JP2011066273A - Method of forming fine mask pattern, nanoimprint lithography method, and method of manufacturing microstructure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a fine mask pattern in which the pattern, in which there is no remaining film on a base material or which is thin, can be formed, and to provide a nanoimprint lithography method which can perform precise and easy lithography process on the base material, and to provide a method of manufacturing a microstructure. <P>SOLUTION: The method of forming the fine mask pattern forms the fine mask pattern composed of a film 15 corresponding to a fine uneven structure 11a, on the base material, by forming the film 15 on a mold 14 having the fine uneven structure 11a, removing the film on the mold to a projection surface 11b or to the vicinity of the projection surface in the fine uneven structure of the mold, superposing the base 16 over a surface 15a after the film on the mold is removed to make them come into contact with each other through physical interaction, and removing the mold from the base. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for forming a fine mask pattern for transferring a fine structure of a mold, a nanoimprint lithography method, and a method for manufacturing a fine structure.

  Nanoimprint lithography is lithography in which a fine structure of a mold is transferred by embossing (see Patent Document 1), and is said to have a resolution of about 10 nm while being a simple and inexpensive method (see Non-Patent Document 1). . FIG. 8 shows a conventional general nanoimprint lithography process.

  As shown in FIG. 8, an ultraviolet curable resin 103 is applied to the substrate 102 by a spin coating method or the like (a). Next, a mold 101 having a fine structure 101a composed of a fine concavo-convex structure or the like is prepared (b), and the resin layer 103 is irradiated with ultraviolet rays while pressing the resin layer 103 with the mold 101 (c). Mold release is performed to separate the cured resin layer 103 from the mold 101 (d). Next, the remaining film 104 in the concave portion of the resin layer (pattern layer) 103 on the base material 102 is removed by ashing (e), and then the base material 102 is removed by etching. Finally, the resin layer 103 is completely removed, and the base material 102 having the microstructure 105 corresponding to the microstructure 101a of the mold 101 is manufactured (f).

  As described above, a nanoimprint method using an ultraviolet curable resin is generally referred to as an optical nanoimprint method or a UV (ultraviolet) nanoimprint method. In FIG. 8, a method may be used in which a thermoplastic resin is used as the resin and the microstructure 101a of the mold 101 is transferred by heating and pressing, and this is called a thermal nanoimprint method. There is room temperature nanoimprint using a sol-gel material such as spin-on-glass (SOG) or hydrogen silsesquioxane (HSQ) instead of resin.

JP 2007-223206 A JP 2009-38085 A JP 2009-4066 A

S.Y.Chou, P.R.Krauss and P.J.Renstrom, Science. 85, 272 (1996) Surface Technology Vol.59 (2008) No.10 p.648

  As described above, the pattern layer (resin layer) 103 having a fine concavo-convex structure obtained on the base material 102 by the nanoimprint method often uses the convex portion as a mask for processing the base material 102. In such a method of use, when the thickness of the remaining film 104 on the bottom surface of the concave portion of the pattern layer 103 is thick, the pattern layer is removed along with the removal of the remaining film 104 as shown in FIG. Since the convex portion 103a of 103 is also removed at the tip portion and changed from the original shape of the broken line, it is difficult to maintain the original shape of the convex portion 103a of the pattern layer 103. For this reason, when the base material 102 in FIG. 8 (e) is etched by using the convex portion 103a whose shape accuracy is reduced as shown in FIG. 9 as a mask and corresponding to this mask. The accuracy of the fine structure 105 shown in FIG. 8F is reduced. As described above, due to the removal process of the remaining film 104, it was not possible to perform an accurate process corresponding to the fine structure 101a of the mold 101. For this reason, it is desired that the remaining film 104 be as thin as possible. That is, the thickness of the remaining film 104 is desirably sufficiently thin with respect to the height of the concavo-convex structure of the pattern layer 103 as a mask, and more desirably 0. However, according to the conventional nanoimprint method, it is very difficult to reduce the thickness of the remaining film 104 to, for example, about 10 to 20 nm, and it is almost impossible to make it zero.

