JP2004288802A - Light transmissive nano-stamping method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a fine pattern having a high aspect ratio by combining and using a nano-printing method using a light-transmissive stamper and a positive resist. <P>SOLUTION: In a light transmissive nano-stamping method in which a substrate and the stamper, in which fine irregularities are formed on the surface, are pressed for forming a fine structure on the substrate and the rear of the stamper is irradiated with light, the method contains a process in which a positive resist layer is formed on the substrate, a process in which the light-transmissive stamper is pressed against the positive resist layer on the substrate and the resist layer is deformed, a process, in which the rear of the stamper is irradiated with light, and a process in which the resist is developed and solubilized partially. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a nanoprint transfer method for forming a fine structure on a substrate using a light-transmitting stamper having a pressing mechanism.
[0002]
[Prior art]
2. Description of the Related Art In recent years, miniaturization and integration of semiconductor integrated circuits have been advanced, and photolithography apparatuses have been improved in precision as a pattern transfer technique for realizing the microfabrication. However, the processing method is approaching the wavelength of the light source for light exposure, and the lithography technique is approaching its limit. For this reason, an electron beam lithography apparatus, which is a kind of charged particle beam apparatus, has come to be used in place of the lithography technique in order to achieve further miniaturization and higher precision.
[0003]
The pattern formation using an electron beam is different from the collective exposure method in pattern formation using a light source such as an i-line or an excimer laser, and is based on a method of drawing a mask pattern. It is a drawback that exposure (drawing) takes time and pattern formation takes time. Therefore, as the degree of integration is dramatically increased to 256 mega, 1 giga, and 4 giga, the pattern formation time is drastically increased correspondingly, and there is a concern that the throughput may be significantly inferior. Therefore, in order to increase the speed of the electron beam lithography system, the development of a collective pattern irradiation method that combines masks of various shapes and irradiates them collectively with an electron beam to form an electron beam of a complicated shape is being advanced. . As a result, while the pattern miniaturization is advanced, the electron beam lithography system must be increased in size, and a mechanism for controlling the mask position with higher accuracy is required. was there.
[0004]
On the other hand, techniques for forming a fine pattern at low cost are disclosed in Patent Literatures 1 and 2, Non-Patent Literature 1, and the like. This is to transfer a predetermined pattern by stamping a stamper having the same pattern irregularities as a pattern to be formed on a substrate onto a resist film layer formed on the surface of a substrate to be transferred. According to the nanoimprint technique described in Document 2 and Non-Patent Document 1, it is stated that a microstructure of 25 nm or less can be formed by transfer using a silicon wafer as a stamper.
[0005]
Further, Patent Document 3 below discloses a step of forming a photocurable substance layer made of a liquid photocurable substance on a substrate, and a step of forming a groove of a predetermined pattern made of a light transmissive substance on one surface side. A step of pressing the formed mold against the substrate and a step of curing the photocurable material layer by irradiating light from the other side of the mold to form a resist pattern having a pattern that fits into the groove pattern And a method of forming a pattern by a step of detaching a mold from a substrate.
[0006]
[Patent Document 1]
US Patent No. 5,259,926 [Patent Document 2]
US Patent No. 5,772,905 [Patent Document 3]
Japanese Patent Application Laid-Open No. 2000-194142 [Non-Patent Document 1]
S. Y. Chou 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 has a high aspect ratio and is not suitable for forming a fine pattern.
In view of the above technical problems, an object of the present invention is to form a fine pattern having a high aspect ratio by using a nanoprinting method using a light transmitting stamper in combination with 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 a resist, and has accomplished the present invention.
That is, the present invention is an invention of a light-transmitting nanostamp method, in which a substrate and a stamper having fine irregularities formed on a surface thereof are pressed to form a fine structure on the substrate, and light is irradiated from the back surface of the stamper. In the light-transmitting nanostamp method, a step of forming a positive resist layer on the substrate, a step of pressing a light-transmitting stamper against the positive resist layer on the substrate, and a step of deforming the resist layer; The method includes a step of irradiating and a step of developing the resist.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
First, a nanoprinting method using a light transmitting stamper will be described with reference to FIG. A stamper having a fine 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). The stamper is pressed on the positive photosensitive resin film at a predetermined pressure using a press device having a pressing mechanism (not shown) (FIG. (B)). After pressing, light is irradiated from above the light-transmitting stamper to cause a reaction only in the exposed portion (FIG. (C)). The stamper and the substrate are separated, 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. 3E).
[0010]
According to the nanoprinting method, (1) the integrated ultra-fine pattern can be efficiently transferred, (2) the apparatus cost is easy, (3) it is possible to cope with complicated shapes and pillars can be formed, and the like. There are features.
