JP2012236371A - Release method in imprint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently release an object to be molded to which a predetermined pattern is transferred without separately providing a release layer to a mold.SOLUTION: The release method for separating the mold 30 from the object to be molded, in imprinting in which the object to be molded is molded by transferring a desired pattern formed on the mold 30 to material to be molded, includes: a contraction process for contracting the object to be molded so as to reduce release force between the object to be molded and the mold 30; and a release process for separating the mode 30 from the object to be molded after the contraction process.

Description

  The present invention relates to an imprint in which a desired pattern formed on a mold is transferred to a material to be molded, and more particularly to a mold release method after transfer.

  In recent years, the conventional magnetic recording medium cannot cope with the increasing demand for higher density of information recorded on a recording medium such as a magnetic disk such as a hard disk. In order to cope with such high density recording information, a magnetic recording medium called a patterned medium has been devised. This patterned medium is a recording medium in which a recording area is magnetically or physically isolated, and an improvement in recording density is expected.

  This patterned media can be duplicated and mass-produced using an imprint apparatus using an imprint technique for transferring a desired pattern formed on a mold to a molding material. In particular, in the case of patterned media, an imprint apparatus that uses nanoimprint technology that supports nanometer order transfer is used.

  This imprint technique is roughly divided into two types, thermal imprint and optical imprint.

  Thermal imprinting is a method in which a mold on which a fine uneven pattern is formed is pressed against a thermoplastic resin as a molding material while being heated, and then the molding material is cooled and released to transfer the fine pattern.

  Optical imprinting is a process in which a mold with a fine uneven pattern is pressed against a photocurable resin, which is a molding material, and irradiated with ultraviolet light to cure, and then the molding material is released to form a fine pattern. It is a method of transcription.

  In mass production in an imprint apparatus, a master mold as a master mold is used, but in reality, this master mold is called a plurality of working replicas duplicated by transferring the master mold to a molding material. A copy mold will be used for each mass production line. That is, since the copy mold is used as an alternative mold for the master mold, which is the original mold, formation with extremely high accuracy is required.

  However, when a mold release process is performed to release the mold from the cured molded object after transferring the fine uneven pattern of the mold to the material to be molded, a certain degree of high release force is required for the mold release. For this reason, defects may occur in the concavo-convex pattern formed by transfer molding, or the mold release may not be successful, causing various problems. In particular, in the nanoimprint technology corresponding to nanometer order transfer, there is a high possibility that such a problem becomes remarkable.

  In addition, if a problem occurs in such a mold release process, it may cause a decrease in throughput, which increases the cost and eventually becomes a barrier to mass production. Therefore, the mold release process is very important in imprinting. Is one of the most important processes.

  Therefore, for example, in Patent Document 1, a mold release agent is formed on a template on which a transfer pattern is formed, thereby facilitating release after the transfer pattern is transferred to a coating film formed on a substrate. Is disclosed.

  In addition, a technique for facilitating mold release by reducing the degree of adhesion between the mold and the workpiece to which the transfer pattern is transferred by physically deforming the mold or the substrate is also known. For example, Patent Document 2 discloses a mechanism that facilitates peeling between a mold and a resin by bending the substrate.

JP2011-5696A JP 2007-83626 A

  However, in the mold release process in which the mold is released from the cured molded product after transferring the concave / convex pattern of the mold to the molding material as described above, for example, the mold release disclosed in Patent Document 1 is performed. When a mold is used, the mold release agent always has a physical film thickness, so this film thickness cannot be ignored in the technical fields that handle ultra-fine patterns such as next-generation semiconductors and patterned media. Therefore, there is a problem that size restrictions are imposed on the transfer pattern.

  In addition, for example, when mold release is performed by physically deforming a mold or a substrate such as bending the substrate as disclosed in Patent Document 2, the transfer pattern becomes finer and larger in area. There is a high possibility that adverse effects such as collapse of the transfer pattern will occur. Specifically, there is a possibility that it will be extremely difficult to cope with the ultra-fine transfer pattern, which is a future technical development direction, and the large area of the transfer pattern that performs transfer with high efficiency.

  In particular, when the transfer pattern is enlarged in a large area, the required release force becomes very high, which causes various problems such as transfer pattern deterioration, throughput reduction, and direct damage to the imprint apparatus. There is a problem such as.

