JP4073343B2 - Light-transmitting nanostamp method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nanoprint transfer method in which a fine structure is formed on a substrate using a light transmissive stamper having a pressurizing mechanism.
[0002]
[Prior art]
2. Description of the Related Art In recent years, semiconductor integrated circuits have been miniaturized and integrated, and photolithography equipment has been improved in accuracy as a pattern transfer technique for realizing fine processing. However, the processing method has approached the wavelength of the light source for light exposure, and the lithography technology has also approached its limit. Therefore, in order to advance further miniaturization and higher accuracy, an electron beam drawing apparatus, which is a kind of charged particle beam apparatus, has been used in place of lithography technology.
[0003]
Unlike the batch exposure method in pattern formation using a light source such as i-line or excimer laser, pattern formation using an electron beam takes a method of drawing a mask pattern. The exposure (drawing) takes time and the pattern formation takes time. For this reason, as the degree of integration increases dramatically, such as 256 mega, 1 giga, and 4 giga, the pattern formation time is also greatly increased, and there is a concern that the throughput is significantly inferior. Therefore, in order to increase the speed of the electron beam drawing apparatus, development of a collective figure irradiation method in which various shapes of masks are combined and irradiated with an electron beam collectively to form an electron beam with a complicated shape is underway. . As a result, while miniaturization of the pattern is promoted, the electron beam lithography apparatus must be enlarged and a mechanism for controlling the mask position with higher accuracy is required. was there.
[0004]
On the other hand, techniques for performing fine pattern formation at low cost are disclosed in Patent Documents 1 and 2 and Non-Patent Document 1 described below. This is a technique for transferring a predetermined pattern by embossing a stamper having a concavo-convex pattern identical to the pattern to be formed on the substrate against the resist film layer formed on the surface of the substrate to be transferred. According to the nanoimprint technique described in Document 2 and Non-Patent Document 1, a silicon wafer is used as a stamper, and a fine structure of 25 nanometers or less can be formed by transfer.
[0005]
In Patent Document 3 below, a step of forming a photocurable material layer made of a liquid photocurable material on a substrate and a groove having a predetermined pattern on one surface side made of a light transmissive material are disclosed. A step of pressure-bonding the formed mold to the substrate, and a step of forming a resist pattern having a pattern that fits the groove pattern by irradiating light from the other surface side of the mold to cure the photocurable material layer And a method of forming a pattern by a step of removing the mold from the substrate.
[0006]
[Patent Document 1]
US Pat. No. 5,259,926 [Patent Document 2]
US Pat. No. 5,772,905 [Patent Document 3]
JP 2000-194142 A [Non-Patent Document 1]
SYChou et al., Appl. Phys. Lett., Vol. 67, p. 3314 (1995)
[0007]
[Problems to be solved by the invention]
In Patent Document 3, a negative resist is used, which is not suitable for forming a fine pattern with a high aspect ratio.
In view of the above technical problems, an object of the present invention is to form a fine pattern with a high aspect ratio by using a combination of a nanoprint method using a light transmissive stamper and a positive resist.
[0008]
[Means for Solving the Problems]
The present inventor has found that the above problem can be solved by using a positive resist as the resist, and has reached the present invention.
That is, the present invention is an invention of a light transmissive nanostamp method, in order to form a fine structure on a substrate, pressurize the substrate and a stamper having fine irregularities formed on the surface, and irradiate light from the stamper back surface. In the light transmissive nanostamp method, a step of forming a positive resist layer on the substrate, a step of pressurizing the light transmissive stamper on the positive resist layer on the substrate and deforming the resist layer, and light from the back surface of the light transmissive stamper It includes a step of irradiating and a step of developing a resist.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
First, a nanoprinting method using a light transmissive stamper will be described with reference to FIG. A stamper having a minute pattern on the surface of a quartz substrate or the like is manufactured. A positive photosensitive resin film is provided on another substrate (FIG. 1A). A stamper having a pressure mechanism (not shown) is used to press the stamper onto the positive photosensitive resin film with a predetermined pressure (FIG. (B)). After pressing, light is irradiated from above the light-transmitting stamper to react only the exposed part (FIG. (C)). The stamper and the substrate are peeled off, and the fine pattern of the stamper is transferred to the resin film on the substrate (FIG. (D)). The substrate is developed to form a resist film having a high aspect ratio (FIG. (E)).
[0010]
According to the nano-printing method, (1) the integrated ultra-fine pattern can be efficiently transferred, (2) the device cost is easy, (3) the complex shape can be handled, and the pillar can be formed, etc. There are features.
