Laminate for pattern transfer and transfer method

Abstract

To laminate a layer which is mainly formed of a water soluble resin coating layer and photosensitive resist layer which has been subjected to exposure, on a patterning base material whose surface is a flat surface or is not a flat surface, instead of bringing a photomask into tight contact with a patterning base material through a photosensitive resist layer or the like for performing exposure, and perform the subsequent processing.SOLUTION: There is provided a laminate for pattern transfer formed by laminating in the order, a photomask, a water soluble resin coating layer and a photosensitive resist layer, and the photomask and the water soluble resin coating layer can be peeled at their interface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to photolithography microfabrication technology, which requires faithfully transferring the fine patterns prepared on a photomask to a photoresist film.

Background Art

[0002] Devices typified by ICs and MEMS have highly combined high-precision and complex structures and are mass-produced by photolithography technology capable of fabricating fine shapes in a batch with high productivity. To increase productivity, the key is to form finer patterns on a photosensitive resist film. Usually, a resist film is formed on a substrate, and the pattern is transferred by irradiating ultraviolet light in a pattern shape. Historically, in the semiconductor industry, around 1980 when a resolution finer than 2 μm was required, the method of bringing a glass mask close to a substrate was changed to a method using a stepper that exposes an optically reduced image of a mask pattern. It became necessary to stably form fine patterns, which means that the accuracy could not be stably obtained by the method of physically bringing a glass mask close. Even when using a stepper, the substrate surface is required to be highly flat. This is to make the plane of the photomask and the plane of the substrate optically coincide with each other through the lens of the stepper device. Great efforts have been made to ensure flatness. When the substrate becomes three-dimensional, it cannot be handled by the above technology.

[0003] Techniques for faithfully transferring the fine patterns prepared on a photomask to a photosensitive resist are disclosed in, for example, Patent Documents 1 to 4 and Non-Patent Documents 1 to 3. Patent Document 1 discloses a method of exposure in which a three-dimensional photomask, made to match the shape of a plastic molded product having a three-dimensional structure, is brought into close contact with the product. The photomask material can be synthetic resin or metal, etc. However, a separate method is required to create a photomask with a fine pattern on top of the three-dimensional shape. In addition, when exposing the photoresist, the photoresist must be exposed from multiple directions, and the surfaces other than the resist surface to be exposed must be shielded with a light-shielding mask, otherwise the photoresist will not be exposed evenly. Special photomasks and exposure equipment that need to be adjusted for each three-dimensional shape are required. Patent Document 2 discloses a method for manufacturing contacts that can reliably contact the external connection part of an electronic component, regardless of its shape. By using short-wavelength X-rays, diffraction is reduced, preventing deterioration of the exposure pattern even if there is a gap between the mask and the exposure area. X-ray exposure equipment is specialized and expensive. Furthermore, the mask also requires a thick metal film to block the X-rays, making it specialized and expensive as well. Patent Document 3 discloses a three-dimensional mask for forming an electrical circuit pattern on a three-dimensional molded product. This three-dimensional mask is obtained by applying an opaque coating to the surface of a molded product made by stereolithography. By joining this three-dimensional mask with a planar film mask, a photomask is obtained that has openings for the desired pattern and is processed to the three-dimensional shape of the surface to be adhered to. This photomask is then placed in close contact with a three-dimensional molded product that has a photosensitive resist film deposited on it, and by exposure and development, a three-dimensional circuit molded product with a three-dimensional and fine electrical circuit pattern is obtained. To further refine the pattern, it is difficult to achieve because it requires not only high-precision manufacturing of both the three-dimensional mask and the three-dimensional molded product, but also close contact on all surfaces of the three-dimensional surface. Patent Document 4 discloses a method in which a photosensitive resist film is prepared on a sheet containing a water-soluble resin, and a fine pattern is prepared as a latent image by exposing the photosensitive resist film to a photomask in close contact with it before attaching the photosensitive resist film to a substrate. This method transfers the pattern onto a three-dimensional object by developing it after attaching it to a three-dimensional substrate. Since the sheet is almost flat, it is easy to make it adhere to the photomask. The example pattern width is 2 μm, but it has not been achieved to obtain a stable pattern over a wide area. As long as the photomask and resist film are prepared as separate components and the wavelength of light is ultraviolet light of about 400 nm, a pattern width of 2 μm becomes the practical limit.

[0004] Non-Patent Document 1 comprehensively describes exposure equipment technology. While steppers operate on the principle of optically aligning the mask plane and the wafer plane via a lens, wafer planar correction techniques are introduced to achieve wafer flatness. It shows that not only do the vacuum grooves of the vacuum chuck deform the wafer, but even minute dust particles trapped between the wafer surface and the chuck surface can cause defocusing. Appendix Table 4 contains a timeline of exposure equipment development by Nikon and Canon, showing their developed models and their resolution capabilities. It reveals that early steppers were introduced in the late 1970s, with a resolution of 2 to 1 μm. Non-patent document 2 describes a three-dimensional circuit board (Molded Interconnect Device) with an electrical circuit formed on the surface of an injection-molded product. It is a plastic injection-molded product with both mechanical and electrical functions. Its manufacturing process involves a. first preparing a sheet with multiple substrates arranged in an array, b. sputtering a thin metal film onto the entire surface, c. removing the thin metal film from the contour of the circuit pattern shape by laser drawing, d. plating, and e. cutting the substrates individually from the sheet. The laser drawing in c. above involves repeated single-point processing. Miniaturizing the single-point processing size is essential for forming high-density circuits. However, reducing the laser spot size reduces the amount of processing at a single point, and even for the same area, it takes longer to process (area increases with the square of the length), thus reducing productivity. In addition, miniaturization requires focusing the laser with a lens with a large NA value, but the depth of focus narrows with the square of the NA, severely limiting autofocus. Performing this according to a three-dimensional shape becomes technically difficult. The brochure from May 2014 states that the minimum line width is 50 μm and the pattern spacing is 50 μm. Non-patent document 3 describes nanoimprint technology, which involves pressing a mold with a finely engraved pattern onto a substrate coated with a polymer material to transfer the pattern in large quantities. It discloses that the development of large-area molds has led to an expansion of applications and increased mass production. Previously, creating arbitrary nanopatterns required the production of master molds using electron beam lithography, which was expensive (10 million yen per mold for a 2-3 cm master mold for a 10-20 nm wide pattern), and there were many technical challenges related to defects specific to imprinting. For this reason, it could not demonstrate a significant advantage over existing semiconductor manufacturing technologies such as photolithography. New applications where patterns of around 100 nm are sufficient include, for example, the formation of anti-reflective layers in liquid crystal panels, polarizing films, improving the light extraction efficiency of organic EL panels, water-repellent coatings for automobile windows, optical components ranging from fine microlens arrays to large lenses, and the cultivation of three-dimensional cells. For these applications, technologies that naturally generate structures, such as structures created by aluminum anodizing, have been utilized. Photolithography also has the advantage of being able to produce fine shapes in one go with high productivity. It is an excellent method that can reduce equipment costs and increase the added value of the substrate as the transferable pattern becomes finer. However, a method that can achieve this with a high degree of freedom has not yet been found. The fine pattern transfer method, in which a photosensitive resist film is prepared on the substrate surface and a photomask is brought close to it for exposure, is still widely used today because aligner equipment has been established and its maintenance costs are relatively low. However, the actual transferable pattern size is limited to about 2 μm. This is because if one tries to transfer a finer pattern than this, ultraviolet light that passes through the transparent glass part of the photomask will inevitably diffract in the gap between the photomask and the resist film, causing the pattern to break down. To obtain patterns finer than 2 μm, a stepper is used. Steppers are expensive in terms of equipment and maintenance costs. Maskless exposure equipment that can reduce these maintenance costs is available on the market, but the purchase price of such equipment does not fall below tens of millions of yen, making it very expensive. A photomask with a width of about 1 μm costs around 100,000 yen, and it would be ideal if pattern transfer could be faithfully performed using such a mask. However, transferring patterns smaller than 2 μm to a non-flat substrate (for example, a curved or grooved substrate) is difficult even with a stepper or maskless exposure system. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-286280 [Patent Document 2] Japanese Patent Publication No. 2005-79055 [Patent Document 3] Japanese Patent Application Publication No. 9-319068 [Patent Document 4] Japanese Patent Publication No. 2017-071202 [Non-patent literature]

