TW201428819A - Nanoimprint method, and manufacturing method for patterned substrate - Google Patents

Abstract

[Problem] To improve the issues of decreased efficiency and the volatilization of curable resin in nanoimprinting, while enabling a reduction in the occurrence of unfilled defects. [Solution] A nanoimprinting method using a mold (1) having a microrelief pattern on the surface thereof, wherein: the mold (1) and a substrate (2) are arranged so that a resist (3) coated on the substrate (2) faces the relief pattern the size of the part of the surface of a space region above the pattern region sandwiched between the mold (1) and the substrate (2) that comes into contact with the atmosphere is smaller than the size of the part of the resist (3) that is present over the pattern region and after the air pressure of the atmosphere has been reduced to below 10kPa when the mold (1) is not in contact with the resist (3), the mold (1) is pressed onto the substrate (2).

Description

Nano imprint method and method of manufacturing patterned substrate using same

The present invention relates to a nanoimprint method using a mold having a fine concavo-convex pattern on its surface, and a method of manufacturing a patterned substrate using the same.

Nanoimprinting is a method of attaching (embossing) a pattern formed by a concave-convex pattern (generally referred to as a mold, a film, a template) to a photoresist coated on a substrate to be transferred, so that the photoresist is affected by the photoresist. A technique in which a force is deformed or flows to precisely transfer a fine pattern to a photoresist film. Since it is possible to simply repeat the formation of a nano-scale fine structure by making a mold once, it is economical and is also a transfer technology with less harmful waste and less effluent, and has been expected in recent years. It is used in various fields such as the semiconductor field.

In the conventional nanoimprinting, it is important to reduce unfilled defects (defects caused by residual gas). As a method of reducing the unfilled defect, for example, a method of performing imprinting under a reduced pressure (or vacuum) environment or a helium (He) environment is known (Patent Documents 1 to 4).

In the case where embossing is performed under a reduced pressure environment, the effect of reducing unfilled defects is reduced by directly reducing the gas remaining between the mold and the photoresist. On the other hand, in the case of performing imprinting in a helium atmosphere, even if helium remains between the mold and the photoresist, by blowing the helium gas The removal of residual helium gas through the mold or substrate containing quartz also has the effect of reducing unfilled defects.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open Publication No. 2004-071934

Patent Document 2 Japanese Patent Laid-Open Publication No. 2004-103817

Patent Document 3 Japanese Patent Publication No. 2007-509769

Patent Document 4 Japanese Patent Laid-Open Publication No. 2011-210942

However, in the case of performing imprinting under a reduced pressure environment, there is a case in which a problem arises due to volatilization of a curable resin constituting a photoresist, for example. For example, in general, when a photoresist is thinly coated on a substrate (for example, several tens of nanometers) in order to reduce the thickness of the residual film, the curable resin is locally insufficient due to volatilization of the curable resin, and further occurs. A case where a defect is generated in a transfer pattern.

Further, in the case where the imprinting is performed in a helium atmosphere, since the penetration speed of the helium gas is slow, the time for pressing the photoresist by the mold must be lengthened, and the overall efficiency of the nanoimprinting step is lowered.

The present invention has been made in view of the above problems, and an object thereof is to provide a nanoimprint method capable of improving the problem of volatilization and inefficiency of a curable resin in nanoimprinting and reducing the occurrence of unfilled defects.

Furthermore, another object of the present invention is to provide a method of manufacturing a patterned substrate which can reduce the occurrence of pattern defects in the manufacture of a patterned substrate.

In order to solve the above problems, the nanoimprint method of the present invention is a nanoimprint method using a mold having a fine concavo-convex pattern on the surface, which is characterized in that a mold and a substrate are disposed such that the concave-convex pattern and the light applied to the substrate are applied. The area of the portion of the surface of the space region on the pattern region sandwiched by the mold and the substrate is in contact with the ambient gas, and is smaller than the surface area of the portion of the photoresist coated on the substrate on the pattern region; The pressure of the ambient gas was reduced to less than 10 kPa in a state of not being in contact with the photoresist, and the mold was pressed against the substrate.

In the present specification, the "space region on the pattern region" refers to a region of the surface of the mold on which the concave-convex pattern is actually formed and the space region sandwiched by the substrate surface.

Next, in the nanoimprint method of the present invention, it is preferred to reduce the pressure of the ambient gas to 5 kPa or less.

Further, in the nanoimprint method of the present invention, it is preferable to apply a photoresist to the substrate by performing an inkjet method.

Further, the nanoimprint method of the present invention is preferably carried out in a helium atmosphere.

Further, in the nanoimprint method of the present invention, a mold having a platform type structure is preferably used as the above mold.

A method for producing a patterned substrate according to the present invention is characterized in that a photoresist film on which a concave-convex pattern is transferred is formed on a substrate by the above-described nanoimprint method, and the photoresist film is used as a mask and etched On the substrate, a concave-convex pattern corresponding to the concave-convex pattern transferred to the photoresist film is formed on the substrate.

