CN103442868A - Method of cleaning mold with release layer and method of manufacturing mold with release layer - Google Patents

Abstract

The present invention is a method for cleaning a mold with a release layer, wherein the mold with the release layer is provided with a release layer (31) on a mold (30) for transferring a predetermined pattern onto a transfer object by imprinting, and the release layer (31) is made of a fluorine compound, and the method comprises: an ultraviolet irradiation treatment step of irradiating ultraviolet rays to a release layer (31) of a mold having the release layer attached thereto; and a cleaning treatment step of cleaning and removing the release layer chemically modified in the ultraviolet irradiation treatment step. Wherein in the ultraviolet irradiation treatment step, when the central wavelength of the ultraviolet light source is 150 nm-200 nm, the cumulative irradiation energy of the ultraviolet light is 5000mJ/cm²～7000mJ/cm²。

Description

Method of cleaning mold with release layer and method of manufacturing mold with release layer

technical field

The invention relates to a method for cleaning a mold with a release layer and a method for manufacturing the mold with a release layer.

Background technique

Conventionally, for magnetic disks used in hard disks and the like, methods of minimizing the width of the magnetic head and narrowing the space between data tracks for recording information to achieve high density have been used.

On the other hand, with such magnetic disks, the magnetic influence between adjacent tracks cannot be ignored as densification progresses. Therefore, existing methods have reached their limit in terms of densification.

Therefore, a new type of medium is proposed, which is a patterned medium formed by magnetically separating data tracks of a magnetic disk. Such a patterned medium refers to a medium intended to improve signal quality by removing (grooving) a portion of the magnetic material not required for recording.

As a mass production technique for this patterned medium, the following imprint technique (imprint) (or nanoimprint technique) is known, in which a master mold or a replica mold (also called a working replica mold) is (working replica)) The patterned medium is produced by transferring the concave-convex pattern of the transfer material to the material to be printed. The replica mold uses the master mold as the original mold and performs one or more transfers. copied.

It should be noted that the imprint technique is roughly divided into two types, thermal imprint and optical imprint.

Thermal embossing refers to a method in which a mold formed with a fine concave-convex pattern is pressed onto a thermoplastic resin as a material to be molded while heating, and then the material to be molded is cooled/released, thereby performing Transfer of fine patterns.

In addition, photoimprinting refers to a method in which a mold formed with a fine concave-convex pattern is press-attached to a photocurable resin as a material to be molded, and then irradiated with ultraviolet light to cure it, and then the material to be molded is released from the mold. , thereby transferring fine patterns.

In the mass production process of a molded object by imprinting, the master mold itself is usually not used. Specifically, as a substitute mold for the master mold, a mold called a working replica mold, that is, a replica mold replicated from the master mold, is used in each mass production line. The replica mold is a secondary mold that is copied by transferring the fine concave-convex pattern of the master mold to another material to be molded, or a tertiary mold that is replicated by further transferring the fine concave-convex pattern of the secondary mold to other molded materials. mould; etc.

Therefore, even if the replica mold is deformed or damaged during the mass production process of imprinting, it will not affect the master mold. That is, as long as the master mold is fine, any number of replica molds can be produced, so it will not interfere with the mass production process of imprinting.

In addition, as mentioned above, when making this replica mold, it is necessary to form a master mold with a fine concave-convex pattern, or a replica mold as an original mold, that is, a secondary mold with respect to a tertiary mold, etc. (It should be noted that Hereinafter, for convenience of description, these molds as the basis for forming the replica mold are referred to as master molds (molds) are pressed and attached to the material to be molded in the transferred object, and accordingly it is necessary to separate the master mold from the molded material, and Released from the transfer material.

In addition, in the mass production process of imprinting, it is also necessary to attach the replica mold to the molded material in the transfer object, and with this, it is necessary to separate the replica mold from the molded material and the transfer object ( It should be noted that, in the following, for the convenience of description, the master mold and the duplicate mold are only referred to as molds).

In order to smoothly release the mold from the object to be transferred, it is known to apply a release agent on the surface of the mold in advance to form a release layer and then transfer the pattern.

By providing the mold release layer on the mold in this way, the mold releasability between the mold and the object to be transferred can be improved.

For example, Patent Document 1 describes a technique of using a surface modifier composed of an organosilicon compound having a linear perfluoropolyether structure as a release agent composition.

In addition, Patent Document 2 describes a silicone-based mold release agent having an organopolysiloxane structure as a basic structure. Specifically, unmodified or modified silicone oil, trimethylsilane-containing Oxysilicic acid polysiloxane, silicone-based acrylic resin, etc.