The fields of application of the nanoprinting method are as follows: (1) Various biodevices such as DNA chips and immunoassay chips, especially disposable DNA chips, (2) Semiconductor multilayer wiring, (3) Printed circuit boards and RF MEMS, (4) Optical or magnetic storage, (5) optical devices such as waveguides, diffraction gratings, microlenses, polarizing elements, photonic crystals, (6) sheets, (7) LCD displays, (8) FED displays, etc. The present invention is preferably applied to these fields.
[0011]
In the present invention, nanoprint refers to transfer in the range of several hundred μm to several nm.
In the present invention, it is preferable that the press apparatus has a pressurizing mechanism and has a mechanism capable of irradiating light from above the light transmissive stamper in order to efficiently perform pattern transfer.
[0012]
In the present invention, the stamper has a fine pattern to be transferred, and the method for forming the pattern on the stamper is not particularly limited. For example, it is selected according to desired processing accuracy such as photolithography or electron beam drawing. The stamper may be made of any material such as quartz, glass, ceramic, plastic, etc., as long as it is transparent and has strength and required workability.
[0013]
In the present invention, the material for the substrate is not particularly limited, but any material having a predetermined strength may be used. Specifically, silicon, various metal materials, glass, ceramic, plastic and the like are preferably exemplified.
[0014]
In the present invention, the positive photosensitive resin is not particularly limited, but is selected according to the desired processing accuracy. Specifically, OFPR800 (manufactured by Tokyo Ohka), AZ3100 (manufactured by Clariant), AZ6112 (manufactured by Clariant), MEGAPOSIT SPR 6800 (manufactured by Shipley) and the like can be used.
[0015]
【Example】
Examples of the present invention will be described below.
[Example 1: Production of stamper]
A stamper used in the light transmission nanostamp method, which is one embodiment of the present invention, will be described with reference to FIGS. FIG. 2 is a conceptual diagram, and it should be noted that the pattern shape is simplified and overwritten.
[0016]
First, a quartz substrate 1 having a thickness of 5 inches and a thickness of 0.5 mm was prepared as shown in FIG. Next, as shown in FIG. 2B, a photoresist 2 for electron beam exposure (OEBR1000, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to a thickness of 100 nm using a spin coater. Subsequently, using an electron beam drawing apparatus JBX6000FS (manufactured by JEOL) as shown in FIG. 2C, exposure is performed by direct drawing with an electron beam 3 and development is performed, as shown in FIG. Concavities and convexities in which circular patterns with a diameter of 30 nm were arranged were formed. The quartz substrate 1 was dry-etched with CF ₄ gas using the irregularities of FIG. 2D as a mask pattern to form irregularities with a depth of 100 nm on the quartz substrate 1 as shown in FIG. Further, Cr was sputtered with a thickness of 50 nm as shown in FIG. Thereafter, the resist was developed to remove the resist and Cr formed on the resist. With the above process, the pattern convex portion of FIG. 2G has light transmittance, but the pattern concave portion has a light-transmitting stamper because the Cr film blocks light.
[0017]
[Example 2: Columnar structure formation]
Next, a light transmissive nanostamp method using the pattern convex light transmissive stamper of FIG. 2G will be described with reference to FIG. As the substrate to be transferred, a quartz substrate was used in order to eliminate the difference in thermal expansion from the stamper. As shown in FIG. 3A, a positive resist OFPR800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was spin-coated on a quartz substrate so as to have a thickness of 500 nm. Further, the pressure was reduced to 0.1 Torr or less, and the solvent component in the resist was volatilized by heating to 250 ° C., thereby increasing the viscosity and imparting moldability. Next, as shown in FIG. 3B, a resist was molded by applying pressure at 3 MPa for 10 minutes. Subsequently, exposure was performed with ultraviolet rays as shown in FIG. Since the stamper convex portion transmits light, the resist under it is solubilized. On the other hand, since the light-shielding Cr film was formed in the stamper recess, the resist under the stamper did not change. As shown in FIG. 3D, the stamp and the quartz substrate to be transferred were fixed with a vacuum chuck, and the stamp was lifted upward at 0.1 mm / s for peeling. Then, a columnar structure having a diameter of 30 nm and a height of 200 nm was formed as shown in FIG. When developed with a resist developer NMD3 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), the resist soluble portion could be removed, and a resist columnar structure was obtained. When a negative resist and a partially light-transmitting stamper are used in combination, the resist is cross-linked by light leaking from the light-shielding portion, and therefore cannot be applied to an ultrafine pattern of several tens of nm. In addition, since it is difficult for the negative resist to stop crosslinking with light at a desired viscosity, it is hard to form stamper irregularities as they are, and it is difficult to form a columnar structure having a high aspect. Therefore, it can be said that the light transmissive nanostamp method using the positive resist of the present invention is an effective method for forming a highly accurate and high aspect structure.