The nanoimprinting method of the present invention is characterized in that the area of the portion of the surface of the space region above the pattern region sandwiched by the mold and the substrate is in contact with the ambient gas, and the pattern is smaller than the photoresist coated on the substrate. The surface area of the portion on the region is depressurized after the mold and the substrate are brought into close contact with each other such that the mold is not in contact with the photoresist. Therefore, even if it is decompressed to the extent that the constituent material of the photoresist is volatilized as in the past, it is possible to suppress the volatilization. This is considered to be because the space between the mold and the substrate is narrow, so that the concentration distribution of the volatilized material tends to be in an equilibrium state. Then, since the imprinting can be performed under reduced pressure, the generation of residual gas can be reduced. As a result, in the nanoimprinting, the problem of volatilization and low efficiency of the curable resin can be improved, and the occurrence of unfilled defects can be reduced.

Further, in the method for producing a patterned substrate of the present invention, the uneven pattern is transferred to the resist film by the above-described nanoimprint method, so that the occurrence of pattern defects can be reduced in the production of the patterned substrate.

1‧‧‧Mold

2‧‧‧Substrate

3‧‧‧Photoresist film

3a‧‧‧Photoresist part

3b‧‧‧ photoresist part

4‧‧‧Gap area

4a‧‧‧Parts in contact with ambient gases

4b‧‧‧ parallel dotted lines

5‧‧‧ photoresist droplets

5a‧‧‧Parts on the pattern area P

5b‧‧‧ photoresist part

S1‧‧‧ surface area

S2‧‧‧ surface area

10‧‧‧ Platform Department

11‧‧‧Flange

P‧‧‧ pattern area

D‧‧‧distance

Fig. 1 is a schematic cross-sectional view showing the relationship between a gap region on a pattern region and a photoresist film.

Figure 2 is a schematic cross-sectional view showing the relationship between the gap region on the pattern area and the photoresist droplets.

3 is a graph showing the relationship between the ratio of the side area of the gap region to the surface area of the photoresist on the pattern region and the volatilization speed of the photoresist material.

[Implementation of the invention]

The embodiments of the present invention are described below using the drawings, but the present invention is not limited by the embodiments. Moreover, in order to make it easy to visually confirm, the dimensional ratio of each component in the drawing is moderately different from the actual one.

Fig. 1 is a schematic cross-sectional view showing the relationship between a gap region on a pattern region and a photoresist film.

In the nanoimprint method of the present embodiment, for example, the mold 1 and the substrate 2 are placed, and the uneven pattern is opposed to the resist film 3, and the resist film 3 is uniformly applied to the substrate 2 by a spin coating method or the like. The area of the portion of the surface of the pattern region P (the gap region 4) sandwiched by the mold 1 and the substrate 2 in contact with the ambient gas is smaller than that of the photoresist film 3 coated on the substrate 2. There is a surface area S ₁ of the portion 3a on the pattern region P, and in a state where the mold 1 is not in contact with the photoresist film 3 (FIG. 1), after the pressure of the ambient gas is reduced to less than 10 kPa, the mold 1 is pressed to The substrate 2 is cured by a photoresist, and the mold 1 is peeled off from the photoresist film 3.

2 is a schematic cross-sectional view showing the relationship between the gap region on the pattern region and the photoresist droplet. In the present invention, for example, as shown in Fig. 2, a method of arranging droplets by an inkjet method or the like may be employed to apply the photoresist. In this case, for example, the mold 1 and the substrate 2 are placed, and the uneven pattern is opposed to the liquid droplet 5 of the photoresist disposed on the substrate 2 by an inkjet method or the like, and the pattern region sandwiched by the mold 1 and the substrate 2 is placed. The area of the portion of the space on the P (the gap region 4) that is in contact with the ambient gas is smaller than the total surface area nS ₂ of the portion 5a on the pattern region P in the droplet 5 coated on the substrate ₂ , and In a state where the mold 1 is not in contact with the liquid droplets 5 (FIG. 2), after the pressure of the ambient gas is reduced to less than 10 kPa, the mold 1 is pressed against the substrate 2. Further, n is the number of droplets 5a, and S ₂ is the surface area of each droplet 5a.

(mold)

The mold 1 used in the embodiment can be manufactured, for example, in the following order. First, an acrylic resin such as a polyhydroxy styrene-based chemically amplified photoresist, a phenol resin-based photoresist, or a polymethyl methacrylate (PMMA) is used as a spin coating method. A photoresist of a main component is coated on the tantalum substrate to form a photoresist layer. Thereafter, on the one hand, the laser light (or electron beam) is modulated corresponding to the expected concave-convex pattern, and on the other hand, it is irradiated to the germanium substrate to expose the concave-convex pattern on the surface of the photoresist layer. Thereafter, the photoresist layer is subjected to development processing, and the pattern of the developed photoresist layer is used as a mask, and selective etching is performed by reactive ion etching (RIE) or the like to obtain a tantalum mold having a predetermined uneven pattern.

On the other hand, the mold is not limited thereto, and a quartz mold can also be used. In this case, the quartz mold can be manufactured by the same method as the above-described method for producing a tantalum mold, or a method of producing a patterned substrate (replica) to be described later.

As shown in FIGS. 1 and 2, the mold 1 may have a platform type structure including a platform portion 10 (the top surface is relatively flat and higher than the surrounding portion), and a flange portion 11 around it. The step of the platform portion 10 is preferably 1 to 1000 μm, more preferably 10 to 500 μm, and more preferably 20 to 100 μm. In the case of performing nanoimprinting using the mold 1 of the platform type structure, the contact area between the mold and the photoresist is reduced, and the mold can be peeled off from the photoresist with a small force as compared with the case of using a flat mold. This advantage. In addition, for example, in the case of repeating a transfer pattern (Step and Repeat) on the same substrate, by using a mold of a platform type structure, "the mold can be prevented from being transferred first when the next pattern is transferred. The printed pattern causes the pattern of the first transfer to be crushed.