In addition, the above-mentioned mold release layer provided on the mold inevitably loses wear due to multiple imprints, so that mold release cannot be performed satisfactorily, and in the worst case, transfer defects may be caused. In addition, when mold release cannot be performed satisfactorily due to loss of the mold release layer, there is a possibility of mold contamination in which residues of the molded material constituting the transferred object adhere to the mold.

Therefore, for a mold provided with a mold release layer, regeneration treatment is usually performed on a mold that has been imprinted a certain number of times. As a specific regeneration process, first, the mold with the mold release layer is washed with a mixture of sulfuric acid and hydrogen peroxide obtained by mixing sulfuric acid and hydrogen peroxide, etc., thereby removing the mold release layer from the mold. After that, washing, drying, etc. are appropriately performed, and a mold release agent is applied to the mold again to thereby provide a new mold release layer, thereby completing the regeneration process of the mold.

It should be noted that in Patent Document 3, in order to remove the photoresist layer remaining on the stamper, alkali aqueous solution treatment, solvent treatment, UV/O ₃ treatment, and pure water treatment were sequentially performed, thereby removing the photoresist layer. Residual photoresist layer on the mold. That is, the idea in Patent Document 3 is to oxidize an organic compound with ozone to make it soluble in alkali in order to remove the resist.

prior art literature

patent documents

Patent Document 1: Japanese National Publication No. 2008-537557

Patent Document 2: Japanese Patent Laid-Open No. 2010-006870

Patent Document 3: Japanese Unexamined Patent Application Publication No. H10-92024

Contents of the invention

The problem to be solved by the invention

As described in Patent Documents 1 and 2, a perfluoropolyether compound or a silicon-based compound is generally used as a release agent for nanoimprinting.

These compounds are generally capable of improving the mold releasability with respect to the object to be transferred due to fluorine or silicon. Specifically, the portion in the molecular chain of the compound that is not provided with a modified silyl group, that is, the portion containing a fluorine group or silicon, lowers the surface free energy of the transfer target portion of the mold that is intended to contact.

As a result, the mold can be smoothly released from the release layer provided on the mold. Therefore, in order to provide a good release layer, it is considered preferable to reduce the surface free energy of the portion to be in contact with the object to be transferred.

For example, in the case of a mold in a state where the surface free energy is large such as the above-mentioned mold release layer that lowers the surface free energy is not provided, when cleaning is performed with a mixed solution of sulfuric acid and hydrogen peroxide, IPA (isopropyl alcohol), or pure water, The cleaning treatment can be carried out favorably.

However, in order to achieve smooth mold release, when the mold is provided with a mold release layer that reduces the surface free energy of the part that is in contact with the object to be transferred, due to the influence of the extremely low surface free energy of the mold release layer , will lead to a mixture of sulfuric acid and hydrogen peroxide, or cleaning solvents such as IPA and pure water, and the wettability of cleaning substances with respect to the release layer will be in a very poor state.

In this way, if the wettability is poor, when cleaning is performed during mold regeneration, there is a problem that cleaning marks, drying unevenness, etc. are induced, and satisfactory mold regeneration is hindered. In addition, poor wettability is also closely related to a reduction in cleaning efficiency, and thus a very serious problem arises in the process of transferring fine patterns in mass production processes such as patterned media.

Therefore, the invention of the present application is proposed in order to solve the above-mentioned problems, and it provides a method of cleaning a mold with a release layer and a method of manufacturing a mold with a release layer, wherein the mold formed on the mold can be almost completely removed. It can be cleaned by means of the mold release layer, and the mold can be regenerated without deteriorating the ultra-fine pattern.

means of solving problems

The first aspect of the present invention is a method of cleaning a mold with a release layer,

In the above-mentioned mold with a release layer, a release layer is provided on the mold for transferring a predetermined pattern to an object to be transferred by embossing,

The above-mentioned cleaning method is characterized in that,

The release layer is made of fluorine compound,

The above cleaning method has:

An ultraviolet irradiation treatment step, wherein ultraviolet rays are irradiated to the mold release layer of the above-mentioned mold with a mold release layer; and

A cleaning treatment step of cleaning and removing the release layer chemically modified in the above-mentioned ultraviolet irradiation treatment step.

