view of the above circumstances, the possibility of a self-supporting multilayer thin film with good controllability at the nano level was examined by various methods, but the use of a dry foam film is still due to controllability at the nano level. The present invention was considered to be satisfactory.

The invention of this application provides the following inventions 1 to 6 as a result of intensive studies conducted by the inventors to solve the above-mentioned problems.
In the multilayer thin film of the first aspect of the present invention, a first vapor deposition layer that covers the fine holes is formed on one side of a self-supporting thin film having a large number of fine holes penetrating the front and back, and further, the first vapor deposition layer is covered. a multilayer thin film in which the second deposition layer formed, made of any material which the deposited layer is of platinum, carbon, silicon, iron, chosen tellurium, indium, from the group of selenide cadmium, the fine When the inner diameter of the hole is 5 × 10 nm to 1 × 10 ⁵ nm, the thickness of the self-supporting thin film is 1 × 10 ² nm to ² × 10 ³ nm, and the first vapor deposition layer is platinum, the thickness thereof Is 1 × 10 ⁻¹ nm to 10 nm, in the case of carbon, the thickness is 1 × 10 ⁻¹ nm to 50 nm, and in the case of silicon, the thickness is 1 × 10 ⁻¹ nm to 50 nm. in the case of iron, the thickness of 1 × 10 ^- and the nm least 10nm or less, in the case of tellurium, its thickness from 100nm or less 1 × ¹⁰ -1 nm or more, in the case of indium, the thickness from 10nm or less 1 × ¹⁰ -1 nm or more, in the case of cadmium selenide The thickness is 1 × 10 ⁻¹ nm or more and 20 nm or less, and the thickness of the second vapor deposition layer is 10 nm to 1 × 10 ² nm, which is smooth.
In the multilayer thin film according to the second aspect of the present invention, in the first aspect of the present invention, one or more additional vapor deposition layers are laminated so as to cover the second vapor deposition layer.
In the multilayer thin film of the present invention 3, the inner diameter of the micropores of the self-supporting thin film in the first or second invention is 1 × 10 ² nm to 5 × 10 ⁴ nm.
The multilayer thin film of the present invention 4 is a multilayer thin film in which the self-supporting thin film is made of a metal or semiconductor inorganic substance.
In the multilayer thin film of the present invention 5, the self-supporting thin film is made of any material selected from the group consisting of polymer, carbon, copper and nickel.
This invention 6 is the manufacturing method of the multilayer thin film in any one of this invention 1-5, Comprising: The 1st process of forming a dry foam film in the micropore of the said self-supporting thin film, The said dry foam film A second step of depositing a predetermined material on one side of the self-supporting thin film, a third step of newly depositing a different material on the surface of the deposited layer, and a step of removing the dry foam film. Features.

The multilayer thin film according to the first aspect of the present invention can give external stimulus not only from the surface of the multilayered vapor deposition layer but also from the back through the micropores of the self-supporting thin film. In other words, it is an ideal self-supporting multilayer thin film, and since it is obtained by vapor deposition, an ultra-precise multilayer thin film of nano level is realized.

In the multilayer thin film of the first invention, the inner diameter of the micropores of the self-supporting thin film is 5 × 10 nm to 1 × 10 ⁵ nm, more preferably 1 × 10 ² nm to 5 × 10 ⁴ nm. Mechanical stability can be improved.

Further, the thickness of the vapor deposition layer according to any one of the first to third inventions is set to 1 × 10 ⁻¹ nm to ¹ × 10 ⁴ nm, more preferably ¹ nm to 1 × 10 ³ nm, so that the mechanical stability is improved. The uniformity of the entire layer as well as the properties can be further improved.

  The method for producing a multilayer thin film of the present invention 7 has found that the already developed technology for forming a vapor deposition layer using a dry foam film can be applied to a self-supporting multilayer thin film. It is possible.