(release treatment)

In the present invention, in order to improve the release property of the photoresist 3 from the surface of the mold 1, it is preferable to perform a release treatment on the concave-convex pattern surface of the mold 1. For the release agent to be used for the release treatment, OPTOOL (registered trademark) DSX manufactured by Daikin Industries Co., Ltd., Novec (registered trademark) EGC-1720 manufactured by Sumitomo 3M Co., Ltd., etc. Decane coupling agent.

Further, a well-known fluorine-based resin, a hydrocarbon-based lubricant, a fluorine-based lubricant, a fluorine-based decane coupling agent, or the like can be used.

For example, examples of the fluorine-based resin include polytetrafluoroethylene (PTFE; Poly Tetra Fluoro Ethylene) and tetrafluoroethylene. Perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene. Hexafluoropropylene copolymer (FEP), tetrafluoroethylene. Ethylene copolymer (ETFE).

Examples of the hydrocarbon-based lubricant include carbonates such as stearin and oleic acid, esters such as butyl stearate, sulfonic acids such as Octadecyl Sulfonic acid, and monooctadecane phosphate. Phosphates such as Phosphoric acid (monooctadecyl ester), alcohols such as stearyl alcohol and oleyl alcohol, carboxylic acid amides such as stearylamine, and stearamide Amines such as (Stearylamine).

For example, examples of the fluorine-based lubricant include a fluoroalkyl group or a perfluoropolyether group, and a part or all of the alkyl group of the hydrocarbon-based lubricant.

For example, as a perfluoropolyether group, it may be a perfluoromethylene oxide polymer, a perfluoroethylene oxide polymer, a perfluoro-n-propylene oxide polymer (CF ₂ CF ₂ CF ₂ O) _n , or a perfluoro group. An isopropylene oxide polymer (CF(CF ₃ )CF ₂ O) _n or such a copolymer or the like. Here, the letter n of the subscript indicates the degree of polymerization.

For example, the fluorine-based decane coupling agent has at least one, preferably 1 to 10, fluorenylalkyl groups and chlorodecyl groups in the molecule, and the molecular weight is preferably 200 to 10,000. For example, examples of the phosphonyl group include a -Si(OCH ₃ ) ₃ group and a -Si(OCH ₂ CH ₃ ) ₃ group; and examples of the chlorodecyl group include a -Si(Cl) ₃ group. Specifically, it is: heptadecafluoro-1,1,2,2-tetra-hydrated mercaptotrimethoxydecane, pentafluorophenylpropyldimethylchlorodecane, and tridecafluoro-1,1,2 A compound such as 2-tetra-hydrated octyltriethoxydecane, tridecafluoro-1,1,2,2-tetra-hydrated octyltrimethoxydecane.

(substrate)

The substrate 2 for imprint is preferably a quartz substrate in order to expose the photoresist to the dies. The quartz substrate is not particularly limited as long as it has translucency and has a thickness of 0.3 mm or more, and can be appropriately selected depending on the purpose. For example, a person who covers a surface of a quartz substrate with a decane coupling agent, a stack of an organic substance layer containing a polymer for enhancing adhesion to a photoresist, and the like, and a stack of Cr, W, Ti, and Ni on a quartz substrate may be mentioned. In the case of a metal layer such as Ag, Pt or Au, a metal oxide film layer containing CrO ₂ , WO ₂ or TiO _{2 is} stacked on a quartz substrate, and the surface of the above stack is coated with a decane coupling agent. The thickness of the organic layer, the metal layer or the metal oxide film layer is generally 30 nm or less, preferably 20 nm or less. When it exceeds 30 nm, the UV transmittance is lowered, and the hardening of the photoresist is liable to occur.

In addition, the above-mentioned "transparent" means that the light is sufficiently incident in the case where light is emitted from the other surface so that "the light can be emitted from one side of the substrate 2 on which the photoresist is formed" The hardening means that the transmittance of light having a wavelength of 200 nm or more from the other surface to the one surface is at least 5% or more.

The thickness of the quartz substrate is generally preferably 0.3 mm or more. If it is 0.3 mm or less, it may be damaged under the pressure during operation or imprinting.

On the other hand, the shape, structure, size, material, and the like of the substrate of the quartz mold are not particularly limited, and may be appropriately selected depending on the purpose. For example, when the application is an information storage medium, the shape is a disk shape. The structure may be a single layer structure or a stacked structure. As the material, it can be appropriately selected from known materials as a substrate material, for example. Examples thereof include ruthenium, nickel, aluminum, glass, and resins. These substrate materials may be used alone or in combination of two or more. The substrate may be a suitable synthesizer, and a commercially available product may also be used. Further, the surface may be coated with a decane coupling agent. The thickness of the substrate is not particularly limited and may be appropriately selected depending on the purpose, and is preferably 0.05 mm or more, and more preferably 0.1 mm or more. When the thickness of the substrate is less than 0.05 mm, there is a possibility that the substrate may be bent on the substrate side when the substrate is in close contact with the mold, and a uniform adhesion state cannot be ensured.

