JP2013074257A - Mold for nanoimprint, method of manufacturing the same, and nanoimprint method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of a mold in a nanoimprint.SOLUTION: A mold 1 for a nanoimprint includes a mold body 12 having, on a surface thereof, a fine uneven pattern 13, and a release layer 14 formed on the surface. The release layer 14 includes a short chain mold release agent 20 of which the number of atoms constituting a main chain is less than 20, and a long chain mold release agent 22 of which the number of atoms constituting a main chain is equal to or more than 20.

Description

  The present invention relates to a mold having a fine concavo-convex pattern on its surface and a method for producing the same, and more particularly to a mold having a release layer on the surface of the concavo-convex pattern and a method for producing the same.

  In the manufacture of semiconductor devices and magnetic recording media such as bit patterned media (BPM), the use of pattern transfer technology for performing nanoimprinting on a resist coated on a workpiece is expected.

  Specifically, in nanoimprinting, a mold (generally called a mold, a stamper, or a template) in which a concavo-convex pattern is formed is pressed (imprinted) against a resist applied on a workpiece, and the resist is mechanically deformed or This is a technology for transferring fine patterns precisely by flowing. Once the mold is made, it is economical because nano-level microstructures can be easily and repeatedly molded, and it is a transfer technology with little harmful waste and emissions, so it has recently been applied to various fields. Expected.

  In nanoimprinting, a mold release agent is usually bonded to the surface of the mold body (substrate having a concavo-convex pattern) so that the resist does not remain on the mold surface when the mold is released from the resist. A mold release treatment is performed to form a mold release layer (Patent Documents 1 and 2). For example, Patent Document 1 discloses surface treatment of a concave / convex pattern of a mold body using a release agent having a functional group that chemically reacts with the mold body at the end of a perfluoropolyether chain. . Further, Patent Document 2 discloses surface treatment of the concavo-convex pattern of the mold body by a vapor phase method using a release agent having a functional group that chemically reacts with the mold body at the end of the fluoroalkyl chain. ing.

JP 2007-326367 A US Patent Application Publication No. 2006/0012079

  However, when the release layer is composed of only one type of release agent as in the methods of Patent Documents 1 and 2, the release layer deteriorates and peels when imprinting is continuously repeated. There is a problem that the performance is lowered.

  Specifically, when the release layer is composed of only a release agent having a relatively long main chain such as a perfluoropolyether chain, if the coverage is high, the shape of the uneven pattern of the mold body is impaired. For this reason, the mold release performance of the mold release agent itself is high, but the coverage of the uneven pattern surface by the mold release agent has to be lowered. As a result, the resist enters the gap of the release agent, and the release agent is easily peeled off when the mold is released from the resist.

  On the other hand, when the release layer is composed only of a release agent having a relatively short main chain such as a fluoroalkyl chain, the release performance of the release agent itself is low. The mold release agent is easy to peel off.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a mold having high durability and a method for producing the same in nanoimprinting.

  A further object of the present invention is to provide a nanoimprinting method with high productivity in nanoimprinting.

In order to solve the above problems, the mold according to the present invention is:
In a mold for nanoimprint comprising a mold body having a fine uneven pattern on its surface and a release layer formed on this surface,
The release layer includes a short-chain release agent having less than 20 atoms constituting the main chain and a long-chain release agent having 20 or more atoms constituting the main chain. Is.

  In the mold according to the present invention, the ratio of the number of molecules of the short-chain release agent to the total number of molecules of the release agent constituting the release layer is preferably 50% or more and 95% or less, and 70% or more. More preferably, it is 90% or less.

  In the mold according to the present invention, it is preferable that at least a part of the long-chain release agent has a perfluoropolyether chain.

  In the mold according to the present invention, it is preferable that at least a part of the short-chain release agent has a fluoroalkyl chain.

  In the mold according to the present invention, it is preferable that at least a part of the release agent constituting the release layer has a hydrolyzable group, a hydroxyl group or a carboxyl group containing Si atoms. In this case, it is preferable that all of the release agents constituting the release layer have a hydrolyzable group containing Si atoms.

The method for producing a mold according to the present invention includes:
In a method for producing a mold for nanoimprint comprising a mold body having a fine uneven pattern on the surface and a release layer formed on the surface,
The concavo-convex pattern is surface-treated using a short-chain release agent having a main chain constituting less than 20 atoms and a long-chain release agent having a main chain constituting 20 or more atoms. It is what.

  In the mold manufacturing method according to the present invention, the surface treatment of the concavo-convex pattern is such that the ratio of the number of molecules of the short-chain release agent to the total number of molecules of the release agent constituting the release layer is from 50% to 95% It is preferable that it is performed so that.

  Moreover, in the manufacturing method of the mold which concerns on this invention, the surface treatment of an uneven | corrugated pattern contains a long-chain mold release agent after performing the 1st surface treatment by the 1st processing agent containing a short-chain mold release agent. It is preferable that the second surface treatment with the second treating agent is performed. In this case, it is preferable to rinse the surface of the concavo-convex pattern after the first surface treatment and before the second surface treatment.

  Alternatively, in the mold manufacturing method according to the present invention, the surface treatment of the concavo-convex pattern is preferably a surface treatment with a treatment agent containing a short-chain release agent and a long-chain release agent.

The nanoimprint method of the present invention comprises:
Using the mold described above,
Apply a resist on the nanoimprint substrate,
Press the mold against the surface of the nanoimprint substrate coated with resist,
The mold is peeled off from the nanoimprint substrate.