Wherein, in the above-mentioned ultraviolet irradiation treatment step, when the central wavelength output by the ultraviolet light source is set at 150 nm to 200 nm, the cumulative irradiation energy of ultraviolet rays is 5000 mJ/cm ² to 7000 mJ/cm ² .

A second aspect of the present invention is the method for cleaning a mold with a release layer according to the first aspect, wherein:

The above-mentioned fluorine compound is the following compound,

[chemical 1]

Among them, m is a natural number.

A third aspect of the present invention is the method for cleaning a mold with a release layer according to the first aspect, wherein:

The above-mentioned fluorine compound is the following compound,

[Chem 2]

Among them, m is a natural number.

A fourth aspect of the present invention is the method for manufacturing a mold with a release layer according to the first aspect, wherein:

The combination includes: at least one of heat treatment of heating the release layer to a predetermined high temperature state, and electron beam irradiation treatment of irradiating the release layer with electron beams; and the ultraviolet irradiation treatment step.

A fifth aspect of the present invention is a method of manufacturing a mold with a release layer, characterized in that,

Clean and remove the mold release layer of the mold using any one of the cleaning methods for molds with a mold release layer described in the first to fourth modes above, and install the mold release again on the mold from which the mold release layer was removed. layer.

Invention effect

According to the present invention, the mold can be cleaned so that the release layer formed on the mold can be almost completely removed, and the mold can be regenerated without deteriorating the ultrafine pattern.

Description of drawings

FIG. 1 is a schematic cross-sectional view illustrating a mold with a release layer according to the present embodiment.

FIG. 2 is a graph showing measurement results of fluorine in Examples by XPS (X-ray Photoelectron Spectroscopy).

Detailed ways

Embodiments of the present invention will be described below. FIG. 1( a ) is a schematic cross-sectional view showing the state of the master mold or a replica mold made from the master mold. It should be noted that, in this embodiment, the master die for imprinting (that is, master die, etc.) or the replica mold made from the master die is simply referred to as a die.

As the material of the mold 30, any material may be used as long as it can be used as an imprint mold. For example, when photoimprinting is performed, it is preferable to use a light-transmitting material (for example, quartz, sapphire, etc.) because it can be exposed through the mold 30 . In addition, as the material of the mold 30, a silicon wafer, nickel, or the like can also be used. Furthermore, when thermal imprinting is performed, a SiC substrate or the like may be used.

It should be noted that the predetermined pattern formed on the mold 30 may be on the order of microns, but considering the performance of electronic devices in recent years, it may also be on the order of nanometers; Performance, preferably on the order of nanometers.

(Setting of the release layer on the mold)

FIG. 1( b ) is a schematic cross-sectional view showing a state in which a mold release layer 31 is provided on a mold 30 . As shown in FIG. 1( b ), in the mold 30 , a release agent is applied at least to a portion where a predetermined pattern is formed to thereby provide a release layer 31 .

A predetermined pattern is transferred by bringing such a mold 30 provided with a mold release layer 31 into contact with an object to be transferred. In addition, the object to be transferred is cured according to each imprint method (optical imprint or thermal imprint). Next, the mold 30 provided with the mold release layer 31 is peeled off from the solidified transfer object. Since the mold 30 is provided with the mold release layer 31 , the surface free energy of the mold 30 is reduced, so the mold 30 can be easily peeled off.

In this way, by providing the mold release layer 31 on the mold 30, the mold 30 can be smoothly released from the object to be transferred, so that the pattern of the mold 30 and the object to be transferred can be suppressed while improving throughput. destruction.

A fluorine compound is used for the release agent applied on the mold 30 , that is, the release layer 31 . In this way, if a chemically very stable fluorine compound is used for the release layer 31, the surface free energy of the mold 30 in contact with the object to be transferred can be reduced favorably, so very good release can be achieved.

In addition, if the mold 30 provided with such a release layer 31 is used to repeatedly transfer a predetermined pattern on the transfer object, the release cannot be performed well due to the occurrence of wear and tear of the release layer 31 and the like. The mold, or the contamination that a part of the object to be transferred adheres to the mold 30 is generated. Therefore, when multiple imprints are performed in order to avoid such a problem, once the mold release layer 31 provided on the mold 30 is removed, it is necessary to regenerate the mold 30 by providing a new mold release layer 31 .

(About mold recycling)

In order to perform high-quality regeneration of the mold 30 as described above, the present inventors have come up with the technical idea that it is effective to chemically modify the mold release layer 31 formed on the surface of the mold 30 . 31 is composed of chemically very stable fluorine compounds.