The substrate 2 may have a platform type structure in such a manner that a region in which the uneven pattern is transferred is located on the land portion. By the presence of the pedestal, the portion in contact with the mold can be limited to the surface of the pedestal, so that structural contact with the pattern forming region of the substrate can be avoided. The preferred range of the step of the platform portion is the same as in the case of the mold. Further, as long as either one of the mold and the substrate has a land-type structure, the above effects can be obtained.

(photoresist)

The photoresist is not particularly limited, and in the embodiment, for example, a photopolymerization initiator (about 2% by mass) or a fluorine monomer (0.1 to 1% by mass) may be added to the polymerizable compound. Modulated photoresist.

In addition, an antioxidant (about 1% by mass) may be added depending on the demand. The photoresist produced in the above order can be hardened by ultraviolet light having a wavelength of 360 nm. For those with poor solubility, it is preferred to remove the solvent after adding a small amount of acetone or ethyl acetate and dissolving it.

As the above-mentioned polymerizable compound, in addition to benzyl acrylate (VISCOAT (registered trademark) #160: manufactured by Osaka Organic Chemical Co., Ltd.), diethylene glycol monoethyl ether acrylate (VISCOAT (registered trademark)# 190: Osaka Organic Chemical Co., Ltd.), polypropylene glycol diacrylate (ARONIX (registered trademark) M-220: manufactured by Toagosei Co., Ltd.), trimethylolpropane PO modified triacrylate (ARONIX (registered) In addition to the trademark (M-310: manufactured by Toagosei Co., Ltd.), etc., the compound A represented by the following structural formula 1 etc. are mentioned.

Further, as the above polymerization initiator, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4- An alkylphenone-based photopolymerization initiator such as phenyl)phenyl]-1-butanone (IRGACURE (registered trademark) 379: manufactured by Toyota Tsusho Co., Ltd.).

In addition, as the fluorine monomer, the compound B represented by the following structural formula 2 and the like are exemplified.

For example, the photoresist has a viscosity of 8 to 20 cP and the photoresist has a surface energy of 25 to 35 mN/m. Here, the viscosity of the photoresist material is based on the RE-80L rotary viscometer (Dongji Industry Co., Ltd. (manufactured by the system), measured at 25 ± 0.2 ° C. The number of revolutions at the time of measurement is 100 rpm in the case of 0.5 cP or more and less than 5 cP, 50 rpm in the case of 5 cP or more and less than 10 cP, 20 rpm in the case of 10 cP or more and less than 30 cP, and 10 rpm in the case of 30 cP or more and less than 60 cP. Further, the surface energy of the photoresist is the method described in "UV nanoimprint materials: Surface energies, residual layers, and imprint quality", H. Schmitt, L. Frey, H. Ryssel, M. Rommel, C. Lehrer, J. Vac. Sci. Technol. B, Volume 25, Issue 3, 2007, Pages 785-790. Specifically, the surface energy of the ruthenium substrate after the ultraviolet ray treatment and the surface energy of the ruthenium substrate surface-treated with OPTOOL (registered trademark) DSX (manufactured by Daikin Co., Ltd.) are obtained, respectively, and the photoresist material is further obtained from the photoresist material. The surface energy of the photoresist material was calculated with respect to the contact angle of the two substrates.

Further, a compound having a strong intermolecular interaction and low volatility (for example, a surfactant) may be added. In this case, when the photoresist is applied, since the compound is formed on the surface of the photoresist surface so as to be mostly distributed at the gas-liquid interface of the photoresist, the effect of "suppressing the volatilization of the photoresist material" can be obtained. Such an effect is particularly effective for suppressing volatilization of a highly volatile polymerizable compound which is a main component of the photoresist.

(Method of coating photoresist)

As a method of applying the photoresist, an inkjet method, a spray method, or the like can be used, and a predetermined amount of droplets can be placed on a predetermined position on a substrate or a mold, or a spin coating method, a dip coating method, or the like, and a uniform film can be used. A method of thick coating photoresist. Formed on a substrate by spin coating or the like In the case of a uniform film, it is difficult to control the film thickness corresponding to the uneven pattern described later, and therefore it is preferable to arrange the liquid droplets at a predetermined position. In addition, compared with a uniform film, the method of arranging minute droplets reduces the area of the gas-liquid interface when coating the same volume of photoresist, and can reduce the influence of the evaporation of the photoresist.

When the droplets of the photoresist are disposed on the substrate, an inkjet printer or a dispenser may be used correspondingly to the desired amount of droplets. For example, there is a method of using an inkjet printer when the amount of droplets is less than 100 nl, and using a dispenser when it is 100 nl or more.

