JPH10202741A - Mold for fine processing by transfer and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer mold for performing fine processing by transfer, having good mold releasability and excellent durability. SOLUTION: The surface of a base plate 1 is processed to form a desired embossed pattern to be transferred and an oxide film 5 is formed on the entire surface of this base plate 1. An org. molecule 7 having a carbon fluoride group at one terminal thereof and a functional group chemically reacting with a hydroxyl group at the other terminal thereof is supplied to the entire surface of the base plate 1 to chemically react the functional group of the molecule 7 with the hydroxyl group of the oxide film 5 to form an org. molecule film 9 on the oxide film 5 of the base plate 1. By this method, a carbon fluoride film can be uniformly formed on the surface of the base plate 1. Since the carbon fluoride film is hard to adhere to a polymer of a material to be transferred, a transfer mold good in mold releasability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for transferring a fine pattern formed by lithography to the surface of a polymer material such as PMMA or polycarbonate resin. More specifically, the present invention relates to a nanometer fine processing technique useful for precisely manufacturing a semiconductor element such as an IC or an LSI or a dense optical element such as a Fresnel zone plate.

[0002]

2. Description of the Related Art One of the processes for manufacturing semiconductor devices such as IC and LSI includes a lithography process for forming a fine IC circuit pattern on the surface of a semiconductor substrate. Conventionally, a photolithography technique has been used for this lithography process. In the photolithography process, a photoresist is applied to the surface of the substrate, and the photoresist is irradiated with electromagnetic waves such as ultraviolet rays through a photomask having a predetermined pattern prepared in advance. Thus, a photomask image is printed on the photoresist, and then the photoresist is treated with a solvent to process the photoresist into a pattern of the photomask image. The semiconductor substrate is etched using this photoresist pattern as an etching mask.

However, in the case of such a conventional photolithography technique, the resolution of an image that can be printed on a photoresist is limited by the wavelength of light, so that the resolution of an image that can be printed is limited. Even if ultraviolet light having a short wavelength was used, a pattern finer than 0.1 μm could not be produced.

There is electron beam lithography as a technique for overcoming such disadvantages and producing finer patterns. However, electron beam lithography draws patterns one by one with a finely focused electron beam, so-called single-stroke writing, and thus has the drawback that it takes a considerable amount of time to draw patterns.

[0005] Similarly, as a technique for forming a fine pattern on the nanometer scale, there is a lithography technique using a scanning probe microscope such as a scanning tunnel microscope or an electron force microscope. However, these methods also have a drawback that, as in the case of electron beam lithography, a pattern is drawn one by one using a probe like a single-stroke drawing, and it takes a long time to draw a pattern.

In order to overcome the drawbacks of so-called one-stroke type lithography using an electron beam or a scanning probe microscope that the drawing speed is low and the productivity is low, a fine structure produced by these lithography techniques is used as a mold. A technique has been proposed in which a microstructure is transferred onto the surface of a polymer layer by pressing a mold against a polymer layer formed on a substrate.

[0007]

However, in the conventional technique of transferring a microstructured mold by pressing it against a polymer layer, it is difficult to release the mold from the polymer molecules. The polymer adhered to the mold, and a part of the polymer was easily left on the mold surface.
Therefore, the fine structure cannot be transferred to the polymer with high accuracy.
In addition, there is a problem that the durability of the mold is lowered.

The present invention has been made in view of the above circumstances, and provides a mold for performing fine processing by transfer, which has good releasability and more excellent durability. It is intended to be.

[0009]

According to the present invention, in order to achieve the above object, according to the present invention, there is provided a substrate having a desired pattern of irregularities formed on a surface thereof, and an oxide film disposed so as to cover the substrate surface. And a film disposed on the oxide film, wherein the film has fluorocarbon only on the film surface.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.

First, a method of manufacturing a mold for fine processing by transfer according to an embodiment of the present invention will be described with reference to FIGS.

First, a fine uneven shape is formed on the surface of a silicon substrate by a lithography technique using a scanning probe microscope using an organic silane monomolecular film as a resist.
Specifically, first, the silicon substrate 1 whose surface has been cleaned
Is left in a container filled with a gas containing hexamethyldisilazane molecules, and an oxide film 2
And a hexamethyldisilazane molecule are chemically reacted. Thus, an organic silane monomolecular film 3 is formed on the silicon substrate 1 as shown in FIG.