  In Patent Document 2, when etching is performed using a resin layer as a mask layer, it is necessary to remove the remaining film existing on the base of the pattern. However, the pattern formed on the resin layer has a triangular shape with the upper edge falling. If the substrate is processed using this as a mask, it may be difficult to obtain verticality and processing accuracy, and it is extremely difficult to control the remaining film thinly. ([0004] [0005] [0007]). Also in Patent Document 3, since it is necessary to remove the residual film generated in the resist pattern after the imprint process before the fine pattern processing, in addition to reducing the residual film as much as possible, the residual film is uniform over the entire surface of the substrate. It points out that gender is important ([0007]).

  According to Non-Patent Document 2, a mask characterized by having high dry etching resistance can be produced by using SOG, which is an inorganic material, instead of a resin layer. There is a problem similar to the above in terms of uniformity. Furthermore, when SOG is imprinted at room temperature, the hardness of SOG material is higher than that of resin material, so according to the literature, it is necessary to press at a high pressure condition of 60 Mpa (about 10 times that of resin). The problem is that the burden is large, the life of the transfer mold is shortened, and the manufacturing cost of the mask pattern is increased.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a method for forming a fine mask pattern that can form a thin pattern with no residual film on a substrate. It is another object of the present invention to provide a nanoimprint lithography method and a fine structure manufacturing method capable of performing lithography processing accurately and easily on a substrate.

  A method for forming a fine mask pattern for achieving the above object is to form a film on a mold having a fine concavo-convex structure, remove the film on the mold to the convex surface of the fine concavo-convex structure of the mold or the vicinity of the convex surface, A substrate was superimposed on the surface after removing the film on the mold and adhered by physical interaction, and the mold was removed from the substrate, thereby corresponding to the fine concavo-convex structure on the substrate. A fine mask pattern made of the film is formed.

  According to this method for forming a fine mask pattern, the film formed on the mold is removed to the convex surface of the fine concave-convex structure of the mold or to the vicinity of the convex surface, and when the substrate is superimposed on the surface after the removal, the film is superimposed. The surface of the substrate and the surface of the substrate are adsorbed to each other by physical interaction and adhere to each other without interposing an adhesive or the like, so that when the mold is removed from the substrate, there is no residual film on the substrate or a thin fine mask A pattern can be formed corresponding to the fine relief structure of the mold.

  In the method for forming a fine mask pattern, the fine concavo-convex structure of the mold is preferably formed of a resin layer made of a resin material. When the mold includes a mold member and a resin layer formed on the mold member, when removing the mold from the base material, the mold member is separated from the resin layer in close contact with the base material, and then the resin layer is removed. By removing, an extra load is not applied to the fine mask pattern on the substrate, and deformation or damage of the fine mask pattern can be prevented.

  The fine uneven structure of the resin layer can be formed by being transferred from a transfer mold. This eliminates the need to press the transfer mold against a hard material such as SOG, thereby reducing the burden on the transfer mold, extending the life of the transfer mold, and reducing the mask pattern manufacturing cost. . The transfer mold can be obtained, for example, by forming a resist mask on a silicon wafer by electron beam drawing and forming a fine concavo-convex structure by etching.

  The film formed on the mold is preferably made of SOG (spin on glass) or a silicon-containing resin material.

  Further, when the film on the mold is removed to the convex surface of the fine concavo-convex structure of the mold or to the vicinity of the convex surface, by detecting the end point of the removal, there is no thin film on the substrate or a thin fine mask pattern Can be reliably formed.

  In addition, it is preferable to perform a pretreatment for improving the adhesion to the surface after removing the film on the mold before the substrate is adhered. As such pretreatment, any of UV ozone treatment, primer treatment, oxygen ashing treatment, charging treatment, nitrogen plasma treatment and cleaning treatment is preferable. Moreover, before forming a film | membrane in a type | mold, the adhesiveness of a resin layer and a film | membrane can be improved by performing the said pre-processing on the surface of a type | mold, for example, a resin layer. Moreover, it can contribute to improvement of adhesiveness of both by performing any one of the leaving for a predetermined time, heat processing, electrostatic adsorption processing, and pressurization processing after the said close_contact | adherence.