Examples of the ink jet head that ejects the photoresist from the nozzle include a piezoelectric type, a thermal type, and an electrostatic type. Among these methods, a piezoelectric method in which an appropriate amount of liquid (amount of each droplet to be disposed) and a discharge speed can be adjusted is preferable. The droplet amount or the discharge speed is adjusted in advance before the droplet of the photoresist is placed on the substrate. For example, in a position corresponding to a region where the spatial volume of the concave-convex pattern of the mold is large on the substrate, it is preferable to adjust an appropriate amount of liquid to a position corresponding to a region where the spatial volume of the concave-convex pattern of the mold is small on the substrate. It is advisable to adjust the appropriate amount of liquid to a lesser extent. Such adjustment can be appropriately controlled in accordance with the amount of droplet discharge (the amount of each droplet 1 discharged). Specifically, in the case where the amount of liquid droplets is set to 5 pl, the amount of liquid droplets is controlled so that the inkjet head having the droplet discharge amount of 1 pl is discharged five times in the same place. For example, the three-dimensional shape of the liquid droplets discharged onto the substrate under the same conditions can be measured by a confocal microscope or the like, and the volume can be calculated from the shape to determine the amount of liquid droplets.

After the amount of droplets is adjusted in the above manner, droplets are placed on the substrate in accordance with a predetermined droplet arrangement pattern. Again, with droplets The two-dimensional coordinate information formed by the lattice group corresponding to the position on the substrate constitutes a droplet arrangement pattern.

(imprint)

Although the vapor pressure of the constituent materials of the above-mentioned photoresist is different depending on the molecular structure and mixing ratio of each compound, it is substantially in the range of 0.1 kPa or more and less than 10 kPa. This value is a vacuum that can be easily achieved using a general vacuum pump. Therefore, if the photoresist material is exposed to a reduced pressure environment or a vacuum environment (especially less than 10 kPa, hereinafter referred to as a reduced pressure environment) below the vapor pressure by the nanoimprint method in the prior art, the photoresist material is used. Volatilization causes a problem of "increased defects due to the volatilization". If the gas pressure is set to a value higher than the vapor pressure in order to avoid the influence of volatilization, an unfilled defect occurs due to the influence of the residual gas component existing in the reduced pressure environment. On the other hand, in order to eliminate the residual gas, there is a method of forming a helium atmosphere at a vacuum of 10 kPa or more, and allowing residual helium gas to penetrate the photoresist, the mold, or the substrate to reduce unfilled defects. The disappearance of gas takes time, resulting in poor productivity, and it is also difficult to completely eliminate unfilled defects.

In the present invention, before the mold 1 comes into contact with the photoresist 3, a residual pressure is formed by forming a pressure-reduced environment in a gap region sandwiched between the mold 1 and the substrate 2. However, in a reduced pressure environment, there is a problem that "the photoresist material before curing is volatilized, and it is difficult to control the film thickness". Therefore, as long as the amount of volatilization of the photoresist under a reduced pressure environment can be reduced, the occurrence of unfilled defects due to residual gas can be reduced, and the occurrence of insufficient photoresist due to volatilization of the photoresist can be reduced.

The inventors of the present invention have found that the gap region 4 is a reduced pressure environment after the distance between the mold 1 and the substrate 2 is brought close to an appropriate distance, and the amount of volatilization of the photoresist material can be reduced even under a reduced pressure environment. More specifically, the area of the portion 4a in contact with the ambient gas in the surface of the gap region 4 on the pattern region P is made smaller than the surface area of the photoresist portion 3a on the pattern region P, and the mold 1 is not combined with the light. In the manner of blocking the contact, the mold 1 and the substrate 2 are brought close to each other, and then the pressure is reduced.

The gap region 4 refers to a space region in which the region where the concave-convex pattern is actually formed (that is, the pattern region P) and the surface of the substrate 2 are sandwiched in the surface of the mold 1. For example, in FIG. 1 and FIG. 2, the gap region 4 is a region surrounded by a dotted line 4a perpendicular to the mold 1 and the substrate 2 and a parallel dotted line 4b, and can be viewed in a three-dimensional manner. It is said that the bottom surface has a columnar body region having the same shape as the pattern region P. In this case, the portion 4a of the surface of the gap region 4 that is in contact with the ambient gas means a portion that is open to the environment, that is, a side surface of the columnar body. In the case where the concave-convex pattern is divided by a plurality of cells, if the cells are spaced apart from each other (for example, 5 mm or less), the cells may be treated as a continuous structure, and for the continuous cells, the cells may be included. The parts between each other are treated as one pattern area.

When the distance between the mold 1 and the substrate 2 is d and the length of the outer circumference of the pattern region P is L, the area of the side surface is indicated by dL. Therefore, "the area of the portion 4a in contact with the ambient gas among the surfaces of the gap region 4 on the pattern region P is smaller than the surface area of the photoresist existing on the pattern region P", and satisfies the following Expression 1. According to the formula 1, the upper limit of the distance d between the mold 1 and the substrate 2 can be specified.

dL<S (Formula 1)

In Formula 1, S represents the surface area of the photoresist existing in the pattern region P. For example, as shown in FIG. 1, in the case where a uniform photoresist film 3 is formed on the substrate 2, S becomes the surface area S of the photoresist portion 3a included in the gap region 4 (or corresponding to the pattern region P). ₁ . Therefore, when the specific value of S is determined, the photoresist portion 3b not included in the gap region 4 is not considered. On the other hand, for example, as shown in FIG. 2, in the case where the droplet 5 of the photoresist is placed on the substrate 2, S becomes the total surface area nS ₂ of the photoresist portion 5a included in the gap region 4. In this case, when the specific value of S is determined, the photoresist portion 5b not included in the gap region 4 is not considered.