  In the mold according to the present invention, the release layer includes a short-chain release agent having less than 20 atoms constituting the main chain and a long-chain release agent having 20 or more atoms constituting the main chain. It is what is included. With such a configuration, since the gap between the long-chain release agents is covered with the short-chain release agent even if the coverage of the long-chain release agent is low, a resist is formed in the gap between the long-chain release agents. It can suppress entering. As a result, it is possible to improve the durability of the mold in the nanoimprint.

  Moreover, the mold manufacturing method according to the present invention uses a short-chain release agent having less than 20 atoms constituting the main chain and a long-chain release agent having 20 or more atoms constituting the main chain. Then, the uneven pattern is subjected to a surface treatment. With such a configuration, the gap between the long-chain release agents can be covered with the short-chain release agent even if the coverage of the long-chain release agent is low. As a result, it is possible to improve the durability of the mold in the nanoimprint.

  In addition, the nanoimprint method according to the present invention uses the mold of the present invention with improved durability, so that when the imprint is continuously repeated, the number of times of performing a re-release process or the number of times of changing the mold is reduced. Will decrease. As a result, productivity can be improved in nanoimprint.

It is a schematic sectional drawing which shows the structure of the mold of embodiment. It is a schematic sectional drawing which shows the uneven | corrugated pattern of the mold of embodiment. It is a schematic sectional drawing which shows the mold release layer of the mold of embodiment. It is the schematic which shows an example of a long-chain mold release agent.

  Hereinafter, although an embodiment of the present invention is described using a drawing, the present invention is not limited to this. In order to facilitate visual recognition, the scale of each component in the drawings is appropriately changed from the actual one.

“Embodiments of mold and manufacturing method thereof”
FIG. 1 is a schematic cross-sectional view illustrating a configuration of a mold according to an embodiment. FIG. 2 is a schematic cross-sectional view showing an uneven pattern of the mold according to the embodiment. FIG. 3 is a schematic cross-sectional view showing a release layer in a region A in FIG.

  The mold 1 of the present embodiment includes a mold body 12 having a fine uneven pattern 13 on the surface, and a release layer 14 formed on the surface of the uneven pattern 13.

(Mold body)
The material of the mold body 12 can be, for example, metal materials such as silicon, nickel, aluminum, chromium, iron, tantalum and tungsten, and oxides, nitrides and carbides thereof. Specifically, examples of the material of the mold body 12 include silicon oxide, aluminum oxide, quartz glass, Pyrex (registered trademark) glass, and soda glass. Alternatively, the material of the mold body 12 may be a resin.

  The shape of the concavo-convex pattern 13 is not particularly limited, and is appropriately selected according to the use of nanoimprint. For example, a typical pattern is a line and space pattern as shown in FIGS. And the length of the convex part of a line & space pattern, the width W1 of a convex part, the space | interval W2 of convex parts, and the height (depth of a recessed part) H of a convex part from a recessed part bottom face are set suitably. For example, the width W1 of the convex portion is 10 to 100 nm, more preferably 20 to 70 nm, the interval W2 between the convex portions is 10 to 500 nm, more preferably 20 to 100 nm, and the height H of the convex portion is 10 to 10 nm. It is 500 nm, more preferably 30 to 100 nm. Moreover, the shape of the convex part which comprises the uneven | corrugated pattern 13 may be the shape where the dot which has cross sections, such as a rectangle, a circle | round | yen, and an ellipse, arranged.

  The mold body 12 as described above can be manufactured, for example, by the following procedure. First, a PHS (polyhydroxy styrene) -based chemically amplified resist, a novolac resist, a resist solution mainly composed of an acrylic resin such as PMMA (polymethyl methacrylate), etc. is applied onto a Si substrate by spin coating, A resist layer is formed. Thereafter, the Si substrate is irradiated with laser light (or electron beam) while being modulated corresponding to the desired concavo-convex pattern to expose the line pattern on the resist layer surface. Thereafter, the resist layer is developed, and selective etching is performed by RIE (reactive ion etching) or the like using the removed resist layer pattern as a mask to obtain a mold body made of Si having a predetermined uneven pattern.

  On the other hand, the mold body 12 is not limited to this, and a mold body made of quartz can also be used. In this case, the mold body made of quartz can be manufactured by a method similar to the above-described method for manufacturing a mold body made of Si, or a method of etching a substrate using a resist pattern formed by a nanoimprint method described later as a mask. it can.

  In order to increase the coverage of the release agent on the surface of the mold main body 12 (the ratio of the mold release agent occupying the surface of the mold main body 12) and to shorten the release treatment time, the amount of adsorbed water on the surface of the mold main body 12 is increased. It is effective. In order to increase the amount of adsorbed water on the surface of the mold body 12, there are a method for modifying the surface of the mold body 12 to be hydrophilic and a method for increasing the relative humidity in the atmosphere. Examples of the method for modifying the surface of the mold body 12 to be hydrophilic include a wet cleaning method using a chemical solution, a dry cleaning method using plasma or UV ozone, or a combination of wet and dry methods. In the present invention, a dry cleaning method using UV ozone that does not require large-scale equipment is preferable because the mold main body 12 is placed in a standby state in the imprint apparatus and the mold release process is simply performed. In the UV ozone cleaning method, for example, light from a low-pressure mercury lamp having a peak wavelength near 185 nm is irradiated on the surface of the mold body 12, thereby activating oxygen contained in the atmosphere near the surface of the mold body 12. Surface organics are oxidized and removed. The relative humidity is preferably controlled in the range of 20% to 70%, more preferably 30% to 50%.