The reason why it can be multi-layered is not clear, but it is probably because the first layer deposited on the free-standing film serves as an alternative to the dry foam film for some reason and accepts the next deposited layer. . However, it is not certain whether an extremely thin vapor deposition layer can perform the same function as a dry foam film.

  The invention of this application has the characteristics as described above. The embodiment will be described below.

  First, the dry foam film will be described. The inventors of this application have previously discovered that foam membranes formed in micrometer range frames maintain the membrane morphology even when the water is completely dry. Such a membrane was generalized as a foam membrane without a liquid water layer and was named dry foam membrane. The details are reported in Non-Patent Document 3 and Patent Document 1.

  A dry foam film is formed by evaporating a solvent from a thin film in a liquid state obtained by attaching a dilute surface active molecule solution to the micropores, and the surface is covered with the molecular film of the surface active molecule. It is a featured solid state nano thin film. The surfactant molecule is not particularly limited, but those having an alkyl chain are preferably used. The dry foam film can be prepared from a compound having a surface activity similar to a surface active molecule, and can also be prepared from a solvent other than water. For example, an ethanol solution of a long-chain alkylsilane compound can be used for producing a dry foam film having high stability.

  The dry foam film can exist stably even under an ultra-high vacuum and can be applied to a dry process.

In the following, the multilayer thin film and the method for producing the same of the invention of this application will be described in more detail in three sections: formation of a dry foam film, formation of a deposited film on the dry thin film, and production of the multilayer thin film.

・ Formation of dry foam film

In the invention of this application, a dry foam film is used to produce a multilayer thin film. The formation of a dry foam film has already been disclosed in Non-Patent Document 3 and the like. Dry foam membranes can be made using a wide range of surface active molecules or compounds having characteristics similar to surface active molecules. The invention of this application is not necessarily limited to those conventionally known, but examples of the surface active molecule suitable for the production of the multilayer thin film or compounds having characteristics similar to the surface active molecule include the following. .

Many surface active molecules have a hydrophobic group and a hydrophilic group in the molecule. The hydrophobic group is not particularly limited, but an alkyl chain is preferably used. The number of hydrophobic groups need not be one. For example, a stable dry foam film can be formed even with a double-stranded or gemini-type surfactant molecule. The hydrophilic group is not particularly limited, and examples thereof include those having a quaternary amine such as trimethylammonium or those having a zwitterionic group. From the surface-active molecules having these hydrophilic groups, a dry foam film having a thermal stability of 160 ° C. or higher may be formed. The surface active molecule may have a hydrophilic portion of an imidazolium salt that tends to form an ionic liquid or the like. Compounds having characteristics similar to surfactant molecules include organometallic compounds such as metal alkoxides having an alkyl chain. For example, octadecyltrimethoxysilane, octadecyldimethyl (3-trimethoxysilyl-propyl) ammonium chloride (hereinafter abbreviated as C18-N-Si), and the like provide excellent dry foam films for producing multilayer thin films.
In forming a dry foam film, it is possible to use a surface active molecule or a combination of compounds having characteristics similar to the surface active molecule.

  On the other hand, water is used as a representative solvent, but it may be an organic solvent such as alcohol, or a mixed solvent of an organic solvent and water. That is, it is important that surface active molecules or compounds having characteristics similar to surface active molecules exhibit the property of forming a molecular film at the gas-liquid interface so as to lower the surface tension of the solvent. There is no.

The micropores for forming the dry foam film have an inner diameter of ⁵ nm to ⁵ × 10 ⁵ nm, more preferably 5 × 10 nm to 1 × 10 ⁵ nm, and still more preferably 1 × 10 ² nm to ⁵ × 10 ⁴ nm. Used. The inner surface of the substantially fine pores is not particularly limited, but those having moderate hydrophilicity are preferable. For example, micropores made of polymer, metal or metal oxide are preferably used. The substantially fine hole may have any cross-sectional shape such as a circle, a square, a polygon, or a different diameter. The inner diameter refers to the minimum hole width of these shapes.