The application fields of the nanoprint method include (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, nanoprinting refers to transfer in the range from several hundreds of μm to several nm.
In the present invention, it is preferable that the press device has a pressing mechanism and a mechanism capable of irradiating light from above the light transmitting stamper in order to efficiently perform pattern transfer.
[0012]
In the present invention, the stamper has a fine pattern to be transferred, and a method of forming the pattern on the stamper is not particularly limited. For example, it is selected according to a desired processing accuracy such as photolithography or electron beam lithography. As the material of the stamper, any material such as quartz, glass, ceramic, and plastic may be used as long as it is transparent, has strength, and has required workability with the required precision.
[0013]
In the present invention, the material used as the substrate is not particularly limited, but may be any material having a predetermined strength. 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), or the like can be used.
[0015]
【Example】
Hereinafter, examples of the present invention will be described.
[Example 1: Production of stamper]
A method for manufacturing a stamper used for a light-transmitting nanostamp method, which is one of the embodiments of the present invention, will be described with reference to FIGS. FIG. 2 is a conceptual diagram, and it is rejected that the pattern shape is simplified and written in a relatively large size.
[0016]
First, a quartz substrate 1 having a diameter 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 (OEBR1000, manufactured by Tokyo Ohka) for electron beam exposure was applied to a thickness of 100 nm using a spin coater. Subsequently, as shown in FIG. 2C, an electron beam lithography apparatus JBX6000FS (manufactured by JEOL Ltd.) is used to perform exposure by directly drawing with an electron beam 3 and develop, thereby obtaining an image as shown in FIG. Irregularities in which circular patterns having a diameter of 30 nm were arranged were formed. Using the unevenness of FIG. 2D as a mask pattern, the quartz substrate 1 was subjected to dry etching using CF ₄ gas to form unevenness having a depth of 100 nm on the quartz substrate 1 as shown in FIG. Further, as shown in FIG. 2F, Cr was deposited by sputtering to a thickness of 50 nm while the resist was left. Thereafter, the resist was developed to remove the resist and Cr formed on the resist. By the above process, a stamper having no light transmittance was obtained because the pattern convex portion in FIG. 2G has light transmittance, but the pattern concave portion shields the Cr film from light.
[0017]
[Example 2: Columnar structure formation]
Next, a light transmitting nanostamp method using the pattern convex light transmitting stamper shown in FIG. 2G will be described with reference to FIG. As a substrate to be transferred, a quartz substrate was used in order to eliminate a thermal expansion difference with a stamper. As shown in FIG. 3A, a positive resist OFPR800 (manufactured by Tokyo Ohka) was spin-coated on a quartz substrate to a thickness of 500 nm. By further reducing the pressure to 0.1 Torr or less and heating to 250 ° C., the solvent component in the resist was volatilized, and the viscosity was increased to impart moldability. Next, as shown in FIG. 3B, a resist was molded by applying a pressure of 3 MPa for 10 minutes. Subsequently, as shown in FIG. Since the stamper convex portion transmits light, the resist thereunder was solubilized. On the other hand, since the light-shielding Cr film was formed in the stamper concave portion, the resist thereunder did not change. As shown in FIG. 3D, the stamp and the transferred quartz substrate were fixed with a vacuum chuck, and the stamp was lifted upward at 0.1 mm / s to perform peeling. As a result, a columnar structure having a diameter of 30 nm and a height of 200 nm was formed as shown in FIG. When the resist was developed with a resist developing solution NMD3 (manufactured by Tokyo Ohka), the soluble portion of the resist could be removed, and a columnar structure of the resist was obtained. When a negative resist and a partially light-transmitting stamper are used in combination, crosslinking of the resist due to light leaking from the light-shielding portion occurs, so that the method cannot be applied to an ultrafine pattern of several tens of nm. Further, since it is difficult to stop the crosslinking by light at a desired viscosity, the negative resist is cured with the dimensions of the stamper irregularities as it is, and it is difficult to form a columnar structure having a high aspect. Therefore, it can be said that the light transmitting 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 the nanoprint using the stamper with a peeling mechanism of the present invention is preferably applied will be described.
[Example 3: Bio (immune) chip]
FIG. 4 is a schematic diagram of the biochip 900. A flow path 902 having a depth of 3 μm and a width of 20 μm is formed in a glass substrate 901, and a sample containing DNA (deoxyribonucleic acid), blood, protein, etc. is introduced from an introduction hole 903, After flowing through the path 902, it flows into the discharge hole 904. A molecular filter 905 is provided in the channel 902. On the molecular filter 905, a projection assembly 100 having a diameter of 250 to 300 nanometers and a height of 3 micrometers is formed.
