JP2014049709A - Imprint method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imprint method which can stably create a pattern structure with high accuracy.SOLUTION: An imprint method includes a static elimination process for destaticizing one surface 11a of an electrically insulative substrate 11, a droplet supply process for discharging droplets of molding resin from an ink jet head to supply droplets 31 onto a surface 11a which have been destaticized of the substrate 11, a contact process for bringing a mold 21 having uneven structure and the substrate 11 into mutual close approach and deploying droplets between the mold 21 and the substrate 11 to form a molding resin layer 32, a curing process for curing the molding resin layer 32 to form a transfer resin layer 35 onto which uneven structure is transferred, and a release process for separating the transfer resin layer 35 from the mold 21 to position a pattern structure 41 as a transfer resin layer, onto the substrate 11.

Description

  The present invention relates to an imprint method, in particular, a structure having a thin film having a desired pattern (figure having a concavo-convex structure such as a line and a pattern) and / or a smooth thin film having no pattern by supplying a resin by an ink jet method. The present invention relates to an imprint method for manufacturing a printer.

In recent years, a pattern forming technique using an imprint method has attracted attention as a fine pattern forming technique that replaces the photolithography technique. The imprint method is a pattern forming technique in which a fine structure is transferred at an equal magnification by using a mold member (mold) having a fine concavo-convex structure and transferring the concavo-convex structure to a molding object. For example, in an imprint method using a photocurable resin, droplets of a photocurable resin are supplied to the surface of the substrate as an object to be molded, and a mold having a desired concavo-convex structure and the substrate are brought close to a predetermined distance. In this state, the photocurable resin is filled into the concavo-convex structure, and light is irradiated from the mold side in this state to cure the photocurable resin, and then the mold is separated from the resin layer, so that the concavo-convex feature of the mold is inverted. A pattern structure having an uneven structure (uneven pattern) is formed.
In such an imprinting method, static electricity is generated when the mold is pulled away from the resin layer, the mold is charged, foreign matter in the atmosphere is likely to adhere to the mold, and the step is performed with the foreign matter etc. attached to the mold. When continuous imprinting by & repeat is performed, there is a problem that a defect of the pattern structure, damage to the mold, and the like occur. In order to cope with this, for example, it has been proposed to perform static elimination of the mold when the mold is separated from the resin layer (Patent Document 1).

JP 2009-286085 A

  In an imprint method, particularly an imprint method for producing a structure having a pattern size on the order of several tens of nanometers, a photocurable resin is applied to a substrate as droplets having a liquid amount of several pL to several tens of pL by an inkjet method, for example. Supplied. However, in such a small amount of droplet supply, if the substrate is charged by static electricity, the trajectory of the droplet discharged from the inkjet head may be bent, and the droplet may not be placed at the intended position. Alternatively, the droplets dropped on the substrate may move due to static electricity and the droplets may be connected. When such a phenomenon occurs, the spreadability of the droplet in the gap between the adjacent mold and the substrate and the filling property of the droplet into the uneven structure of the mold are affected, and the remaining film thickness of the formed structure is affected. There has been a problem of unevenness and pattern defects. In addition, even if the ejected droplet is dropped at the intended position of the substrate, if the mold is charged, the droplet on the substrate moves under the influence of static electricity from the mold, As a result, there is a problem in that droplets cannot be supplied to the intended position of the substrate, resulting in unevenness in the remaining film thickness of the formed structure and pattern defects.

On the other hand, the charge removal performed in the imprint apparatus described in Patent Document 1 is performed on the mold when the mold is separated from the resin layer, and the mold is reliably discharged when contacting the droplet. is not. In addition, the static elimination of the substrate is performed only before the substrate is held on the substrate chuck, and the static elimination of the substrate is not performed in the static elimination of the mold when separating from the resin layer as described above. In printing, there is a risk that the amount of charge on the substrate gradually increases. Therefore, the above problem due to the charging of the substrate and the above problem due to the charging of the mold to be brought into contact with the droplets are also problems that occur in the imprint apparatus described in Patent Document 1.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an imprint method capable of stably producing a high-precision pattern structure.