Dry foam membranes are made using dilute solutions of surface active molecules or compounds having characteristics similar to surface active molecules. The concentration of the dilute solution depends on the size of the micropores to be attached, but is preferably in the range of 1 × 10 ⁻⁵ M to 1M (M represents the molar concentration), and 1 × 10 ⁻⁴ M To 1 × 10 ⁻¹ M is more preferable, and 1 × 10 ⁻³ M to 1 × 10 ⁻² M is more preferable. Various methods such as a spray method, a coating method, and a spin coating method can be used as a method for attaching the diluted solution to the micropores. In general, however, a self-supporting thin film having micropores is generally used as a dilute solution. A method of immersing in is preferably used.

The dry foam film is formed by evaporating the solvent from the diluted solution attached to the micropores. The evaporation of the solvent can generally be performed by leaving it in the air for several seconds to several tens of minutes. The rate of evaporation depends on the temperature of the environment in which it is left, and becomes faster at higher temperatures. The speed can also be increased by blowing dry air onto the self-supporting thin film. If necessary, drying under reduced pressure is also possible. The dry foam film thus formed is sufficiently stable even under vacuum conditions of about 10 ⁻⁵ Pa.

A normal dry foam film has a thickness of two molecules. However, for example, if a solute (protein, polymer, inorganic particle, etc.) that interacts with the hydrophilic portion of the surface active molecule is contained, the solute is taken into the dry foam film and the thickness of the dry foam film increases. In addition, when a relatively concentrated surfactant molecule or a solution of a compound having characteristics similar to the surfactant molecule is used, the edge portion of the dry foam film may be thick. For such reasons, the thickness of the dry foam film is preferably 1 nm to 1 × 10 ³ nm, more preferably ² nm to ² × 10 ² nm, and further preferably ³ nm to ³ × 10 nm. More preferred.

  The dry foam film can be mixed with one or more organic, inorganic, or metal components, and part or all of the organic components can be removed by a method such as washing, baking, or oxygen plasma treatment. As a result, a thin film made of an inorganic or metal component can be obtained. The thin film formed in this way is also included in the dry foam film and can be used for the production of a multilayer thin film like the others.

Based on the above knowledge, the formation of the self-supporting thin film and the dry foam film for the production of the multilayer thin film is specifically exemplified in Tables 1 and 2.

As an example of a polymer film (form bar) having micropores, an experiment was performed using a support film for electron microscope (Oken Shoji 150-B type). This support film has fine pores of about 0.5 μm to 10 μm, and carbon is vapor-deposited on the surface, showing a slight hydrophobicity. The length of the micropores matches the thickness of the polymer film and is about 0.1 μm.


In Table 2, the self-supporting thin film No. No. in Table 1 The material etc. were used by showing.


・ Formation of vapor-deposited film on dry foam film

The multilayer thin film of the invention of this application is manufactured by stacking a deposited film at least once on a self-supporting thin film having micropores closed by a dry foam film. A dry foam film is a solid nano-thin film characterized in that its surface is covered with a molecular film, and usually has a thickness of two molecules. Despite having such an ultra-thin structure, the dry foam film generally has a thermal stability of 100 ° C. or higher and some has a thermal stability of 160 ° C. or higher. Furthermore, according to the method of the invention of this application, the dry foam film can maintain the shape of the film even when the deposited films of metals, semiconductors, inorganic substances and the like are stacked.

  As shown in the examples, sputtering, electron beam evaporation, vacuum evaporation, or the like can be used as the evaporation method. The substance that can be deposited is not particularly limited, and examples thereof include iron, silicon, tellurium, indium, selenium, platinum, and carbon. In the vapor deposition method, a gaseous substance in a gas phase adheres and is deposited to form a thin film. The availability of various materials and vapor deposition methods as described above indicates that the dried foam film is very stable against gaseous substances in the gas phase.