[0006] [Non-Patent Document 1] "Systematic Survey of the Development of Exposure Equipment Technology," Kazuo Takahashi, National Museum of Nature and Science, Systematic Survey Report of Technology, Vol. 6 (March 31, 2006) http: / / sts.kahaku.go.jp / diversity / document / system / pdf / 022.pdf [Non-Patent Document 2] Panasonic Corporation, MIPTEC 3D Packaging Device (Brochure and other materials, "High-Speed ​​Laser Processing System for MID," Takashi Shindo, Hiroshi Takahashi, Panasonic Electric Works Technology (vol. 57, No. 3), pp. 10-15) [Non-Patent Document 3] "A New Trend in Nanoimprint Printing: Expanding Applications Through Large-Area Printing" Nikkei Electronics (March 14, 2014) pp. 49-58 [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention does not involve attaching a photomask to a patterning substrate via a photosensitive resist layer or the like to induce photosensitivity. Instead, it aims to enable the lamination of layers based on a water-soluble resin coating layer and a photosensitive resist layer onto a patterning substrate with a planar or non-planar surface, and then performing subsequent processing. Furthermore, the present invention aims to achieve a method that can realize transferable patterns, even if they are fine, with a high degree of freedom depending on the conditions. [Means for solving the problem]

[0008] As a result of diligent efforts to solve the above-mentioned problems, the inventors discovered that they could be solved by the following means, leading to the present invention. 1. A pattern transfer laminate for transferring a pattern to a patterning substrate, comprising a photomask, a water-soluble resin coating layer, and a photosensitive resist layer laminated in this order, wherein the photomask and the water-soluble resin coating layer are peelable at their interface. 2. The laminate for pattern transfer according to claim 1, wherein the water-soluble resin coating layer is a layer formed by coating a water-soluble resin solution onto a photomask. 3. A pattern transfer laminate according to 1 or 2, wherein the photosensitive resist layer has a latent image pattern exposed in accordance with the fine pattern of the photomask. 4. The pattern transfer laminate according to 3, wherein the width of the latent image pattern is 2 μm or less. 5. A pattern transfer laminate according to any one of 1 to 4, wherein the thickness of the water-soluble resin coating layer is less than or equal to the thickness calculated by the following formula 1. Formula 1: Thickness = [0.50 × (pattern width)] 2 (Refractive index of water-soluble resin coating layer) / (Exposure wavelength)] 6. A pattern transfer laminate according to any one of 1 to 5, wherein the water-soluble resin coating layer is polyvinyl alcohol. 7. A pattern transfer laminate according to any one of 1 to 6, wherein a frame is fixed to the photosensitive resist layer surface of the pattern transfer laminate, and the photomask and the water-soluble resin coating layer are peelable at their interface. 8. A pattern transfer laminate according to any one of 1 to 7, having a layer on the side of the photomask facing the water-soluble resin coating layer that promotes peeling of the interface between the photomask and the water-soluble resin coating layer. 9. A pattern transfer laminate according to any one of 1 to 8, for exposing a photosensitive resist layer before being brought into contact with a patterning substrate to be processed. 10. A laminate for pattern transfer consisting only of a water-soluble resin coating layer and a photosensitive photoresist layer. 11. A method for transferring a photosensitive resist layer onto a substrate, comprising the following steps (a) to (g). (a) A step of applying a water-soluble resin solution to one side of a photomask, (b) A step of drying the obtained water-soluble resin solution layer to obtain a water-soluble resin coating layer, (c) A step of forming a photosensitive resist layer on a water-soluble resin coating layer, (d) A step of exposing the photosensitive resist layer by irradiating it with light from the photomask side, (e) A step of peeling off a laminate consisting of a water-soluble resin coating layer and a photosensitive resist layer from a photomask, (f) A step of adhering a laminate consisting of a peeled water-soluble resin coating layer and a photosensitive resist layer to the surface of a patterned substrate such that the photosensitive resist layer is in contact with the surface of the patterned substrate. (g) Washing and removing the water-soluble resin coating layer located on the surface, and developing and / or drying the surface of the patterning substrate as necessary

Advantages of the Invention

[0009] According to the present invention, it is possible to form a laminate for pattern transfer in which a photomask, a water-soluble resin coating layer, and a photosensitive resist layer are laminated in this order, and the photomask and the water-soluble resin coating layer are separable at their interface. Therefore, even if the surface of the patterning substrate is flat or not flat, a photosensitive resist layer can be laminated on the surface, and thus various treatments and processes can be performed on various surfaces through the photosensitive resist layer. Also, during exposure, the distance between the photosensitive resist film and the photomask can be set to a water-soluble resin coating layer that allows sufficient proximity. In addition to this effect, if the thickness of the water-soluble resin coating layer is below the parameter value obtained by the following formula 1, blurring of the pattern due to diffraction broadening during exposure can be minimized. Furthermore, ideal conditions for transferring a fine pattern with a width of 2 μm or less to the photosensitive resist can be obtained, and pattern transfer becomes possible by performing a development process after attaching to a flat or three-dimensional substrate. Formula 1: Thickness = [0.50 × (pattern width) 2 × (refractive index of the water-soluble resin coating layer)] / (exposure wavelength)

Brief Description of the Drawings

[0010] [Figure 1] Figure showing a state of forming a laminate for pattern transfer by spin-coating a water-soluble resin solution and a photosensitive resist in sequence on a photomask [Figure 2] Figure showing formation of a latent image in the photosensitive resist layer by irradiating ultraviolet rays from the photomask side of the laminate for pattern transfer and exposing [Figure 3] Figure showing a state of peeling the water-soluble resin coating layer and the photosensitive resist layer from the photomask [Figure 4]This diagram shows how a latent image is formed in the photosensitive resist layer by irradiating a pattern transfer laminate, in which a frame is fixed to the photosensitive resist layer surface around the periphery of the photomask, with ultraviolet light from the photomask side to expose it. [Figure 5] A view from the frame side of a pattern transfer laminate in which a frame is fixed to the photosensitive resist layer surface around the periphery of a photomask. [Figure 6] This diagram shows the process of peeling off the water-soluble resin coating layer and the photosensitive resist layer, which have frames fixed to the photosensitive resist layer surface, from the photomask to the periphery of the photomask. [Figure 7] A diagram showing the process of transferring a photosensitive resist layer onto planar and three-dimensional substrates. [Figure 8] Scanning electron microscope images of SKD11 die steel onto which five different widths of photosensitive resist patterns have been transferred. [Figure 9] Enlarged view of the outermost pattern with a width of 1.1 μm in Figure 8. [Modes for carrying out the invention]

[0011] The pattern transfer laminate of the present invention is based on the principle of laminating a photomask, a water-soluble resin coating layer, and a photosensitive resist layer in the order described above. The photomask and the water-soluble resin coating layer are peelable at their interface, making the pattern transfer laminate particularly useful for transferring fine patterns. The structure of the pattern transfer laminate of the present invention will be described below in order.

