JP2008193035A - Fine shape transfer method and fine shape transfer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve fine shape transfer which enables excellent continuous processing with a high throughput, has extremely high releasability, hardly causes damage on a mold, and enables processing at low cost. <P>SOLUTION: Convex portions 1b of a mold 1 where concave portions 1a and the convex portions 1b are formed in a predetermined pattern are brought into contact with a substrate 3 having a processed film 2 thereon. Laser light 4 is emitted from the mold 1 to sublime and remove the processed film 2 in the concave portion 1a of the mold 1, and then the mold 1 is separated from the substrate 3. The processed film 2a corresponding to the concave portions 1a of the mold 1 is removed in this state, and a residual 5 of the removed processed film 2 is partially accumulated in the concave portions 1a of the mold 1. On the other hand, a processed film 2b corresponding to the convex portions 1b of the mold 1 remains. It is thus possible to transfer a predetermined mold pattern to the processed film 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fine shape transfer method for transferring a desired fine shape onto a substrate, and a fine shape transfer apparatus for realizing the transfer method.

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

  However, with the recent price reduction of electronic devices, there is a strong demand for cost reduction of the process, and the patterning method using an expensive exposure apparatus / etching apparatus is the biggest obstacle in cost reduction, and is simple. There is a need for a low-cost patterning method.

  As one of the methods, in recent years, a technique called imprint, which transfers a pattern applying a molding technique, has been actively developed.

  This method is a method of transferring the shape of a mold by pressing a mold (mold member) in which irregularities having a predetermined pattern shape are brought into close contact with a work piece. There are a “resist imprint method” using “a” and a “direct imprint method” not 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, one of the main causes of high cost and the exposure and development steps in the photolithography process, which is one of the semiconductor manufacturing processes, can be omitted, so that a device requiring fine patterning can be reduced. It can be manufactured at a 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 grooves from the micro order to the nano order on the surface of the substrate by pressing a molding die having fine processed grooves formed on the surface thereof onto a glass substrate. Yes.

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

  Further, 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. (For example, refer to Patent Document 3).

  In Patent Document 3, a carbon substrate on which an oxidation-resistant mask has been formed in advance is placed in an oxidizing atmosphere, and heated to about 400 to 700 ° C. to selectively select a portion not covered with the mask. A method of forming a desired shape at low cost by oxidizing and etching is disclosed, and it is described that stable processing is possible as compared with conventional machining.

Furthermore, as a method and an apparatus proposed by the present inventors, a mold having a fine unevenness made of carbon atoms is pressed in an oxygen atmosphere, and the substrate is irradiated with a laser beam to form a recess and the surface of the substrate. There is a method of transferring the predetermined shape formed on the mold by selectively burning the surface of the substrate with oxygen contained in the space (see Patent Document 4).
JP 2003-77807 A JP 2003-85740 A JP-A-5-274667 JP 2006-86249 A

  However, in the conventional imprint method, as disclosed in, for example, Patent Document 1, the mold releasability is improved by applying a certain treatment to the surface of the mold, but the mold releasability over a long period of time. Is difficult to secure, and for example, reprocessing is required every several hundred to several thousand shots.

  In addition, in the imprint method, when a mold release failure occurs with a work piece, 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), which can increase the throughput. It was difficult.

  In addition, the method of selectively etching carbon by oxidation requires heating to a high temperature of 400 to 700 ° C., and it takes time for heating and cooling. It was difficult. In addition, the oxidation-resistant film used as a mask during etching requires a formation process and a removal process after etching, and thus the process is complicated.

  Furthermore, the method of transferring the mold shape by pressing the mold and irradiating with the laser is performed in an oxygen atmosphere, and the material to be processed is limited to the carbon material. Furthermore, after the laser light irradiation, the carbon material sublimated with oxygen adheres to the minute recesses of the mold, and the adhered carbon film hinders the laser intensity for the next processing, and the continuous fine pattern. Transcription was impossible.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to have a high throughput and a high continuous processability, and furthermore, a releasability is extremely good, and the mold is not damaged. An object of the present invention is to provide a fine shape transfer method and a fine shape transfer apparatus that are unlikely to occur and can be processed at low cost.

  The fine shape transfer method according to the present invention includes a step of bringing a convex portion of a mold member having a predetermined uneven pattern shape into contact with a substrate having a film to be processed, and a laser beam from the substrate side or the mold member side. , And sublimating and removing the film to be processed in the recess of the mold member, and separating the mold member from the substrate.

  Furthermore, after executing the step of separating the mold member from the substrate, a fine shape transfer method including a step of moving the mold member out of a processing region and a step of irradiating the mold member with a laser beam to clean it. is there.