  Therefore, the present invention has been devised to solve the above-mentioned problems, and it is possible to satisfactorily release a molding object to which a predetermined pattern is transferred without separately providing a release layer on the mold. A mold release method that enables the

The first aspect of the present invention is:
A mold release method for separating a mold from a molding in an imprint for molding the molding by transferring a desired pattern formed on the mold to the molding material,
A shrinking step of shrinking the molding so as to reduce a releasing force between the molding and the mold;
A mold release method in imprint, comprising: a mold release process for separating the mold from the molding object after the contraction process.

The second aspect of the present invention is:
When the molding material is a photo-curable resin and the imprint is a light imprint,
The shrinking step determines an irradiation time of light applied to the molding material and a rate of shrinking the molding so as to reduce a releasing force between the molding and the mold. It is the mold release method in the imprint as described in a 1st aspect.

The third aspect of the present invention is:
When the molding material is a thermoplastic resin and the imprint is a thermal imprint,
The shrinking step is characterized in that a ratio of shrinking the molding object is determined by increasing a thermal expansion coefficient of the molding material in advance so as to reduce a releasing force between the molding object and the mold. A mold release method in imprinting according to the first aspect.

  According to the present invention, it is possible to satisfactorily release a molding object to which a predetermined pattern is transferred without separately providing a release layer on the mold.

It is a figure for demonstrating the concept of shrinking and releasing a to-be-molded object with respect to a mold. It is a figure for demonstrating the process of producing a copy mold by optical imprint using a mold. It is the figure which showed the mode of the change of the exposure time at the time of irradiating with ultraviolet light (ultraviolet light irradiation time), and the film thickness of a resist layer in order to verify the shrinkage | contraction rate of the resist layer optimal for mold release.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the imprint, the inventor transfers the fine uneven pattern formed on the mold to the molding material, and then cures the molded article formed by curing, by the curing process or some stimulus. It was found that the mold can be easily released without contracting a separate release layer by shrinking the molding.

  As described above, if the molding can be contracted after transferring the fine concavo-convex pattern, the fine concavo-convex pattern of the mold 30 is applied to the resist layer 4 as the molding as shown in FIG. After the transfer, a slight gap is formed between the mold 30 and the resist layer 4 that is the molding object, as shown in FIG. Thereby, the pressure which acts between a to-be-molded object and the mold 30 will fall. Accordingly, the mold release force required to separate the mold 30 from the molding object can be greatly reduced without providing a mold release layer separately on the mold 30, so that easy mold release is possible.

  This concept can be used for both thermal imprinting and optical imprinting, and can also be applied to nanoimprint technology. In particular, the present embodiment can be suitably applied to patterned media manufactured using an imprint technique.

<In case of optical imprint>
First, the case of optical imprint will be described.
(Preparation of the original mold)
As shown in FIG. 1, a mold 30 is prepared as a mold 30 for a pattern to be transferred to a copy mold. The mold 30 may be any mold as long as it can be used as an imprint mold, but is preferably a translucent mold (for example, quartz or sapphire) because exposure described later can be performed from above the mold 30.

  If the copy mold substrate has translucency, exposure can be performed from the copy mold substrate side. In this case, the material of the mold 30 can be used even if it does not have translucency (for example, silicon wafer, nickel). In the present embodiment, a case will be described in which a quartz substrate provided with a groove corresponding to a predetermined pattern is used.

  The predetermined pattern provided on the quartz substrate may be on the micron order, but may be on the nano order from the viewpoint of the performance of electronic devices in recent years, or the final pattern produced by an imprint mold or the like. This is preferable when considering the performance of the product.

  In addition, the predetermined pattern formed on the mold 30 takes into account the shrinkage ratio in advance from the viewpoint of shrinking the molded object in order to realize easy releasability that is the gist of the present invention as described above. The pattern shape is calculated and formed so as to match it. When considering the shrinkage rate from the viewpoint of volume, it is estimated that the vertical, horizontal, and height shrinkage rates are different. It is necessary to calculate such a shrinkage rate.

  When a predetermined pattern provided on the mold 30 is transferred by imprinting, a pattern opposite to the predetermined pattern is formed on the copy mold. Therefore, if the pattern of the copy mold is a pattern to be finally obtained, a pattern opposite to the pattern may be formed on the mold 30. Moreover, after transferring a pattern to a temporary copy mold, the same pattern as the mold 30 may be obtained by transferring the temporary copy mold pattern to another copy mold.

  Hereinafter, the process of producing a copy mold by optical imprinting using this mold 30 will be described with reference to FIG.