[0012] (Photomask) The photomask used in this invention is not particularly limited, and known binary masks, phase-shift masks, etc., can be used. It is necessary that a water-soluble resin coating layer can be formed on one side of the photomask. The photomask can be a monochrome mask (binary mask) that only changes brightness, or a phase-shift mask with a textured surface like glass. Its size and shape can also be adjusted as needed. Furthermore, the water-soluble resin coating layer must have sufficient adhesion to allow the photomask, water-soluble resin coating layer, and photosensitive resist layer to be handled as a single unit. At the same time, the water-soluble resin coating layer must also have sufficient peelability to be peeled off the photomask during use. Therefore, the surface of the photomask on the side with the water-soluble resin coating layer may be treated as needed to adjust the adhesion and peelability between it and the water-soluble resin coating layer. To this end, a release agent layer, such as a CFx film made of a known fluorine compound (such as C4F8), can be pre-formed on the surface of the photomask on the side where the water-soluble resin coating layer is formed, as a layer that promotes peeling at the interface between the photomask and the water-soluble resin coating layer. As a means of peeling the water-soluble resin coating layer from the photomask, known methods for peeling film-like laminates can be employed. This means can include pinching the edge of the photomask with fingers or an instrument and applying force in the peeling direction.

[0013] (Water-soluble resin coating layer) The water-soluble resin coating layer in the present invention is a layer formed on the entire surface or a sufficient portion of one side of a photomask. The layer may be made of a known water-soluble resin, but among them, a layer made of one or more selected from polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyester, and polystyrene sulfonic acid is preferred, with a layer made of polyvinyl alcohol being preferred. The water-soluble resin coating layer in this invention is a layer obtained by coating a photomask with a water-soluble resin solution and drying it. Therefore, a layer obtained by coating and drying a water-soluble resin solution on the surface of a substrate such as a resin film, and then transferring and laminating it onto a photomask, is not the water-soluble resin coating layer in this invention. For the formation of a uniform water-soluble resin coating layer, it is preferable that the viscosity of the water-soluble resin solution at 25°C be 1000 mPa·s or less. Furthermore, the concentration of the water-soluble resin in the water-soluble resin solution can be arbitrarily adjusted to achieve the desired thickness of the water-soluble resin coating layer. The water-soluble resin constituting the water-soluble resin coating layer must, in addition to providing appropriate water solubility, reliably peel off the water-soluble resin coating layer from the photomask, and prevent deformation of the water-soluble resin coating layer and the photosensitive resist layer after peeling. For this purpose, it is preferable that the water-soluble resin coating layer has a high tensile modulus. The tensile modulus of such a water-soluble resin coating layer is 500 N / mm² after humidity control in a 23°C-50%RH environment. 2 The above is preferable, and 800 N / mm 2 The above is more preferable, 1100 N / mm 2 The above is even more preferable, 1300 N / mm 2 The above is the most preferable. 500 N / mm 2 If the temperature is less than the specified value, the water-soluble resin coating layer will stretch when peeled off the photomask. Care must be taken to prevent the photosensitive resist layer from stretching and causing cracks in the resist pattern. This polyvinyl alcohol may be modified and / or unmodified, but unmodified is preferred. In the case of modified polyvinyl alcohol, other monomers can be copolymerized in the main chain in a range that does not inhibit the effects of the present invention, for example, 10 mol% or less, preferably 7 mol% or less. However, if monomers having anionic and cationic functional groups are copolymerized, peeling from the photomask may become difficult, and the effects of the present invention may be inhibited by reaction with the resist material, so monomers having nonionic properties are preferred. Examples of nonionic monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; dialkyl esters such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid; polyoxyalkylene vinyl ethers such as polyoxyethylene vinyl ether and polyoxypropylene vinyl ether; and N-vinylpyrrolidone. These other monomers may be used individually or in combination.

[0014] When using polyvinyl alcohol, the degree of saponification is preferably 60 mol% or higher, and more preferably 70 to 95 mol%. If the degree of saponification is less than 60 mol%, it may not have sufficient water solubility, and it may not be possible to sufficiently dissolve and remove it with water during the transfer process, which may cause problems in subsequent processes. Furthermore, the degree of polymerization of polyvinyl alcohol is preferably 500 or higher, more preferably 600 to 2000, and even more preferably 1000 to 1500. If the degree of polymerization of polyvinyl alcohol is less than 500, the mechanical strength of the formed polyvinyl alcohol layer may be weak, and the film may be damaged when peeled from the photomask. If the degree of polymerization of polyvinyl alcohol exceeds 2000, the viscosity of the aqueous solution will be high, which may cause problems when forming the polyvinyl alcohol layer as a water-soluble resin coating layer on the photomask.

[0015] Known plasticizers can be added to polyvinyl alcohol, as long as they do not adversely affect the photosensitive resist layer. Preferably, the mixture contains at least one diol compound and / or a triol compound in which the adjacent hydroxyl group is located at the δ position or later. The preferred diol compound has a number average molecular weight of 600 or more, more preferably 800 or more, and even more preferably 1000 or more. If no plasticizer is added, or if a compound other than a diol compound or a triol compound in which the adjacent hydroxyl group is located at the δ position or later is added as a plasticizer, problems such as inability to reliably peel off the photomask may occur, and knocking during peeling may affect the resist pattern. Here, a triol compound in which adjacent hydroxyl groups are located at the δ position or further back is a compound having three hydroxyl groups, where, using one of the hydroxyl groups as a reference, the carbon element bonded to it is designated as the α position, and between that reference hydroxyl group and the remaining two hydroxyl groups, there are at least four atoms with a valence of 2 or higher, such as carbon or oxygen, bonded to each of them. Furthermore, it is necessary that in all combinations of any two of the three hydroxyl groups, there are at least four atoms with a valence of 2 or higher bonded to them.