  On the other hand, a dry foam film tends to be fragile when a substance attached to the surface of the molecular film undergoes a phase transition. For example, C18-N-Si can form a very stable dry foam film having a thickness of two molecules and deposit platinum having a thickness of 10 nm. Will be torn. This is thought to be because the particulate platinum that was first deposited fused with the increase in thickness and gave a large tension. With carbon or the like in which such phase transition does not occur, a thin film having a thickness of 50 nm can be deposited. It has been demonstrated that thin films having a thickness of 50 nm and 100 nm can be deposited on silicon and tellurium, which are semiconductors, respectively. On the other hand, in the case of indium or iron, which is a metal, the film is broken by depositing a 50 nm thin film. Although the thickness which can be vapor-deposited depends on the vapor deposition method and conditions, when a metallic substance is vapor-deposited on a dry foam film formed in micropores of several micrometers, a vapor-deposited film having a thickness of 10 nm to 50 nm is formed. Sometimes the membrane tends to break. On the other hand, such a phenomenon hardly occurs in semiconductors and insulators.

  Since the dry foam film is stable even under ultra-high vacuum, the degree of vacuum during vapor deposition is not particularly limited. Moreover, since a dry foam film generally breaks when heated to 200 ° C. or higher, normal vapor deposition is performed near room temperature. Further, the material to be deposited may be a compound. For example, cadmium selenide (CdSe) or the like can obtain a good vapor deposition film by a vacuum vapor deposition method.

  A single or a plurality of organic, inorganic, or metal components can be mixed into the dry foam film, and in this case, the thickness is larger than two molecules. When the dry foam film is thick, the surface-active molecule used or a compound having characteristics similar to the surface-active molecule depends on the type, but in general, it is easy to form a deposited film on the surface.

A self-supporting thin film having micropores closed by a dry foam film is usually deposited from one side. However, if the arrangement in the chamber of the vapor deposition apparatus is devised, it is not impossible to simultaneously form the vapor deposition film on both surfaces of the self-supporting thin film. In this case, a vapor deposition film is formed on both sides of the dry foam film.

・ Manufacture of multilayer thin films

  A multilayer thin film can be manufactured by re-depositing on the surface of a self-supporting thin film that has been deposited at least once by the operation described in the previous section without destroying the shape of the film.

  In general, if the first vapor deposition layer is stably formed, the mechanical stability is increased and the formation of the second vapor deposition layer is facilitated. For example, platinum having a thickness of 20 nm cannot be formed on the surface of a dry bubble film of C18-N-Si, but after depositing tellurium having a thickness of 10 nm, 20 nm of platinum can be deposited. . In addition, although indium with a thickness of 50 nm cannot be deposited on the surface of a dry bubble film of C18-N-Si, indium with a thickness of 100 nm can be deposited after tellurium with a thickness of 10 nm is deposited.

  Carbon and platinum having a thickness of 20 nm are uniformly deposited on the surface on which tellurium having a thickness of 10 nm is deposited. However, when indium having a thickness of 50 nm is deposited, unevenness on the surface becomes large. Thus, the combination of materials is important for producing a uniform multilayer thin film.

  A third vapor deposition layer can be formed on the second vapor deposition layer. For example, when tellurium having a thickness of 10 nm is vapor-deposited on the surface of a dry bubble film of C18-N-Si, indium having a thickness of 10 nm is vapor-deposited, and further platinum having a thickness of 10 nm is vapor-deposited. Is formed. Similarly, after tellurium having a thickness of 10 nm is vapor-deposited, platinum having a thickness of 10 nm can be vapor-deposited, and further carbon having a thickness of 20 nm can be vapor-deposited. In general, the formation of the third vapor deposition layer is easier than the formation of the first and second vapor deposition layers.

  There are infinite combinations of multilayer thin films, and not all of them can be explained, but various multilayer thin films can be produced by the method described above.