[0018]
[Application example of the present invention]
Hereinafter, several fields to which nanoprints using the stamper with a peeling mechanism of the present invention are preferably applied will be described.
[Example 3: Bio (immune) chip]
FIG. 4 is a schematic diagram of the biochip 900. A glass substrate 901 is formed with a flow path 902 having a depth of 3 micrometers and a width of 20 micrometers, and a sample containing DNA (deoxyribonucleic acid), blood, protein, and the like is introduced from the introduction hole 903 to flow. After flowing through the path 902, it is structured to flow into the discharge hole 904. A molecular filter 905 is installed in the flow path 902. On the molecular filter 905, a protrusion assembly 100 having a diameter of 250 to 300 nanometers and a height of 3 micrometers is formed.
[0019]
FIG. 5 is a bird's-eye view of the cross section in the vicinity where the molecular filter 905 is formed. A flow path 902 is formed in the substrate 901, and the projection aggregate 100 is formed in a part of the flow path 902. The substrate 901 is covered with the upper substrate 1001, and the specimen moves inside the flow path 902. For example, in the case of DNA chain length analysis, when a sample containing DNA is electrophoresed in the channel 902, the DNA is separated with high resolution by the molecular filter 905 according to the DNA chain length. The specimen that has passed through the molecular filter 905 is irradiated with laser light from a semiconductor laser 906 mounted on the surface of the substrate 901. When DNA passes through, the incident light to the photodetector 907 decreases by about 4%, so that the chain length of the DNA in the sample can be analyzed by the output signal from the photodetector 907. A signal detected by the photodetector 907 is input to the signal processing chip 909 via the signal wiring 908. A signal wiring 910 is connected to the signal processing chip 909, and the signal wiring 910 is connected to an output pad 911 and connected to an external terminal. The power was supplied to each component from a power pad 912 installed on the surface of the substrate 901.
[0020]
FIG. 6 shows a cross-sectional view of the molecular filter 905. The molecular filter 905 of this embodiment includes a substrate 901 having a recess, a plurality of protrusions formed in the recess of the substrate 901, and an upper substrate 1001 formed so as to cover the recess of the substrate. Here, the tip of the protrusion is formed so as to contact the upper substrate. Since the main component of the protrusion assembly 100 is an organic substance, it can be deformed. Therefore, the protrusion assembly 100 is not damaged when the upper substrate 1001 is placed on the flow path 902. Therefore, the upper substrate 1001 and the protrusion assembly 100 can be brought into close contact with each other. With such a configuration, the specimen does not leak from the gap between the protrusion and the upper substrate 1001, and highly sensitive analysis is possible. As a result of actually performing DNA chain length analysis, the resolution of the base pair in the glass projection assembly 100 was 10 base pairs at half-value width, whereas in the organic projection assembly 100, base pair It was found that the resolution of 3 can be improved to 3 base pairs at half width. In the molecular filter of this embodiment, the protrusion and the upper substrate are in direct contact with each other. For example, if a film of the same material as the protrusion is formed on the upper substrate and the protrusion and the film are in contact with each other, Adhesion can be improved.
In this embodiment, the number of the flow paths 902 is one, but it is also possible to perform different analyzes at the same time by arranging a plurality of flow paths 902 provided with protrusions of different sizes.
[0021]
Further, in this example, DNA was examined as a specimen, but specific sugar chains, proteins, and antigens were analyzed by modifying molecules that react with sugar chains, proteins, and antigens on the surface of the protrusion assembly 100 in advance. Also good. Thus, the sensitivity of the immunoassay can be improved by modifying the antibody on the surface of the protrusion.
[0022]
By applying the present invention to a biochip, an effect of easily forming a projection for analysis made of an organic material having a nano-scale diameter can be obtained. Moreover, the effect which can control the position, diameter, and height of the protrusion made from an organic material by controlling the unevenness of the mold surface and the viscosity of the organic material thin film is also obtained. A highly sensitive microchip for analysis can be provided.