[0016] For example, in 1,4,8-octantriol shown in Chemical Formula 1 below, if we take the hydroxyl group bonded to the carbon atom at position 4 as the reference point, the positions of the adjacent hydroxyl groups at positions 1 and 8 are δ and ε, respectively. Similarly, in oxyethylene glyceryl ether shown in Chemical Formula 2 below, if we take the hydroxyl group located in the middle of the molecule as the reference point, the adjacent hydroxyl groups are each located at position θ. The triol compounds in this invention in which adjacent hydroxyl groups are located at the δ position or further back are compounds in which all hydroxyl groups in the triol compound are located at the δ position or further back relative to each other. Compounds in which the hydroxyl groups between two adjacent hydroxyl groups are located beyond the δ position, as shown in 1,2,8-octanetriol below, but the combination of two other adjacent hydroxyl groups is located up to the γ position, are not triol compounds in the present invention in which the adjacent hydroxyl groups are located beyond the δ position. (chemical 1) JPEG0007904443000001.jpg24170 (Case 2) JPEG0007904443000002.jpg37170 (3) JPEG0007904443000003.jpg24170

[0017] Furthermore, the water-soluble resin solution may contain a leveling agent to prevent repulsion when forming a photomask, and an antifoaming agent to prevent foaming when dissolving in water, to the extent that it does not hinder the effects of the present invention. Known materials can be used for both, and non-silicone materials are preferred. Furthermore, since a photosensitive resist layer is formed on top of the water-soluble resin coating layer, it is necessary that it not be affected by solvents contained in the photosensitive resist solution, such as acetone, cyclohexanone, methyl ethyl ketone, 2-methoxy-1-methylethyl acetate, etc. If it is affected, the water-soluble resin coating layer may dissolve, causing pores or other damage, which may impair the effects of the present invention.

[0018] The preferred thickness of the water-soluble resin coating layer is less than or equal to the thickness calculated by the following formula 1. Equation 1: Thickness = [0.50 × (pattern width)² × (refractive index of water-soluble resin coating layer) / (exposure wavelength)] When using a water-soluble resin with a refractive index of 1.50, and with a desired pattern width of 1 μm and an exposure wavelength of 400 nm, the thickness is preferably approximately 1.9 μm or less, as shown in Equation 1: Thickness = [0.50 × (1 μm)² × (1.5) / (0.4 μm)] = 1.9. Similarly, when the pattern width is 2 μm and the exposure wavelength is 400 nm, the thickness is preferably 7.5 μm or less. Likewise, when the pattern width is 1 μm and the exposure wavelength is 250 nm, the thickness is preferably 3.0 μm or less, and when the exposure wavelength is 365 nm, the thickness is preferably 2.0 μm or less. If the thickness of the water-soluble resin coating layer exceeds the thickness calculated by Equation 1, pattern blurring may occur due to light diffraction between the photomask and the photosensitive resist layer, potentially damaging the pattern shape. While the thickness can be adjusted to a wide range of values ​​depending on the desired pattern width, for typical use assuming exposure with finer patterns, a thickness of 3.0 μm or less is preferred, 2.6 μm or less is more preferred, 2.3 μm or less is even more preferred, and 1.9 μm or less is most preferred. Furthermore, it is preferable that the light transmittance at wavelengths of 248 nm or higher is 80% or higher. If it is less than 80%, the irradiated light will be absorbed by the water-soluble resin coating layer, weakening the intensity of the light irradiated onto the photosensitive resist film and potentially damaging the pattern shape.

[0019] To provide such a water-soluble resin coating layer on one side of a photomask, a method may be employed in which a water-soluble resin solution, obtained by dissolving a water-soluble resin in a solvent, is used to coat and dry the entire surface of the photomask by known means such as spin coating, which involves supplying the water-soluble resin solution onto the photomask while rotating the photomask placed on a rotating device; spray coating, which involves spraying the water-soluble resin solution onto the photomask; or slit coating, which involves using a slit die. Alternatively, a water-soluble resin solution layer may be formed on a release film in advance, and this water-soluble resin solution layer may be transferred onto the photomask by known means before it dries. When coating by spin coating, it is preferable that the viscosity at 25°C, measured using a B-type viscometer at a shear rate of 1.7 s⁻¹, is 350 mPa·s or less. If it exceeds 350 mPa·s, it may cause problems when forming the water-soluble resin coating layer. In this way, a water-soluble resin solution layer is formed on the side of the photomask where the water-soluble resin coating layer will be formed, by means of applying a water-soluble resin solution, and by drying this water-soluble resin solution layer, a uniform water-soluble resin coating layer can be formed over the entire desired area of ​​the photomask, with reliable adhesion to that area. If a water-soluble resin layer or photosensitive resist layer formed on a separate film is to be superimposed on the surface of the photomask, there is a possibility that gaps will be formed between it and the photomask surface where adhesion is not possible. As a result, the pattern may spread due to optical diffraction, or the pattern may deteriorate due to the superposition of optical interference fringes.

[0020] (Photosensitive resist layer) In the embodiment of the present invention, both known positive-type and negative-type resists can be used for the photosensitive resist layer, which can be formed on a water-soluble resin coating layer. Among these, resists suitable for exposure wavelengths of 248 nm to 436 nm (248 nm: KrF excimer laser, 365 nm: i-line, 436 nm: g-line) are preferred. As a result of development, when a positive-type resist is used, the exposed areas are removed, and the unexposed areas remain on the substrate. When a negative-type resist is used, the unexposed areas are removed, and the exposed areas remain on the substrate. In either case, the photosensitive resist layer forms a pattern based on the latent image pattern that is exposed, reflecting the fine pattern of the photomask. The thickness of the photosensitive resist layer should preferably be sufficient to withstand etching and deposition processes that follow patterning on the substrate. For example, when performing deposition with a width of 1 μm and a height of 2 μm, the thickness of the photosensitive resist film should preferably be 2 μm or more.

[0021] (frame) In this invention, in order to facilitate the peeling of the layers beyond the water-soluble resin coating layer from the interface between the photomask and the water-soluble resin coating layer, a frame can be provided as a reinforcing frame on the photosensitive resist layer surface in the peripheral portion of the photomask corresponding to the region outside the outer edge of the pattern formation area of ​​the patterned substrate. This improves the rigidity of the photosensitive resist layer, making it easier to peel the photomask from the interface with the water-soluble resin coating layer without the use of solvents. Furthermore, it is possible to provide a certain degree of rigidity to the laminate consisting of the peeled water-soluble resin coating layer and the photosensitive resist layer after exposure. The frame can be provided on the periphery of the surface of the photosensitive resist layer, and may be provided along the entire periphery, or it may be provided independently at multiple locations on the periphery. The frame is provided on the periphery and not in the center in order to press the surface of the photomask against the surface of the patterning substrate (the article to which the pattern is to be transferred). Furthermore, if the surface of the patterning substrate is a convex or curved surface, pressure may be applied to the photosensitive resist surface of the pattern transfer laminate. Even in such cases, the frame can be used to maintain the shape of the pattern transfer laminate while performing pattern transfer. The frame thickness is preferably 0.050 mm or more, more preferably 0.080 mm or more, even more preferably 0.100 mm or more, and most preferably 0.140 mm or more. It is also preferably 1.000 mm or less, more preferably 0.500 mm or less, and even more preferably 0.300 mm or less. An example is the Riva Alpha manufactured by Nitto Denko Corporation. The frame may be a thick film sheet with an adhesive layer on one side, and may be peelable or non-peelable from the photosensitive resist layer. An adhesive sheet used during wafer processing is preferred.