  A fourth vapor deposition layer, a fifth vapor deposition layer, and a sixth vapor deposition layer can be sequentially formed on the third vapor deposition layer. Formation of the vapor deposition layer after the fourth vapor deposition layer is easier than the formation of the third vapor deposition layer. For this reason, the multilayer thin film of the invention of this application is not limited to the multilayer thin film up to the third vapor deposition layer. Moreover, the direction of vapor deposition is not limited to the front side or the back side of the self-supporting thin film, and can be from any surface.

Finally, the multilayer thin film obtained by the above method can be subjected to various post-treatments. Examples include curing and densification by heat treatment, removal of organic components by oxygen plasma treatment, coating of polymers, imparting molecular functions by adsorption of organic molecules, imparting biofunctions by adsorption of biological substances, and the like.
Table 3 specifically illustrates the formation of the vapor deposition layer based on the above findings.

* Presence or absence of vapor deposition layer was confirmed by electron diffraction.
(Example for the self-supporting thin film of No. 1 in Table 1 with the dry foam film of No. 8 in Table 2)

FIG. 1 schematically shows the formation of a dry foam film on a self-supporting thin film having a large number of micropores.
In FIG. No. 1 in Table 2 is formed in the fine hole of 1 form bar. The observation image by the transmission electron microscope of the dry foam film formed on condition of 8 was shown.
In FIG. The observation image by the transmission electron microscope of the dry bubble film | membrane which vapor-deposited platinum of 1 was shown.

In Table 4 showing Examples, Table 5 showing Reference Examples, and Table 6 showing Comparative Examples, the self-supporting thin film No. 1 was used. No. in Table 1. , Dry foam film No. No. in Table 2. No. of each vapor deposition layer. No. in Table 3. The material etc. were used by showing.


<Example 1>

In Example 1, a multilayer thin film having a function as a catalyst electrode that can be used mainly for energy conversion was produced.
In FIG. 4, the transmission electron micrograph of the multilayer thin film produced in Example 1 is shown. Thereby, the fine pores of the form bar (porous polymer film) were covered with the dry bubble film of C18-N-Si, and the first vapor deposition layer, the second vapor deposition layer, and the third vapor deposition layer were vapor deposited thereon. Later, it can be confirmed that the shape as a film is maintained. Moreover, these vapor deposition layers are uniformly formed on the surface of the porous polymer film. When the electrical conductivity of the multilayer thin film was examined for use as a catalyst electrode, it was proved by the measurement by the 4-terminal method that it had metallic electrical conductivity. Moreover, it was confirmed by observation using a high-resolution scanning electron microscope that the platinum layer of the third vapor deposition layer has irregularities of about 1 nm on the surface, which can be expected to have high activity as a catalyst.

<Example 2>

In Example 2, a multilayer thin film was produced mainly for use in actuators, MEMS, and the like.
In FIG. 5, the transmission electron micrograph of the multilayer thin film produced in Example 2 is shown. Thereby, even after forming the vapor deposition layer from the 1st vapor deposition layer to the 3rd vapor deposition layer, it can confirm that the shape as a film | membrane is maintained. Moreover, these vapor deposition layers are uniformly formed on the surface of the porous polymer film.

In this multilayer thin film, a platinum layer having metallic electrical conductivity is sandwiched between a tellurium layer which is a semiconductor and a conductive carbon layer. For this reason, it can be expected to act as an actuator by applying a potential. In addition, it has been confirmed from experiments using an electron microscope that the multilayer thin film is very stable with respect to the focused electron beam. Further, it has been confirmed that the outermost carbon layer has high mechanical strength and high stability to water and organic solvents. For this reason, utilization as a thin film for MEMS can be expected.