(Preparation of copy mold manufacturing substrate)
First, as shown in FIG. 2A, a substrate 1 for a copy mold 20 is prepared.
The substrate 1 may be any material as long as it can be used as the copy mold 20 and may be the same material as the mold 30 described above. Moreover, the same material as the mold 30 may be used. In addition, when performing a light imprint, it is preferable that it is a translucent board | substrate from a viewpoint of light irradiation to a to-be-transferred material. Examples of the light-transmitting substrate 1 include a glass substrate such as a quartz substrate. In addition, if the mold 30 has translucency, it may be a non-translucent substrate such as a Si substrate.

  Further, as for the shape of the substrate 1, it is preferably a disc shape. This is because when applying the resist, the resist can be uniformly applied while rotating the disk-shaped substrate 1. The shape may be other than a disk shape, and may be a rectangle, a polygon, or a semicircle. In the present embodiment, a description will be given using a substrate 1 made of disc-shaped quartz.

(Formation of hard mask layer)
Next, as shown in FIG. 2B, the substrate 1 is introduced into a sputtering apparatus. In this embodiment, it is preferable to form a chromium nitride layer 3 by sputtering a chromium target with a mixed gas of argon and nitrogen to form a hard mask layer having a fine pattern.

Further, a conductive layer may be formed to ensure conductivity. The material of the conductive layer may be any material that is used as a known conductive layer. As an example, a compound containing Ta as a main component can be mentioned. In this case, Ta compounds such as TaHf, TaZr, TaHfZr, and alloys thereof are suitable. On the other hand, at least one element of hafnium (Hf) and zirconium (Zr) or a compound thereof (for example, HfZr) can be selected, and these materials are used as base materials, for example, B, Ge, Nb, Si, C, etc. , N and other sub-materials can be selected. Further, the conductive layer may be formed on either the upper layer or the lower layer of the hard mask layer (in this embodiment, the chromium nitride layer 3).
In addition to such a conductive layer, an antioxidant layer may be formed.

  As the material for the hard mask layer, chromium nitride (CrN) is preferable as described above from the viewpoint that it is not necessary to use oxygen in sputtering at the time of film formation. I just need it. For example, a molybdenum compound, chromium oxide (CrO), SiC, amorphous carbon, or Al may be used. In this embodiment, a hard mask layer made of chromium nitride (CrN) will be described.

  Thus, as shown in FIG. 2B, the chromium nitride layer 3 is formed on the substrate 1 using the hard mask layer.

The “hard mask layer” in this embodiment is composed of a single layer or a plurality of layers, can protect a portion where a groove corresponding to a pattern is to be formed, and is used for etching a groove on a substrate. It shall mean the layered thing used for a mask.
Thus, what provided the hard mask layer on the board | substrate is called mask blanks in this Embodiment.

(Formation of resist layer)
After appropriately cleaning and baking the chromium nitride layer 3 that is the hard mask layer in the mask blank, as shown in FIG. 2C, the chromium nitride layer 3 that is the hard mask layer in the mask blank is Then, a resist for photoimprinting is applied to form a resist layer 4, and mask blanks with resist used for manufacturing the copy mold 20 in the present embodiment are produced. Here, the resist corresponds to a material to be molded, and the resist layer 4 corresponds to a material to be molded.

  Examples of the resist for photoimprinting include a photocurable resin, particularly an ultraviolet curable resin. Any photocurable resin may be used as long as it is suitable for an etching process performed later.

  Further, this resist has a composition such that when the mold 30 is released from the mold 30, the resist layer 4 as a molding contracts and a gap is provided between the mold 30 and the release force can be reduced. It is desirable. For example, a composition in which contraction of the resist layer 4 is promoted by stimulation such as irradiation with electromagnetic waves such as light and microwaves, or irradiation with ionizing radiation such as electron beams is conceivable. Further, the resist layer 4 is not limited to a single composition, and may be a mixture with a polymerization initiator or the like for promoting curing / shrinkage, and various characteristics (viscosity, volatility, Young's modulus) necessary for nanoimprinting. -A mixture of a plurality of compositions may be used in order to satisfy adhesiveness. Such an in-mold material is under intensive investigation by the inventor.

In addition, the thickness of the resist layer 4 at this time is preferably such a thickness that the resist serving as a mask remains until various etchings are completed.

  In addition, before providing the resist layer 4, you may provide an adhesion | attachment layer previously on the chromium nitride layer 3 which is a hard mask layer. By providing the adhesion layer, it is possible to prevent the resist layer 4 from being peeled off during imprinting or etching.