  A nanoimprint lithography method for achieving the above-described object is characterized in that lithography processing is performed on the base material using the fine mask pattern formed on the base material as a mask by the fine mask pattern forming method described above. .

  According to this nanoimprint lithography method, since there is no residual film or a thin fine mask pattern can be formed on the substrate, it is not necessary to remove the residual film, or it can be easily removed even if the residual film is removed, The precision of the fine mask pattern does not decrease, and therefore, lithography processing can be performed accurately and easily on the substrate.

  In order to achieve the above object, a fine structure manufacturing method includes the fine mask pattern formed on the base material by the fine mask pattern forming method and the mask structure having the base material. A fine structure having a fine structure corresponding to the fine mask pattern is manufactured by removing the mask pattern and the base material.

  According to this method for manufacturing a fine structure, a fine mask pattern having no remaining film or a thin film can be formed on the substrate, so that it is not necessary to remove the remaining film or even if the remaining film is removed. It can be removed, and the precision of the fine mask pattern is not lowered. Therefore, the fine mask pattern and the substrate can be removed accurately and easily, and a fine structure having a precise fine structure is manufactured. can do.

  According to the fine mask pattern forming method of the present invention, it is possible to form a thin pattern with no residual film on the substrate. Further, according to the nanoimprint lithography method of the present invention, it is possible to accurately and easily perform lithography processing on the base material, and according to the fine structure manufacturing method, the fine mask pattern and the base material can be processed. Therefore, the removal process can be performed accurately and easily, and a fine structure having a fine structure with high precision can be manufactured.

It is a schematic side view of the base material for demonstrating process (a)-(f) of the formation method of the fine mask pattern by this embodiment. It is a schematic side view for demonstrating the production process (a)-(c) of the resin type | mold which can be used in FIG. It is a schematic side view for demonstrating another production process (a)-(d) of the resin type | mold which can be used in FIG. It is a side view which shows typically a mode that two base materials adsorb | suck mutually in order to demonstrate the self-adsorption effect | action by the physical interaction in FIG.1 (d). FIG. 1D illustrates the adhesion forces Fa, Fb, and Fc that act on each interface between the glass of the mold member 12, the resin 11, the SOG 15, and the silicon (Si) of the base member 16, respectively. It is a typical side view. It is a schematic side view of the base material for demonstrating process (a)-(d) which produces a microstructure from the mask structure obtained in FIG. 6 is a graph showing the result of measuring the intensity change of the emission spectrum from the start of etchback in Example 2. It is a figure which shows the process (a)-(f) of the conventional general nanoimprint lithography. It is the schematic for demonstrating the problem which arises with the residual film removal on the base material in FIG.8 (e).

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a substrate for explaining the steps (a) to (f) of the fine mask pattern forming method according to the present embodiment. FIG. 2 is a schematic side view for explaining steps (a) to (d) of resin molds usable in FIG.

<Production of resin mold>
First, a method for producing a resin mold as a mold having a fine uneven structure will be described with reference to FIG. First, the ultraviolet curable resin layer 11 is applied to the transfer mold 10 having the fine concavo-convex structure 10a by applying the ultraviolet curable resin layer 11 in a state where the fine concavo-convex structure 10a is buried and further deposited thereon by spin coating (a).

  Next, the ultraviolet curable resin layer 11 (hereinafter, also simply referred to as “resin layer 11”) is cured by irradiating ultraviolet rays, and the surface of the resin layer 11 is subjected to UV ozone treatment to thereby form the resin layer 11. The surface is activated (-OH orientation), a mold member 12 made of a glass substrate is bonded to the surface of the resin layer 11, and the entire surface of the resin layer 11 is covered by self-adsorption force (intermolecular force) due to physical interaction. Adhere to the surface (b).