[0022] (Patterning base material) The patterning substrate is the object to be processed using the pattern transfer laminate of the present invention. The patterning substrate is a patterning substrate with a smooth or three-dimensional surface. This three-dimensional patterning substrate is not a substrate with a smooth and durable surface like a semiconductor wafer or a flat glass plate for a display, but rather a substrate with recesses, protrusions, or unevenness formed in the area where the pattern is formed, a substrate with surface roughness, or a soft sheet. Furthermore, substrates with such surface areas that can be used for various applications, such as printed circuit boards, resin and metal substrates, can be used, and various materials such as metals, nonmetals and resins can be used. Processing of the patterning substrate using the pattern transfer laminate of the present invention can be for known purposes such as forming patterns and circuits, etching, etc. In particular, patterning substrates that aim to obtain patterns with a width of 2.0 μm or less, such as curved molds with fine textures (anti-reflective structures for infrared lenses, etc.), rolling rolls with fine patterns, three-dimensional wiring provided on curved surfaces and walls, microcoil electrical circuit components and magnetic sensors, and separators in the internal structure of batteries, can be used as processing targets. Furthermore, patterning substrates with patterns of 2.0 μm or less in width, even on a flat surface, can also be processed. Furthermore, the application, material, shape, relative size, arrangement, film formation method, process conditions in the fine pattern transfer method, and additional pre- and post-treatments of the patterning substrate are not limited. Therefore, the pattern transfer laminate of the present invention includes not only patterning substrates with smooth and durable surfaces, but also those for transferring patterns to patterning substrates with three-dimensional or soft surface shapes. Furthermore, it is preferable to expose the photosensitive resist layer of the pattern transfer laminate of the present invention before adhering the pattern transfer laminate to the patterning substrate to be processed. However, since a step is required to remove the water-soluble resin coating layer with water, the patterning substrate must be insoluble in water.

[0023] (Structure of a laminate for pattern transfer and its manufacturing method) As shown in Figure 1, the pattern transfer laminate 1 of the present invention is based on a laminate formed by sequentially stacking a photomask 4, a water-soluble resin coating layer 3, and a photosensitive resist layer 2. Its specific structure, manufacturing method, and usage examples are shown below. Although not shown in the figures, a peelable protective layer may be provided on the surface of the photosensitive resist layer 2 to prevent contamination of the photosensitive resist layer 2 surface during storage of the pattern transfer laminate and immediately before adhesion to the patterning substrate after exposure.

[0024] As shown in Figure 1, the pattern transfer laminate 1 of the present invention is obtained by fixing a photomask 4 to the upper surface of a spin deposition head 5 and rotating it, first supplying a water-soluble resin solution to the surface on which the mask pattern 4A is located on the photomask 4 and spin coating it, drying this layer to form a water-soluble resin coating layer 3, and then spin coating a photosensitive resist layer 2 on top of that to sequentially form the films.

[0025] (a) A step of applying a water-soluble resin coating layer 3 to one side of the photomask. The application process for the water-soluble resin solution to obtain a water-soluble resin coating layer 3 on one side of the photomask can be any method that can reliably form a uniform water-soluble resin coating layer 3. In addition to the spin coating method described above, any other method such as spray coating or slit coating can be used.

[0026] (b) A step of drying the obtained water-soluble resin solution layer to obtain a water-soluble resin coating layer 3. The drying method for the resulting water-soluble resin solution layer is not particularly limited. It may be dried by heating using any heating method, or if the water-soluble resin solution layer is sufficiently thin, it may be dried by natural drying. The resulting water-soluble resin coating layer 3 adheres completely to the photomask 4 in all areas. If a method were employed in which a pre-prepared film made of water-soluble resin is coated onto the photomask, considerable skill would be required to ensure complete adhesion between the two, and even with such skill, it would be extremely difficult.

[0027] (c) Step of forming a photosensitive resist layer 2 on a water-soluble resin coating layer 3. A liquid photosensitive resist solution can be applied to the water-soluble resin coating layer using the same means as those used to form the water-soluble resin coating layer 3. In any case, any means that can reliably form a uniform photosensitive resist layer 2 is acceptable. Furthermore, the photosensitive resist layer 2 immediately after formation may be dried by heating using any heating means as needed, or it may be dried by natural drying, taking into consideration the thickness of the photosensitive resist layer 2.

[0028] Figure 2 is a cross-sectional view of a pattern transfer laminate, which is formed by depositing a photosensitive resist layer 2 on a water-soluble resin coating layer 3 formed on a photomask 4. (d) A step of exposing the photosensitive resist layer by irradiating it with light from the photomask side. By irradiating the photosensitive resist layer 2 with ultraviolet light 6 or the like from the side of the photomask 4 that does not have the mask pattern 4A (the top in Figure 2) in advance, a pattern transfer laminate 1A is obtained having a photosensitive resist 2A that has been exposed to ultraviolet light, which is the latent image pattern. This photosensitive resist 2A that has been irradiated with ultraviolet light is a photosensitive resist that has been changed by irradiation with ultraviolet light, while 2B is a photosensitive resist that has not been irradiated as a result of being blocked by the photomask and remains in its original state.

[0029] (e) Step of peeling off the laminate consisting of a water-soluble resin coating layer 3 and a photosensitive resist layer 2 from the photomask. Figure 3 shows the process of peeling the pattern transfer laminate 1A at the interface between the photomask 4 and the water-soluble resin coating layer 3, separating the photomask 4 from the water-soluble resin coating layer 3 and the photosensitive resist layer 2. Note that the step of peeling the laminate consisting of the water-soluble resin coating layer 3 and the photosensitive resist layer 2 from the photomask also includes the step of peeling the photomask from the laminate consisting of the water-soluble resin coating layer 3 and the photosensitive resist layer 2. In the process of peeling a laminate consisting of a water-soluble resin coating layer 3 and a photosensitive resist layer 2 from a photomask, a small peeling area is formed at the edge of the water-soluble resin coating layer 3 that is in close contact with the photomask as a starting point for peeling. This area is then grasped with a jig or the like, and the peeling area is gradually expanded to cover the entire water-soluble resin coating layer 3, thereby peeling the entire photomask 4 from the water-soluble resin coating layer 3. As a result, a laminate consisting of the water-soluble resin coating layer 3 and the photosensitive resist layer 2 is obtained from the photomask. Alternatively, when forming the water-soluble resin coating layer 3 on the photomask 4, a small piece (paper piece, resin film piece, fiber piece, etc.) with stronger adhesion to either the photomask 4 or the water-soluble resin coating layer 3 may be placed between the photomask 4 and the water-soluble resin coating layer 3, with the edge of the small piece protruding from the edge of the water-soluble resin coating layer 3. When peeling the laminate consisting of a water-soluble resin coating layer 3 and a photosensitive resist layer 2 from the photomask, the photomask 4 and the water-soluble resin coating layer 3 can be separated by pinching the edges of the small pieces with a jig or fingertips. Alternatively, an adhesive tape made of polyimide or the like can be attached to the edge surface of the photomask 4 (the side on which the water-soluble resin coating layer 3 is not formed), and the end of this tape can be pinched with the fingertips and pulled in the direction of peeling off the photomask, thereby slightly peeling off the edges of the interface between the photomask 4 and the water-soluble resin coating layer 3, creating a starting point for further peeling. Then, the starting point at the edge can be grasped with tweezers and the photomask 4 can be peeled off from the layers after the water-soluble resin coating layer 3. Furthermore, known release agents such as organic solvents can be used, as long as they do not affect the water-soluble resin coating layer 3 and the photosensitive resist layer 2.