Formula 1 is derived from the following experimental data. 3 is a graph showing the relationship between the side area of the gap region 4 and the total surface area nS ₂ of the photoresist on the pattern region P (=dL/nS ₂ ), which is related to the volatilization speed of the photoresist material. The pressure environment at this time was 5 kPa. The volatilization rate is the actual amount of volatilization per unit time, which is the amount of volatilization of the photoresist material minus the amount of volatilization and returning to the liquid state. The vertical axis shows the relative value of the volatilization velocity with respect to the free evaporation of the photoresist material (i.e., the surrounding obstacles). As can be seen from the graph, in the range of R<1, as the dL decreases, the volatilization rate also decreases. Therefore, it can be said that as long as dL < nS ₂ (= S), the occurrence of the insufficient photoresist can be reduced. Moreover, the above-mentioned data is a case where the liquid droplets are placed on the substrate, and the same tendency is exhibited in the case where the photoresist film is formed on the substrate. Further, although the above information is a case where the pressure environment is 5 kPa, as long as it is a pressure smaller than the vapor pressure of the photoresist material, the other pressures also show the same tendency.

The above phenomenon is considered to be caused by the following reasons. In general, the concentration of the photoresist material in the gas phase (here in a reduced pressure environment) decreases as it leaves the liquid phase surface. The more rapid the change in concentration (concentration gradient), the higher the rate of volatilization. On the other hand, if the photoresist material volatilized in the gas phase reaches a saturated state, the phase change is closer to the equilibrium state near the interface (the amount of components volatilized from the liquid phase to the gas phase and the component returned from the gas phase to the liquid phase) When the amount is equal, the volatilization speed is lowered. Therefore, it can be considered that even if the volatilization of the photoresist material occurs, as long as it is treated in such a manner that "the volatilization portion contributes to the elimination of the concentration gradient", the unrestricted volatilization of the photoresist material can be avoided by itself, thereby reducing the occurrence of the above-mentioned occurrence. Insufficient photoresist. If the above situation is considered, even the volatilized photoresist material contributes to the elimination of the concentration gradient while remaining in the gap region 4, and also has a photoresist material which returns to the liquid phase as the case may be. In fact, it can be considered that it has not had a serious impact in nanoimprinting. However, once the volatilized photoresist material leaves the gap region 4, it does not contribute to the elimination of the concentration gradient, and the possibility of returning to the liquid phase photoresist material is also low, so that a problem arises. If the area dL of the portion 4a in contact with the ambient gas is reduced in the surface of the gap region 4, the volume of the gap region 4 is reduced, and the outlet from which the volatilized photoresist material escapes from the gap region 4 is narrowed. Therefore, it can be considered that the photoresist material volatilized in the gas phase is also saturated, so that the volatilization speed can be reduced.

Thus, it is preferable that the area dL of the portion 4a in contact with the ambient gas among the surfaces of the gap region 4 is smaller than the surface area S of the photoresist layer, and it is preferable to make dL < 0.2S.

On the other hand, the shorter the distance between the mold 1 and the substrate 2, the more the influence of volatilization can be reduced, but it is necessary to avoid the case where the mold 1 is in contact with the photoresist. This is because if the mold 1 comes into contact with the photoresist before the formation of the reduced pressure environment, the bubbles enter between the mold 1 and the photoresist 3, and unfilled defects may occur. Therefore, the lower limit of the distance d between the mold 1 and the substrate 2 is defined so as to correspond to the film thickness of the photoresist film 3 and the height of the photoresist droplets 5 in the nanoimprint. In general, as long as the total amount of the photoresist is the same, the height of the photoresist droplet is higher than the film thickness of the photoresist film. Therefore, in the case where the photoresist droplet is disposed, the distance between the mold 1 and the substrate 2 is preferably, for example, 1 μm or more. More preferably, it is 10 μm or more.

As described above, for reducing the amount of volatilization, for example, in It is important to form a reduced pressure environment after the distance between the mold 1 and the substrate 2 held in parallel with each other is close. That is, the decompression operation itself may be started before the mold 1 approaches the substrate 2, and if the pressure environment is less than 10 kPa, the above formula 1 may be satisfied. It is preferable to make the environment between the mold and the substrate a helium gas decompression environment, thereby reducing the residual gas more efficiently. The reduced pressure environment is preferably 1 kPa or more and less than 10 kPa, and particularly preferably 1 kPa or more and 5 kPa or less.

The substrate 2 and the mold 1 on which the photoresist is formed are brought into contact with each other so as to overlap each other so as to form a predetermined relative positional relationship. Calibration marks should be used for positional coincidence. It is preferable to form a calibration mark by a concavo-convex pattern which can be detected using an optical microscope, a Moire Interferometry or the like. The accuracy of the positional overlap is preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 100 nm or less.

The pressure to which the mold 1 is pressed is performed in a range of 100 kPa or more and 10 MPa or less. The pressure is larger, and the surface shapes of the mold 1 and the substrate 2 are easily imitated, and the flow of the photoresist can be promoted. Further, in the case where the pressure is large, the removal and compression of the residual gas, the dissolution of the residual gas with respect to the photoresist, and the penetration of the flaw in the quartz substrate are also promoted, which is associated with the quality of the lifted resist pattern. However, if the force of the pressurization is too strong, the mold 1 or the substrate may be damaged in the case where the foreign matter is caught in contact with the mold 1. Therefore, the pressure to which the mold 1 is pressed is preferably from 100 kPa to 5 MPa, particularly preferably from 100 kPa to 1 MPa. When the pressure is 100 kPa or more, when the ink is imprinted in the air, the mold 1 and the substrate are pressurized at atmospheric pressure (about 101 kPa) when the liquid is filled between the mold 1 and the substrate.