(Release layer)
A release layer 14 is provided on the surface of the mold 1 in order to improve the mold release property between the mold 1 and the resist. As shown in FIG. 3, the release layer 14 includes a short-chain release agent 20 in which the number of atoms (number of carbon atoms and oxygen atoms) constituting the main chain is less than 20, and the number of atoms constituting the main chain. It is comprised from 2 or more types of mold release agents which consist of long-chain mold release agent 22 whose is 20 or more. That is, it is sufficient that at least one type of release agent is included as the short-chain release agent 20, and at least one type of release agent may be included as the long-chain release agent 22.

  The “main chain” means the longest chain in the molecule among chains composed of carbon atoms and oxygen atoms excluding terminal functional groups (including hydrolyzable groups). For example, in the case of the long-chain release agent 22 shown in FIG. 4, the main chain is a chain composed of carbon atoms and oxygen atoms excluding the terminal functional groups 23, 24 and 25, and the release agent molecule. The longest chain 26 among them.

  Here, the reason why the main chain length of the short-chain release agent 20 is defined as “less than 20 atoms” is that the long-chain release agent having a main chain length of 20 or more is used as the mold body 12. This is because when the surface is coated at a high density, the average film thickness of the release layer 14 is increased. In such a case, the shape information of the concavo-convex pattern 13 of the mold 1 is lost, and the pattern transfer accuracy in nanoimprinting is reduced. On the other hand, when the long-chain release agent is coated on the surface of the mold body 12 at a low density, the average film thickness can be reduced, but the horizontal force between the long-chain release agents decreases. This is because the strength of the release layer is weakened.

  In the present invention, the durability of the release layer is improved by complementing one of the short-chain release agent 20 and the long-chain release agent 22 with the other.

  Specifically, it is as follows. The merit of the short-chain release agent 20 is that even if the surface of the mold body 12 is coated at a high density, the shape information of the concave / convex pattern 13 is not impaired, and since there is no steric hindrance, the interaction between the short-chain release agents 20 is strong. The strength of the release layer is high, and the short-chain release agents 20 are closely arranged so that the resist is difficult to contact the mold main body 12. The disadvantage is that there is no lubricity and a large release force is required. (That is, releasability is low). On the other hand, the merit of the long-chain release agent 22 is that a small release force is sufficient due to the lubricity, and the demerit is that the shape information of the concavo-convex pattern 13 is damaged when the surface of the mold body 12 is coated at a high density. Due to its own steric hindrance, the interaction between the long-chain release agents 22 is weak and the strength as a release layer is low, and the long-chain release agents 22 cannot be closely arranged, so that the resist is molded. It is easy to contact the main body 12. Therefore, in the present invention, the contact of the resist with the mold main body 12 can be suppressed by interpolating the gap of the long-chain release agent 22 having a high release property with the short-chain release agent 20, and the release property. It is possible to improve the durability of the release layer 14 without lowering. Furthermore, in this invention, since the increase in the average film thickness of the mold release layer 14 whole can also be suppressed, it can also prevent that the shape information of the uneven | corrugated pattern 13 of the mold main body 12 is impaired.

  The ratio of the number of molecules of the short-chain release agent 20 to the total number of molecules of the release agent constituting the release layer 14 (mixing ratio of the short-chain release agent 20) is preferably 50% or more and 95% or less. 70% or more and 90% or less is more preferable. Within the above range, in particular, it is possible to realize a release layer 14 having a high release property and durability by optimally complementing the merits and demerits of the short-chain release agent 20 and the long-chain release agent 22 respectively. Found by the inventors (see Examples below).

  At least a part of the release agent constituting the release layer 14 preferably has a hydrolyzable group, a hydroxyl group or a carboxyl group containing Si atoms. Since the release agent having these groups forms a film in a self-organized manner, the release layer 14 can be easily formed. Moreover, it is preferable that all the mold release agents which comprise the mold release layer 14 have a hydrolysis group containing Si atom. In this case, since the adjacent hydrolyzing groups are bonded to each other, the durability of the release layer 14 can be further improved.

  Needless to say, the higher the coverage of the surface of the mold body 12 as the whole mold release agent, the better.

(Short chain release agent)
The short chain release agent 20 is a release agent having less than 20 atoms constituting the main chain.

  As the short-chain release agent 20, (tridecafluoro-1,1,2,2-tetrahydrooctyl) trimethoxysilane (SIN8176.0: manufactured by Gelest Co., Ltd.), perfluorooctyl ethanol (manufactured by F-Tech Co., Ltd.), Capric acid or the like can be used.

  In addition, known hydrocarbon-based lubricants, fluorine-based lubricants, fluorine-based silane coupling agents, and the like can be used.

  Examples of the hydrocarbon-based lubricant include carboxylic acids such as stearic acid and oleic acid, and alcohols such as stearyl alcohol and oleyl alcohol.

Examples of the fluorine-based lubricant include a lubricant in which part or all of the alkyl group of the hydrocarbon-based lubricant is substituted with a fluoroalkyl group or a perfluoropolyether group. Examples of perfluoropolyether groups include perfluoromethylene oxide polymer, perfluoroethylene oxide polymer, perfluoro-n-propylene oxide polymer (CF ₂ CF ₂ CF ₂ O) _n , perfluoroisopropylene oxide polymer (CF (CF ₃ ) CF ₂ O) _n or a copolymer thereof.

The fluorine-based silane coupling agent has at least one alkoxysilane group or chlorosilane group in the molecule. Examples of alkoxysilane groups include —Si (OCH ₃ ) ₃ groups and —Si (OCH ₂ CH ₃ ) ₃ groups. Examples of the chlorosilane group include —Si (Cl) ₃ group.

