JP2006086249A - Form transferring method and device thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a form transferring method which is excellent in release properties and high in throughput. <P>SOLUTION: The form transferring method comprises processes of keeping a mold 2 with irregularities which are provided in a prescribed pattern and a board 1 in an oxygen-containing atmosphere; pressing the mold 2 against the front surface of the board 1 so as to bring the projections of the mold 2 into close contact with the front surface of the board 1; and transferring the prescribed form provided on the mold 2 by irradiating the front surface of the board 1 with laser rays 3 so as to heat up the front surface of the board 1 and by selectively burning the front surface of the board 1 with oxygen contained in a space formed of the recesses of the mold 2 and the front surface of the board 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shape transfer method for transferring a desired shape onto a substrate in a manufacturing process of an electronic device, an optical device or the like in which a fine shape is formed, and a shape transfer apparatus for realizing the transfer method.

  In a manufacturing process of electronic devices, optical devices, and the like, a patterning method using a photolithography technique and an etching technique is generally used as a method for forming a predetermined shape on the surface of a workpiece. These are photosensitive resists formed on a substrate, partially exposed to light and developed to form a predetermined pattern. Using this patterned resist as a mask, vacuum such as ion milling or reactive ion etching is performed. A predetermined shape is processed by performing an etching process using a technique.

  However, with the recent price reduction of electronic devices, there is a strong demand for cost reduction of the process, and the above-described patterning method using an expensive exposure apparatus / etching apparatus is the biggest obstacle to cost reduction, and is easy to use. Therefore, there is a need for a low-cost patterning method.

  As one of the methods, development of a method for transferring a pattern, which is called imprinting and applying a molding technique, has been actively performed in recent years.

  This method is a method of transferring the shape of a mold by bringing a mold (mold) having irregularities of a predetermined pattern shape into close contact with a workpiece and applying pressure. Typically, a resist is used. There are a “resist imprint method” and a “direct imprint method” without using a resist.

  Among these, the “resist imprint method” is a method of transferring the shape of the mold to the resist by pressing the mold onto the resist using a substrate coated with the resist. According to this method, since exposure in the photolithography process, which is one of the main causes of high cost, can be omitted, a device that requires fine patterning can be manufactured at low cost (see, for example, Patent Document 1). ). However, it is necessary to further etch the base using an etching apparatus using the patterned resist as a mask.

  On the other hand, the “direct imprint method” is a method for directly transferring the surface shape of a mold to a substrate such as glass without using a resist. Patent Document 2 discloses a method of directly forming a nano-order groove on the surface of a substrate by pressing a molding die having fine processed grooves formed on the surface thereof onto a glass substrate.

  According to the direct imprint method, not only the exposure step but also the etching step can be omitted. Therefore, it is considered that the cost reduction effect is greater than the resist imprint method in which only the exposure step can be omitted.

  In addition, as a method for processing an inexpensive shape other than the imprint method, a method is disclosed in which a substrate is etched by a selective oxidation reaction on a carbon substrate, thereby performing fine uneven processing without using an expensive etching apparatus. (See, for example, Patent Document 3).

In the above method, a carbon substrate on which an oxidation resistant mask is formed in advance is placed in an oxidizing atmosphere and heated to about 400 to 700 ° C., so that the portion not covered with the mask is selectively oxidized and oxidized. A method of forming a desired shape at low cost by etching is disclosed, and stable processing is possible as compared with conventional machining.
JP 2003-77807 A JP 2003-85740 A JP-A-5-274667

  However, the imprint method described above, for example, as disclosed in Patent Document 1, has improved mold releasability by applying a certain treatment to the surface of the mold. It is difficult to ensure, for example, reprocessing is required every several hundred to several thousand shots.

  In addition, in the imprint method, when a mold release failure occurs, a fine work piece adheres to the mold or processing is performed with a large pressing force. There was a problem that it was likely to occur and pattern defects were likely to occur.

