MOLD CLEANING APPARATUS AND MOLD CLEANING METHOD

According to one embodiment, a mold cleaning apparatus includes a holding unit, a medium supply unit, an energy supply unit and an energy control unit. The holding unit is configured to hold a mold including at least a concave pattern provided on a first surface of a base material. The mold is held with the first surface directed downward. The medium supply unit is configured to supply a medium to the concave pattern. The energy supply unit is configured to supply energy toward the mold from opposite side from the first surface of the base material. The energy control unit is configured to control amount of the energy reaching the concave pattern.

DETAILED DESCRIPTION

In general, according to one embodiment, a mold cleaning apparatus includes a holding unit, a medium supply unit, an energy supply unit and an energy control unit. The holding unit is configured to hold a mold including at least a concave pattern provided on a first surface of a base material. The mold is held with the first surface directed downward. The medium supply unit is configured to supply a medium to the concave pattern. The energy supply unit is configured to supply energy toward the mold from opposite side from the first surface of the base material. The energy control unit is configured to control amount of the energy reaching the concave pattern.

Various embodiments will be described hereinafter with reference to the accompanying drawings. In the following description, like members are labeled with like reference numerals. The description of the members once described is omitted appropriately.

First Embodiment

FIG. 1is a schematic view illustrating the configuration of a mold cleaning apparatus according to a first embodiment.

FIGS. 2A and 2Bare schematic views illustrating the configuration of a mold.

FIG. 2Ais a plan view of the mold100.FIG. 2Bis a sectional view taken along line A-A ofFIG. 2A.

As shown inFIG. 1, the mold cleaning apparatus110according to the first embodiment is an apparatus for cleaning a mold100used in the imprint method. The mold cleaning apparatus110includes a holding unit10, a medium supply unit20, an energy supply unit30, and an energy control unit35.

The holding unit10is a unit for holding the mold100. The medium supply unit20is a unit for supplying a medium Md toward the mold100. The medium Md is at least one of liquid and gas. The energy supply unit30is a unit for supplying energy toward the mold100.

In the mold cleaning apparatus110, the medium Md supplied to the mold100is activated by energy to remove foreign matter in the concave pattern P1. The energy is supplied from the opposite side of the mold100from the side where the concave pattern P1is formed. That is, the energy is attenuated before reaching the concave pattern P1. Thus, only the foreign matter is removed without affecting the concave pattern P1.

Here, the mold100cleaned by the mold cleaning apparatus110is described.

As shown inFIGS. 2A and 2B, the mold100includes a base material101and a pattern portion102. The base material101has a first surface101a.The pattern portion102is provided at the first surface101aand includes at least a concave pattern P1.

On the opposite side of the base material101from the region where the concave pattern P1is formed, a recess103is provided. For instance, the recess103is a partly removed portion of a second surface101bon the opposite side from the first surface101aof the base material101. Outside the recess103of the base material101, a peripheral portion105is provided.

On the opposite side from the bottom surface103bof the recess103of the base material101, a pedestal portion104is provided. The pedestal portion104is provided in a shape protruding from the first surface101a.The pattern portion102is provided on the pedestal portion104. The pattern portion102includes at least one concave pattern P1. The concave pattern P1is provided in e.g. a line shape extending in one direction. The concave pattern P1may be provided in an island shape with an opening shaped like a circle, ellipse, oval, rectangle and the like. In the case of providing a plurality of concave patterns P1, a convex pattern P2is provided between two adjacent concave patterns P1.

The plan view outline of the base material101is e.g. a rectangle approximately 150 millimeters (mm) long and approximately 150 mm wide. The plan view outline of the recess103is e.g. a circle having a diameter of approximately 50 mm. The plan view outline of the pedestal portion104is e.g. a rectangle 32 mm long and 26 mm wide. The height of the pedestal portion104is approximately 30 micrometers (μm). The thickness of the portion of the recess103of the base material101where the pedestal portion104is not provided is approximately 1 mm. The thickness of the peripheral portion105of the base material101is approximately 6 mm.