[0023]
[Example 4: Multilayer wiring board]
FIG. 7 is a diagram illustrating a process for manufacturing a multilayer wiring board. First, as shown in FIG. 7A, a resist 702 is formed on the surface of a multilayer wiring board 1001 composed of a silicon oxide film 1002 and a copper wiring 1003, and then pattern transfer is performed by a stamper (not shown). Next, when the exposed region 703 of the multilayer wiring substrate 1001 is dry-etched with CF ₄ / H ₂ gas, the exposed region 703 on the surface of the multilayer wiring substrate 1001 is processed into a groove shape as shown in FIG. 7B. Next, the resist 702 is resist-etched by RIE, and the exposed portion 703 is enlarged and formed as shown in FIG. When dry etching of the exposed region 703 is performed from this state until the depth of the previously formed groove reaches the copper wiring 1003, a structure as shown in FIG. 7D is obtained, and then the resist 702 is removed. As a result, a multilayer wiring substrate 1001 having a groove shape on the surface as shown in FIG. From this state, a metal film is formed on the surface of the multilayer wiring substrate 1001 by sputtering (not shown), and then electroplating is performed to form a metal plating film 1004 as shown in FIG. Thereafter, if the metal plating film 1004 is polished until the silicon oxide film 1002 of the multilayer wiring board 1001 is exposed, a multilayer wiring board 1001 having metal wiring on the surface as shown in FIG. 7G can be obtained.
[0024]
In addition, another process for manufacturing the multilayer wiring board will be described. When performing dry etching of the exposed region 703 from the state shown in FIG. 7A, the structure shown in FIG. 7H is obtained by etching until reaching the copper wiring 1003 inside the multilayer wiring board 1001. . Next, the resist 702 is etched by RIE, and the resist having a low step is removed to obtain the structure shown in FIG. From this state, when a metal film 1005 is formed by sputtering on the surface of the multilayer wiring board 1001, the structure shown in FIG. 7J is obtained. Next, the structure shown in FIG. 7K is obtained by removing the resist 702 by lift-off. Next, by performing electroless plating using the remaining metal film 1005, the multilayer wiring board 1001 having the structure shown in FIG. 7L can be obtained.
By applying the present invention to a multilayer wiring board, wiring with high dimensional accuracy can be formed.
[0025]
[Example 5: Magnetic disk]
FIG. 8 is an overall view and a cross-sectional enlarged view of the magnetic recording medium according to the present embodiment. The substrate is made of glass having fine irregularities. A seed layer, an underlayer, a magnetic layer, and a protective layer are formed on the substrate. Hereinafter, the manufacturing method of the magnetic recording medium according to the present embodiment will be described with reference to the drawings. FIG. 9 shows a method for forming concavities and convexities on the glass by the nanoprint method in a sectional view cut in the radial direction. First, a glass substrate is prepared. In this embodiment, soda lime glass is used. The substrate material is not particularly limited as long as it has flatness, and another glass substrate material such as aluminosilicate glass or a metal substrate such as Al may be used. Then, as shown in FIG. 9A, a positive resist OFPR800 (manufactured by Tokyo Ohka) was formed using a spin coater so as to have a thickness of 200 nm.
[0026]
On the other hand, as a stamper, a quartz stamper is prepared in which grooves are formed so as to be concentric with the hole in the center of the magnetic recording medium. The groove dimensions were 88 nm wide and 200 nm deep, and the distance between the grooves was 110 nm. Since the unevenness of this stamper is very fine, it was formed by photolithography using an electron beam. In addition, a Cr film was formed in the pattern concave portion by the same method as in Example 1 to provide light shielding properties. Next, as shown in FIG. 9B, a resist was molded by applying pressure at 3 MPa for 10 minutes. Subsequently, exposure was performed with ultraviolet rays as shown in FIG. Since the stamper convex portion transmits light, the resist under it is solubilized. Stripping similar to that in Example 1 is performed, and development is performed with a resist developer NMD3 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) to remove the solubilized portion, whereby a resist pattern as shown in FIG. 9D is formed. By using this resist as a mask and further etching the substrate with hydrofluoric acid, the substrate can be processed as shown in FIG. 9E. By removing the resin with a stripping solution, the substrate shown in FIG. A groove having a width of 110 nm and a depth of 150 nm was formed. Thereafter, a seed layer made of NiP is formed on the glass substrate by electroless plating. In a general magnetic disk, the NiP layer is formed with a thickness of 10 μm or more, but in this embodiment, the fine uneven shape formed on the glass substrate is reflected on the upper layer, so that the NiP layer is kept at 100 nm. Further, by using a sputtering method generally used for forming a magnetic recording medium, a Cr underlayer of 15 nm, a CoCrPt magnetic layer of 14 nm, and a C protective layer of 10 nm are sequentially formed, whereby the magnetic recording medium of the present embodiment is formed. Produced. In the magnetic recording medium of the present embodiment, the magnetic material is separated in the radial direction by the nonmagnetic layer wall having a width of 88 nm. As a result, the in-plane magnetic anisotropy could be increased. Note that concentric pattern formation (texturing) using a polishing tape has been conventionally known, but the pattern interval is as large as a micron scale and is difficult to apply to a high-density recording medium. The magnetic recording medium of this example secured a magnetic anisotropy with a fine pattern using a nanoprinting method, and realized high density recording of 400 Gb / square inch. The pattern formation by nanoprinting is not limited to the circumferential direction, and nonmagnetic partition walls can be formed in the radial direction. Further, the magnetic anisotropy imparting effect described in the present embodiment is not particularly limited by the materials of the seed layer, the underlayer, the magnetic layer, and the protective layer.