Next, the atomic force microscope probe 4 is brought sufficiently close to or in contact with the surface of the monomolecular film 3. As the probe 4, a probe made of a silicon material having conductivity by high concentration doping or a probe having conductivity by metal coating is used. Then, by applying a voltage between the silicon substrate 1 and the probe 4, an electrochemical reaction is induced in a portion of the monomolecular film 3 approaching or in contact with the probe 3, and the monomolecular film 3
Is locally decomposed. This electrochemical reaction is a reaction in which the monomolecular film 3 is oxidized and decomposed by oxygen in the atmosphere or oxygen adsorbed on the surface of the monomolecular film 3. As described above, the probe 4 and the monomolecular film 3 are brought close to or in contact with each other, and the probe 4 is relatively scanned on the monomolecular film 3 while applying a voltage, so that the monomolecular film 3 has a desired shape. Patterning is performed (FIG. 1B).

Next, the sample on which the monomolecular film 3 has been patterned is etched with an etching solution (a mixed aqueous solution of ammonium fluoride and hydrogen peroxide). The monomolecular film 3 of the silicon substrate 1 is decomposed by being scanned by the probe 4, and a portion not covered with the monomolecular film 3 is preferentially etched to form a groove (FIG. 1).
(C)).

[0015] The surface of the mold having the irregularities formed by the above process is covered with a fluorocarbon molecular film. Hereinafter, this step will be described. First, the surface of the sample 6 etched in the step of FIG. 1C is once cleaned by ultraviolet-ozone cleaning. As a result, the monomolecular film 3 remaining in the area where the probe scanning has not been performed is decomposed, and the entire surface of the sample is oxidized and covered with a clean silicon oxide film 5 having a thickness of about 2 nm (FIG. 2A). ).
Hydroxyl groups are present on the surface of the silicon oxide film 5 thus formed. The presence of hydroxyl groups is determined by ATR (Atte
nuated Total Reflection) method. Note that the ultraviolet-ozone cleaning is a method of supplying oxygen to the surface of the sample 6 and irradiating the surface with ultraviolet light to generate ozone, thereby performing cleaning.

Next, in the closed container 8, the cleaned sample 6 and a molecule in which the terminal of the fluorocarbon is substituted by a trimethoxysilyl group, that is, a fluorocarbon silane (R-
And a liquid 7 of Si (OCH ₃ ) ₃ ). Here, R represents fluorocarbon. In this embodiment mode, CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OCH ₃ ) ₃ is used as fluorocarbon silane. Then, the entire container 8 is heated to 50 to 150 ° C. to evaporate fluorocarbon silane molecules (FIG. 2).
(B)). As a result, the vapor of the fluorocarbon silane molecules fills the space in the closed container 8 and wraps around into the fine pattern on the surface of the sample 6, and the trimethoxysilyl group of the fluorocarbon silane and the surface of the sample 6 Chemically reacts with the hydroxyl groups of the oxide film, and fluorocarbon silane molecules are fixed on the entire surface of the sample 6. Thus, a monomolecular film 9 of fluorocarbon silane molecules is formed on the entire surface of the sample 6 (FIG. 2C).

At this time, since the trimethoxysilyl group at one end of the fluorocarbon silane molecule is fixed to the sample 6 side, the fluorocarbon group at the other end of the molecule is Will be located. Therefore, by this step, the monomolecular film 9 having a fluorocarbon group on the surface is converted to the sample
Can be formed on the surface.

The speed at which the second monolayer of fluorocarbon silane molecules is formed on the monomolecular film 9 is compared with the speed at which the first monolayer is formed on the sample surface. Since the sample 6 is much slower, the monomolecular film 9 can be formed on the surface of the sample 6 without precisely controlling the time for keeping the sample 6 in the closed container 8.