After the mold 1 is pressed to form a photoresist film, exposure is performed with light having a wavelength matching the polymerization initiator contained in the photoresist to harden the photoresist. As a method of demolding after hardening, for example, in a state in which the back surface or the outer edge portion of one of the mold 1 or the substrate is held, and the back surface or the outer edge portion of the other substrate or mold is held, The holding portion of the outer edge or the holding portion of the back surface relatively moves in a direction opposite to the pressurization.

As described above, the nanoimprint method of the present invention is characterized in that the area of the portion of the surface of the space region sandwiched between the mold and the substrate in contact with the ambient gas is smaller than the light applied to the substrate. The surface area of the portion on the pattern region exists in the resist, and the mold and the substrate are brought close to each other so that the mold is not in contact with the photoresist, and then the pressure is reduced. Therefore, even if it is conventionally decompressed to the extent that the constituent material of the photoresist is volatilized, volatilization can be suppressed. This is considered to be because The space between the substrate and the substrate is narrow, and the concentration distribution of the volatilized material also forms an equilibrium state. Then, since the imprinting can be performed under reduced pressure, the generation of residual gas can be reduced. As a result, the problem of volatilization and low efficiency of the curable resin can be improved in the nanoimprint, and the occurrence of unfilled defects can be reduced.

Moreover, in the above-described embodiment, the case where the curable resin has photocurability is described, but the present invention is not limited thereto. That is, in the present invention, for example, a thermosetting resin can also be used.

"Manufacturing method of patterned substrate"

Next, an embodiment of a method of manufacturing a patterned substrate (for example, a mold replica) will be described. In the present embodiment, the tantalum mold is used as the original, and the above-described nanoimprint method is used to produce a replica of the mold 1.

First, the photoresist film of the transferred pattern is formed on the surface of one side of the substrate by the above-described nanoimprint method. Next, the photoresist film of the transferred pattern is used as a mask, and dry etching is performed to form a concave-convex pattern corresponding to the uneven pattern formed on the photoresist film on the substrate to obtain a substrate having a predetermined pattern.

On the other hand, in the case where the substrate has a stacked structure and the surface contains a metal layer, the photoresist film is used as a mask, dry etching is performed, and a concave-convex pattern corresponding to the uneven pattern formed on the photoresist film is formed on the metal. The layer is used as an etch stop layer, and the substrate is further subjected to dry etching to form a concave-convex pattern on the substrate to obtain a substrate having a predetermined pattern.

The dry etching is not particularly limited as long as it can form a concave-convex pattern on the substrate, and can be appropriately selected depending on the purpose, for example, Examples thereof include an ion milling method, reactive ion etching (RIE), and plasma etching. Among these methods, an ion milling method or a reactive ion etching method is particularly preferable.

The ion milling method, also known as ion beam etching, introduces an inert gas such as argon into an ion source to generate ions. The ions are passed through a grid to accelerate them, and the test piece substrate is bombarded for etching. Examples of the ion source include a Kaufman type, a high frequency type, an electron flush type, a double plasma tube type, a Freeman type, and an electron cyclotron resonance (ECR) type.

Argon gas can be used as the process gas in the ion milling method, and a fluorine-based gas or a chlorine-based gas can be used as the etchant for reactive ion etching.

As described above, according to the method of manufacturing a patterned substrate of the present invention, a photoresist film having a concavo-convex pattern and a photoresist film capable of suppressing generation of unfilled defects are used as a mask to perform etching of the substrate, and the substrate can be patterned. In manufacturing, the situation of pattern defects is reduced.

[Examples]

An embodiment of the nanoimprint method of the present invention is shown below.

(manufacturing of the mold)

A photoresist layer containing a chemically amplified photoresist such as polyhydroxy styrene (PHS) as a main component is applied onto a ruthenium substrate by a spin coating method to form a photoresist layer. Thereafter, while scanning the ruthenium substrate on the XY stage, the electron beam corresponding to the pattern modulation was irradiated, and the photoresist layer in the range of 10 mm × 10 mm was subjected to total exposure. After that, the photoresist layer is developed to remove the exposed portion and will go The removed photoresist layer pattern was used as a mask, and selective etching was performed by a reactive ion etching method so that the depth of the groove became 100 nm, thereby obtaining a ruthenium mold. The cone angle is 85 degrees. The mold surface was subjected to release treatment by OPTOOLDSX by dip coating.

In the above Si mold, the pattern is located at the center of the base material, and a region of 10 mm × 10 mm is a pattern region. The concavo-convex pattern is composed of a groove-like linear pattern having a length of 10 mm, a width of 50 nm, a pitch of 100 nm, and a depth of 100 nm.