The depth of the concave pattern P1is e.g. 50 nanometers (nm) or more and 70 nm or less. The width of the concave pattern P1is e.g. 10 nm or more and 20 nm or less. The height of the convex pattern P2is approximately 50 nm or more and 70 nm or less. The width of the convex pattern P2is approximately 10 nm or more and 20 nm or less. In the pattern portion102, for instance, a line-and-space pattern made of a plurality of convex patterns P2and a plurality of concave patterns P1is provided.

In the mold cleaning apparatus110shown inFIG. 1, the holding unit10holds the mold100by e.g. vacuum chucking the peripheral portion105of the base material101. The holding unit10may hold the mold100by vertically or horizontally grasping the peripheral portion of the base material101.

The holding unit10holds the mold100with the first surface101aof the base material101directed downward. That is, when the mold100is held by the holding unit10, the first surface101aof the base material101faces downward, and the second surface101bfaces upward. The holding unit10may obliquely hold the mold100. In this case, the mold100is held so that the first surface101aof the base material101is located below the second surface101bof the base material101.

Although not shown inFIG. 1, the mold cleaning apparatus110includes a transport unit for transporting the mold100to be cleaned. The transport unit transports the mold100to be cleaned from outside the apparatus to the holding unit10.

The medium supply unit20supplies a medium Md to the concave pattern P1of the mold100held by the holding unit10. The medium supply unit20includes e.g. a nozzle21. Toward the first surface101aof the base material101directed downward, the nozzle21jets the medium Md upward. If the first surface101afaces downward, excessive accumulation of the jetted medium Md on the first surface101ais avoided. The medium supply unit20may supplies the medium Md to the concave pattern P1by flooding method.

The medium Md is at least one of liquid, gas and bubble. The liquid can be at least one of e.g. ultrapure water (e.g., with a specific resistance of approximately 18 MΩ·cm), alkaline solution and alcohol. The gas can be e.g. an inert gas such as argon.

The energy supply unit30supplies energy toward the mold100from the opposite side from the first surface101aof the base material101. The tip30aof the energy supply unit30is located in the recess103of the mold100. The energy supplied from the energy supply unit30is transmitted from the bottom surface103bof the recess103to the concave pattern P1of the first surface101a.

The energy supplied from the energy supply unit30is e.g. one of ultrasound and laser light. In the case where the energy is ultrasound, the energy supply unit30includes an ultrasound generating device. In the case where the energy is laser light, the energy supply unit30includes a laser light source (e.g., YAG (yttrium aluminum garnet) laser light source).

The mold cleaning apparatus110further includes a medium control unit25, an energy control unit35, and a processing bath40. The medium control unit25controls e.g. the supply amount and supply timing of the medium Md supplied from the nozzle21of the medium supply unit20.

The energy control unit35controls e.g. the amount and irradiation timing of the energy reaching the concave pattern P1. For instance, the energy control unit35performs at least one of controlling the amount of energy emitted from the tip30aof the energy supply unit30, and controlling the distance between the tip30aof the energy supply unit30and the concave pattern P1.

The processing bath40is provided at least below the mold100held by the holding unit10and the nozzle21of the medium supply unit20. In this embodiment, the processing bath40is provided so as to surround the holding unit10, the medium supply unit20, and the energy supply unit30. The processing bath40serves to receive the medium Md supplied from the medium supply unit20.

FIG. 3is a schematic view illustrating the removal of foreign matter.

FIG. 3shows the state in which foreign matter F is inserted in the concave pattern P1of the mold100. In the mold cleaning apparatus110according to this embodiment, a medium Md is supplied between the concave pattern P1of the mold100and the foreign matter F. Energy Eg is supplied from the opposite side from the concave pattern P1of the mold100.

The tip30aof the energy supply unit30is located in the recess103provided on the opposite side from the concave pattern P1of the mold100. For instance, the distance between the tip30aof the energy supply unit30and the bottom surface103bof the recess103is approximately 2 mm or more and 3 mm or less. For instance, the energy control unit35controls the distance between the energy supply unit30and the concave pattern P1based on the distance between the tip30aof the energy supply unit30and the bottom surface103bof the recess103. Thus, the energy control unit35adjusts the amount of energy Eg′ reaching the concave pattern P1.