  Next, heat treatment is performed to improve the adhesion between the surface of the ultraviolet curable resin layer 11 and the glass mold member 12, and then the resin is cooled to room temperature and released from the transfer mold 10. A resin mold 14 composed of the layer 11 and the glass mold member 12 is obtained (c). The resin layer 11 of the resin mold 14 has a fine concavo-convex structure 11 a to which the fine concavo-convex structure 10 a of the transfer mold 10 is transferred.

  Next, another method for producing a resin mold will be described with reference to FIG. In the following description, the same material as that shown in FIG. First, an ultraviolet curable resin layer 11 is applied to a glass mold member 12 by spin coating (a). Next, the transfer mold 10 having the fine concavo-convex structure 10a is pressed against the ultraviolet curable resin layer 11 (b). Next, the ultraviolet curable resin layer 11 is cured by irradiating with ultraviolet rays (c). Next, the transfer mold 10 and the ultraviolet curable resin layer 11 are released to obtain the resin mold 14 having the fine concavo-convex structure 11 a in which the fine concavo-convex structure 10 a of the transfer mold 10 is transferred to the resin layer 11. (D).

  The transfer mold 10 shown in FIGS. 2 and 3 is made of a silicon wafer. A resist mask is formed on the silicon wafer by electron beam drawing, and an uneven structure 10a having fine unevenness is periodically formed by etching. Although it can obtain, it is not limited to this method.

<Formation of fine mask pattern>
Next, the method for forming the fine mask pattern according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 2 or FIG. 3, the resin mold 14 having the resin layer 11 on which the fine uneven structure 11a is formed is produced (a). Next, an SOG film 15 is applied and formed by spin coating in a state where the fine concavo-convex structure 11a is buried in the resin mold 14 and further deposited thereon (b). The SOG film 15 can be accurately formed with a uniform thickness by spin coating. Here, the uniform thickness is a thickness neglecting the depth of the fine concavo-convex structure (the thickness of the SOG film due to the fine concavo-convex structure).

  Next, the SOG film 15 is etched back by dry etching to expose the convex surface 11b of the concave-convex structure 11a of the resin mold 14 on the surface (c). At this time, the SOG film 15 exists in the recess of the concavo-convex structure 11a.

  Next, the silicon substrate 16 is superposed on the surface 15a where the convex surface 11b of FIG. 1C is exposed (d). At this time, the surface 15a and the silicon base material 16 are self-adsorbed by the physical interaction (intermolecular force) without interposing an adhesive or the like between the surface 15a where the convex surface 11b is exposed and the silicon base material 16. Adhere to each other (self-adsorption) and adhere.

  Next, the glass substrate of the resin mold 14 is subjected to heat treatment for further improving the adhesion between the surface 15a where the convex surface 11b is exposed and the silicon substrate 16, and then cooled to room temperature and released. 12 is separated from the resin layer 11 (e). As a result, the SOG film 15 and the resin layer 11 are transferred to the silicon substrate 16.

  Next, the resin layer 11 on the silicon substrate 16 is removed by ashing to obtain a mask structure 17 having no SOG film and having the SOG film 15 on the silicon substrate 16 (f).

  As described above, the mask structure 17 having a fine mask pattern made of the SOG film 15 to which the concavo-convex structure 11a of the resin mold 14 is transferred can be produced.

  As described above, according to the fine mask pattern forming method of the present embodiment, the SOG film 15 formed on the resin mold 14 is removed until the convex surface 11b of the fine concavo-convex structure 11a is exposed, and the surface after the removal. When the silicon base material 16 is overlaid on 15a, the superposed surface 15a and the surface of the silicon base material 16 are adsorbed to each other by physical interaction and are brought into close contact with no adhesive or the like. Therefore, when the resin mold 14 is finally removed from the silicon base material 16, the SOG film 15 remains on the silicon base material 16, there is no unnecessary residual film on the silicon base material 16, and the uneven structure 11a of the resin mold 14 A mask structure 17 having the SOG film 15 transferred as a fine mask pattern can be obtained.