[0019]
FIG. 5 is a sectional bird's-eye view of the vicinity where the molecular filter 905 is formed. A flow path 902 is formed in the substrate 901, and a projection assembly 100 is formed in a part of the flow path 902. The substrate 901 is covered by the upper substrate 1001, and the sample 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 flow path 902, the DNA is separated into high resolution by the molecular filter 905 according to the DNA chain length. The sample 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 the DNA passes, the light incident on the photodetector 907 decreases by about 4%, so that the output signal from the photodetector 907 can be used to analyze the chain length of the DNA in the sample. The 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 supply pad 912 provided 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 concave portion, a plurality of protrusions formed in the concave portion of the substrate 901, and an upper substrate 1001 formed so as to cover the concave portion of the substrate. Here, the tip of the protrusion is formed so as to be in contact with the upper substrate. Since the main component of the projection assembly 100 is an organic substance, it can be deformed, so that the projection assembly 100 is not damaged when the upper substrate 1001 is put on the flow path 902. Therefore, the upper substrate 1001 and the projection assembly 100 can be brought into close contact with each other. With such a configuration, the sample does not leak from the gap between the protrusion and the upper substrate 1001, and high-sensitivity analysis can be performed. As a result of actual analysis of the DNA chain length, the resolution of base pairs was 10 base pairs at half width in the glass protrusion assembly 100, whereas the base protrusion resolution was 100 base pairs in the organic protrusion assembly 100. Was improved to 3 base pairs in half width. In the molecular filter of the present embodiment, the projections and the upper substrate have a structure in which they are in direct contact. The adhesion can be improved.
In this embodiment, the number of the flow paths 902 is one. However, different analyzes can be performed at the same time by arranging a plurality of flow paths 902 provided with protrusions of different sizes.
[0021]
In this example, DNA was examined as a specimen, but specific sugar chains, proteins, and antigens were analyzed by previously modifying molecules that react with sugar chains, proteins, and antigens on the surface of the projection assembly 100. Is also good. As described above, by modifying the surface of the protrusion with the antibody, the sensitivity of the immunoassay can be improved.
[0022]
By applying the present invention to a biochip, it is possible to obtain an effect of easily forming a projection for analysis made of an organic material having a nanoscale diameter. Further, by controlling the unevenness of the mold surface and the viscosity of the organic material thin film, the position, diameter, and height of the organic material projection can be controlled. 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 copper wiring 1003, and then a pattern is transferred by a stamper (not shown). Next, when the exposed area 703 of the multilayer wiring board 1001 is dry-etched with CF ₄ / H ₂ gas, the exposed area 703 on the surface of the multilayer wiring board 1001 is processed into a groove shape as shown in FIG. Next, the resist 702 is subjected to resist etching by RIE to remove a portion of the resist having a low step, thereby forming an enlarged exposed region 703 as shown in FIG. 7C. From this state, when the dry etching of the exposed region 703 is performed 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. By doing so, a multilayer wiring board 1001 having a groove shape on the surface as shown in FIG. 7E is obtained. From this state, after forming a metal film on the surface of the multilayer wiring board 1001 by sputtering (not shown), electrolytic plating 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, the multilayer wiring board 1001 having metal wiring on the surface can be obtained as shown in FIG.
[0024]
Another process for manufacturing a multilayer wiring board will be described. When dry etching of the exposed region 703 from the state shown in FIG. 7A is performed until the copper wiring 1003 in the multilayer wiring board 1001 is reached, the structure shown in FIG. 7H is obtained. . Next, the resist 702 is etched by RIE to remove a portion of the resist having a low step, thereby obtaining the structure shown in FIG. From this state, when a metal film 1005 is formed on the surface of the multilayer wiring substrate 1001 by sputtering, 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, a multilayer wiring board 1001 having a structure shown in FIG. 7L can be obtained.
By applying the present invention to a multilayer wiring board, a wiring having high dimensional accuracy can be formed.
[0025]
[Example 5: Magnetic disk]
FIG. 8 is an overall view and an enlarged sectional view of the magnetic recording medium according to the present embodiment. The substrate is made of glass having fine irregularities. On the substrate, a seed layer, an underlayer, a magnetic layer, and a protective layer are formed. Hereinafter, the method for manufacturing the magnetic recording medium according to the present embodiment will be described with reference to the drawings. FIG. 9 is a cross-sectional view of a method of forming concavities and convexities on glass by a nanoprint method, which is cut in a radial direction. First, a glass substrate is prepared. In the present embodiment, soda lime glass is used. The material of the substrate 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 to a thickness of 200 nm.