(Placing the original mold on the resist layer)
After appropriately baking the resist layer 4, a mold 30 on which a fine pattern is formed is placed on the resist layer 4 as shown in FIG. At this time, if the resist layer 4 is liquid, it is only necessary to mount the mold 30. Moreover, when the resist layer 4 is a solid shape, the resist layer 4 may be soft enough to press the mold 30 against the resist layer 4 and transfer a fine pattern.

(Pattern transfer by exposure)
Thereafter, the fine pattern of the mold 30 is transferred to the resist layer 4 using an ultraviolet light irradiation device. At this time, the ultraviolet light exposure is usually performed from the mold 30 side. However, when the mask blank substrate 1 is a translucent substrate, the exposure may be performed from the substrate 1 side.

  The exposure time at this time is such that when the mold 30 is released from the mold 30, the resist layer 4, which is a molding object, contracts and a gap is provided between the mold 30 and the release force can be reduced. And Since the shrinkage of the resist layer 4 which is a molding object depends on the exposure time, the shrinkage is promoted by extending the exposure time necessary for curing the resist.

  Specifically, it is desirable that the shrinkage rate, which is the rate of shrinkage, is such that an appropriate gap is formed between the mold 30 and the transfer pattern position accuracy and size do not vary. Therefore, while taking into account the above-described adverse effects, the irradiation time of the light to be irradiated on the molding material and the molding are contracted so as to reduce the release force between the resist layer 4 and the mold 30 as the molding. The ratio to be determined will be determined.

  At this time, in order to prevent a transfer failure due to a positional shift between the mold 30 and the mask blank, preparation for providing a groove for the alignment mark on the substrate may be performed.

(Removal of residual film layer in resist layer)
After the fine pattern is transferred, the mold 30 is released from the mask blank with resist as shown in FIG. At this time, since the resist layer 4 is contracted by providing a predetermined gap with respect to the fine uneven pattern of the mold 30, the releasing force is greatly reduced. Therefore, the mold 30 can be easily and easily released from the resist layer 4 that is a molding target.

  After the mold release, the remaining resist layer on the chromium nitride layer 3 is removed by ashing using a plasma of a gas such as oxygen or ozone. In this way, a resist pattern corresponding to a desired fine pattern is formed as shown in FIG. A groove is formed on the substrate 1 in a portion where the resist pattern is not formed.

(First etching)
Next, the substrate 1 having a resist pattern formed on the substrate is introduced into a dry etching apparatus. Then, first etching with a gas containing a chlorine-based gas is performed in an atmosphere substantially free of oxygen gas. At this time, it is preferable to perform etching using the above gas together with the reducing gas from the viewpoint of preventing oxidation of the hard mask layer.

  Note that “under an atmosphere that does not substantially contain oxygen gas” means “under an atmosphere in which the amount of inflow is such that anisotropic etching can be performed even if oxygen gas flows in during etching”. Preferably, it is an atmosphere when the inflow amount of oxygen gas is 5% or less of the entire inflow gas.

  By this etching, as shown in FIG. 2G, a hard mask layer (chromium nitride layer 3) having a fine pattern is formed. Note that the etching end point at this time is determined by using a reflection optical end point detector.

(Second etching)
Subsequently, after the gas used in the first etching is evacuated, second etching using a fluorine-based gas is performed on the substrate 1 in the same dry etching apparatus. At this time, the substrate 1 is etched using the chromium nitride layer 3 as the hard mask layer as a mask, and grooves corresponding to the fine pattern are formed on the substrate 1 as shown in FIG. Before and after that, the resist is removed with an alkaline solution or an acid solution.

Examples of the fluorine-based gas used here include C _x F _y (for example, CF ₄ , C ₂ F ₆ , C ₃ F ₈ ), CHF ₃ , a mixed gas thereof, or a rare gas (He, Ar) as an additive gas thereto. , Xe, etc.).

  Thus, as shown in FIG. 2 (h), a groove corresponding to the fine pattern is formed on the substrate 1, and a chromium nitride layer 3 which is a hard mask layer having the fine pattern is formed on a portion other than the groove of the substrate 1. The In this way, the mold 10 before removing the remaining hard mask layer is produced.

(Removal of hard mask layer)
The chromium nitride layer 3, which is a hard mask layer remaining on the mold 10 before the remaining hard mask layer removal, is subsequently applied to the mold 10 before the remaining hard mask layer thus manufactured by the same method as the first etching. Is removed by dry etching, thereby producing a copy mold 20 which is an imprint mold (FIG. 2 (i)).