  Specific examples of the short-chain release agent 20 include heptadecafluoro-1,1,2,2-tetra-hydrodecyltrimethoxysilane, pentafluorophenylpropyldimethylchlorosilane, tridecafluoro-1,1,2 , 2-tetra-hydrooctyltriethoxysilane, tridecafluoro-1,1,2,2-tetra-hydrooctyltrimethoxysilane, and the like.

(Long chain release agent)
The long chain release agent 22 is a release agent having 20 or more atoms constituting the main chain.

  Examples of the long-chain release agent 22 include OPTOOL (registered trademark) DSX (manufactured by Daikin Industries, Ltd.), Novec (registered trademark) EGC-1720 (manufactured by Sumitomo 3M Limited), Fomblin (registered trademark) Z-Dol (Solve Isolexis Co., Ltd.), Krytox (registered trademark) 157FSL (DuPont Co., Ltd.) and the like can be used.

  In addition, known fluorine resins, fluorine lubricants, fluorine silane coupling agents, and the like can be used.

  Fluorine resins include PTFA (polytetrafluoroethylene resin), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), ETFE (tetrafluoroethylene / Ethylene copolymer).

An example of the fluorine-based lubricant is a lubricant having a perfluoropolyether chain. Examples of perfluoropolyether groups include perfluoromethylene oxide polymer, perfluoroethylene oxide polymer, perfluoro-n-propylene oxide polymer (CF ₂ CF ₂ CF ₂ O) _n , perfluoroisopropylene oxide polymer (CF (CF ₃ ) CF ₂ O) _n or a copolymer thereof.

The fluorine-based silane coupling agent has at least 1, preferably 1 to 10, alkoxysilane groups and chlorosilane groups in the molecule. Examples of alkoxysilane groups include —Si (OCH ₃ ) ₃ groups and —Si (OCH ₂ CH ₃ ) ₃ groups. Examples of the chlorosilane group include —Si (Cl) ₃ group.

(Formation method of release layer)
The release layer 14 is formed by surface-treating the concavo-convex pattern 13 of the mold body 12 using a short chain release agent 20 and a long chain release agent 22. And it is preferable that the surface treatment of the uneven | corrugated pattern 13 is performed so that the mixing rate of the short chain release agent 20 may be 50% or more and 95% or less.

  The surface treatment of the concavo-convex pattern can be broadly divided into three processes: a pretreatment process, a release agent coating process, and a posttreatment process.

(Pretreatment process)
The pretreatment process is, for example, a process of cleaning the mold body 12 that performs the surface treatment. The cleaning method is not particularly limited. For example, UV ozone cleaning, dry processing such as plasma processing, ultrasonic cleaning in an organic solvent (acetone, ethyl alcohol, isopropyl alcohol, etc.), acid such as sulfuric acid, and / or Examples thereof include wet treatment such as boiling washing in a solution of peroxide such as hydrogen peroxide. These washings may be performed alone or in combination.

(Release agent application process)
In the release agent application step, the release agent is actually applied. As a method for applying the release agent, a dip coating method, a vacuum deposition method, a spin coating method, or the like can be used.

  The surface treatment of the concavo-convex pattern is the first surface treatment using the first treatment agent containing the short-chain release agent 20 and the second treatment agent using the second treatment agent containing the long-chain release agent 22. As the surface treatment, the surface treatment step may be performed separately, or in one step by the surface treatment using the third treatment agent containing the short-chain release agent 20 and the long-chain release agent 22. You may implement.

  As a method of performing the surface treatment process separately, for example, the short chain release agent 20 is bonded to the mold body 12 by a vacuum vapor deposition method, and then the long chain release agent 22 is molded by a dip coating method. 12 and the like. In addition, it is preferable to rinse the surface of the uneven | corrugated pattern 13 of the mold main body 12 after performing a 1st surface treatment and before performing a 2nd surface treatment. Thereby, it is possible to prevent the binding of the long-chain release agent 22 from being inhibited by the excess short-chain release agent 20.

When the surface treatment process is performed separately as described above, for example, the mixing ratio of the short-chain release agent 20 is determined by measuring the film thickness with an ellipsometer every time one type of release agent is applied. It can be calculated from the rate ratio. Specifically, the chain length of the whole molecule of the release agent A applied first is l _A (Å), the film thickness in the state where the release agent A is bonded is d _A (Å), and then the application is performed next. Assuming that the chain length of the entire release agent B molecule is l _B (Å) and the film thickness in a state where the release agents A and B are combined is d _{A + B} (Å), the coverage C _A of each release agent and C _B is calculated as shown in Equation 1 below.

Formula 1:
C _A (%) = d _A / l _A × 100, C _B (%) = (d _{A + B} −d _A ) / l _B × 100

  And the mixing rate R of the short chain release agent 20 is computed like the following formula 2 using the coverage of each release agent.

Formula 2:
R (%) = C _A / (C _A + C _B ) × 100

  In addition, the said mixing rate R is calculated | required similarly also when the surface treatment process performs surface treatment separately about 3 or more types of mold release agents, respectively. That is, the sum of the coverages of the release agents may be assigned to the denominator of the ratio R, and the sum of the coverages of the short-chain release agents 20 may be assigned to the numerator.

  In addition, the mixing ratio of the short-chain release agent 20 can be calculated, for example, by using a surface analysis method such as ESCA (X-ray photoelectron spectrometer) for the ratio of atoms characteristic to each release agent.

  In addition, as a method of performing the surface treatment step in one step, for example, when all the release agents can be dissolved in the same solvent, the short-chain release agent 20 and the long-chain release agent 22 are used. There is a method in which a mixed solution of the above is prepared and all the release agents are simultaneously treated by a dip coating method or a spin coating method.