<Examples 3 to 4>

In Examples 3 and 4, a multilayer thin film was produced mainly for use in nanoseparation membranes.
In FIG. 6, the transmission electron micrograph of the multilayer thin film produced in Example 3 is shown. Because the tellurium of the first vapor deposition layer is deposited as a nanometer-size crystal and amorphous carbon is vapor deposited thereon, it appears to be a multilayer film that is not uniform at first glance. However, observation at a high magnification using a scanning electron microscope confirmed that the multilayer thin film was a very smooth dense film. The multilayer thin film was stable against an active gas such as hydrogen. Furthermore, it was confirmed that this multilayer thin film can remove the dry foam film by washing with water, and the shape as a film is maintained even after the dry foam film is removed.
In Example 4, the experiment was performed by setting the thickness of the first vapor deposition layer of Example 3 to 10 nm, and the same result as in Example 3 was obtained.

<Examples 5-9>

In Examples 5 to 9, multilayer thin films were produced which were mainly intended for use as thin film catalysts.
FIG. 7 shows a scanning electron micrograph of the multilayer thin film produced in Example 5. From the upper diagram of FIG. 7, it can be confirmed that the micropores of the copper mesh are covered with the multilayer thin film, and from the middle diagram of FIG. 7, it can be seen that the surface is covered with aggregates of platinum nanoparticles. Moreover, it can be confirmed from the lower diagram of FIG. 7 that the multilayer thin film has a two-layer structure of tellurium and platinum. This multilayer thin film has been confirmed to have high thermal stability and high chemical stability against oxygen, water, and the like.
In Examples 6 to 9, the experiment was performed by changing the thickness of the support and the tellurium layer and the thickness of the platinum layer. In each case, the same result as in Example 5 was obtained.

<Examples 10 to 14>

In Examples 10 to 14, multilayer thin films having metal components mainly intended for use in nanoseparation membranes were produced.
FIG. 8 shows a transmission electron micrograph of the multilayer thin film produced in Example 10. From the left figure of FIG. 8, the shape of the film is maintained after the fine pores of form bar are covered with a dry bubble film of C18-N-Si, and the first vapor deposition layer and the second vapor deposition layer are deposited thereon. It can be confirmed that On the other hand, it can be seen from the right diagram in FIG. 8 that indium formed on the tellurium layer exists as particles of several tens of nm. This multilayer thin film was confirmed to have stability to hydrogen and the like. Here, the tellurium layer is a semiconductor, and the indium layer has metallic characteristics.

In Examples 11 to 14, the experiment was performed by changing the thickness of the support or tellurium layer and the thickness of the indium layer. In either case, the shape as a film was maintained, but the smoothness of the surface decreased as the thickness of the indium layer increased. In Example 13, a tellurium layer of 50 nm and an indium layer of 10 nm were formed, but formation of a particularly smooth multilayer thin film was confirmed. In Example 14, a 50 nm tellurium layer and a 50 nm indium layer were formed, but the surface smoothness was slightly reduced. All of these multilayer thin films have been confirmed to have stability to hydrogen gas and the like.

<Reference example>

The multilayer thin film shown in the above embodiment is manufactured by stacking deposited films. In general, the formation of the first vapor deposition layer on the dry foam film is more difficult than the formation of the second vapor deposition layer and the third vapor deposition layer, and the film is often broken. For this reason, whether or not a single-layer thin film can be formed on a dry foam film is largely related to the possibility of producing a multilayer thin film. In order to demonstrate the diversity of the multilayer thin film of the invention of this application, examples of formation of a single layer thin film are introduced in Table 5.

  FIG. 1 shows a scanning electron micrograph of the carbon film 1. From FIG. 9, it can be confirmed that the fine holes of the nickel mesh are covered with the carbon film except for a part. That is, it can be confirmed that carbon can be deposited on the dry foam film, and the carbon film can be kept stable even after the dry foam film is removed and heat-treated.

Table 5 shows the formation of dry foam membranes such as C18-N-Si and D-PC using porous polymer membranes and nickel mesh as a support, depending on the application of nano-separation membranes and thin-film catalysts. In addition, carbon, silicon, iron, platinum, indium, tellurium, cadmium selenide, and the like can be deposited by a method such as thermal vapor deposition, electron beam vapor deposition, or sputtering. The obtained thin film can be subjected to water washing or heat treatment. Each thin film has been confirmed to have various characteristics such as formation of a dense film, stability to gas, thermal stability, and chemical stability.