  Note that only one of the etchings may be wet etching, and other etchings may be dry etching, or all etchings may be wet etching or dry etching. Further, when the pattern size is in the micron order, wet etching may be introduced according to the pattern size, such as wet etching at the micron order stage and dry etching at the nano order stage.

  Although the first and second etchings are performed in the present embodiment, additional etching may be added between the first and second etchings depending on the constituent material of the mask blank.

(Completion of copy mold)
Through the above steps, after removing the chromium nitride layer 3 which is a hard mask layer other than the groove forming portion, the substrate 1 is cleaned if necessary. In this way, the copy mold 20 as shown in FIG. 2 (i) is completed.

<In case of thermal imprint>
Next, the case of thermal imprint will be described. In the following description, parts not particularly mentioned are the same as in the case of optical imprint.

First, regarding the substrate used for manufacturing the copy mold 20 for the master mold for thermal imprinting, an SiC substrate, an SiO ₂ substrate, etc. resistant to chlorine gas used for dry etching for the hard mask layer may be mentioned.

Note that the substrate 1 in the case of performing thermal imprinting, in addition to SiO ₂ substrate is a substrate having resistance to chlorine-based gas, the resistance to chlorine-based gas by devising the following relatively Weak silicon wafers can also be used. That is, an SiO ₂ layer is first provided on a silicon wafer. By providing a hard mask layer on the SiO ₂ layer, even if the hard mask layer is removed with chlorine gas, the SiO ₂ layer protects the silicon wafer from chlorine gas. Then, the SiO ₂ layer is removed with buffered hydrofluoric acid, that is, a mixed acid composed of ammonium fluoride and hydrofluoric acid. By doing so, a silicon wafer can also be used to produce a thermal imprint mold. Further, those having a SiO ₂ layer as a working layer on the silicon wafer can be used as a substrate. At this time, since a groove is provided in the SiO ₂ layer which is a processed layer, it is preferable to make the SiO ₂ layer thicker than when a silicon wafer is used.
In the present embodiment, description will be made using a disk-shaped SiC substrate.

  In the present embodiment, a chromium nitride layer 3 is formed on the substrate 1 as a hard mask layer.

  Next, a resist for thermal imprinting is applied to the chromium nitride layer 3 that is a hard mask layer in the mask blanks, and a resist layer 4 is formed to be used for manufacturing the copy mold 20 in the present embodiment. Attached mask blanks are produced.

  Examples of the resist for thermal imprinting include resins that are cured when cooled, and any resin that is suitable for an etching process to be performed later may be used. The resin preferably has such a softness that a fine pattern to be transferred is formed when the original mold is pressed. This is because when the original mold is pressed onto the resist, the resist easily deforms in accordance with the fine pattern of the mold 30 and the fine pattern can be accurately transferred by the subsequent cooling process.

  Further, it is desirable that the thermal imprint resist to be applied has a high coefficient of thermal expansion. As a specific method for increasing the coefficient of thermal expansion of the resist, in order to weaken the intermolecular force of the resist, the average molecular weight is reduced, and functional groups that contribute to electron bias and hydrogen bonding are not included. And so on. In addition, in order to increase the free volume of resist molecules, it does not contain double bonds or triple bonds that hinder the rotation and vibration of the molecules, and it has a linear structure and a rigid structure such as a tetrahedral structure. To avoid it.

  As a result, when a mold in which a desired pattern is formed on a resist as a molding material is pressed while being heated and cured by cooling, the resist layer 4 as a molding contracts when released from the mold 30. Thus, the release force can be reduced by providing a gap with the mold 30.

  Specifically, the shrinkage amount of the resist layer 4 is desirably set to such an extent that a suitable gap is formed between the resist layer 4 and the positional accuracy and size of the transfer pattern does not vary. Therefore, by designing the thermal expansion coefficient of the molding material in advance so as to reduce the mold release force between the resist layer 4 as the molding and the mold 30 while taking into account the above-described adverse effects, the molding is performed. The amount of shrinkage of the object will be determined.

  As described above, by changing the thermal expansion coefficient of the molding object by the above-described method, it is possible to reduce the releasing force satisfactorily without causing adverse effects such as variations in the positional accuracy and size of the transfer pattern. In addition, by appropriately setting the temperature range for cooling, it is possible to reduce the releasing force satisfactorily without causing any harmful effects.