  As described above, when the surface treatment step is performed in a single step, the mixing ratio of the short-chain release agent 20 can be calculated using a surface analysis method such as ESCA as described above.

  When processing multiple release agents at the same time, the same type of release agent may be adsorbed in the form of islands, resulting in uneven processing, or adsorption of some release agents may be difficult to proceed. Because there is, attention is necessary. From such a viewpoint, it is preferable that the surface treatment of the uneven pattern 13 is performed by dividing the surface treatment steps as in the first surface treatment and the second surface treatment. Thus, uniform surface treatment is possible by treating the release agent one by one. In this case, the short-chain release agent 20 is preferably bonded to the mold body 12 first. Thereby, it is possible to avoid the binding inhibition of the short chain release agent 20 to the mold body 12 by the long chain release agent 22, and a more uniform surface treatment is possible.

(Post-processing process)
In the post-processing step, for example, a step of rinsing excess release agent with a solvent is performed. This is because if the excess release agent remains, the shape information of the uneven pattern 13 on the surface of the mold body 12 may be impaired. The method of rinsing with a solvent is not particularly limited. For example, there is a dip method in which a mold is immersed in a solvent and pulled up after a certain time. Moreover, in order to accelerate | stimulate the coupling | bonding to the mold main body 12 of a mold release agent, you may perform a baking process as needed.

  As described above, according to the mold according to the present invention, the gap between the long-chain release agents 22 is covered with the short-chain release agent even when the coverage of the long-chain release agent 22 is low. The resist can be prevented from entering the gap between the chain release agents 22. As a result, it is possible to improve the durability of the mold in the nanoimprint.

  Further, according to the mold manufacturing method of the present invention, the gap between the long-chain release agents can be covered with the short-chain release agent even when the coverage of the long-chain release agent is low. As a result, it is possible to improve the durability of the mold in the nanoimprint.

“Embodiment of Nanoimprint Method”
Hereinafter, an embodiment of a nanoimprint method using the mold of the present invention will be described.

  In the nanoimprinting method of the present embodiment, for example, a mold 1 as shown in FIG. 1 is used to apply a photocurable resist onto a quartz nanoimprinting substrate, and the mold 1 is coated with the resist of the nanoimprinting substrate. This is characterized in that the resist 1 is cured by irradiating ultraviolet light from the back surface of the substrate for nanoimprint, and the mold 1 is peeled off from the resist.

(Nanoimprint substrate)
The nanoimprint substrate is a substrate on which a resist is applied. For example, the nanoimprint substrate is a target to be processed by etching or the like in a subsequent process.

  When the mold 1 is light transmissive, the nanoimprint substrate is not particularly limited as to its shape, structure, size, material, and the like, and can be appropriately selected according to the purpose. Specifically, “having light transparency” means that the resist is sufficiently cured when light is incident on the resist coated on the substrate through the substrate. The surface of the nanoimprint substrate that is the target of pattern transfer is the surface on which the resist is applied. For example, when the nanoimprint substrate is for manufacturing an information recording medium, the shape of the nanoimprint substrate is usually a disk shape. The structure may be a single layer structure or a laminated structure. The material can be appropriately selected from those known as substrate materials, and examples thereof include silicon, nickel, aluminum, glass, and resin. These board | substrate materials may be used individually by 1 type, and may use 2 or more types together. There is no restriction | limiting in particular as thickness of the board | substrate for nanoimprint, Although it can select suitably according to the objective, 0.05 mm or more is preferable and 0.1 mm or more is more preferable. If the thickness of the nanoimprint substrate is less than 0.05 mm, the substrate may be bent when the nanoimprint substrate and the mold 1 are bonded, and a uniform bonded state may not be ensured.

When the mold 1 does not have optical transparency, it is preferable to use a quartz substrate as the nanoimprint substrate in order to enable exposure of the resist. The quartz substrate is appropriately selected according to the purpose without particular limitation as long as it has light transparency and a thickness of 0.3 mm or more. In this embodiment, the light transmittance of the quartz substrate may be, for example, that the transmittance of light having a wavelength of 200 nm or more is at least 5%. For example, a quartz substrate coated with a silane coupling agent may be used. Further, a quartz substrate having a metal layer made of Cr, W, Ti, Ni, Ag, Pt, Au or the like and / or a metal oxide film layer made of CrO ₂ , WO ₂ , TiO ₂ or the like on the surface is used. May be. The thickness of the metal layer or metal oxide film layer is usually 30 nm or less, preferably 20 nm or less. This is because if it exceeds 30 nm, the UV transmittance is lowered, and the curing of the resist is liable to occur. The quartz substrate may be one in which the surface of the laminate is coated with a silane coupling agent. The thickness of the quartz substrate is usually preferably 0.3 mm or more. If it is 0.3 mm or less, it is likely to be damaged by pressing during handling or imprinting.

(Resist)
The resist is not particularly limited, but in this embodiment, for example, a photopolymerization initiator (about 2% by mass) and a fluorine monomer (0.1 to 1% by mass) are added to a polymerizable compound. A resist can be used.

  Moreover, antioxidant (about 1 mass%) can also be added as needed. The resist prepared by the above procedure can be cured by ultraviolet light having a wavelength of 360 nm. For those having poor solubility, it is preferable to add a small amount of acetone or ethyl acetate for dissolution, and then distill off the solvent.

  Examples of the polymerizable compound include benzyl acrylate (Biscoat (registered trademark) # 160: manufactured by Osaka Organic Chemical Co., Ltd.), ethyl carbitol acrylate (Biscoat (registered trademark) # 190: manufactured by Osaka Organic Chemical Co., Ltd.), polypropylene glycol di In addition to acrylate (Aronix (registered trademark) M-220: manufactured by Toagosei Co., Ltd.), trimethylolpropane PO-modified triacrylate (Aronix (registered trademark) M-310: manufactured by Toagosei Co., Ltd.), etc. The compound A etc. which are represented can be mentioned.