  As a preferred embodiment, the film to be processed is a metal thin film, and the film thickness of the film to be processed is preferably 5 nm to 1000 nm.

  Moreover, it is desirable that the pattern dimension of the mold member is 5 nm or more and 100 μm or less.

  Further, it is desirable to use a short pulse laser or excimer laser of 100 nm or more and less than 1100 nm as the laser light source, and the atmosphere for irradiating the laser light may be atmospheric pressure or a pressure lower than atmospheric pressure.

  The fine shape transfer device according to the present invention is a fine shape transfer device that executes the fine shape transfer method according to any one of claims 1 to 7, and holds a mold member on which a predetermined uneven pattern shape is formed. Means, means for pressing the mold member against the substrate, means for irradiating the mold member with laser light, and means for moving the mold member.

  According to the fine shape transfer method of the present invention, since there is a space in the concave portion of the mold member (mold), the film to be processed that has absorbed the laser energy by the laser light irradiation is ablated (sublimated) and the film to be processed is removed. Is done. On the other hand, the part facing the convex part of the mold is covered with the convex part of the mold, so that the ablation area (sublimation area) is blocked even if the film to be processed receives energy. Will not be removed. As a result, a pattern corresponding to the unevenness of the mold can be formed on the substrate in a very short time.

  In addition, after moving the mold to a part not related to pattern transfer, the mold is irradiated with laser light, and a cleaning process is introduced to remove the film removed during ablation adhering to the concave portion of the mold. Even if it does not do, it becomes possible to use a mold.

  In addition, according to the fine shape transfer device according to the present invention, a pressing force is not required on the processing principle, so that a large pressure generator is unnecessary and a structure capable of withstanding a large load compared to a conventional imprint device. Therefore, the configuration of the apparatus can be simplified, and the price of the apparatus can be reduced.

  As described in the background art and the problem to be solved by the invention, the conventional technique for performing patterning using the imprint method includes a process accompanied by plastic deformation, and is likely to cause a mold release failure. As a result, in order to ensure releasability, it is necessary to perform a process for urging the mold surface. Further, 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.

  Therefore, as a result of intensive studies and experiments, the present inventor has realized that it is possible to realize transfer of a fine pattern at a high throughput by irradiating the surface of the substrate, which is a pattern transfer target, with laser light and ablating. The inventors have found that it exhibits good releasability, and have come up with the present invention.

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

  1A to 1G are cross-sectional views for explaining an embodiment of a fine shape transfer method according to the present invention, and FIGS. 1A to 1D schematically show the transfer method in the embodiment. FIGS. 1E to 1G are process diagrams schematically showing mold cleaning in the present embodiment. FIG. 2 is a plan view schematically showing an apparatus structure for explaining an embodiment of the fine shape transfer apparatus according to the present invention.

  In this embodiment, the shape 1 is transferred to a film to be processed using a mold 1 having a surface on which a desired uneven pattern is formed. In this embodiment, since the surface of the processing material is irradiated with the laser beam 4 so as to pass through the mold 1, the material of the mold 1 is preferably as high as possible with respect to the laser beam 4. As a material of the mold 1 that satisfies such requirements, for example, sapphire or quartz is preferable.

  First, as shown in FIG. 1A, the mold 1 is brought into contact with the surface of the processing target film 2 formed on the substrate 3, and pressure is applied to the surface of the substrate 3. The substrate 3 used in this embodiment is preferably made of a material having as high a transmittance as possible so that the substrate 3 is not processed by irradiation with the laser light 4.

  On the other hand, the processing target film 2 needs to have as large a light absorption coefficient as possible for the processing target film 2 with respect to the irradiated laser light 4 so that the surface efficiently absorbs the energy of the laser light 4. The thickness of the processing target film 2 is preferably 5 nm or more and 1000 nm or less in order to be efficiently ablated by the laser beam 4.

  The arrow in Fig.1 (a) has shown the direction of the pressure. This pressure is not for the purpose of plastically deforming the substrate 3 as in the imprint method, but for bringing the convex portion 1b of the mold 1 into close contact with the film 2 to be processed, and is set within a range of 0.1 to 1 MPa, for example. Is done.

  Next, as shown in FIG. 1B, the surface of the processing target film 2 is irradiated with the laser beam 4 in a state where the mold 1 is in contact, and energy is applied to the processing target film 2. The laser light source used in this embodiment is not a process by heat, but a single pulse laser with a short irradiation time is desirable because the film 2 to be processed is processed in a short time with the energy of the laser beam 4. The wavelength of the laser beam 4 is determined by the absorption coefficient of the film 2 to be processed, the substrate material that is not processed, and the transmittance, but it is desirable to use a short pulse laser of 100 nm or more and less than 1100 nm. For example, an excimer laser or a YAG laser is preferably used as a laser light source that satisfies such requirements.