(transferred substrate)

A quartz substrate of 152 mm × 152 mm and a thickness of 6.35 mm was used as the substrate. First, a platform portion of 10 mm × 10 mm and a height of 30 μm was formed by wet etching at a transfer region in the center portion of the substrate. Then, the surface of the quartz substrate was subjected to surface treatment by using a decane coupling agent KBM-5103 (manufactured by Shin-Etsu Chemical Co., Ltd.) excellent in adhesion to the photoresist. Specifically, KBM-5103 was diluted to 1% by mass with Propylene Glycol Mono-methyl Ether Acetate, and then applied to the surface of the substrate by a spin coating method. Next, the coated substrate was placed on a hot plate, and annealed at 150 ° C for 5 minutes to bond the decane coupling agent to the surface of the substrate.

(photoresist)

The photoresist containing 48% by mass of the compound A, 48% by mass of ARONIX M220, 35% by mass of IRGACURE 379, and 1% by mass of the compound B was adjusted.

(coating step of photoresist)

DMP-2838 manufactured by FUJIFILM Dimatix Co., Ltd. was used as a piezoelectric inkjet printer. A dedicated nozzle DMC-11610 is used as an inkjet head. The discharge condition was adjusted in advance so that the amount of liquid droplets became 6 pl. The droplet arrangement pattern has a square lattice shape in which the droplet spacing is 400 μm, and the droplets are entirely disposed in the transfer region on the land portion in accordance with the droplet arrangement pattern. At this time, in the pattern area of 10 mm × 10 mm, the number of droplets was 25 × 25, a total of 625. The shape data of the droplet shape was measured by a confocal microscope, and the surface area of each droplet was calculated, and the result was 0.00788 mm ² . Therefore, the total surface area nS ₂ of the photoresist droplets is 4.92 mm ² .

(nano imprint method)

The mold and the quartz substrate are brought close to the values described in the following table, and the positions are superimposed so that the correction marks on the substrate coincide with the correction marks on the mold from the back surface of the quartz substrate.

The space between the mold and the quartz substrate was filled with helium gas to form a helium atmosphere of 99% by volume or more, and the pressure was reduced to 5 kPa. Under the condition of depressurizing helium, the position of the mold with respect to the substrate is superposed and contacted with the droplet containing the photoresist. The time before the pressure reached 5 kPa and before the mold was in contact with the photoresist was about 5 minutes.

After the contact, the film was pressed at a pressure of 300 kPa for 5 seconds, and exposed to ultraviolet light having a wavelength of 360 nm to form an exposure amount of 300 mJ/cm ² to cure the photoresist. In a state in which the outer edge portion or the back surface of the substrate and the mold are mechanically attracted, the substrate or the mold is relatively moved in a direction opposite to the pressurization, whereby the mold is peeled off.

(evaluation method)

The concave-convex pattern of the photocurable resin film in the pattern region was examined by a scanning electron microscope.

The case where the pattern defect not seen in the normal pattern is detected is regarded as a defect caused by the residual gas. Calculate the total number of defects in the defect caused by residual gas. In the case where the number of defects per 1 cm × 1 cm is 0, as the defect-free (OK), one or more cases have defects (NG).

(result)

As shown in Table 1, it was found that the problem of volatilization and low efficiency of the curable resin can be improved according to the present invention, and generation of unfilled defects can be reduced.

1‧‧‧Mold

2‧‧‧Substrate

3‧‧‧Photoresist film

3a‧‧‧Photoresist part

3b‧‧‧ photoresist part

4‧‧‧Gap area

4a‧‧‧Parts in contact with ambient gases

4b‧‧‧ parallel dotted lines

S1‧‧‧ surface area

10‧‧‧ Platform Department

11‧‧‧Flange

P‧‧‧ pattern area

D‧‧‧distance

Claims (13)

A nanoimprint method, which is a nanoimprint method for a mold having a fine concavo-convex pattern on a surface, wherein the mold and the substrate are disposed such that the concavo-convex pattern is opposite to a photoresist applied on the substrate; An area of a portion of the surface of the space region on the pattern region sandwiched by the mold and the substrate in contact with the ambient gas is smaller than a surface area of the portion of the photoresist coated on the substrate on the pattern region; and the mold is not In a state in which the photoresist is in contact with the photoresist, the pressure of the ambient gas is reduced to less than 10 kPa, and then the mold is pressed against the substrate. The nanoimprint method of claim 1, wherein the pressure of the ambient gas is reduced to 5 kPa or less. The nanoimprint method of claim 1, wherein the photoresist is applied to the substrate by an inkjet method. The nanoimprint method of claim 2, wherein the photoresist is applied to the substrate by an inkjet method. The nanoimprint method of claim 1 is carried out in a helium environment. The nanoimprint method of claim 2 is carried out in a helium environment. The nanoimprint method of claim 3 is carried out in a helium environment. The nanoimprint method of claim 4 is carried out in a helium environment. The nanoimprint method of claim 1, which uses a mold having a platform type structure as the mold. The nanoimprint method of claim 2, which uses a mold having a platform type structure as the mold. The nanoimprint method of claim 3, which uses a mold having a platform type structure as the mold. The nanoimprint method of claim 5, which uses a mold having a platform type structure as the mold. A method of manufacturing a patterned substrate, characterized in that a photoresist film of a transferred concave-convex pattern is formed on a substrate by a nanoimprint method according to any one of claims 1 to 12; The film is used as a mask, and the substrate is etched, whereby a concave-convex pattern corresponding to the concave-convex pattern transferred to the photoresist film is formed on the substrate.