Structural formula 1:

  As the polymerization initiator, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone (IRGACURE 379: Toyotsu And alkylphenone photopolymerization initiators such as Chemiplus Co., Ltd.).

  Moreover, as said fluorine monomer, the compound B etc. which are represented by following Structural formula 2 etc. can be mentioned.

Structural formula 2:

(Resist application process)
As a resist application method, a predetermined amount of droplets such as an ink jet method or a dispense method can be placed at a predetermined position on a substrate or a mold, or a resist with a uniform film thickness such as a spin coat method or a dip coat method can be used. A method that can be applied is used.

  When disposing the resist droplets on the nanoimprint substrate, an ink jet printer or a dispenser may be used depending on the desired droplet amount. For example, an ink jet printer is used when the droplet amount is less than 100 nl, and a dispenser is used when the droplet amount is 100 nl or more.

  Examples of the inkjet head that discharges the resist from the nozzle include a piezo method, a thermal method, and an electrostatic method. Among these, a piezo method capable of adjusting an appropriate amount of liquid (amount per droplet disposed) and a discharge speed is preferable. Before disposing the resist droplets on the nanoimprint substrate, the droplet amount and ejection speed are adjusted and set in advance. For example, the appropriate amount of liquid increases at a position on the nanoimprint substrate corresponding to a region where the spatial volume of the concave / convex pattern of the mold is large, or at a position on the nanoimprint substrate corresponding to a region where the spatial volume of the concave / convex pattern of the mold is small. It is preferable to adjust by decreasing. Such adjustment is appropriately controlled according to the droplet discharge amount (the amount per discharged droplet). Specifically, when the droplet amount is set to 5 pl, the droplet amount is controlled to be ejected to the same place five times using an inkjet head having a droplet ejection amount of 1 pl. The amount of droplets can be obtained, for example, by measuring the three-dimensional shape of droplets discharged on the substrate under the same conditions in advance with a confocal microscope or the like and calculating the volume from the shape.

  After adjusting the droplet amount as described above, the droplets are arranged on the nanoimprint substrate according to a predetermined droplet arrangement pattern.

  When using the spin coating method or dip coating method, the resist is diluted with a solvent so that it has a predetermined thickness, and the spin coating method is uniform by controlling the number of revolutions and the dip coating method by controlling the pulling speed. An appropriate coating film is formed on the nanoimprint substrate.

(Imprint process)
Before contacting the mold and the resist, the residual gas is reduced by reducing the atmosphere between the mold and the nanoimprint substrate to a reduced pressure or vacuum atmosphere. However, in a high vacuum atmosphere, the resist before curing is volatilized and it may be difficult to maintain a uniform film thickness. Therefore, the residual gas is preferably reduced by setting the atmosphere between the mold and the nanoimprint substrate to a He atmosphere or a reduced pressure He atmosphere. Since He permeates the quartz substrate, the trapped residual gas (He) gradually decreases. Since it takes time to permeate He, it is more preferable to use a reduced pressure He atmosphere. The reduced pressure atmosphere is preferably 1 to 90 kPa, and particularly preferably 1 to 10 kPa.

  The nanoimprint substrate coated with the resist and the mold are brought into contact with each other after being aligned with each other so as to have a predetermined relative positional relationship. An alignment mark is preferably used for alignment. The alignment mark is formed in a concavo-convex pattern that can be detected by an optical microscope, moire interferometry, or the like. The alignment accuracy is preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 100 nm or less.

  The pressing pressure of the mold is in the range of 100 kPa to 10 MPa. The higher the pressure, the more the resist flow is promoted, and the compression of the residual gas, the dissolution of the residual gas into the resist, and the penetration of He into the quartz substrate are promoted, leading to an improvement in the removal rate of the residual gas. However, if the applied pressure is too strong, there is a possibility that the mold and the nanoimprint substrate may be damaged when a foreign object is caught when contacting the mold. Therefore, the pressing pressure of the mold is preferably 100 kPa to 10 MPa, more preferably 100 kPa to 5 MPa, and still more preferably 100 kPa to 1 MPa. The reason why the pressure is set to 100 kPa or more is that when imprinting is performed in the atmosphere, when the space between the mold and the nanoimprint substrate is filled with a liquid, the pressure between the mold and the nanoimprint substrate is pressurized at an atmospheric pressure (about 101 kPa). Because.

  After the mold 1 is pressed against the nanoimprint substrate and the resist is exposed, the mold 1 is peeled from the resist. For example, the outer edge of either the mold 1 or the nanoimprint substrate is held, and the other nanoimprint substrate or the back surface of the mold 1 is sucked and held. The method of making it peel by making it move relatively in the direction opposite to a press is mentioned.

  By performing the above imprinting method while moving the relative position of the nanoimprint substrate and the mold, it is also possible to continuously perform imprinting at a plurality of locations on the nanoimprint substrate.

  As described above, according to the nanoimprinting method according to the present invention, when the imprinting of the present invention with improved durability is used, when imprinting is repeated continuously, the number of times the mold release process is performed again or the mold is replaced. The number of times to do will decrease. As a result, productivity can be improved in nanoimprint.

  Examples of the method for producing a master mold according to the present invention are shown below.