  In order to achieve such an object, the imprinting method of the present invention comprises a step of neutralizing one surface of an electrically insulating substrate, a droplet of a resin to be molded from an inkjet head, and the substrate A droplet supplying step for supplying the droplets to the surface from which the charge is removed, a mold having a concavo-convex structure and the substrate are brought close to each other, and the droplets are spread between the mold and the substrate to be molded resin. A contact step of forming a layer, a curing step of curing the molded resin layer to transfer the concavo-convex structure, and separating the transfer resin layer and the mold to form the transfer resin layer. And a mold release step for placing the pattern structure on the substrate.

As another aspect of the present invention, in the droplet supply step, a dropping position for supplying droplets of the molding resin is set on the substrate in advance.
As another aspect of the present invention, the dropping position is at least one of a concave volume, a pattern density, a pattern shape, a thickness of a residual film of the pattern structure, and a surface shape of the substrate provided in the mold. The configuration is set based on the above.
As another aspect of the present invention, there are a plurality of dropping positions, and an interval between droplets that are dropped and adjacent to a dropping position for forming one molded resin layer is 300 μm or less. The dropping position is set to the above.
As another aspect of the present invention, the dropping position is set so that the thickness of the remaining film of the pattern structure is 100 nm or less.
As another aspect of the present invention, in the contact step, after removing the surface of the mold having the concavo-convex structure, the mold and the substrate are brought close to each other to form the molded resin layer.

  In the present invention, since the electrically insulating substrate is discharged before discharging and supplying droplets of the resin to be molded from the inkjet head, the trajectory of the discharged droplets is stable and intended at the intended position. The molding resin can be supplied in an amount, and a highly accurate pattern structure can be stably produced.

FIG. 1 is a process diagram for explaining the imprint method of the present invention. FIG. 2 is a plan view showing the substrate in a state where droplets are supplied.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Note that the drawings are schematic or conceptual, and the dimensions of each member, the ratio of sizes between the members, etc. are not necessarily the same as the actual ones, and represent the same members. However, in some cases, the dimensions and ratios may be different depending on the drawing.
The imprint method of the present invention includes a static elimination process, a droplet supply process, a contact process, a curing process, and a mold release process, and FIG. 1 illustrates an embodiment of such an imprint method of the present invention. It is process drawing for doing.

<Static elimination process>
In the present invention, first, in one charge removal step, one surface 11a of the electrically insulating substrate 11 is discharged (FIG. 1A). This static elimination process is a processing process performed before the below-mentioned droplet supply process, for example, in the continuous imprint by a step & repeat, it is a processing process performed at the time of each imprint.
The electrically insulating substrate 11 to be used is a substrate having the property that the surface on the side to which the resin to be molded is supplied by inkjet is charged in the substrate transport process or imprint atmosphere. Specifically, a substrate made of an insulating material, a substrate whose electric charge is in a floating state on the side to which the resin to be molded is supplied by inkjet, and the like can be given. A substrate made of an insulating material is a substrate having a volume resistivity measured by a four-terminal method of 1.0 × 10 ¹⁰ Ω · cm or more. Specifically, quartz, soda lime glass, boron Examples include glass such as silicate glass, resin substrates such as polycarbonate, polypropylene, and polyethylene, and substrates that have an electrically insulating coating made of silicon oxide, silicon nitride, etc. on the side to which the resin to be molded is supplied by inkjet. Can do. Further, for example, a fine pattern used for a semiconductor, a display, or the like, or a desired pattern structure such as an optical structure such as a photonic crystal structure, an optical waveguide, or a hologram may be formed.