  When the resin mold 14 includes the mold member 12 and the resin layer 11 formed on the mold member 12, the mold 14 is removed from the silicon substrate 16 as shown in FIGS. 1 (d) to 1 (e). In addition, by separating the mold member 12 from the resin layer 11 and then removing the resin layer 11, an extra load is not applied to the fine mask pattern made of the SOG film 15 on the silicon substrate 16, and the fine mask pattern Can be prevented from being deformed or damaged. Further, as shown in FIGS. 1E to 1F, when the resin layer 11 is removed, since the SOG film 15 is an inorganic material, only the resin layer 11 is removed by ashing or the like to leave the SOG film 15. Is easy.

  Also, as shown in FIG. 2 or FIG. 3, the transfer mold 10 is used to create the resin mold 14 and the SOG film 15 is formed on the resin layer 11 of the resin mold 14 by spin coating. For example, a resin layer is formed on the transfer mold 10 by spin coating in FIG. 2A, and in FIG. 3B, the transfer mold 10 is made more than SOG. Since it suffices to press against a soft resin (UV curable resin before curing), the burden on the transfer mold 10 is small, the life of the transfer mold 10 can be extended, and the mask pattern manufacturing cost can be reduced.

  In addition, in the etch back process of the SOG film 15 in FIG. 1C, the remaining film is eliminated by detecting the end point of the etch back, or the remaining film is made sufficiently thin even if the remaining film remains. Can do. In order to detect the end point of this etch back, for example, a reaction component (for example, SiF) between Si in SOG and an etching gas (for example, a CF system) may be detected.

  Further, when the remaining film remains thin on the silicon base material 16, the thickness of the remaining film is desirably sufficiently thin with respect to the structural height h of the fine concavo-convex structure 11a in FIG. It is desirable that the height is not more than 1/2 of the structural height h.

  Next, the physical interaction between the silicon substrate 16 and the surface 15a where the convex surface 11b is exposed in FIG. 1D will be described with reference to FIG. FIG. 4 is a side view schematically showing how two substrates adsorb to each other in order to explain the self-adsorption action due to the physical interaction in FIG.

  When the two substrates C and D are overlapped for bonding, the flatness of each is different, so there is a certain distance between the two substrates C and D at the beginning of the overlap, and Newton stripes are visible However, when a certain period of time has passed (or when a force is applied to one place to make contact), the base materials C and D are in a state of being in partial contact at the portion E as shown in FIG. When this state is achieved, in the vicinity of the contact portion E, attraction forces a, b, c derived from intermolecular forces between the base materials C, D (a> b> c from the shortest distance between the base materials C, D). ), The contact area gradually expands while the counterpart substrates C and D are deformed relative to each other or the relatively easily deformable substrates C and D are deformed. The entire surface is in close contact with the surface. Thus, when the two base materials C and D are overlapped, they are self-adsorbed by the above-described physical interaction, and the entire surface is in close contact.

  Next, three examples (1) to (3) will be described with respect to a preferred embodiment relating to the self-adsorption described above.

  (1) In FIG.1 (d), it is preferable that the mutual surface of the silicon | silicone base material 16 and the surface 15a to be self-adsorbed is flat, and average surface roughness is 1 nm or less by centerline average roughness Ra as flatness. It is preferable that In addition, Ra in this case is surface roughness, and does not include the uneven component derived from the fine structure.

  (2) The self-adsorption process in FIG. 1 (d) may be performed under atmospheric pressure (normal pressure), but by performing under vacuum, air bubbles are not trapped between the silicon substrate 16 and the surface 15a. Since it contributes to the improvement of adhesiveness more, it is more preferable to carry out in a vacuum (reduced pressure) state.

  (3) It is preferable that the surface to be self-adsorbed and the surface of the silicon substrate in FIG. 1 (d) have such rigidity that they can be deformed by intermolecular force.

  Next, the reason why the silicon substrate 16 and the surface 15a are in close contact with each other and the mold member 12 can be separated from the resin layer 11 of the resin mold 14 in the separation step of FIG. 1E will be described with reference to FIG. To do. FIG. 5 shows the adhesion that acts at each interface between the glass of the mold member 12, the resin of the resin layer 11, the SOG of the SOG film 15, and the silicon (Si) of the silicon substrate 16 in FIG. It is a typical side view for demonstrating force Fa, Fb, Fc.