<Comparative example>

In contrast to the examples and reference examples, the film may be broken by vapor deposition. Such cases are summarized in Table 6 as comparative examples.

When a dry foam film is formed using C18-N-Si in the fine pores of form bar, the thin film is broken when 20 nm of platinum is deposited as the first deposited layer. Similarly, when 50 nm of iron, 50 nm of indium, or 10 nm of selenium is deposited, the thin film is broken.
As shown in Example 6, if 10 nm tellurium is deposited as the first deposition layer, 20 nm platinum can be deposited as the second deposition layer. However, as shown in Table 6, even when 10 nm tellurium is vapor-deposited as the first vapor deposition layer, the multilayer thin film is broken when 50 nm platinum is vapor-deposited as the second vapor deposition layer.

In the invention of this application, a nanometer precision self-supporting multilayer thin film is easily and reliably manufactured by using a dry foam film. Such a multilayer thin film can be formed so as to cover nano- to micrometer-scale micropores and is mechanically stable, so that various functions as a separation membrane can be expected. Specifically, it is expected to be used for gas separation membranes, reverse osmosis membranes, water purification, odor, virus, bacteria removal membranes, facilitated transport membranes, pervaporation membranes, and the like. In particular, there will be great potential for application to gas separation membranes that selectively permeate hydrogen, oxygen, carbon dioxide, and the like. Moreover, the dry foam film can be formed into various shapes of materials having micropores such as a sheet shape, a tube shape, and a particle shape. For this reason, when a multilayer thin film is manufactured using such a dry foam film, efficient substance separation or control of substance permeability becomes possible. For example, by applying the invention of this application to hollow fibers, industrial applicability will be greatly expanded.

Furthermore, since the invention of this application can manufacture a self-supporting multilayer thin film having an asymmetric structure, it can also be used for designing functional materials such as actuators and MEMS that involve structural changes. In addition, multilayer thin films containing metals and semiconductors can be expected as catalysts and energy conversion materials, and will be useful for the effective use of light energy and the production of fuel cells. The use as a sensor has a wide range of possibilities, and the multilayer thin film of the invention of this application can be expected to be a component of physical sensors, chemical sensors, biosensors, magnetic sensors, and the like. In addition, various physical functions can be expected from multilayered thin films of metals, semiconductors, and insulators, and applications as devices can also be expected. Furthermore, the multilayer thin film of the invention of this application has electrical characteristics such as antistatic films, magnetic characteristics such as spin electronics, optical characteristics such as antireflection films and absorption of ultraviolet rays, and surface characteristics such as superhydrophilicity and tribology. It leads to the development of excellent materials, and if a patterned substrate is used, it has great potential as a component of a display element.