  As a substrate in which the above charge is in a floating state, a part of the insulating material having a volume resistivity measured by the above four-terminal method has a volume resistivity that is less than the above range and is conductive. The board | substrate etc. which have the part used as can be mentioned. For example, when a metal thin film is formed on a part of the surface of a quartz substrate, and a charge is given to the metal thin film, the charge remains accumulated unless a measure for releasing the charge is performed. If sustained, the quartz substrate having the metal thin film on the surface can be regarded as having a charge in a floating state.

The neutralization of the one surface 11a of the substrate 11 can be performed using, for example, an ionizer 100 as shown in the drawing. The ionizer may be either a conventionally known soft X-ray irradiation method or a corona discharge type, but when a monomolecular layer such as an adhesion layer is provided on the surface 11a of the substrate 11, the soft X-ray irradiation is performed. Since there is a possibility of destroying the monomolecular layer in the system, it is preferable to use a corona discharge type ionizer. In static elimination using a corona discharge type ionizer, compared to the soft X-ray irradiation method, air blowing and air purge are required, and there is a concern about the possibility of dust generation. In addition, since air is blown, air current may be disturbed. For this reason, it is preferable to improve the cleaning of the discharge needle etc. which perform corona discharge, and the cleanliness of the gas sent. In addition, it is preferable to carry out the air blowing so as not to oppose a desired air flow inside the imprint apparatus.
For example, when the board | substrate 11 is provided with the electroconductive thin film on the surface 11a, static elimination can be performed by contacting the grounded pin to the said electroconductive thin film. Such a conductive thin film has a shape that covers at least a region of the surface 11a of the substrate 11 where the droplets 31 are dropped in the droplet supplying step described later and the molded resin layer 32 is formed in the contacting step. It is necessary to have an area. This is because, with the above-described static elimination using a grounded pin, it is difficult to eliminate static electricity in an area where no conductive thin film exists on the surface 11a of the substrate 11, and the droplet 31 is dropped on such an area. In this case, the effect of the present invention is not achieved and this is to avoid this.

The time required for static elimination of the surface 11a of the substrate 11 as described above can be appropriately set depending on the static elimination method. In addition, for example, the surface potential of the surface 11a of the substrate 11 is measured by confirming that the charge removal of the substrate 11 has been performed to such an extent that the droplet trajectory in the droplet supply process described later is not adversely affected. This can be done by determining whether or not the potential is below a predetermined value.
In addition, the measurement of the surface potential each time may be omitted by predicting and determining the timing of performing the static elimination process from the measurement results of the surface potential several times in the initial stage of implementation. In addition, when performing imprint operations with the same reproducibility, an appropriate charge removal process is performed in each imprint process using conditions such as the time required for charge removal obtained in advance. Also good.

<Droplet supply process>
Next, in the droplet supplying step, droplets of the resin to be molded are ejected from the ink jet head, and the droplets 31 are supplied to the surface 11a of the substrate 11 that has been neutralized (FIG. 1B). As described above, since the electrically insulating substrate 11 is neutralized in the static elimination process, the trajectory of the droplet 31 discharged in the droplet supply process is stabilized, and the resin to be molded is in an intended amount at the intended position. Droplets 31 can be supplied. FIG. 2A is a plan view showing the substrate 11 to which such droplets 31 are supplied. In the illustrated example, the individual droplets 31 have landed at the dropping positions set, and the liquids The separated state is maintained without causing connection between the droplets. On the other hand, when the substrate 11 is charged by static electricity, the trajectory of the discharged droplet 31 is bent so that it cannot land on the set dropping position, and the droplet 31 dropped on the substrate 11 The droplets may move and be connected by static electricity. FIG. 2B is a plan view showing the substrate 11 to which the droplet 31 is supplied in such a case. When such a droplet supply is made, the substrate 11 and the mold 21 come close to each other in a later process. When this is done, the spreadability of the droplets 31 and the filling property of the resin to be molded into the concavo-convex structure of the mold 21 are adversely affected, and the formation of a pattern structure of the order of several tens of nm may be hindered.