As shown in FIG. 5, the adhesion force Fa at the interface between the glass of the mold member and a resin made of, for example, an acrylic resin, and the adhesion force Fb at the interface between the SOG and the resin are the interaction between the —OH group and —CH _3. Usually, Fa≈Fb, but since the SOG and the resin are in close contact with each other by the concavo-convex structure, the surface area is large and Fb> Fa due to the anchor effect.

  Further, since the adhesion force Fc at the interface between SOG and silicon is increased by the electrostatic interaction between the -OH group on the surface of SOG and the -OH group of silicon, Fc> Fa even without pretreatment. become.

  As described above, since the adhesion force Fa at the interface between the glass and the resin of the mold member is smaller than the adhesion forces Fb and Fc at the other interfaces, the mold from the resin layer 11 to the mold at the interface between the resin layer 11 and the mold member 12. The member 12 can be separated with priority over other interfaces.

  Further, as post-processing after the silicon substrate 16 is brought into close contact, it is possible to contribute to improvement in adhesion by performing any one of standing for a predetermined time, heat treatment, electrostatic adsorption treatment, and pressure treatment.

  Further, as shown in FIG. 1C, in the surface 15a where the convex surface 11b of the resin layer 11 is exposed, the surface of the SOG layer 15 and the convex surface 11b are mixed and the adhesion force Fc in FIG. Adhesion is improved by performing any one of UV ozone treatment, excimer lamp treatment, oxygen ashing treatment, alkali washing and alcohol washing on the surface 15a as a pre-treatment before the material 16 is adhered. Let

  Next, a process of manufacturing a fine structure from the mask structure 17 having the fine mask pattern obtained in FIG. 1F will be described with reference to FIG. FIG. 6 is a schematic side view of a base material for explaining steps (a) to (d) for producing a fine structure from the mask structure obtained in FIG.

  As shown in FIG. 6A, the mask structure 17 obtained in FIG. 1F has a fine mask pattern made of the SOG film 15 having the concavo-convex structure 11a of the resin mold 14 transferred onto the silicon substrate 16. Have. The mask structure 17 is subjected to a known etching process from above in the drawing on the side where the SOG film 15 exists, so that the SOG film 15 and the SOG film 15 other than the SOG film 15 are obtained as shown in FIG. 6 is removed (lithographic processing), and the SOG film 15 is completely removed as shown in FIG. 6C to form a fine relief structure 18 corresponding to the fine mask pattern of the SOG film 15. By forming and further etching as necessary, a final fine uneven structure 19 is formed on the silicon substrate 16 as shown in FIG. In this way, the microstructure 20 having the desired fine relief structure 19 can be obtained.

  As described above, there is no remaining film 104 as shown in FIG. 8D on the bottom surface of the concave portion of the SOG film 15 of the mask structure 17 obtained in FIG. In the etching process of FIG. 6B, the removal of the residual film is unnecessary or almost unnecessary, and the shape accuracy of the convex surface of the SOG film 15 is hardly lowered by the residual film removal as shown in FIG. The target fine concavo-convex structure 19 corresponding to the fine mask pattern can be formed with high accuracy. In this way, the fine structure 20 having the fine concavo-convex structure 19 with high accuracy can be produced.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