  Furthermore, the imprint method generally requires heating the resist or glass to the glass transition point or higher (about 100 to 200 ° C. in the case of resist, about 500 to 700 ° C. in the case of glass), and it is difficult to increase the throughput. Met.

  In addition, the above-described method of selectively etching carbon by oxidation requires heating to a high temperature of 400 to 700 ° C. and requires time for heating and cooling. It was difficult. Further, regarding the oxidation resistant film used as a mask during etching, the formation process and the removal process after the etching are necessary, so that the process is complicated.

  The present invention has been made in view of the above circumstances, and its purpose is a high-throughput, extremely good releasability, less prone to mold contamination and breakage, and can be processed at low cost. It is an object to provide a transfer method and a transfer apparatus thereof.

  In the shape transfer method according to the present invention, the step of holding the mold and the substrate in which irregularities are formed in a predetermined pattern shape in an atmosphere containing oxygen, and the convex portion of the mold and the surface of the substrate are in close contact with each other. And pressing the mold against the surface of the substrate, and irradiating the surface of the substrate with laser light, thereby heating the surface of the substrate to a space formed by the concave portion of the mold and the surface of the substrate. And transferring the predetermined shape formed on the mold by selectively burning the surface of the substrate with the contained oxygen.

  In a preferred embodiment, the substrate is made of a material composed of carbon atoms.

  In another preferred embodiment, the substrate has a transfer layer made of a material composed of carbon atoms formed on the surface thereof.

  In the transfer device according to the present invention, the means for holding the mold and the substrate in which irregularities are formed in a predetermined pattern shape in an atmosphere containing oxygen, and the convex portion of the mold and the surface of the substrate are in close contact with each other. And means for pressing the mold against the surface of the substrate, and means for irradiating the surface of the substrate with laser light.

  According to the shape transfer method of the present invention, the surface of the substrate is heated in an extremely short time by laser light irradiation, and the surface of the substrate facing the concave portion of the mold is oxidized and etched because it is in an oxidizing atmosphere. The On the other hand, since the portion of the substrate facing the convex portion of the mold is covered with the convex portion and is not exposed to the oxidizing atmosphere, it is heated but does not undergo oxidation reaction and is not etched. As a result, a pattern corresponding to the unevenness of the mold is formed on the substrate in a very short time.

  Thus, the shape transfer method of the present invention can greatly reduce the processing time as compared with the conventional imprint method and carbon oxidation process. Moreover, contamination of the mold can be prevented by vaporizing the etched portion of the substrate by oxidation. Further, since there is no deformation between the mold and the substrate, there is a space between the concave portion of the mold and the substrate even after the transfer process is completed, and as a result, there is no occurrence of mold release defects. In addition, since there is no need to press like an imprint, it is difficult for the mold to be damaged, and the life of the mold can be extended.

  Furthermore, since the transfer device having the shape of the present invention does not require a pressing force due to the processing principle, it does not require a large pressure generating device and does not require a structure that can withstand a large load compared to the conventional imprint device. Therefore, it is possible to reduce the cost of the apparatus.

  When patterning is performed using a conventional imprint method, a mold release failure is likely to occur due to a process involving plastic deformation. As a result, in order to ensure releasability, it is necessary to perform a process for urging the mold surface. In addition, since it is necessary to heat the substrate to a predetermined temperature (temperature from the glass transition point to the softening point) by the heating means, it is difficult to increase the throughput, and it is difficult to realize a significant reduction in manufacturing cost. Further, in the conventional patterning method by oxidation, it is difficult to increase the throughput because of the process at a high temperature of 400 to 700 ° C. The present inventor has found that a fine pattern transfer can be realized at a high throughput by irradiating the surface of a substrate, which is a pattern transfer target, with laser light and heating, and exhibits a very good release property. The present invention has been conceived.