The resin to be molded is not particularly limited as long as it has fluidity that can be ejected from an inkjet head, and examples thereof include a photocurable resin, a thermosetting resin, and a thermoplastic resin. For example, the photocurable resin is composed of a main agent, an initiator, and a crosslinking agent, and if necessary, improves the adhesion to the mold release agent and the substrate 11 for suppressing adhesion to the mold. It may contain the adhesion agent for. And according to the use of the pattern structure manufactured by imprint, the required characteristic, physical properties, etc., the to-be-molded resin to be used can be selected suitably. For example, if the use of the pattern structure is a lithography application, it is required to have etching resistance, a low viscosity and a small residual film thickness, and if the use of the pattern structure is an optical member, a specific refractive index, Light transmittance is required, and a photocurable resin can be appropriately selected according to these requirements. However, in any application, it is required to have characteristics (viscosity, surface tension, etc.) satisfying the compatibility with the ink jet head to be used. Note that the viscosity, surface tension, and the like of a compatible liquid differ depending on the structure and material of the inkjet head. For this reason, it is preferable to appropriately adjust the viscosity, surface tension and the like of the molding resin to be used, or to appropriately select an ink jet head suitable for the molding resin to be used.
Prior to the droplet supply step, the ink jet head may be neutralized by a neutralizing means such as an ionizer. Thereby, it is possible to stabilize the flying of the droplet when the droplet is ejected from the inkjet head.

<Contact process>
Next, in the contacting step, the mold 21 having the concavo-convex structure and the substrate 11 are brought close to each other, and the droplet 31 is developed between the mold 21 and the substrate 11 to form the resin layer 32 to be molded (FIG. 1 ( C)).
In the illustrated example, the mold 21 has a mesa structure having a convex structure portion, and the concavo-convex structure region 22 is located in the convex structure portion. Although the material of such a mold 21 can be selected as appropriate, it can be formed using a transparent substrate that can transmit irradiation light for curing the photocurable resin layer. For example, quartz glass, silicic acid can be used. System glass, calcium fluoride, magnesium fluoride, acrylic glass, etc., or any laminated material thereof can be used.
In the present invention, when the mold 21 is made of an electrically insulating material such as quartz glass, the mold 21 and the substrate 11 are brought close to each other after the surface having the concavo-convex structure region 22 of the mold 21 is removed, and the molded resin layer 32 is formed. Is preferably formed. As a result, it is possible to prevent the droplet 31 dropped on the intended position of the substrate 11 from moving due to the influence of static electricity from the mold 21.
The thickness of the mold 21 can be set in consideration of the shape of the concavo-convex structure, material strength, handling suitability, and the like, and can be set as appropriate within a range of about 300 μm to 10 mm, for example. The mold 21 may not have a mesa structure.

<Curing process>
Next, in a curing step, the molding resin layer 32 is cured to form a transfer resin layer 35 to which the concavo-convex structure has been transferred (FIG. 1D). In this curing step, if the molding resin is a photo-curable resin, the molding resin layer 32 can be cured by irradiating light from the mold 21 side. Further, if the substrate 11 is a material that transmits light, light irradiation may be performed from the substrate 11 side, and further, light irradiation may be performed from both sides of the substrate 11 and the mold 21.
When the molding resin is thermosetting or thermoplastic, it can be cured by subjecting the molding resin layer 32 to a heat treatment or a cooling (cooling) treatment.