Finally, the sample having the monomolecular film 9 fixed on the surface is rinsed with an organic solvent and pure water and dried. As a result, as shown in FIG. 2 (c), a transfer mold composed of a substrate 1 having an oxide film 5 on its surface and a monomolecular film 9 of fluorocarbon silane molecules on the surface is patterned as shown in FIG. Complete.

The transfer type monomolecular film 9 has a fluorocarbon group on the film surface. Fluorocarbon is polycarbonate or PM
Since the adhesion to the polymer material such as the MA resin is remarkably low, the transfer mold of the present embodiment in which the surface is covered with the monomolecular film 9 also has high releasability between the mold and the polymer material. Therefore, the concave and convex pattern of the mold can be accurately transferred to the polymer material, and the number of reuses of the transfer mold can be increased.

Further, the monomolecular film 9 formed in the above-described steps is formed.
Is formed by a chemical reaction between an oxide film and fluorocarbon silane molecules, so that it is difficult to form a film by a film forming method such as vapor deposition or sputtering on a sample surface. In the same manner as described above, the monomolecular film 9 having a uniform thickness can be formed. Thereby, it is possible to prevent the material to be transferred from adhering to the transfer mold at any part of the mold surface.

Further, since the monomolecular film 9 is bonded to the oxide film 5 by a chemical reaction, both are strongly bonded, and the monomolecular film 9 is less likely to peel off.

In addition, since the monomolecular film 9 has a thickness of only one molecule, there is no concern that the shape of the surface of the sample 6 is impaired even if it is fine irregularities on the order of nanometers. Therefore, a transfer mold having a fine pattern can be manufactured.

In this embodiment, in order to supply fluorocarbon silane molecules to the surface of the sample 6, a method of arranging the sample 6 in a container filled with vapor of fluorocarbon silane molecules is used. Instead of such a gas phase method, a liquid phase method, for example, in a methanol solution of fluorocarbon silane,
Can also fix fluorocarbon molecules on the surface of the sample.

Further, in this embodiment, the terminal functional group is a trimethoxysilyl fluorocarbon silane molecule as a molecule for forming the monomolecular film 9, but a group which reacts with a hydroxyl group of the oxide film 5 is used. In this case, a molecule having such a group as a terminal functional group can be used. For example, a molecule having another alkoxysilyl group such as a triethoxysilyl group or a halogenated silyl group such as trichlorosilyl can be used as the terminal functional group. Further, the length of the carbon chain of the fluorocarbon of the molecule for forming the monomolecular film 9 is not limited to the above-mentioned length of the carbon chain of the molecule. If so, a molecule whose carbon chain length is freely designed can be used. For example, specifically, the following molecules (1) to (7) can be used as molecules for forming the monomolecular film 9.

[0026]

Embedded image

When a trimethoxysilyl group or a halogenated silyl group is used as a terminal functional group as a molecule for forming the monomolecular film 9, the hydroxyl group of the oxide film 5 can be formed at a normal temperature and a normal pressure of 50 ° C. to 150 ° C. And the monomolecular film 9 can be easily formed. However, it is also possible to carry out this process at high temperature and high pressure. In this case, a monomolecular film 9 is formed by using a molecule whose terminal functional group is an alcohol group and reacting the molecule with a hydroxyl group of the oxide film 5. Can be.

Further, in this embodiment, in order to clean the surface of the sample 6 and to form a clean oxide film 5,
Although ultraviolet-ozone cleaning was performed, this process can be replaced with a cleaning process using a solution. For example, similar effects can be obtained by washing with an acid such as hydrochloric acid or sulfuric acid, or a mixed solution of hydrochloric acid or sulfuric acid and a hydrogen peroxide solution.

In the present embodiment, an organic silane monomolecular film 3 is used as a resist when the silicon substrate 1 is finely processed into a desired pattern by etching, and a voltage is applied to the monomolecular film 3 from an atomic force microscope probe. However, as long as the silicon substrate can be processed into a desired fine structure, another method can be used without being limited to this method. For example, the silicon substrate 1 can be finely processed by ordinary photolithography and etching.

In this embodiment, the film of fluorocarbon silane molecules formed on the surface of the sample is a monomolecular film.
It does not necessarily have to be a monomolecular film;
The same effect can be obtained even when a multimolecular film in which molecules are stacked is used.