[0027]
[Example 6: Optical waveguide]
In this embodiment, an example in which the optical device 100 in which the traveling direction of incident light changes is applied to an optical information processing apparatus will be described.
FIG. 10 is a schematic configuration diagram of the manufactured optical circuit 500. An optical circuit 500 is composed of an aluminum nitride substrate 501 having a length of 30 millimeters, a width of 5 millimeters, and a thickness of 1 millimeter, and 10 transmitting units 502, an optical waveguide 503, and an optical waveguide composed of an indium phosphide-based semiconductor laser and a driver circuit. The connector 504 is configured. Note that the emission wavelengths of the ten semiconductor lasers differ by 50 nanometers, and the optical circuit 500 is a basic component of an optical multiplex communication system device.
[0028]
FIG. 11 is a schematic layout diagram of the protrusion 406 inside the optical waveguide 503. The end portion of the optical waveguide 503 has a trumpet shape with a width of 20 micrometers so that an alignment error between the transmission unit 502 and the optical waveguide 503 can be allowed, and the signal light has a width of 1 micrometer due to the photonic band gap. The structure is guided by Note that the protrusions 406 are arranged at intervals of 0.5 micrometers, but in FIG. 21, the protrusions 406 are shown in a simplified manner and less than the actual number.
[0029]
In the optical circuit 500, signal light of 10 different wavelengths can be superimposed and output. However, since the traveling direction of the light can be changed, the horizontal width of the optical circuit 500 can be extremely shortened to 5 millimeters, and the optical communication device is downsized. There is an effect that can be done. In addition, since the protrusion 406 can be formed by pressing the mold, an effect of reducing the manufacturing cost can be obtained. In this embodiment, the input light is superposed, but it is clear that the optical waveguide 503 is useful for all optical devices that control the light path.
[0030]
By applying the present invention to an optical waveguide, it is possible to obtain an effect that the traveling direction of light can be changed by advancing signal light in a structure in which protrusions mainly composed of organic substances are periodically arranged. Moreover, since the protrusion can be formed by a simple manufacturing technique called mold pressing, an effect of manufacturing an optical device at low cost can be obtained.
[0031]
【The invention's effect】
According to the present invention, a novel light-transmitting nanoprint method is provided. Further, by using a combination of a nanoprint method using a light transmissive stamper and a positive resist, it is possible to form a fine pattern with a high aspect ratio.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing each step of nanoprinting.
FIG. 2 is a method for manufacturing a stamper used in a light transmitting nanostamp method.
FIG. 3 shows a light transmissive nanostamp method using a pattern convex light transmissive stamper.
FIG. 4 is a schematic view of a biochip.
FIG. 5 is a cross-sectional bird's-eye view of the vicinity where a molecular filter is formed.
FIG. 6 is a cross-sectional view of a molecular filter.
FIGS. 7A and 7B are diagrams illustrating a process for manufacturing a multilayer wiring board. FIGS.
FIG. 8 is an overall view and a cross-sectional enlarged view of a magnetic recording medium.
FIG. 9 is a cross-sectional view taken along a radial direction of a method for forming irregularities on glass by a nanoprint method.
10 is a schematic configuration diagram of an optical circuit 500. FIG.
FIG. 11 is a schematic layout diagram of protrusions inside an optical waveguide.

Claims (1)

In order to form a fine structure on the substrate, in the light transmissive nanostamp method in which the substrate and a stamper with fine irregularities formed on the surface are pressurized and light is irradiated from the back of the stamper.
Forming a positive resist layer on the substrate, pressurizing the positive resist layer on the substrate with a light-transmitting stamper having a light-transmitting surface only on the convex surface of the surface on which the fine irregularities are formed; , Irradiating light from the rear surface of the light transmissive stamper , exposing the positive resist layer existing between the substrate and the convex portion of the stamper , and developing the resist. A light-transmitting nanostamp method characterized.

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