(Embodiment 1)
First, a first embodiment of a shape transfer method according to the present invention will be described with reference to FIGS. FIGS. 1A to 1C are process cross-sectional views schematically showing a shape transfer method in the present embodiment.

  In this embodiment, the shape 2 is transferred to the substrate 1 using a mold 2 having a surface on which an uneven pattern is formed.

  First, as shown in FIG. 1A, the mold 2 is brought into contact with the surface of the substrate 1, and pressure is applied to the surface of the substrate 1 using a transfer device (not shown). The arrow in the figure indicates the pressure. This pressure is not for the purpose of plastically deforming the substrate 1 as in the imprint method, but for the purpose of bringing the mold 2 into close contact with the substrate 1, and is set, for example, in the range of 0.1 to 1 MPa. In this state, at least the surface of the substrate 1 facing the concave portion of the mold 2 is kept in an oxidizing atmosphere.

  Next, as shown in FIG. 1B, the surface of the substrate 1 is irradiated with the laser beam 3 while the mold 2 is in contact with the surface of the substrate 1 to heat the surface of the substrate 1. On the surface of the heated substrate 1, the portion 1A facing the concave portion of the mold 2 is in an oxidizing atmosphere, and therefore selectively oxidizes when heated under certain conditions. By configuring the substrate 1 with a material that is gasified by oxidation, the selectively oxidized portion 1A is etched. On the other hand, the portion other than the portion 1A facing the concave portion of the mold 2, that is, the portion facing and closely contacting the convex portion of the mold 2 is heated by the laser beam 3, but is covered by the convex portion of the mold 2 and oxidized. Since there is no atmosphere, oxidation does not occur and etching is not performed.

  When irradiating the laser beam 3 through the mold 2 as shown in the figure, the mold 2 is preferably made of a material that transmits the laser beam 3. Preferably, a material having a transmittance of 80% or more at the wavelength of the laser beam 3 is used. The intensity of the laser beam 3 and the irradiation time are set to a time during which the substrate 1 is oxidized.

  Finally, as shown in FIG. 1C, the processing step is completed by separating the mold 2 from the surface of the substrate 1.

  At this time, as shown in the figure, the contact between the substrate 1 and the mold 2 is only the convex portion formed on the substrate 1 and the convex portion of the mold 2, and the contact between the single surfaces is further released. The properties are very good.

  According to this embodiment, since the surface of the substrate is heated and oxidized to a temperature that can be processed in a short time (for example, 1 millisecond or less) by laser light irradiation, processing in an imprint method using a conventional heating means is performed. The pattern can be transferred in a much shorter time than the time.

  Specifically, when glassy carbon is used as the substrate, the mold pattern can be effectively transferred by irradiating laser light under the following conditions.

Wavelength: 248nm
Pulse width: 20 nanoseconds Irradiation frequency: 1
Power density: 0.5 J / cm ²
According to the present embodiment, since the surface of the substrate 1 is heated in a short time and selectively oxidized, the shape formed on the surface of the mold 2 can be formed on the surface of the substrate 1 in an extremely short time (within about 1 millisecond). It will be transferred to the surface. In the conventional direct imprint method, considering that the transfer to the substrate 1 generally takes 5 minutes or more including heating and cooling required before and after the transfer, the production efficiency is remarkably increased by this embodiment.

  When the output of the laser light source is low, the irradiation area is narrowed and a predetermined power density (value obtained by dividing the output of the light source by the irradiation area) is secured, while the mold is moved in the substrate, or It is also possible to perform so-called step-and-repeat, in which the main transfer process is repeatedly performed while moving only the laser beam.

  The substrate 1 used in this embodiment needs to have a light absorption coefficient of the substrate 1 as large as possible with respect to the irradiated laser light 3 so that the surface of the substrate 1 is efficiently heated by the irradiation of the laser light 3. On the other hand, in this embodiment, since the laser beam 3 is irradiated on the surface of the substrate 1 so as to pass through the mold 2, the transmittance of the mold 2 with respect to the laser beam 3 is preferably as large as possible. For example, sapphire or quartz is preferable as the material of the mold 2 that satisfies such requirements.