<Release process>
Next, in the mold release step, the transfer resin layer 35 and the mold 21 are separated, and the pattern structure 41 that is the transfer resin layer 35 is positioned on the substrate 11 (FIG. 1E).
In the above-described imprint method of the present invention, since the electrically insulating substrate is discharged before the droplets of the resin to be molded are discharged from the inkjet head and supplied, the trajectory of the discharged droplets is stabilized. The molding resin can be supplied to the intended position in the intended amount, and a highly accurate pattern structure can be stably produced.
The above-described embodiment of the imprint method is an exemplification, and the present invention is not limited to this. In recent years, in imprint lithography in which lithography is performed using a structure having a pattern dimension on the order of several tens of nm, the remaining film thickness t of the pattern structure 41 to be formed may be set to be 100 nm or less. In imprint lithography, the pattern structure 41 is used as an etching resist, and the substrate 11 is etched. When the remaining film thickness t (see FIG. 1E) of the pattern structure 41 exceeds 100 nm, It takes time to remove the remaining film, and after removing the remaining film, a desired etching resist shape cannot be obtained, the processing accuracy of the substrate 11 is lowered, and it is difficult to form a pattern on the order of several tens of nm on the substrate 11. It may become. Therefore, it is desired to make the residual film as thin as possible and to make the residual film uniform with no portion where the substrate surface is exposed in a predetermined transfer region of the substrate. Therefore, in the droplet supply step, for example, at least one of the concave volume of the concavo-convex structure provided in the mold 21, the pattern density, the pattern shape, the thickness t of the remaining film of the pattern structure 41 to be formed, and the surface shape of the substrate 11. It is preferable that a dropping position for supplying the droplet 31 of the resin to be molded is set on the substrate 11 in advance. Based on the information shown above, a droplet amount and a droplet dropping position are set in advance as a dropping recipe, and the droplets 31 of the molding resin are supplied onto the substrate 11 in accordance with the dropping recipe. A uniform residual film is obtained which is a film and has no portion where the substrate surface is exposed in a predetermined transfer region of the substrate. In the imprint method of the present invention, since the molding resin can be supplied to the intended position in the intended amount, a highly accurate pattern can be produced on the substrate.

In the above-described embodiment, as shown in FIG. 2A, the droplets 31 are dropped at the dropping positions set at predetermined pitches in the orthogonal X and Y directions. For example, at least one of the concave volume, pattern density, pattern shape, remaining film thickness t of the pattern structure 41 to be formed (see FIG. 1E), and the surface shape of the substrate 11 is provided. Can be set based on. For example, the total amount of droplets required to form the molding resin layer 32 can be set from the concave volume of the concave-convex structure provided in the mold 21 and the thickness t of the remaining film of the pattern structure 41, and the pattern density, From the pattern shape, it is possible to set an optimum distribution of the dropped droplets.
In addition, for example, the dropping position can be set so that the interval between the droplets that are dropped and placed adjacent to the dropping position for forming one molded resin layer is 300 μm or less, preferably 50 μm or less. . When the interval between adjacent droplets exceeds 300 μm, the area for forming the resin layer 32 to be molded is increased by spreading the dropped droplets, and it is necessary to increase the amount of liquid per dropped portion. is there. However, when a large droplet is developed and when a small droplet is developed, the former tends to cause unevenness in the thickness of the molded resin layer 32 formed by developing the droplet, which is not preferable. Further, in the concavo-convex structure of the mold 21, the filling of the liquid droplets into the concavo-convex structure located far from the dropped portion may be hindered, which is not preferable. Note that the lower limit of the interval between adjacent droplets is determined by the nozzle pitch of the inkjet head and the resolution of the drive mechanism of the inkjet head, and can be, for example, about 10 μm.

Needless to say, the dropping position set as described above may be one having a non-constant pitch or a variation in density. In the imprint method of the present invention, since the droplet 31 can be reliably dropped at the dropping position set in this way, the molding resin can be supplied in the intended amount at the intended position according to the dropping recipe. And since the connection of the supplied droplets is prevented, a pattern structure of the order of several tens of nm can be stably manufactured.
In the imprinting method of the present invention, when continuous imprinting is performed by step and repeat, it can be preferably performed as follows. First, a charge removal process is performed so as to include the first transfer region of the substrate to be imprinted, and droplets of the resin to be molded are supplied to the first transfer region by ink jet, and the mold that has been discharged is removed as necessary. A molded resin layer is formed in contact with the droplets, and after the molded resin layer is cured, release is performed. Then, during or after the mold release, a charge eliminating process is performed so as to include the second transfer region of the substrate to be imprinted next. The subsequent steps are as described above. In order to improve the throughput of the continuous imprint process while eliminating each element related to the imprint process, the mold is discharged in the droplet supply process of the first transfer area, and the first transfer area contacting process or the first transfer process. It is preferable to sequentially carry out operations such as neutralizing the substrate during the preparation stage (for example, during movement of the inkjet head) of the droplet supply process in the second transfer region.