[0030] Figure 4 shows the photomask 4 and the pattern transfer laminate 1B, to which a frame 7 has been attached in advance as a reinforcing frame to facilitate the peeling of the layers from the water-soluble resin coating layer 3 onwards. Figure 5 shows the state with the photomask 4 installed, viewed from the frame 7 side. Since the peripheral portion of the photomask 4 can be designed to extend beyond the substrate to be patterned, the frame 7 can be provided in this peripheral portion as a reinforcing frame. As a result, for example, during use, by gripping the frame 7 and applying force to separate the photomask 4 from the water-soluble resin coating layer 3, the laminate consisting of the water-soluble resin coating layer 3 and the photosensitive resist layer 2 can be peeled off more smoothly than when the frame 7 is not present.

[0031] Figure 6 shows the peeling of the layers from the water-soluble resin coating layer 3 onwards from the interface between the photomask 4 and the water-soluble resin coating layer 3 of a pattern transfer laminate 1B to which a frame 7 has been attached as a reinforcing frame. By providing the frame 7, the water-soluble resin coating layer 3 and the photosensitive resist layer 2 are reinforced and act as a starting point for peeling, making a solvent-free process possible without the use of release agents. By providing such a frame 7, the rigidity of the entire laminate consisting of the water-soluble resin coating layer 3 and the photosensitive resist layer 2 can be increased. As a result, this peeling process can proceed smoothly, and the handling of the laminate consisting of the water-soluble resin coating layer 3 and the photosensitive resist layer 2 afterwards can be made easier. The frame shape is not limited to that shown in Figure 5; the inner circumference does not have to be circular, and the outer shape does not have to be square. Furthermore, the frame thickness in Figure 6 is arbitrary, and it only needs to be thick enough to reinforce the water-soluble resin coating layer 3 and the photosensitive resist layer 2 and to provide a starting point for peeling.

[0032] (f) A step of adhering the laminate, which consists of the peeled water-soluble resin coating layer 3 and the photosensitive resist layer 2, to the surface of the patterned substrate so that the photosensitive resist layer 2 is in contact with it. Figure 7 shows the water-soluble resin coating layer 3 and photosensitive resist layer 2, peeled from the photomask 4 of the pattern transfer laminates 1A and 1B, being brought into close contact with the patterning planar substrate 8 and patterning three-dimensional substrate 9 from the photosensitive resist layer 2 side, and being attached by heating as needed. Subsequently, the water-soluble resin coating layer 3 is removed by washing with water because it dissolves in water, and can be removed by washing with water without affecting the photosensitive resist layer 2. Furthermore, by developing, the fine pattern of the photosensitive resist layer 2 can be transferred onto the patterning planar substrate 8 and patterning three-dimensional substrate 9.

[0033] (g) A step to remove the water-soluble resin coating layer 3 located on the surface by washing with water, and develop the surface of the patterning substrate if necessary. In step (f) above, the water-soluble resin coating layer 3, which is provided on the surface of the patterning substrate via the photosensitive resist layer 2, is removed by washing with water. As for the washing method, any means can be employed, such as spraying an aqueous liquid onto the water-soluble resin coating layer 3 to dissolve and remove the water-soluble resin, or immersing the patterning substrate together with the aqueous liquid to dissolve the water-soluble resin. In this way, the photosensitive resist layer can be transferred onto the substrate.

[0034] After step (g) above, development is performed under any conditions suitable for the photosensitive resist layer 2. Subsequently, known processes such as vapor deposition, plating deposition, ion implantation, and etching can be performed to obtain the desired pattern. [Examples]

[0035] The present invention will be described in more detail below with reference to examples. Note that the examples represent only one embodiment of the present invention, and the present invention is not limited thereto. (Photomask) The photomask used was a binary mask designed with five line-and-space patterns arranged around the circumference. The patterns gradually became finer from the center to the periphery, with pattern widths of 11.5 μm, 6.6 μm, 3.7 μm, 2.1 μm, and 1.1 μm.

[0036] (Water-soluble resin aqueous solution) J-POVA manufactured by Nippon Vivipar Co., Ltd. (JP-15: degree of saponification 90 mol%, degree of polymerization 1500 (for PVA1), JP-10: degree of saponification 90 mol%, degree of polymerization 1000 (for PVA2), JP-05: degree of saponification 89 mol%, degree of polymerization 600 (for PVA3, 7 and 8), JR-05: degree of saponification 70 mol%, degree of polymerization 600 (for PVA4 and 9), JP-03: degree of saponification 90 mol%, degree of polymerization Using 300 (for PVA5), JP-24 (saponification degree 90 mol%, polymerization degree 2400 for PVA6), aqueous solutions of PVA1 to PVA9 with the compositions shown in Table 1 were prepared. The amount of plasticizer added to PVA1 to PVA8 was 5 parts by weight per 100 parts by weight of the aqueous resin. The viscosity in Table 1 was measured using a B-type viscometer (TVB-10, manufactured by Toki Sangyo Co., Ltd.) at 25°C and a shear rate of 1.7 s⁻¹.

[0037] [Table 1]

[0038] (Photosensitive resist) For the photosensitive resist, we used a novolac resin-based positive resist (AZ1500, Clariant).

[0039] (Patterning base material) Patterning base material 1 was made of SKD11 die steel with an outer diameter of 21.4 mm. Its surface was polished with #10000 grit sandpaper. Patterning substrate 2 uses a plano-convex lens as a three-dimensional substrate, with an outer diameter of 25 mm, a radius of curvature of 130 mm, and a height difference of 0.6 mm on the curved surface.

[0040] (Preparation of laminate for pattern transfer) A photomask was fixed to the film deposition head of a spin coater, and a water-soluble resin aqueous solution described in Table 1 was dropped onto the photomask. The spin head was then rotated and dried to obtain a water-soluble resin coating layer. The thickness of the water-soluble resin coating layer was adjusted by the rotation speed of the spin head during coating. Drying was performed at 80°C. Subsequently, a positive-type resist was dropped onto the water-soluble resin coating layer as a photosensitive resist, the spin head was rotated, and the layer was baked to obtain the pattern transfer laminates of Examples 1-4 and 6 described in Table 2. The thickness of the photosensitive resist layer was adjusted by the rotation speed of the spin head. Furthermore, in Examples 5 and 7 of Table 2, a 175 μm thick frame (thick film frame (Riva Alpha, Nitto Denko Corporation)) was fixed as a reinforcing frame outside the outer diameter of the patterned substrate. The thickness of the water-soluble resin coating layer and the photosensitive resist layer was measured using a step meter and an ellipsometer (wavelength 632.8 nm). (exposure) Using a mask aligner, the pattern transfer laminates of Examples 1-7 were exposed from the photomask side (mercury lamp, wavelength 365 nm) to obtain latent image patterns in the photosensitive resist layer.