Next, a method of performing fine processing using the transfer mold manufactured according to the present embodiment will be described.

First, a method of performing fine processing by transfer by compression molding will be described. When performing microfabrication by compression molding, first, the transfer mold is heated to 100 to 120 ° C., and this is pressed against, for example, an acrylic resin surface. Thereby, the concave and convex pattern on the transfer mold surface can be transferred onto the resin substrate, and the resin substrate can be finely processed. At this time, since the transfer mold of the present embodiment has a monomolecular film having a fluorocarbon group formed on the surface, the transfer mold has good releasability from the acrylic resin, and the transfer mold surface pattern is precisely formed on the acrylic resin. Can be transferred to Further, even if the transfer is repeated, the acrylic resin does not adhere to the transfer mold, so that the transfer mold can be used repeatedly without damaging the pattern.

Next, a method of performing fine processing by transfer using an ultraviolet polymerization resin will be described. A spacer is sandwiched between the transfer mold and the quartz glass, and an ultraviolet polymerization resin is injected into a gap between the transfer mold and the quartz glass. Then, ultraviolet rays are irradiated from the back side of the quartz glass to cure the ultraviolet polymerized resin.
Since the transfer mold is formed with a monomolecular film having a fluorocarbon group on the surface, the adhesiveness of the cured resin to the transfer mold is lower than the adhesiveness to quartz glass. When the resin is removed, the cured resin remains on the quartz glass side. Therefore, a resin film pattern using quartz glass as a substrate can be obtained.

The processing of the resist in the process of manufacturing a semiconductor element such as an IC can be performed by compression molding using the transfer mold of the present embodiment. In this case, a resist film is formed on a semiconductor substrate and heated, and a transfer mold is pressed against the resist film to transfer an uneven pattern onto the resist film. Thereafter, when the entire resist is etched to such an extent that the concave portions of the concave-convex pattern of the resist film become through holes, the resist film remains only in the convex portions. The substrate can be etched using this resist as an etching mask. Since this method does not use light unlike photolithography, there is an advantage that the resolution is not limited by the wavelength of light.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as an embodiment of the present invention, a transfer mold for manufacturing a diffraction grating and a method for manufacturing a diffraction grating using the same will be described.

First, a method of manufacturing a transfer mold for a diffraction grating will be described. As shown in FIG. 3, a single-crystal silicon substrate 10 whose main plane 11 has 100 surfaces is treated with a 1% hydrofluoric acid solution, and
At the same time as removing the natural oxide film on the surface 11, the surface is terminated with hydrogen. The substrate 10 whose surface 11 is hydrogen-terminated is scanned by a probe 12 of a scanning probe microscope while applying a voltage between the two. Thereby, the surface 1
A line of the oxide film 13 is drawn on 1.

Next, the substrate 10 on which the lines of the oxide film 13 are formed is etched in a 25% by weight aqueous solution of tetramethylammonium hydroxide. The etching selectively proceeds on the surface where the oxide film 13 is not formed, and as a result, fine grooves 14 are formed in the silicon substrate 10 as shown in FIG.

Thereafter, similarly to the above-described embodiment, the silicon substrate 10 is subjected to ultraviolet-ozone cleaning to form a clean oxide film on the entire surface of the silicon substrate 10 in which the grooves 14 are formed. Furthermore, a monomolecular film is formed on the surface of the silicon substrate 10 by arranging the substrate 10 in a container filled with the vapor of fluorinated alkylsilane, as in the above-described embodiment. The monomolecular film has a fluorocarbon group on the surface. As described above, the transfer mold 15 for the diffraction grating can be manufactured.

Next, a method of manufacturing a diffraction grating using the transfer mold 15 will be described.

First, the acrylic resin substrate 1 as a transfer material
6 was heated to a temperature equal to or higher than the glass transition point.
5 is pressed to transfer the shape of the groove 14 of the transfer die 15 onto the acrylic resin substrate (FIG. 6). After the transfer, the transfer mold 15 is separated from the acrylic resin substrate 16 to obtain the diffraction grating 17.