In the mold cleaning apparatus110according to this embodiment, the tip30aof the energy supply unit30is inserted in the recess103of the mold100. Thus, the tip30acan be made very close to the concave pattern P1. Accordingly, even in the case where a small amount of energy Eg is applied from the opposite side from the pattern portion102of the mold100, sufficient energy Eg′ for removing the foreign matter F in the concave pattern P1can be provided.

The energy Eg supplied from the energy supply unit30is attenuated in the base material101of the mold100, but penetrated into the concave pattern P1. The energy Eg′ penetrated into the concave pattern P1activates the medium Md filled in between the concave pattern P1and the foreign matter F.

For instance, in the case where the energy is ultrasound, activation of the medium Md generates a cavitation in the medium Md. By this cavitation, the foreign matter F inserted in the concave pattern P1is pushed out toward the opening of the concave pattern P1.

For instance, in the case where the energy is laser light, a laser-induced impact on the medium Md is generated. By this induced impact, the foreign matter F inserted in the concave pattern P1is pushed out toward the opening of the concave pattern P1.

In the case of removing the foreign matter F by using cavitation of the medium Md, a medium allowing easy control of air bubbles generated by cavitation is preferably used as the medium Md.

The side surface of the concave pattern P1is provided with a slope. For instance, the angle of the side surface of the concave pattern P1with respect to the first surface101aof the base material101is approximately 88° or more and 89° or less. The width of the concave pattern P1becomes wider with the distance from the first surface101aof the base material101. By providing energy from the opposite side from the concave pattern P1of the mold100, the foreign matter F is pushed out to the direction in which the width of the concave pattern P1becomes wider. Accordingly, the foreign matter F is easily removed from inside the concave pattern P1.

Thus, in the mold cleaning apparatus110according to this embodiment, using the recess103provided in the mold100, foreign matter F is reliably removed from the concave pattern P1even with a small amount of energy. The energy is applied in a small amount and from the opposite side from the concave pattern P1of the mold100. Thus, no breaks or defects occur in the concave pattern P1.

Second Embodiment

Next, a mold cleaning method according to a second embodiment is described.

FIG. 4is a flow chart illustrating the mold cleaning method.

FIGS. 5A to 5Eare schematic sectional views illustrating an imprint method.

Before describing the mold cleaning method according to this embodiment, an imprint method using a mold is described.

First, as shown inFIG. 5A, a mold100is prepared. The mold100includes a base material101made of a translucent material such as quartz, and a pattern portion102provided in the base material101. The pattern portion102is formed by forming a resist pattern on the base material101by e.g. the electron beam lithography method, and then etching the base material101. The pattern portion102includes at least a concave pattern P1.

Next, as shown inFIG. 5B, a photocurable material M is applied onto a substrate S. The material M is dropped onto the substrate S by e.g. the ink jet method. Then, as shown inFIG. 5C, the pattern portion102of the mold100is brought into contact with the material M on the substrate S. The material M is filled in the concave pattern P1of the mold100by capillarity.

Next, as shown inFIG. 5C, light (e.g., ultraviolet light) is applied from the rear surface side (the side where the pattern portion102is not formed) of the mold100. The light passes through the mold100and reaches the material M. Thus, the material M is cured. After the material M is cured, the mold100is released.

By releasing the mold100, as shown inFIG. 5D, a transfer pattern P10having an inverted pattern shape of the pattern portion102is formed on the substrate S. Next, the residual film provided on the substrate S side of the transfer pattern P10is removed by e.g. RIE (reactive ion etching). Thus, as shown inFIG. 5E, a convex pattern P11is formed on the substrate S.

In the imprint method, by repeating the steps shown inFIGS. 5B to 5E, the concave-convex shape of the pattern portion102of the mold100is transferred to the material M. Thus, the same pattern is repetitively formed.

As described above, in a pattern formation method based on the imprint method, the mold100is brought into contact with the material M. Thus, the material M may be attached as foreign matter F in the concave pattern P1of the mold100. Furthermore, the foreign matter F attached onto the substrate S may be moved to the mold100side. Foreign matter F attached to the mold100may incur the decrease of yield due to the influence of the foreign matter F. Thus, the mold100needs to be periodically cleaned.