Specifically, in the preceding stage of cleaning with a mixed solution of sulfuric acid and hydrogen peroxide, etc., ultraviolet treatment of irradiating the release layer 31 with ultraviolet rays is performed as a reforming treatment on the release layer 31 . Here, in the ultraviolet irradiation treatment, it is preferable to irradiate the mold release layer 31 with ultraviolet light having a central wavelength of 150 nm to 200 nm output by the ultraviolet light source so that the cumulative irradiation energy is 5000 mJ/cm ² to 7000 mJ/cm ² . It should be noted that any one or both of the heat treatment of heating the release layer 31 to a predetermined high temperature state and the electron beam irradiation treatment of irradiating the release layer 31 with electron beams may be implemented in combination with the above-mentioned ultraviolet irradiation treatment. . In addition, any treatment may be used as long as the mold release layer 31 can be chemically modified other than the above-mentioned method.

As a result, the release agent molecules of the release layer 31 are decomposed, and the surface free energy of the mold 30 itself increases. Thereafter, the mold 30 is washed with a mixed solution of sulfuric acid and hydrogen peroxide, IPA/pure water, etc. to remove the mold release layer 31 , and is washed or dried as appropriate. In addition, regeneration is achieved by applying a release agent again to install a new release layer 30 on the mold 30 again.

<Effects of Embodiments of the Present Invention>

In the present embodiment as described above, the following effects can be obtained. In the regeneration process of the mold, the mold release layer 31 made of a chemically very stable fluorine compound is first chemically modified to decompose the mold release agent molecules, so it can be easily removed in the subsequent cleaning process A release agent for forming the release layer 31 .

Thereby, since the mold release layer 31 which cannot be removed can be almost completely removed only by the cleaning by the conventional cleaning method, high-quality cleaning can be realized. Therefore, the regeneration process of the mold 30 can be smoothly carried out so that the imprint process can be realized with high efficiency. Further, since the mold 30 can be regenerated with sufficiently reduced pattern deterioration even for the used mold 30 , the life of the mold 30 can be extended. Therefore, especially for an expensive mold for transferring an ultrafine pattern, since the reuse life can be extended, a significant cost reduction can be achieved.

Such a mold can be used in both thermal imprinting and photoimprinting, and can also be applied to nanoimprinting technology. In particular, this embodiment can be suitably applied to a patterned medium produced using an imprint technique.

As mentioned above, although embodiment of this invention was mentioned, the above-mentioned disclosure is for showing the exemplary embodiment of this invention. The scope of the present invention is not limited to the above-described exemplary embodiments. Regardless of whether it is explicitly described or implied in this specification, those skilled in the art can implement various modifications to the embodiments of the present invention based on the disclosure of this specification.

Example

Next, an Example is shown and this invention is demonstrated concretely. It is needless to say that the present invention is not limited to the following examples.

<Example 1>

In this embodiment, a mold 30 composed of a quartz substrate provided with a line-and-space pattern of a half-pitch 25 nm periodic structure with a depth of 30 nm, a line length of 15 nm, and an interval of 10 nm was used. This mold 30 was dipped in VERTRELXF-UP (VERTREL is a registered trademark, manufactured by DuPont-Mitsui Fluorochemicals Co., Ltd.) for 5 minutes in a release agent containing the following compound (same as [Chem. 1]) diluted to 0.5 wt%. . Among them, m is a natural number.

[Chem 3]

Thereafter, the mold 30 is pulled up at a speed of 120 mm/min.

In this way, the release agent was applied by the dipping method. In this case, the sample was heat-treated at a temperature of 170°C. Thereafter, the mold 30 was rinsed. At this time, use VERTRELXF-UP as the rinse solution and perform a 10-minute rinse. In this way a mold with a release layer was obtained.

Such a mold with a release layer was irradiated with ultraviolet light having a center wavelength of 172 nm and an output (lamp) of 50 mW/cm ² for 2 minutes. It should be noted that the irradiation environment at this time is a mixed atmosphere of N ₂ and O ₂ , and the range of the flow rate ratio is such that O ₂ is 5% to 10%. In addition, after irradiating ultraviolet rays, washing treatment was performed for 30 minutes each with hot sulfuric acid and cold sulfuric acid, and further washing treatment was performed with pure water and IPA.

In Fig. 2, the F1s spectrum of fluorine was observed using X-ray photoelectron spectroscopy (XPS). As shown in FIG. 2 , the F1s peak was hardly observed, so it is considered that the release agent forming the release layer was almost completely removed.