  First, a resin mold was produced by the process shown in FIG. First, using a silicon wafer (4 inches, thickness 0.525 mm, flatness PV = 5 μm (effective diameter 50 mm)) as a transfer mold material, a resist mask is prepared by electron beam drawing, and periodically by dry etching. A transfer mold was fabricated by digging out a fine shape with fine irregularities. This fine shape is a hole array structure having a structure period of 620 nm, a hole diameter of 310 nm, and a structure depth of 200 nm. An acrylic ultraviolet curable resin (PAK02 manufactured by Toyo Gosei Co., Ltd.) as a transfer material was applied to this transfer mold by a spin coating method (3000 rpm, 60 seconds) to form a resin layer. Thereafter, the ultraviolet curable resin layer was cured by irradiating ultraviolet rays having a peak wavelength of 365 nm for 1 minute. The surface of the resin layer was activated (-OH orientation) by performing UV ozone treatment (UV light source: low-pressure mercury lamp, treatment time: 2 minutes). A Tempax glass substrate (3 inches, thickness 0.6 mm) was bonded to the surface of the resin layer as a base material, and the entire surface was brought into close contact by self-adsorption force (intermolecular force). Thereafter, heat treatment (120 ° C., 20 seconds) was performed to improve adhesion to the substrate. Then, the resin mold | die was produced by cooling to room temperature and performing mold release.

  In addition, a resin mold was produced in the process shown in FIG. First, using a silicon wafer (4 inches, thickness 0.525 mm, flatness PV = 5 μm (effective diameter 50 mm)) as a transfer mold material, a resist mask is prepared by electron beam drawing, and periodically by dry etching. A transfer mold was fabricated by digging out a fine shape with fine irregularities. This fine shape is a hole array structure having a structure period of 620 nm, a hole diameter of 310 nm, and a structure depth of 200 nm. An acrylic ultraviolet curable resin (PAK02 manufactured by Toyo Gosei Co., Ltd.) was applied to a Tempax glass substrate (3 inches, thickness 0.6 mm) by a spin coating method (3000 rpm, 60 seconds) to form a resin layer. The transfer mold was pressed (4 MPa) on this resin layer, and the ultraviolet curable resin layer was cured by irradiating ultraviolet rays having a peak wavelength of 365 nm for 1 minute. Then, the resin mold was produced by releasing the transfer mold and the resin layer.

Example 1
In Example 1, a fine mask pattern is formed on a silicon substrate in the process shown in FIG.

SOG (OCD T-12 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to the produced resin mold by a spin coating method (6000 rpm, 30 seconds) to form an SOG film. Next, the SOG film was etched back (ICP dry etching apparatus, pressure 5 Pa, CHF ₃ 50 sccm, antenna power 300 W, bias 200 W) to expose the resin-type microstructure on the surface. Next, a silicon wafer (2 inches, thickness 0.5 mm) as a base material was bonded to the exposed surface of the resin mold microstructure, and the entire surface was brought into close contact by self-adsorption force (intermolecular force). Thereafter, heat treatment (120 ° C., 20 seconds) was performed to improve adhesion to the silicon substrate. Thereafter, the SOG film and the resin layer were transferred onto the silicon substrate by cooling to room temperature and releasing the mold. Finally, the resin layer was removed by oxygen ashing (5 Pa, O ₂ 50 sccm, antenna power 50 W), and a mask structure made of an SOG film having no remaining film on the silicon substrate was produced.

(Example 2)
Example 2 is basically the same process as Example 1, but the end point of the removal process is detected when the SOG film is removed from FIG. 1 (b) to (c). is there.

SOG (OCD T-7 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to the produced resin mold by a spin coating method (5000 rpm, 60 seconds) to form an SOG film. Next, the SOG film was etched back (RIE dry etching apparatus, pressure 1 Pa, CHF _{3 10} sccm, power 300 W). At this time, using endpoint detector (XINIX Co. Model1015DS), CF-based (etching gas CHF ₃₎ ion and the Si from the SOG is focused on the emission spectra from SiF generated by reaction endpoint detection The etching back was stopped near the convex surface of the resin-type concavo-convex structure. Next, a silicon wafer (2 inches, thickness 0.5 mm) is bonded as a base material to the surface where the SOG film is removed to the vicinity of the convex surface of the resin-type concavo-convex structure, and the entire surface is applied by self-adsorption force (intermolecular force) Adhered. Thereafter, heat treatment (120 ° C., 20 seconds) was performed to improve adhesion to the silicon substrate. Thereafter, the SOG film and the resin layer were transferred onto the silicon substrate by cooling to room temperature and releasing the mold. Finally, the resin layer was removed by oxygen ashing (5 Pa, O ₂ 50 sccm, antenna power 150 W), and a mask structure made of an SOG film having no remaining film on the silicon substrate was produced.