Since the transfer mold 15 of this embodiment is covered with a monomolecular film having a fluorocarbon group on its surface, the acrylic resin substrate 16 and the transfer mold 15 can be separated from each other cleanly. In addition, since the thickness of the monomolecular film is extremely small, ie, one molecule, even if the groove 14 has irregularities on the order of nanometers,
Since a monomolecular film can be coated without impairing the groove shape, a diffraction grating having a pitch on the order of nanometers can be easily manufactured by transfer. In addition, since the transfer type has a monomolecular film, it can be repeatedly used without the acrylic resin adhering to the groove shape being damaged. For this reason, a diffraction grating having a pitch on the order of nanometers can be mass-produced by transfer.

[0042]

As described above, according to the present invention, it is possible to provide a transfer mold for performing fine processing by transfer, which has good releasability and excellent durability. It is.

[Brief description of the drawings]

FIGS. 1A, 1B, and 1C are cross-sectional views showing steps of manufacturing a transfer mold according to an embodiment of the present invention.

FIGS. 2A, 2B, and 2C are cross-sectional views illustrating steps of manufacturing a transfer mold according to an embodiment of the present invention.

FIG. 3 is an explanatory view showing a manufacturing process of a transfer mold for a diffraction grating according to one embodiment of the present invention.

FIG. 4 is an explanatory view showing a manufacturing process of a transfer mold for a diffraction grating according to one embodiment of the present invention.

FIG. 5 is an explanatory view showing a manufacturing process of a transfer mold for a diffraction grating according to one embodiment of the present invention.

FIG. 6 is an explanatory view showing a step of manufacturing a diffraction grating using the transfer mold according to one embodiment of the present invention.

FIG. 7 is an explanatory view showing a step of manufacturing a diffraction grating using the transfer die according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Oxide film, 3 ... Organosilane monomolecular film, 4 ... Probe, 5 ... Oxide film,
6 ... sample, 7 ... fluorocarbon silane liquid, 8.
..Closed container, 9: monomolecular film of fluorocarbon silane molecules, 10: single crystal silicon substrate, 11: substrate surface, 12: probe, 13: oxide film, 14 ...
Groove, 15: transfer type, 16: acrylic resin substrate,
17 ... Diffraction grating.

Claims (9)

[Claims] A substrate having a desired pattern of irregularities formed on a surface thereof; an oxide film disposed so as to cover the substrate surface; and a film disposed on the oxide film. A transfer mold, wherein the film is chemically bonded to the oxide film and has fluorocarbon only on the film surface. 2. The transfer mold according to claim 1, wherein the film is made of an organic molecule having a terminal carbon fluoride group. 3. The transfer mold according to claim 2, wherein the film is a monomolecular film of the organic molecule. 4. A substrate having a desired pattern of irregularities formed on a surface thereof; an oxide film disposed to cover the substrate surface; and a film containing carbon fluoride disposed on the oxide film. Wherein the oxide film is chemically bonded to the film. 5. A first step of processing the surface of the substrate into a desired concavo-convex pattern to be transferred, a second step of forming an oxide film on the entire surface of the substrate, and a fluorocarbon group at one end. By supplying an organic molecule having a functional group that chemically reacts with a hydroxyl group at the other end to the entire surface of the substrate, the hydroxyl group of the oxide film and the functional group chemically react with each other to form an oxide film on the substrate. A third step of forming a film of the organic molecule thereon. 6. The method according to claim 5, wherein in the third step,
A method for manufacturing a transfer die, comprising: disposing the substrate in a space filled with vapor of the organic molecule in order to supply the organic molecule to the entire surface of the substrate. 7. The method according to claim 5, wherein the organic molecule is
A method for producing a transfer mold, comprising using fluorocarbon silane. 8. The method according to claim 5, wherein in the second step,
A method for manufacturing a transfer mold, wherein the surface of the substrate is subjected to ozone treatment in order to form an oxide film on the entire surface of the substrate. 9. The method according to claim 5, wherein in the first step,
In order to form the uneven pattern, a resist film is formed on the substrate, a probe is brought close to the resist film, and a voltage is applied between the probe and the substrate to locally decompose the resist film. And etching the substrate using the resist film as an etching mask.