(Embodiment 2)
Next, a first embodiment of the shape transfer method according to the present invention will be described with reference to FIGS. 2A to 2C are process cross-sectional views schematically showing the shape transfer method in the present embodiment.

  In this embodiment, the shape 2 is transferred to the substrate 2 on which the transfer layer 4 is formed using the mold 2 having the surface on which the uneven pattern is formed.

  First, as shown in FIG. 2A, a substrate 1 on which a transfer layer 4 that efficiently absorbs laser light is formed is prepared, and a mold 2 is formed on the surface of the substrate 1 (substantially the surface of the transfer layer 4). And a pressure is applied to the surface of the substrate 1 using a transfer device (not shown). The arrow in the figure indicates the pressure. This pressure is not for the purpose of plastically deforming the substrate 1 as in the imprint method, but for the purpose of bringing the mold 2 into close contact with the substrate 1, and is set, for example, in the range of 0.1 to 1 MPa. In this state, at least the surface (substantially the transfer layer 4) of the substrate 1 facing the recess of the mold 2 is kept in an oxidizing atmosphere.

  Next, as shown in FIG. 2B, the surface of the substrate 1 (substantially the transfer layer 4) is irradiated with the laser beam 3 in a state where the mold 2 is in contact with it, and the transfer layer 4 is heated. In the heated transfer layer 4, the portion 4 </ b> A facing the concave portion of the mold 2 is in an oxidizing atmosphere, and therefore selectively oxidizes when heated under a certain condition. By configuring the transfer layer 4 with a material that is gasified by oxidation, the selectively oxidized portion 4A is etched. On the other hand, the portion 4B facing and closely contacting the convex portion of the mold 2 is heated by the laser beam 3, but is covered by the convex portion of the mold 2 and does not become an oxidizing atmosphere, so oxidation does not occur and etching is not performed. .

  When irradiating the laser beam 3 through the mold 2 as shown in the figure, the mold 2 is preferably made of a material that can sufficiently transmit the laser beam 3. Preferably, a material having a transmittance of 80% or more at the wavelength of the laser beam 3 is used. The intensity and irradiation time of the laser beam 3 are set to a time during which the transfer layer 4 is oxidized.

  Finally, as shown in FIG. 2C, the processing step is completed by separating the mold 2 from the surface of the substrate 1.

  At this time, as shown in the figure, the substrate 1 (substantially the transfer layer 4) and the mold 2 are in contact with each other because the protrusions of the transfer layer 4 remaining without being oxidized and the protrusions of the mold 2 are in contact with each other. In addition, since the single surfaces are in contact with each other, the releasability is very good.

  According to this embodiment, since the surface of the substrate is heated and oxidized to a temperature that can be processed in a short time (for example, 1 millisecond or less) by laser light irradiation, processing in an imprint method using a conventional heating means is performed. The pattern can be transferred in a much shorter time than the time.

  Specifically, when a carbon film is used as the transfer layer, the mold pattern can be transferred effectively by irradiating laser light under the following conditions.

Wavelength: 248nm
Pulse width: 20 nanoseconds Irradiation frequency: 1
Power density: 0.1 J / cm ²
According to this embodiment, since the transfer layer 4 is heated and selectively oxidized in a short time, the shape formed on the surface of the mold 2 is transferred to the transfer layer 4 for an extremely short time (within about 1 millisecond). Will be. In the conventional direct imprint method, considering that the transfer to the substrate 1 generally takes 5 minutes or more including heating and cooling required before and after the transfer, the production efficiency is remarkably increased by this embodiment.