  As described above, on the surface of the processing target film 2 to which energy is applied, the processing target film 2 is ablated in the concave portion 1a of the mold 1 and gasification occurs to be scattered in the space of the concave portion 1a. At this time, by irradiating the laser beam 4 in an atmosphere having a pressure lower than the atmospheric pressure, the processing target film 2 is further ablated with low energy and easily removed. On the other hand, in the portion of the convex portion 1b that is in close contact with the processing target film 2, the processing target film 2 remains without being ablated because there is no space for gasification and gasification of the processing target film 2.

  When irradiating the laser beam 4 through the mold 1 as shown in FIG. 1B, the mold 1 is preferably made of a material that transmits the laser beam 4. Preferably, a material having a transmittance of 80% or more at the wavelength of the laser beam 4 is used. The intensity of the laser beam 4 and the irradiation time are set to the time during which the processing target film 2 is ablated. Further, depending on the material of the substrate 3, the laser beam 4 may be irradiated from the substrate 3 side.

  As shown in FIG. 1 (c), the processing target film 2 a corresponding to the concave portion 1 a of the mold 1 is removed by the irradiation of the laser light 4, and the removed debris 5 of the processing target material is removed from the concave portion 1 a of the mold 1. Part of it accumulates. On the other hand, the processing target film 2b corresponding to the convex portion 1b of the mold 1 remains. For this reason, a predetermined mold pattern can be transferred to the processing target film 2.

  As shown in FIG. 1D, the processing step is completed by separating the mold 1 from the surface of the substrate 3.

  At this time, as shown in FIG. 1 (c), the process target film 2 b and the mold 1 are in contact with each other between the process target film 2 and the mold 1. Since only the portion 1b is in contact with each other, the releasability is extremely good.

  According to the present embodiment, the surface of the substrate 3 is ablated in a short time (for example, 1 millisecond or less) by the irradiation with the laser beam 4, and thus is much more than the processing time in the imprint method using the conventional heating means. The pattern can be transferred in a short time.

  Next, mold cleaning according to the present invention will be described with reference to FIGS.

  First, as shown in FIG. 1E, the mold 1 to which the debris 5 of the processing target film 2 is attached is moved to a place where the processing is not affected. That is, as shown in FIG. 2, from the substrate holding stage 6 at the position where processing has been performed so far (left side in FIG. 2) to the cleaning stage 7 installed at a position where the processing is not affected (right side in FIG. 2). The mold 1 is moved.

  In this case, the mold 1 may be moved by rotating the mold holder 8. Further, two or more molds 1 may be alternately processed and cleaned so as to improve processing continuity.

  Next, as shown in FIG. 1 (f), in order to remove the debris 5 of the processing target film 2, the mold 1 is irradiated with the laser beam 4 in the same manner as in FIG. Ablate wreckage 5 The laser irradiation at this time is performed under the same intensity as the laser irradiation condition described above or under a condition where the laser energy is higher than that condition. Thereby, the remnants 5 of the processing target film 2 can be completely removed.

  The cleaning stage 7 at the mold cleaning place on the left side in FIG. 2 is preferably provided with an exhaust mechanism or the like so that the debris 5 of the processing target film 2 excluded by cleaning can be exhausted.

  Finally, in FIG. 1 (g), the mold 1 is moved from the cleaning stage 7 to the substrate holding stage 6 in FIG. By repeating this, pattern transfer can be maintained at a high throughput with a high throughput.

Specifically, when PET (polyethylene terephthalate) is used as the substrate 3 and a chromium thin film is used as the processing target film 2, the mold pattern can be effectively transferred by irradiating the laser beam 4 under the following conditions. it can.
Wavelength: 532 nm (twice harmonic of YAG laser)
Pulse width: 10 microseconds Irradiation number: Once Power density: 0.5 mJ / cm ²
According to the present embodiment, the surface of the processing target film 2 can absorb energy in a short time and is selectively ablated, so that the shape formed on the surface of the mold 1 has an extremely short time (about 1). It is transferred to the surface of the film 2 to be processed within (milliseconds). In the conventional direct imprint method, the time required for transfer to the substrate 3 is approximately 5 minutes including heating and cooling required before and after the transfer. Efficiency increases significantly.

  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.

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

  First, a square PET (polyethylene terephthalate) film having a side of 20 mm on which a chromium thin film having a thickness of 100 nm was formed by an electron beam (EB) evaporation method was prepared.