It is a schematic diagram showing formation of the dry foam film to the self-supporting thin film which has many micropores. No. in Table 1 1 is an observation image of a dry foam film formed in a fine hole of form bar shown in FIG. 1 using a transmission electron microscope. The lower figure is observed at a higher magnification than the upper figure. The dry foam film is No. 1 in Table 2. Formed under 8 conditions. No. in Table 3 1 is an observation image of a dry bubble film deposited with platinum shown in FIG. 1 using a transmission electron microscope. 2 is an observation image of a multilayer thin film in Example 1 with a transmission electron microscope. This multilayer thin film is obtained by forming a dry bubble film of C18-N-Si in fine pores of form bar, and depositing a 10 nm tellurium layer, a 10 nm indium layer, and a 10 nm platinum layer on the surface. The lower figure is observed at a higher magnification than the upper figure. 6 is an observation image of a multilayer thin film in Example 2 with a transmission electron microscope. This multilayer thin film is obtained by forming a dry bubble film of C18-N-Si in fine pores of form bar, and depositing a 10 nm tellurium layer, a 10 nm platinum layer, and a 20 nm carbon layer on the surface. The lower figure is observed at a higher magnification than the upper figure. It is an observation image by the transmission electron microscope of the multilayer thin film in Example 3. This multilayer thin film is obtained by forming a dry bubble film of C18-N-Si in fine pores of form bar, and depositing a 50 nm tellurium layer and a 20 nm carbon layer on the surface. The lower figure is observed at a higher magnification than the upper figure. 6 is an image observed by a scanning electron microscope of a multilayer thin film in Example 5. In this multilayer thin film, a dry bubble film of C18-N-Si is formed in a fine hole of copper mesh (2000), and a 20 nm tellurium layer and a 20 nm platinum layer are vapor-deposited on the surface. The upper figure (a) is an observation image at a low magnification, the middle figure (b) is an observation image of a surface at a high magnification, and the lower figure (c) is an observation image of a cross section at a high magnification. From the figure below, it can be confirmed that the multilayer thin film has a two-layer structure of tellurium and platinum. It is an observation image by the transmission electron microscope of the multilayer thin film in Example 10. FIG. This multilayer thin film is obtained by forming a dry bubble film of C18-N-Si in fine pores of form bar, and depositing a 10 nm tellurium layer and a 10 nm indium layer on the surface thereof. The right figure is observed at a higher magnification than the left figure. It is an observation image by the scanning electron microscope of the carbon film formed in the fine hole of the nickel mesh in a reference example. The carbon film is obtained by performing heat treatment at 350 ° C. after washing with water.

Claims (6)

A first vapor deposition layer that covers the fine holes is formed on one side of a self-supporting thin film having a large number of fine holes penetrating the front and back surfaces, and a second vapor deposition layer is formed so as to cover the first vapor deposition layer. A multilayer thin film,
Becomes the deposited layer of platinum, carbon, silicon, iron, tellurium, indium, from any of the materials selected from the group selenide cadmium,
The inner diameter of the micropore is 5 × 10 nm to 1 × 10 ⁵ nm, and the thickness of the self-supporting thin film is 1 × 10 ² nm to ² × 10 ³ nm,
When the first vapor deposition layer is platinum, the thickness thereof is 1 × 10 ⁻¹ nm or more and 10 nm or less,
In the case of carbon, the thickness is 1 × 10 ⁻¹ nm or more and 50 nm or less,
In the case of silicon, the thickness is 1 × 10 ⁻¹ nm or more and 50 nm or less,
In the case of iron, the thickness is 1 × 10 ⁻¹ nm or more and 10 nm or less,
In the case of tellurium, the thickness is 1 × 10 ⁻¹ nm or more and 100 nm or less,
In the case of indium, the thickness is 1 × 10 ⁻¹ nm or more and 10 nm or less,
In the case of cadmium selenide, the thickness is 1 × 10 ⁻¹ nm or more and 20 nm or less,
The multilayer thin film characterized in that the thickness of the second vapor deposition layer is 10 nm to 1 × 10 ² nm and is smooth. 2. The multilayer thin film according to claim 1, wherein one or more vapor deposition layers are further laminated so as to cover the second vapor deposition layer. 3. The multilayer thin film according to claim 1, wherein an inner diameter of the micropore of the self-supporting thin film is 1 × 10 ² nm to 5 × 10 ⁴ nm. The multilayer thin film according to claim 1, wherein the self-supporting thin film is made of a metal or a semiconductor inorganic substance. The multilayer thin film according to claim 4, wherein the self-supporting thin film is made of any material selected from the group consisting of polymer, carbon, copper, and nickel. In the manufacturing method of the multilayer thin film in any one of Claim 1 to 5, the 1st process of forming a dry foam film in the micropore of the said self-supporting thin film, and the single side | surface of the said self-supporting thin film containing the said dry foam film A multilayer thin film comprising: a second step of depositing a predetermined material on the surface; a third step of newly depositing a different material on the surface of the deposited layer; and a step of removing the dry foam film. Production method.