  When the output of the laser light source is low, the irradiation area is narrowed and a predetermined power density (value obtained by dividing the output of the light source by the irradiation area) is secured, while the mold is moved in the substrate, or It is also possible to perform so-called step-and-repeat, in which the main transfer process is repeatedly performed while moving only the laser beam.

  The transfer layer 4 used in the present embodiment needs to have a light absorption coefficient as large as possible with respect to the laser beam 3 to be irradiated so that the transfer layer 4 is efficiently heated by the laser beam 3 irradiation. On the other hand, in this embodiment, since the laser beam 3 is irradiated on the surface of the substrate 1 so as to pass through the mold 2, the transmittance of the mold 2 with respect to the laser beam 3 is preferably as large as possible. For example, sapphire or quartz is preferable as the material of the mold 2 that satisfies such requirements.

  In this embodiment, the laser beam is irradiated onto the transfer layer from the mold side. However, if the substrate material allows the laser beam to pass through efficiently, the transfer layer is irradiated from the back surface (the surface opposite to the transfer layer) of the substrate. You may do it.

  In addition to a material composed of carbon atoms such as carbon, a material that burns at a high temperature, such as boron or tungsten, can be used for the transfer layer.

(Example)
Hereinafter, specific examples of the present embodiment will be described.

  First, a disk-shaped glass substrate having a diameter of 20 mm, on which a carbon transfer layer having a thickness of 20 nm was formed by RF sputtering, was prepared.

  Next, using a quartz mold having a diameter of 25 mm in which a 5 μm linear pattern was formed at a pitch of 10 μm, transfer to the transfer layer was performed according to the following conditions. At this time, the height of the pattern (the height difference of the unevenness) was about 500 nm. A mold and a substrate (including a transfer layer) were placed in the chamber, and air in the chamber was replaced by introducing dry nitrogen, so that the oxygen concentration was 200 ppm.

Pressure (pushing force): 0.5 MPa
Laser wavelength: 248nm
Pulse width: 20 nanoseconds
Number of irradiation: 1 shot
Power: 0.1 J / cm ²
Under this condition, the time required for the transfer process was 1 second or less. According to this example, the 5 μm linear pattern formed on the mold could be transferred to the transfer layer in a short time. The depth of the pattern at that time was 20 nm which is the thickness of the transfer layer before transfer. Also, the mold and the substrate could be released naturally without applying any force. Furthermore, after that, the surface of the mold was observed with an optical microscope, but no pattern defect due to foreign matter or damage was confirmed.

  According to the present invention, since microfabrication can be realized at low cost and high throughput, devices with fine shapes can be mass-produced at low cost, which is extremely useful industrially.

Manufacturing process sectional drawing which shows one Embodiment of this invention Manufacturing process sectional drawing which shows one Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 1A Part selectively oxidized in substrate 2 Mold 3 Laser light 4 Transfer layer 4A Part selectively oxidized in transfer layer 4B Part not oxidized in transfer layer

Claims (4)

Holding the mold and the substrate on which the irregularities are formed in a predetermined pattern shape in an atmosphere containing oxygen;
Pressing the mold against the surface of the substrate so that the convex portion of the mold is in close contact with the surface of the substrate;
By irradiating the surface of the substrate with laser light, the surface of the substrate is heated, and the surface of the substrate is selectively burned by oxygen contained in a space formed by the concave portion of the mold and the surface of the substrate. And transferring the predetermined shape formed on the mold;
A shape transfer method including: The shape transfer method according to claim 1, wherein the substrate is a material composed of carbon atoms. The shape transfer method according to claim 1, wherein a transfer layer is formed on a surface of the substrate, and the transfer layer is a material composed of carbon atoms. Means for holding the mold and the substrate in which irregularities are formed in a predetermined pattern shape, in an atmosphere containing oxygen;
Means for pressing the mold against the surface of the substrate so that the convex portion of the mold is in close contact with the surface of the substrate;
Means for irradiating the surface of the substrate with laser light;
A transfer device having a shape.

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