<Example 1>
(Mold body production)
On the Si substrate, a resist solution containing a PHS (polyhydroxy styrene) -based chemically amplified resist as a main component was applied by spin coating to form a resist layer. After that, while scanning the Si substrate on the XY stage, the electron beam modulated corresponding to the line pattern with a line width of 30 nm and a pitch of 60 nm is irradiated to expose the line pattern on the entire surface of the resist layer in a range of 0.5 mm square. did. Thereafter, the resist layer is developed, the exposed portion is removed, selective etching is performed by RIE so that the groove depth becomes 60 nm by using the pattern of the removed resist layer as a mask, and a linear concavo-convex pattern is obtained. A mold body made of Si was obtained.

(Release agent)
(Tridecafluoro-1,1,2,2-tetrahydrooctyl) trimethoxysilane (SIN8176.0, manufactured by Gelest, number of main chain atoms: 8) as a short-chain release agent, terminal as a long-chain release agent In addition, OPTOOL (registered trademark) DSX (manufactured by Daikin Industries, Ltd., number of main chain atoms: about 120) having methoxysilane was used.

(Release processing)
−Pretreatment−
UV ozone cleaning was performed on the Si mold main body using an optical surface treatment device (manufactured by Sen Engineering Co., Ltd., UB1101N-71, light source: low-pressure mercury lamp, SUV110GS-36). The distance between the lamp / mold body was about 2 cm and UV irradiation was performed for 5 minutes to clean the surface of the mold body.

-Application of release agent 1
First, a first release treatment is performed by adding a short-chain release agent to a fluorine-based solvent Bartrel (registered trademark) (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) so as to have a concentration of 2.0% by mass. A liquid was prepared. Then, using a dip coater, the mold body after washing in the first mold release treatment liquid is inserted into the first mold release treatment liquid at an immersion speed of 5 mm / sec, and then immersed for 1 minute. The film was pulled up at a speed of about 1 mm / sec (dip coating).

-Post-processing 1
In order to remove the excess release agent, a mold body treated with a short-chain release agent in a fluorine-based solvent Bartrel (registered trademark) using a dip coater is inserted into the solvent at an immersion speed of 5 mm / sec. Then, after being immersed for 1 minute, it was pulled up at a speed of about 1 mm / sec (dip rinse).

-Application of release agent 2-
Next, a long-chain release agent was added and dissolved in a fluorine-based solvent HD-ZV (manufactured by Daikin Industries, Ltd.) so that the concentration became 0.1% by mass to prepare a second release treatment liquid. . Then, using a dip coater, the mold body after rinsing in the second mold release treatment liquid is inserted into the second mold release treatment liquid at an immersion speed of 5 mm / sec, and then immersed for 1 minute. The film was pulled up at a speed of about 1 mm / sec (dip coating).

-Post-processing 2-
In order to remove the excess release agent, a mold body treated with a long-chain release agent in a fluorinated solvent HD-ZV using a dip coater is inserted into the solvent at an immersion speed of 5 mm / sec. After being immersed for 1 minute, it was pulled up at a speed of about 1 mm / sec (dip rinse).

(Bake processing)
Finally, in order to promote the bonding of the release agent to the mold main body, the mold main body after the mold release treatment is performed at 120 ° C. for 10 minutes using an oven (Espec Co., Ltd., Clean Even PVC-210). The baking process was carried out.

  Through the above steps, a mold having a release layer containing a short-chain release agent and a long-chain release agent was obtained.

(Nanoimprint substrate)
A quartz substrate was used as the nanoimprint substrate. The surface of the quartz substrate was surface-treated with KBM-5103 (manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silane coupling agent having excellent adhesion to the resist. KBM-5103 was diluted to 1% by mass with PGMEA (propylene glycol monomethyl ether acetate) and applied to the substrate surface by spin coating. Subsequently, the substrate was annealed on a hot plate at 150 ° C. for 5 minutes to bond the silane coupling agent to the substrate surface.

(Resist)
Compound A represented by the above structural formula 1 was 48 w%, Aronix (registered trademark) M220 was 48 wt. %, IRGACURE (registered trademark) 379 3%, and a resist containing 1% by weight of the compound B represented by the structural formula 2 was prepared.

(Resist application process)
A piezo inkjet printer, DMP-2831, manufactured by FUJIFILM Dimatix was used. DMC-11610, a dedicated 10 pl head, was used for the inkjet head. The ejection conditions were set and adjusted in advance so that the droplet amount was 10 pl. After adjusting the amount of droplets as described above, the droplets were arranged on the substrate according to a predetermined droplet arrangement pattern adjusted so that the remaining film thickness was 10 nm.

(imprint)
The mold and the quartz substrate were brought close to a position where the gap was 0.1 mm or less, and the alignment was performed so that the alignment mark on the substrate and the alignment mark on the mold coincided from the back of the quartz substrate. The space between the mold and the quartz substrate was replaced with 99% by volume or more of He gas, and the pressure was reduced to 20 kPa or less after the He replacement. Foreign matter on the mold was brought into contact with a droplet made of resist under reduced-pressure He conditions. After the contact, the resist was cured by applying a pressure of 1 MPa for 1 minute, and exposing it to an irradiation amount of 300 mJ / cm ² with ultraviolet light having a wavelength of 360 nm.

  Thereafter, the mold was peeled by moving the substrate or the mold in the direction opposite to the pressing in a state where the outer edge portion of the substrate and the mold was mechanically held or the back surface was sucked and held.

(Evaluation method)
The durability of the release layer, mold peelability, release layer coverage, and average thickness of the release layer were evaluated. Details of each evaluation item are as follows.

  The durability was evaluated by repeating nanoimprinting 100 times and inspecting the cured resist film obtained by the 100th mold release by dark field measurement with an optical microscope (magnification 50 times to 1,500 times). The degree of peeling failure observed was sensory evaluated in three stages according to the following criteria.