  FIG. 7 shows the results of measuring the change in the emission spectrum intensity derived from SiF from the start of etchback using an SOG film previously applied on a substrate having no uneven structure for the end point detection. In FIG. 7, the period from 110 seconds to 125 seconds, which shows a sharp decrease in the intensity of the emission spectrum, corresponds to a state in which the SOG film is completely removed after the surface of the substrate without the uneven structure begins to be exposed. Therefore, if the etch back is stopped during this period (110 seconds to 125 seconds), the etching reaction can be stopped near the convex surface of the resin-type uneven structure. Moreover, since the etching rate of SOG is 1.2 nm / sec under this condition, it can be seen that the in-plane distribution of the remaining film can be suppressed to about 1.2 × (125−110) = 18 nm. In Example 2, the etch-back was stopped at a point where there was a change in emission spectrum intensity corresponding to 115 seconds from the start of etching in FIG.

  In the second embodiment, the end point is detected by SOG applied to the resin mold. However, when it is desired to leave a little residual film or when the detection sensitivity is increased, a dummy substrate provided with an etching layer is prepared and the etching is performed. Etchback may be stopped based on a change in emission spectrum caused by the layer or its substrate.

  As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the film 15 in FIG. 1B may be formed of a material whose main component is a silicon (Si) -containing resin.

Further, in order to improve the adhesion between the silicon substrate 16 and the surface 15a of FIG. 1D, a SiO ₂ film may be formed on the surface of the silicon substrate 16 in advance. The base material 16 may be a base material other than silicon, and examples thereof include, but are not limited to, gallium arsenide, gallium nitride, sapphire, and the like. In this case, an SiO ₂ film may be formed on the surface of the base material in order to improve adhesion.

  According to the fine mask pattern forming method, nanoimprint lithography method, and fine structure manufacturing method of the present invention, an accurate fine concavo-convex structure can be easily formed on a substrate. , Discrete Media), mask manufacturing process for various semiconductor products, LED light extraction structure, photonic crystal laser, MEMS mask manufacturing process, etc. It can be realized at low cost.

11 UV curable resin layer (resin layer)
11a Fine uneven structure (uneven structure)
11b Convex surface 12 Mold member 14 Resin mold 15 SOG film 15a Surface 16 Silicon base material 17 Mask structure 19 Fine uneven structure 20 Fine structure Fa, Fb, Fc Adhesive force

Claims (7)

Form a film on a mold with a fine relief structure,
Removing the film on the mold to the convex surface of the micro uneven structure of the mold or to the vicinity of the convex surface,
Overlay the base material on the surface after removing the film on the mold and make it adhere by physical interaction,
A method for forming a fine mask pattern, comprising: forming a fine mask pattern made of the film corresponding to the fine concavo-convex structure on the substrate by removing the mold from the substrate.   The method for forming a fine mask pattern according to claim 1, wherein the fine concavo-convex structure of the mold is formed of a resin layer made of a resin material.   The method for forming a fine mask pattern according to claim 2, wherein the fine concavo-convex structure of the resin layer is formed by being transferred from a transfer mold.   4. The method of forming a fine mask pattern according to claim 1, wherein the film formed on the mold is made of SOG or a silicon-containing resin material.   5. The formation of a fine mask pattern according to claim 1, wherein an end point of the removal is detected when the film on the mold is removed to a convex surface of the fine concavo-convex structure of the mold or to the vicinity of the convex surface. Method.   A nanoimprint characterized by performing lithography processing on the base material using the fine mask pattern formed on the base material as a mask by the method of forming a fine mask pattern according to any one of claims 1 to 5. Lithographic method.   The fine mask pattern and the mask structure having the fine mask pattern formed on the base material by the fine mask pattern forming method according to any one of claims 1 to 5 and the base material, A fine structure manufacturing method, wherein a fine structure having a fine structure corresponding to the fine mask pattern is produced by performing a removal process of the base material.

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