[0026]
On the other hand, as the stamper, a quartz stamper in which a groove is formed so as to be concentric with the center hole of the magnetic recording medium is prepared. The groove dimensions were 88 nm in width and 200 nm in depth, and the distance between grooves was 110 nm. Since the irregularities of this stamper are very fine, they were formed by photolithography using an electron beam. Further, a Cr film was formed in the pattern concave portion in the same manner as in Example 1 so as to have a light shielding property. Next, as shown in FIG. 9B, the resist was molded by applying pressure at 3 MPa for 10 minutes. Subsequently, as shown in FIG. Since the stamper convex portion transmits light, the resist thereunder was solubilized. Stripping is performed in the same manner as in Example 1, and development is performed with a resist developer NMD3 (manufactured by Tokyo Ohka) to remove the solubilized portion, thereby forming a resist pattern as shown in FIG. 9D. By using this resist as a mask and further etching the substrate with hydrofluoric acid, the substrate can be processed as shown in FIG. 9 (e). 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 the present embodiment, the thickness is set to 100 nm in order to reflect the fine irregularities formed on the glass substrate also in the upper layer. Further, by using a sputtering method generally used for forming a magnetic recording medium, a Cr underlayer 15 nm, a CoCrPt magnetic layer 14 nm, and a C protective layer 10 nm are sequentially formed to form the magnetic recording medium of the present embodiment. Produced. In the magnetic recording medium of the present embodiment, the magnetic material is radially separated by a nonmagnetic layer wall having a width of 88 nm. Thereby, the in-plane magnetic anisotropy could be increased. Although concentric pattern formation (texturing) using a polishing tape is conventionally known, the pattern interval is as large as a micron scale, and it is difficult to apply it to a high-density recording medium. The magnetic recording medium of this example secured magnetic anisotropy with a fine pattern using a nanoprinting method, and was able to realize high-density recording of 400 Gb / sq. The pattern formation by nanoprinting is not limited to the circumferential direction, and the non-magnetic partition can be formed in the radial direction. Furthermore, the effect of imparting magnetic anisotropy 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 is described in which the optical device 100 in which the traveling direction of incident light changes is applied to an optical information processing apparatus.
FIG. 10 is a schematic configuration diagram of the manufactured optical circuit 500. The optical circuit 500 is composed of an aluminum nitride substrate 501 having a length of 30 mm, a width of 5 mm, and a thickness of 1 mm. It comprises a connector 504. 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 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 tolerated. The structure is led to. Although the protrusions 406 are arranged at intervals of 0.5 micrometers, in FIG. 21, the protrusions 406 are illustrated in a simplified manner and the number is smaller than the actual number.
[0029]
The optical circuit 500 can superimpose and output ten types of signal light having different wavelengths. However, since the traveling direction of light can be changed, the width of the optical circuit 500 can be made extremely short as 5 mm, and the size of the optical communication device can be reduced. There is an effect that can be done. Further, since the protrusions 406 can be formed by pressing the mold, an effect of reducing the manufacturing cost can be obtained. In this embodiment, the device is a device that superimposes input light. However, it is clear that the optical waveguide 503 is useful for all optical devices that control the optical 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 propagating signal light in a structure in which protrusions mainly composed of an organic substance are periodically arranged. In addition, since the projection can be formed by a simple manufacturing technique of pressing a mold, 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 nanoprinting method is provided. Further, by using a nanoprinting method using a light-transmitting stamper in combination with a positive resist, a fine pattern having a high aspect ratio can be formed.
[Brief description of the drawings]
FIG. 1 is a schematic view showing each step of nanoprinting.
FIG. 2 is a method for manufacturing a stamper used for a light transmitting nanostamp method.
FIG. 3 is a light transmitting nanostamp method using a pattern convex light transmitting stamper.
FIG. 4 is a schematic diagram 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.
FIG. 7 illustrates a step for manufacturing a multilayer wiring board.
FIG. 8 is an overall view and an enlarged cross-sectional view of a magnetic recording medium.
FIG. 9 is a cross-sectional view of a method of forming concavities and convexities on glass by a nanoprint method, which is cut in a radial direction.
FIG. 10 is a schematic configuration diagram of an optical circuit 500.
FIG. 11 is a schematic layout diagram of protrusions inside the optical waveguide.

Claims (2)

In order to form a microstructure on the substrate, in the light transmitting nanostamp method of pressing the substrate and a stamper having fine irregularities formed on the surface, and irradiating light from the back of the stamper,
Forming a positive resist layer on the substrate, pressing a light-transmitting stamper against the positive resist layer on the substrate to deform the resist layer, irradiating light from the back of the light-transmitting stamper, and developing the resist A light-transmitting nanostamp method. The light transmitting nanostamp method according to claim 1,
The light-transmitting nanostamp method, wherein only the surface of the convex portion on which the fine unevenness is formed has a light-transmitting property.

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