Further, the imprint method of the present invention may include a step of confirming in advance that a droplet is dropping at a dropping position set on the substrate. Here, in order to prevent the adjacent droplets from being dropped and connected to each other and to accurately observe the dropped state, the substrate and the resin to be molded so that the contact angle of the droplet with respect to the substrate is 60 ° or more. Is used. For example, when the dripping state is confirmed using a substrate used in the imprint method, and the contact angle of the droplet of the molding resin used in the imprint method with respect to the substrate is less than 60 °, A resin to be molded having a contact angle of 60 ° or more can be used. Further, when the dropping state is confirmed using a molding resin used for the imprinting method, the droplet of the molding resin has a contact angle of less than 60 ° with respect to the substrate used for the imprinting method. In some cases, a substrate provided with a water-repellent layer or a substrate having water repellency can be used. And like the static elimination process of this invention, one surface of a board | substrate can be neutralized, a droplet can be supplied according to the dripping recipe set to this surface, and a dripping state can be confirmed. The contact angle of the droplet with respect to the substrate was measured by dropping a droplet (5 μL) from a microsyringe at a temperature of 25 ° C., a humidity of 30% and atmospheric pressure, and 10 seconds later. ) CA-Z type).
Such a confirmation step can be performed, for example, in determining the conditions for the static elimination treatment of the substrate, and it is not necessary to perform it at each imprint in continuous imprinting by step & repeat.

  The present invention can be applied to the manufacture of various pattern structures using an imprint method and the fine processing of workpieces such as substrates.

DESCRIPTION OF SYMBOLS 11 ... Board | substrate 21 ... Mold 31 ... Droplet 32 ... Molding resin layer 35 ... Transfer resin layer 41 ... Pattern structure

Claims (6)

A static elimination process for eliminating one surface of the electrically insulating substrate;
A droplet supply step of discharging droplets of a resin to be molded from an inkjet head and supplying the droplets to the surface of the substrate that has been neutralized;
A contact step in which a mold having a concavo-convex structure and the substrate are brought close to each other, and the droplet is spread between the mold and the substrate to form a resin layer to be molded;
A curing step of curing the molding resin layer and transferring the concavo-convex structure to the transfer resin layer;
And a mold releasing step of separating the transfer resin layer and the mold to place the pattern structure as the transfer resin layer on the substrate.   The imprinting method according to claim 1, wherein in the droplet supplying step, a dropping position for supplying a droplet of the molding resin is set in advance on the substrate.   The dripping position is set based on at least one of a concave volume, a pattern density, a pattern shape, a thickness of a residual film of the pattern structure, and a surface shape of the substrate provided in the mold. The imprint method according to claim 2, wherein the method is an imprint method.   The dropping position is a plurality of locations, and the dropping position is set so that the interval between droplets that are dropped and adjacent to the dropping position for forming one molded resin layer is 300 μm or less. The imprint method according to claim 2, wherein:   The imprint method according to any one of claims 2 to 4, wherein the dropping position is set so that the thickness of the remaining film of the pattern structure is 100 nm or less.   6. The method according to claim 1, wherein, in the contacting step, the surface of the mold having the concavo-convex structure is neutralized, and then the mold and the substrate are brought close to each other to form the resin layer to be molded. The imprint method according to the above.

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