  Thereafter, a fine pattern of the mold 30 is transferred to the resist layer 4 using a cooling processing apparatus. After transferring the fine pattern, the mold 30 is released from the mask blank with resist. At this time, since the resist layer 4 is contracted by providing a predetermined gap with respect to the fine uneven pattern of the mold 30, the releasing force is greatly reduced. Therefore, the mold 30 can be easily and easily released from the resist layer 4 that is a molding target.

  After transferring the fine pattern, the remaining film layer of the resist on the chromium nitride layer 3 that is the hard mask layer is removed by ashing, and then the copy mold 20 for the imprint master mold is completed by the above-described steps.

<Effect of Embodiment of the Present Invention>
In the present embodiment as described above, the following effects can be obtained. According to the present invention, a release layer has been provided in the past by applying a release agent to the mold 30, but the imprint is based on a revolutionary idea that the release force is reduced due to shrinkage of the molding object. The throughput in nanoimprinting can be greatly improved.

  In addition, even if the mold is used more than once, it does not affect the mold release at all, so it is completely free from complicated processes such as mold regeneration, and is also very effective in imprint and nanoimprint process management. It becomes.

  Further, in the present invention, the resist layer 4 is contracted in the curing process by light irradiation in the optical imprinting and in the curing process by cooling in the thermal imprinting, but the present invention is not limited to this. However, a step of shrinking the resist layer 4 may be provided separately from such a curing process. Specifically, the inventor is diligently examining, but it is conceivable to use a thermosetting resin for the resist layer 4 as an example. It is conceivable to obtain the above-described effect by liquefying before pattern transfer, curing by heating after pattern transfer, and contracting with it.

  It is also conceivable to provide a curing shrinkage step by using a resin that is cured by an electromagnetic wave such as microwaves or ionizing radiation such as an electron beam to obtain the above effect. Furthermore, in the optical imprint, a cooling process may be provided and the above effects may be obtained by performing cooling contraction.

  As mentioned above, although embodiment which concerns on this invention was mentioned, said disclosure content shows exemplary embodiment of this invention. The scope of the present invention is not limited to the exemplary embodiments described above. Whether or not explicitly described or suggested herein, those skilled in the art will make various modifications to the embodiments of the present invention based on the disclosure of the present specification. Can be implemented.

Next, an Example is shown and this invention is demonstrated concretely. Of course, the present invention is not limited to the following examples.

<Example>
In this example, optical nanoimprinting was performed using a mold 30 made 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 of 15 nm, and a space of 10 nm.

  Using such a mold 30, a photocurable resin was applied to a disk-shaped substrate made of Si. Then, the relationship between the film thickness (depth) of the resist layer 4 cured by irradiation with ultraviolet light and the exposure time of ultraviolet light was verified. The film thickness was measured with an optical spectral film thickness meter.

  FIG. 3 shows the relationship between exposure time and film thickness. In FIG. 3, the horizontal axis represents the ultraviolet light (UV) irradiation time [sec], that is, the ultraviolet light exposure time, and the vertical axis represents the shrinkage rate in the film thickness direction of the resist layer 4 with respect to the ultraviolet light irradiation time. By taking the film reduction rate [%] shown, the film thickness changes according to the exposure time. As shown in FIG. 3, it can be seen that the film thickness of the resist layer 4 formed by curing increases as the exposure time elapses.

<Evaluation>
Accordingly, an exposure time for reducing the release force by forming an appropriate gap between the mold 30 and shrinking the resist layer 4 so as not to cause variations in the position accuracy and size of the transfer pattern. Can be estimated as about 15 seconds (film reduction rate of about 17.5%).

1 Substrate 3 Chromium nitride layer 4 Resist layer 10 Mold before removing remaining hard mask layer 20 Copy mold 30 Mold

Claims (3)

A mold release method for separating a mold from a molding in an imprint for molding the molding by transferring a desired pattern formed on the mold to the molding material,
A shrinking step of shrinking the molding so as to reduce a releasing force between the molding and the mold;
A mold release method for imprint, comprising: a mold release process for separating the mold from the molding object after the shrinking process. When the molding material is a photo-curable resin and the imprint is a light imprint,
The shrinking step determines an irradiation time of light applied to the molding material and a ratio of shrinking the molding so as to reduce a releasing force between the molding and the mold. Item 2. A mold release method for imprints according to Item 1. When the molding material is a thermoplastic resin and the imprint is a thermal imprint,
The shrinking step is characterized in that a ratio of shrinking the molding object is determined by increasing a thermal expansion coefficient of the molding material in advance so as to reduce a releasing force between the molding object and the mold. The mold release method in imprinting according to claim 1.

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