[0041] [Table 2]

[0042] (Examples and Comparative Examples) (Preparation of laminate for pattern transfer) As examples and comparative examples, laminates for pattern transfer shown in Table 3 were obtained. Examples 8 and 9 are variations of Example 1 in which the thickness of the water-soluble resin coating layer was changed. Example 10 used the same laminate for pattern transfer as Example 8, but as shown in Table 5 below, it is an example of forming only fine patterns, and it shows that there are pattern widths that cannot be accommodated depending on the thickness of the water-soluble resin coating layer. Comparative Example 1 did not have a water-soluble resin coating layer, and Comparative Examples 2 and 3 were variations of Example 3 in which the degree of polymerization of the water-soluble resin coating layer was changed. Comparative Examples 4 and 5 were variations of Example 3 in which the type of plasticizer in the water-soluble resin coating layer was changed, and Comparative Example 6 was a water-soluble resin coating layer that did not contain a plasticizer. The thickness of the water-soluble resin coating layer was adjusted by the rotation speed of the spin head when applying the water-soluble resin aqueous solution, and drying was carried out at 80°C. After that, a positive-type resist was dropped onto the water-soluble resin coating layer as a photosensitive resist, the spin head was rotated, and it was baked to obtain the laminates for pattern transfer of Comparative Examples 1 to 6. (exposure) Using a mask aligner, exposure (mercury lamp, wavelength 365 nm) was performed from the photomask side of the pattern transfer laminates of Comparative Examples 1 to 6 to obtain latent image patterns in the photosensitive resist layer.

[0043] [Table 3]

[0044] In Comparative Example 7, PVA1 from Table 1 was applied to a polyester film using a bar coater and dried at 80°C to form a 2.0 μm thick water-soluble resin layer. A positive-type photosensitive resist was then applied to this water-soluble resin layer using a spin coater and dried to obtain a 1.5 μm thick photosensitive resist layer. Subsequently, the polyester film was peeled off, and the photomask and the surface of the water-soluble resin layer were aligned and bonded together by applying heat and pressure from the photosensitive resist side. In this case, the water-soluble resin layer is not the water-soluble resin coating layer as defined in the present invention. Next, exposure (mercury lamp, wavelength 365 nm) was performed in the same manner as in Example 1 to obtain a latent image pattern on the photosensitive resist layer.

[0045] In Comparative Example 8, a positive-type photosensitive resist was directly spun-deposited onto the patterning substrate 2 without providing a water-soluble resin coating layer or a photosensitive resist layer. Subsequently, a photomask was placed close to the resist side, and exposure (mercury lamp, wavelength 365 nm) was performed using a mask aligner to obtain a latent image pattern on the photosensitive resist layer.

[0046] (Tensile modulus of water-soluble resin coating layer) The aqueous water-soluble resin solutions shown in Table 1 were coated onto a release-treated polyester film by bar coating and dried. After humidification under conditions of 23°C and 50%RH, the water-soluble resin coating layer was peeled off, and the tensile modulus was measured using a tensile testing machine in accordance with JIS K 7161-1:2014.

[0047] (Pattern transfer) <Peeling from photomask> For Examples 1-4, 6, 8 and Comparative Examples 1-6, in which a latent image pattern was obtained after exposure, polyimide adhesive tape was attached to the edge surface of the photomask. By pinching this tape with fingertips and pulling it in the direction of peeling off the photomask, a starting point for peeling was created at the edge of the interface between the photomask and the water-soluble resin coating layer. Then, the starting point at the edge was grasped with tweezers and the photomask was peeled away from the layers after the water-soluble resin coating layer to check whether it affected the photosensitive resist layer, etc. For Examples 5, 7, 9, and 10, the thick film frame was grasped with tweezers and peeled away from the interface between the photomask and the water-soluble resin coating layer. ○: Can be peeled off from the photomask without adversely affecting the resist layer, etc. ×: Cannot be peeled off from the photomask without adversely affecting the resist layer, etc.

[0048] <Transfer to patterning substrate 1> For Examples 1-5, 8 and 9, and Comparative Examples 1-6, the layers from the water-soluble resin coating layer onwards, peeled from the photomask, were vacuum-bonded to the patterning substrate 1, which was the substrate, from the photosensitive resist layer side. After that, the aqueous resin coating layer was removed by washing with water, and then the substrate was immersed in a developer solution to develop the latent image pattern. In Examples 5 and 9, the frames were removed simultaneously during the water washing process of the water-soluble resin coating layer. In Comparative Example 7, after exposure, the water-soluble resin layer was removed by washing with water, and then the substrate was immersed in a developer solution to develop the latent image pattern. ○: No pattern defects ×: Pattern defects such as blurring.

[0049] <Transfer to patterning substrate 2> In Examples 6, 7, and 10, the layers from the water-soluble resin coating layer onwards, after being peeled from the photomask, were vacuum-bonded to the patterning substrate 2 from the photosensitive resist layer side. Afterward, the aqueous polymer layer was removed by washing with water, and then the latent image pattern was developed by immersion in a developer solution. In Examples 7 and 10, the frames were removed simultaneously during the water washing step of the water-soluble resin coating layer. In Comparative Example 8, the latent image pattern was developed by immersion in a developer solution after exposure. ○: No pattern defects ×: Pattern defects such as blurring.

[0050] [Table 4]

[0051] [Table 5]

[0052] According to Table 4, Examples 1-5 yielded good transfer results at all pattern widths. Figure 8 is an example of a scanning electron microscope image of a resist pattern transferred to a patterning substrate. There are five types of patterns that become progressively finer from the center to the outer edge. Figure 9 is a magnified view of the outermost pattern of Figure 8 with a width of 1.1 μm. In this embodiment, with a refractive index of 1.50 and an i-line exposure wavelength of 365 nm, the thicknesses calculated by Equation 1 for pattern widths of 1.1 μm, 2.1 μm, 3.7 μm, 6.6 μm, and 11.5 μm were 2.5 μm, 9.1 μm, 28.1 μm, 89.5 μm, and 271.7 μm, respectively. Since the thicknesses of the water-soluble resin coating layers in Examples 1 to 5 in Table 2 were less than or equal to the thickness for a pattern width of 1.1 μm, it was possible to transfer a pattern width of 1.1 μm without pattern blurring or other issues.