As one of the cleaning methods, a mixed liquid of sulfuric acid and hydrogen peroxide water is used to dissolve the foreign matter F made of organic substance such as resin. Then, rinse is performed with an alkaline solution and pure water. Finally, residual chemicals are shaken out and dried.

Rinse with an alkaline solution and pure water serves to remove fine foreign matter. On the other hand, it is difficult to reliably remove foreign matter without damaging the mold100provided with a fine pattern.

Next, the mold cleaning method according to this embodiment is described.

As shown inFIG. 4, the mold cleaning method according to this embodiment includes the steps of supplying a medium (step S102) and supplying energy (step S103). In this embodiment, before the step of supplying a medium (step S102), the method further includes the step of removing organic substance (step S101). After the step of supplying energy (step S103), the method further includes a first rinse step (step S104), a second rinse step (step S105), and a drying step (step S106).

The step of removing organic substance (step S101) performs processing for cleaning the mold100with a mixed liquid of sulfuric acid and hydrogen peroxide water. This removes organic substance attached to the mold100.

The step of supplying a medium (step S102) performs processing for supplying a medium Md to the concave pattern P1of the mold100. The medium Md is at least one of liquid and gas. The liquid can be e.g. ultrapure water (e.g., with a specific resistance of approximately 18 MΩ·cm). The gas can be e.g. an inert gas such as argon.

In the step of supplying a medium (step S102), the medium Md is preferably supplied toward the first surface101awith the first surface101aof the base material101of the mold100directed downward. This suppresses excessive accumulation of the supplied medium Md on the first surface101a.

The step of supplying energy (step S103) performs processing for supplying energy toward the mold100from the opposite side from the first surface101aof the base material101of the mold100. The energy is e.g. one of ultrasound and laser light. In this embodiment, the energy is transmitted from the bottom surface103bof the recess103of the mold100toward the concave pattern P1. The amount of energy is controlled by the supply amount of energy or the distance between the tip30aof the energy supply unit30and the concave pattern P1.

The medium Md is activated by energy irradiation. For instance, in the case where the energy is ultrasound, the medium Md is activated and generates a cavitation. By this cavitation, the foreign matter F inserted in the concave pattern P1is pushed out toward the opening of the concave pattern P1.

For instance, in the case where the energy is laser light, a laser-induced impact on the medium Md is generated. By this induced impact, the foreign matter F inserted in the concave pattern P1is pushed out toward the opening of the concave pattern P1. Thus, the foreign matter F is removed from inside the concave pattern P1.

The first rinse step (step S104) performs processing for rinsing the mold100with an alkaline solution. Thus, even if the foreign matter F pushed out from inside the concave pattern P1is reattached to the surface of the mold100, such foreign matter F is reliably removed.

The second rinse step (step S105) performs processing for rinsing the mold100with e.g. ultrapure water. Thus, the alkaline solution attached to the mold100is removed. In the second rinse step, rinse is performed with a solution more neutral than the alkalinity of the alkaline solution used in step S104. Ultrapure water is most preferable.

The drying step (step S106) performs processing for drying e.g. the ultrapure water used in the second rinse step.

By these steps, cleaning of the mold100is performed.

In the mold cleaning method according to this embodiment as described above, the medium Md supplied to the mold100is activated by energy to reliably remove foreign matter F in the concave pattern P1. The energy is applied in a small amount and from the opposite side from the concave pattern P1of the mold100. Thus, no breaks or defects occur in the concave pattern P1.

As described above, the mold cleaning apparatus110and the mold cleaning method according to the embodiments can clean the mold100while suppressing breaks and defects in the pattern.

The embodiments and the variations thereof have been described above. However, the invention is not limited to these examples. For instance, the mold cleaning apparatus110described above may be stand-alone as a cleaning apparatus, or may be incorporated in an imprint apparatus. In the mold100to be cleaned, the base material101may be a hard material such as quartz, or may be a flexible material such as resin. Furthermore, those skilled in the art can modify the above embodiments by suitable addition, deletion, and design change of components, and by suitable combination of the features of the embodiments. Such modifications are also encompassed within the scope of the invention as long as they fall within the spirit of the invention.