◎: When there is no peeling failure ○: When there are 3 or less peeling failures with a size of 100 μm square or less ×: When there are 4 or more peeling failures with a size of 100 μm square or less, or larger than 100 μm square When there is a peeling failure

  In the evaluation of peelability, nanoimprint was repeated 10 times, and the average peel force from the first time to the 10th time was calculated.

  In the evaluation of coverage, the contact angles of water and diiodomethane on the mold surface after the mold release treatment were measured at 10 locations, and the surface energy was calculated from the average contact angles at 10 locations.

  In the evaluation of the average film thickness, the average film thickness was calculated using an ellipsometer for the thickness of the release layer.

<Comparative Example 1>
In the release agent of Example 1, a long chain release agent was not used, and only the above (tridecafluoro-1,1,2,2-tetrahydrooctyl) trimethoxysilane was used as a short chain release agent. The same as Example 1 except that the concentration was adjusted to 2.0% by mass.

<Comparative example 2>
In the release agent of Example 1, the short-chain release agent is not used, but only the above OPTOOL (registered trademark) DSX as a long-chain release agent is used, and the concentration thereof is 0.1% by mass. Except for the adjusted points, the second embodiment is the same as the first embodiment.

<Comparative Example 3>
In the release agent of Example 1, the short-chain release agent is not used, and only the above OPTOOL (registered trademark) DSX is used as the long-chain release agent, and the concentration is 1.0% by mass. Example 1 is the same as Example 1 except that the prepared point and the post-treatment dip rinse step were not performed.

<Examples 2 to 19>
Example 1 is the same as Example 1 except that the concentration of the first release treatment liquid containing the short-chain release agent is changed to change the mixing ratio R of the short-chain release agent. .

<Example 20>
The concentration of the above (tridecafluoro-1,1,2,2-tetrahydrooctyl) trimethoxysilane as a short-chain release agent is 2.0% by mass in the above-mentioned fluorine-based solvent Bartrel (registered trademark). Next, as a long-chain release agent, the above-mentioned OPTOOL (registered trademark) DSX was added so as to have a concentration of 0.1% by mass to prepare a third release treatment liquid. Then, using a dip coater, the mold body after washing in the third mold release treatment liquid is inserted into the third mold release treatment liquid at an immersion speed of 5 mm / sec, and then immersed for 1 minute. The wire was pulled up at a speed of about 1 mm / sec. As described above, the second embodiment is the same as the first embodiment except that two mold release agents are simultaneously applied to the mold body.

(Evaluation results)
Table 1 summarizes the results of the above examples and comparative examples.

  From Table 1, it was found that the durability of the mold can be improved without impairing the shape information of the uneven pattern 13 of the mold body 12. It has also been found that the coverage of the release layer can be improved. It was also found that an increase in the average film thickness of the release layer can be suppressed.

DESCRIPTION OF SYMBOLS 1 Mold 12 Mold main body 13 Concavity and convexity pattern 14 Release layer 20 Short chain release agent 22 Long chain release agent 23, 24, 25 Functional group 26 of terminal 26 Main chain of release agent

Claims (13)

In a mold for nanoimprint comprising a mold body having a fine uneven pattern on the surface, and a release layer formed on the surface,
The release layer includes a short-chain release agent having less than 20 atoms constituting the main chain and a long-chain release agent having 20 or more atoms constituting the main chain, Mold.   The mold according to claim 1, wherein the ratio of the number of molecules of the short-chain release agent to the total number of molecules of the release agent constituting the release layer is 50% or more and 95% or less.   The mold according to claim 2, wherein the ratio of the number of molecules of the short-chain release agent to the total number of molecules of the release agent constituting the release layer is 70% or more and 90% or less.   The mold according to any one of claims 1 to 3, wherein at least a part of the long-chain release agent has a perfluoropolyether chain.   The mold according to any one of claims 1 to 4, wherein at least a part of the short-chain release agent has a fluoroalkyl chain.   The mold according to any one of claims 1 to 5, wherein at least a part of the release agent constituting the release layer has a hydrolyzable group, a hydroxyl group or a carboxyl group containing Si atoms.   The mold according to claim 6, wherein all of the release agents constituting the release layer have a hydrolyzable group containing Si atoms. In a method for producing a mold for nanoimprint, comprising a mold body having a fine uneven pattern on the surface, and a release layer formed on the surface,
The concavo-convex pattern is surface-treated using a short-chain release agent having a main chain constituting less than 20 atoms and a long-chain release agent having a main chain constituting 20 or more atoms. A method for manufacturing a mold.   The surface treatment of the concavo-convex pattern is performed such that the ratio of the number of molecules of the short-chain release agent to the total number of molecules of the release agent constituting the release layer is 50% or more and 95% or less. The method for producing a mold according to claim 8.   After the surface treatment of the concavo-convex pattern performs the first surface treatment with the first treatment agent containing the short-chain release agent, the second treatment with the second treatment agent containing the long-chain release agent is performed. The method for producing a mold according to claim 8 or 9, wherein the surface treatment is performed.   The method for manufacturing a mold according to claim 10, wherein the surface of the concave-convex pattern is rinsed after the first surface treatment and before the second surface treatment.   The method for producing a mold according to claim 8 or 9, wherein the surface treatment of the concavo-convex pattern is a surface treatment with a treatment agent containing the short-chain release agent and the long-chain release agent. Using the mold according to any one of claims 1 to 7,
Apply a resist on the nanoimprint substrate,
The mold is pressed against the surface of the nanoimprint substrate on which the resist is applied,
A nanoimprinting method comprising peeling the mold from the nanoimprint substrate.