[0053] The comparative examples below are cases where the water-soluble resin coating layer could not be applied uniformly, or where it was difficult to peel the photomask and the water-soluble resin coating layer at their interface. Uniform application can be improved by adjusting the concentration of the water-soluble resin aqueous solution, and peelability can be improved by adjusting the additives in the water-soluble resin aqueous solution. These comparative examples are shown as examples that do not satisfy the condition in the present invention that the photomask and the water-soluble resin coating layer can be peeled off at their interface. In Comparative Example 1, since no water-soluble resin coating layer was provided, the photosensitive resist layer could not be peeled off, making transfer impossible. In Example 8, good pattern transfer was possible when the pattern width was 2.1 μm or more, but good pattern transfer was not obtained when the thickness of the water-soluble resin coating layer did not satisfy Equation 1, resulting in a pattern width of 1.1 μm. Similarly, in Example 9, good pattern transfer was possible when the pattern width was 3.7 μm or more, but good pattern transfer was not obtained when the thickness of the water-soluble resin coating layer did not satisfy Equation 1, resulting in a pattern width of 2.1 μm or less. Based on the above results, to obtain an even finer and better pattern transfer, it is preferable that the thickness of the water-soluble resin coating layer be less than or equal to the thickness obtained from Equation 1. In Comparative Example 2, the degree of polymerization of the polyvinyl alcohol used as the water-soluble resin coating layer was low, resulting in weak strength of the water-soluble resin coating layer. When peeling from the initiation point at the edge of the photomask, the water-soluble resin coating layer ruptured, and the photosensitive resist layer was damaged as a result. In other words, it could not be formed in a peelable state. In Comparative Example 3, the viscosity of the water-soluble resin aqueous solution was high, making it impossible to create a uniform water-soluble resin coating layer on the photomask by spin coating. As a result, the thickness of the subsequent photosensitive resist layer was also uneven, which interfered with the pattern shape. In Comparative Examples 4 and 5, the elastic modulus of the water-soluble resin coating layer was low, causing the film to stretch when peeled from the edge of the photomask, resulting in damage to the photosensitive resist layer. In other words, it was not possible to form a peelable structure. In Comparative Example 6, peeling from the edge of the photomask was difficult, and the photosensitive resist layer was damaged. In other words, it could not be formed in a peelable state. In Comparative Example 7, since no water-soluble resin coating layer was provided on the photomask, when the photomask was brought into close contact with the water-soluble resin layer during exposure, light diffraction occurred between the photomask and the water-soluble resin layer. As a result, although the thickness of the water-soluble resin layer satisfied Equation 1 at pattern widths of 6.6 μm, 3.7 μm, 2.1 μm, and 1.1 μm, a good pattern could not be obtained.

[0054] According to Table 5, in both Examples 6 and 7, the thickness of the water-soluble resin coating layer in Table 2 was less than or equal to the thickness given by Equation 1 for pattern widths of 2.1 μm and 1.1 μm, respectively, and good pattern transfer was obtained for three-dimensional patterning substrates. In Example 10, good pattern transfer was obtained for a pattern width of 2.1 μm where the thickness of the water-soluble resin coating layer satisfied Equation 1, but good pattern transfer was not obtained for a pattern width of 1.1 μm where Equation 1 was not satisfied. From these results, it is preferable that the thickness of the water-soluble resin coating layer be less than or equal to the thickness given by Equation 1 in order to obtain even finer and better pattern transfer for three-dimensional patterning substrates. Comparative Example 8 involved directly coating a patterning substrate with a photosensitive resist and exposing it through a photomask 4. Due to the curved surface of the patterning substrate, there was a height difference of 0.6 mm, and uniform exposure could not be achieved due to light diffraction occurring in this gap, resulting in an unsatisfactory pattern. In all examples, when a frame was provided on the photosensitive resist layer, handling during photomask removal and adhesion of the resist layer to the patterning substrate was improved compared to when the frame was not provided. [Industrial applicability]

[0055] The pattern transfer laminate of the present invention can transfer fine patterns not only to highly smooth substrates such as silicon wafers, but also to substrates with relatively rough surfaces such as steel, and can also transfer fine patterns to three-dimensional substrates. When biomimetic patterns are designed as the fine patterns, it is possible to impart biological functions to the surface. Microfabrication of three-dimensional substrates using photolithography technology is required for applications such as MEMS devices like sensors, actuators, and microchannels that require three-dimensional shapes for their function; optical device systems where elements need to be arranged in a way that is compatible with optical waveguides; miniature integrated systems such as 3D LSIs realized by stacking multiple existing planar devices such as LSIs and image sensors; and components with localized flat and curved surfaces in precision mechanical parts that cannot be handled in the same way as wafers, as well as molds used in their manufacture. The more processing technology that can meet these needs while maintaining the simultaneous multi-point processing characteristics of photolithography, the more productive the technology will be and the greater its potential for industrial use. [Explanation of Symbols]

[0056] 1: Laminate for pattern transfer 1A: Laminate for pattern transfer having a latent image pattern 1B: Laminate for pattern transfer with frame 2: Photosensitive resist layer 2A: Photosensitive resist irradiated with ultraviolet light 2B: Photosensitive resist in its original state after being shielded from ultraviolet light. 3: Water-soluble resin coating layer 4: Photomask 5: Head for spin deposition 6: Ultraviolet rays 7: Frame 8: Flat substrate for patterning 9: Three-dimensional base material for patterning (curved surface)

Claims

1. A pattern transfer laminate for transferring a pattern to a patterning substrate, comprising a photomask, a water-soluble resin coating layer, and a photosensitive resist layer laminated in this order, wherein the photomask and the water-soluble resin coating layer are peelable at their interface, and the pattern transfer laminate for exposing the photosensitive resist layer before being brought into close contact with the patterning substrate to be processed.

2. The laminate for pattern transfer according to claim 1, wherein the water-soluble resin coating layer is a layer formed by coating a water-soluble resin solution onto a photomask.

3. The pattern transfer laminate according to claim 1 or 2, wherein the photosensitive resist layer has a latent image pattern exposed in accordance with the fine pattern of the photomask.

4. The laminate for pattern transfer according to claim 3, wherein the width of the latent image pattern is 2 μm or less.

5. A laminate for pattern transfer according to any one of claims 1 to 4, wherein the thickness of the water-soluble resin coating layer is less than or equal to the thickness determined by the following formula 1. Formula 1: Thickness = [0.50 × (pattern width)] ２ × (Refractive index of water-soluble resin coating layer) / (Exposure wavelength)

6. The laminate for pattern transfer according to any one of claims 1 to 5, wherein the water-soluble resin coating layer is polyvinyl alcohol.

7. A pattern transfer laminate according to any one of claims 1 to 6, wherein a frame is fixed to the photosensitive resist layer surface of the pattern transfer laminate, and the photomask and the water-soluble resin coating layer are peelable at their interface.

8. A pattern transfer laminate according to any one of claims 1 to 7, wherein the photomask has a layer on the side of the photomask facing the water-soluble resin coating layer that promotes peeling of the interface between the photomask and the water-soluble resin coating layer.

9. A method for transferring a photosensitive resist layer onto a substrate, comprising the following steps (a) to (g). (a) A step of applying a water-soluble resin solution to one side of the photomask, (b) A step of drying the obtained water-soluble resin solution layer to obtain a water-soluble resin coating layer, (c) A step of forming a photosensitive resist layer on a water-soluble resin coating layer, (d) A step of exposing the photosensitive resist layer by irradiating it with light from the photomask side. (e) A step of peeling off a laminate consisting of a water-soluble resin coating layer and a photosensitive resist layer from a photomask. (f) A step of adhering a laminate consisting of a peeled water-soluble resin coating layer and a photosensitive resist layer to the surface of a patterned substrate such that the photosensitive resist layer is in contact with the surface of the patterned substrate. (g) A process of washing away the water-soluble resin coating layer located on the surface with water, and developing and / or drying the surface of the patterned substrate if necessary.

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