<Example 2>

In this example, it carried out similarly to Example 1 except having used the release agent containing the following compound (the same as [Chem. 2] mentioned above). As a result of observing the F1s spectrum of fluorine, as in Example 1, almost no F1s peak was observed. Among them, m is a natural number.

[chemical 4]

<Comparative example>

In the comparative example, three molds with a release layer produced by the same method as in the examples were prepared, and this time the time dependence of irradiation with ultraviolet rays was studied. The first example is a case where no ultraviolet rays are irradiated at all; the second example is a case where the irradiation time is set to 5 minutes; and the third example is a case where the irradiation time is set to 10 minutes. In either case, cleaning treatment was performed for 30 minutes each with hot sulfuric acid and cold sulfuric acid, and further cleaning treatment was performed with pure water and IPA in the same manner as in the examples.

As shown in FIG. 2 , in the case of the first example where the conventional cleaning method was applied without irradiating ultraviolet light at all, the F1s spectrum of fluorine showed a high value, indicating that the release agent was not removed. In addition, in the case of the second example and the third example, the peak of the F1s energy spectrum of fluorine was confirmed, so it can be seen that the cleaning of the release agent was not sufficient in either case.

<Evaluation>

From the examples and comparative examples, it can be seen that the treatment for chemically modifying the release layer, i.e., the irradiation of ultraviolet rays, has a time dependence. It shows a very high effect.

This is considered to be because, in the fluorine-based polymer whose terminal functional group is a hydroxyl group, the cleavage of the main chain starts from the part close to the terminal by the ultraviolet irradiation treatment, and the molecule gradually starts to decompose. From this, it is presumed that when ultraviolet rays are irradiated for more than 2 minutes, the entire main chain is decomposed, and thus the generated fluorine low-molecular compound chemically modifies the surface of the mold.

Therefore, it is presumed that the mold release agent cannot be removed satisfactorily even if a predetermined cleaning treatment is performed after the ultraviolet irradiation. On the other hand, when ultraviolet rays are irradiated for about 2 minutes, molecular cleavage is thought to occur only in the vicinity of the end, that is, in the vicinity of the adsorption group, so the release agent can be favorably removed by the subsequent predetermined cleaning treatment.

Based on the above, optimal conditions in the ultraviolet irradiation treatment were studied. In the above-mentioned examples, ultraviolet rays with an output of 50 mW/cm ² were irradiated for 2 minutes, so the cumulative irradiation energy of ultraviolet rays was obtained as follows.

50mW/cm ² ×120sec=6000mJ/cm ²

From this, it is considered that the same effect as in the above-mentioned embodiment can be produced by setting the cumulative irradiation energy in the range of 5000mJ/cm ² to 7000mJ/cm ² within the range of the central wavelength of the output of the ultraviolet light source in the range of 150nm to 200nm.

Explanation of symbols

30 molds

31 release layer

Claims (5)

1. A method for cleaning a mold with a release layer, in the mold with a release layer, a mold for transferring a predetermined pattern to an object to be printed by embossing is provided with a mold release layer, the cleaning method is characterized in that, The release layer is made of fluorine compound, The cleaning method has: An ultraviolet irradiation treatment step, wherein ultraviolet rays are irradiated to the release layer of the mold with a release layer; and A cleaning treatment step, wherein the release layer chemically modified by the ultraviolet irradiation treatment step is cleaned to be removed; Wherein, in the ultraviolet irradiation treatment step, when the central wavelength output by the ultraviolet light source is set at 150 nm to 200 nm, the cumulative irradiation energy of ultraviolet rays is 5000 mJ/cm ² to 7000 mJ/cm ² . 2. the cleaning method of the mold with release layer as claimed in claim 1, is characterized in that, The fluorine compound is the following compound,

Among them, m is a natural number. 3. the cleaning method of the mold with release layer as claimed in claim 1, is characterized in that, The fluorine compound is the following compound,

Among them, m is a natural number. 4. the cleaning method of the mold with release layer as claimed in claim 1, is characterized in that, The combination includes at least one of heat treatment of heating the release layer to a predetermined high temperature state, and electron beam irradiation treatment of irradiating the release layer with electron beams; and the ultraviolet irradiation treatment step . 5. A method of manufacturing a mold with a release layer, characterized in that, Use any one of the cleaning methods for the mold with the release layer described in claim 1 to claim 4 to clean the release layer of the mold and remove it, and set the release layer again on the mold from which the release layer has been removed layer.

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