  Next, transfer to a chromium thin film was performed according to the following conditions using a quartz mold in which a 5 μm linear pattern was formed at a pitch of 10 μm and a square having a side of 20 mm. At this time, the height of the pattern (the height difference of the unevenness) was about 3 μm. A quartz mold and a PET substrate (including a chromium thin film) were placed in the chamber, and a pressure of 100 Pa was set with a rotary pump.

Next, laser light was irradiated from the upper surface of the quartz mold under the following conditions.
Pressure (pressing force): 0.3 MPa
Wavelength: 532 nm (twice harmonic of YAG laser)
Pulse width: 10 microseconds Irradiation number: Once Power density: 0.5 mJ / cm ²
The chromium thin film used in this example has a constant absorption rate of about 40 to 50% at a wavelength of 300 nm to 1500 nm. Further, since the PET film transmits about 95% or more at a wavelength of 300 nm to 1500 nm, energy can be applied only to the chromium thin film if irradiation is performed with a laser of the above wavelength or a YAG laser of 1064 nm. Therefore, the PET film is not damaged and only the chromium thin film can be ablated.

  Under this condition, the time required for the pattern transfer process was 1 second or less. According to this embodiment, a 5 μm linear pattern formed on a quartz mold can be transferred to a chromium thin film in a short time. Moreover, the quartz mold and the substrate could be naturally separated without applying any particular force. Further, after that, the surface of the quartz mold was observed with an optical microscope, but no pattern defect due to foreign matter or damage was confirmed.

  Next, the quartz mold is moved from the processing location to a mold cleaning location that does not affect the processing. Thereafter, laser irradiation was performed from the upper part of the quartz mold under the same condition as that described above, or under a condition where the laser energy was higher than that condition. As a result, the debris of the processing material could be completely removed in the concave portion of the quartz mold during the pattern transfer.

  As described above, according to the fine shape transfer according to the present embodiment, the processing time can be significantly reduced as compared with the conventional imprint method and the carbon oxidation process, that is, the processing can be performed with high throughput. . Further, by providing a post-treatment cleaning step as described above, it is possible to have high continuous processability.

  Furthermore, 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 completion of the transfer process, and as a result, no mold release defect occurs. . Further, since there is no need to press like in the case of imprinting, it is difficult for the mold to be damaged, and the life of the mold can be extended.

  The fine shape transfer method and apparatus according to the present invention are applied to a manufacturing process of an electronic device, an optical device, or the like in which a fine shape is formed, and in particular, fine processing can be realized at low cost and high throughput. It can be said that the device in which a fine shape is formed can be mass-produced at low cost and is extremely useful in industry.

(A)-(g) is sectional drawing explaining embodiment of the fine shape transfer method which concerns on this invention, (a)-(d) is process drawing which shows the transfer method in this embodiment typically, (E)-(g) is process drawing which shows the mold cleaning in this embodiment typically The top view which shows typically the apparatus structure for describing embodiment of the fine shape transfer apparatus which concerns on this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 1a Concave part 1b Mold convex part 2 Process target film 3 Substrate 4 Laser beam 5 Debris of process target film 6 Substrate holding stage 7 Cleaning stage 8 Mold holder

Claims (8)

A step of closely adhering a convex portion of a mold member on which a predetermined uneven pattern shape is formed and a substrate having a film to be processed;
Irradiating a laser beam from the substrate side or the mold member side to sublimate and remove the film to be processed in the concave portion of the mold member;
And a step of separating the mold member from the substrate. After performing the step of separating the mold member from the substrate, moving the mold member outside the processing region;
2. The fine shape transfer method according to claim 1, further comprising a step of cleaning the mold member by irradiating the mold member with laser light.   3. The fine shape transfer method according to claim 1, wherein the film to be processed is a metal thin film.   The fine shape transfer method according to claim 1, wherein the film to be processed has a thickness of 5 nm to 1000 nm.   The fine shape transfer method according to claim 1 or 2, wherein the pattern dimension of the mold member is 5 nm or more and 100 µm or less.   2. The fine shape transfer method according to claim 1, wherein a short pulse laser or excimer laser of 100 nm or more and less than 1100 nm is used as the laser light source.   2. The fine shape transfer method according to claim 1, wherein the atmosphere in which the laser beam is irradiated is an atmospheric pressure or a pressure lower than the atmospheric pressure. A fine shape transfer apparatus for executing the fine shape transfer method according to claim 1,
Means for holding a mold member on which a predetermined uneven pattern shape is formed;
Means for pressing the mold member against the substrate;
Means for irradiating the mold member with laser light;
A fine shape transfer apparatus comprising means for moving the mold member.

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