A material having a strip-like nano-slit structure, and a preparation method and applications thereof

Abstract

This application relates to a material with a strip-like nanoslit structure, its preparation method, and its application. The method includes the following steps: coating a photosensitive material onto the surface of a (110) monocrystalline silicon wafer covered with a thin layer of silicon nitride; then etching to obtain a silicon wafer with a micrometer-sized vertical wall structure on the monocrystalline silicon surface; subsequently etching the silicon wafer to form a silicon wafer with a nano-silica vertical wall array structure; and finally coating the surface of the silicon wafer with a polymer film to ultimately form a material with a strip-like nanoslit structure. The method of this application has the advantages of stability, reliability, and reusability, and the prepared nanoslits are in the size range of 10-100 nm.

Description

Technical Field

[0001] This invention belongs to the field of nanostructure processing technology, specifically relating to a material with a strip-shaped nano-slit structure, its preparation method, and its application. Background Technology

[0002] Nanoslits have applications in many fields, including surface-enhanced Raman spectroscopy, biomolecular analysis, small molecule filtration, and DNA sequencing. Their application potential is growing. Numerous studies have demonstrated that the choice of application depends primarily on the size and morphology of the nanostructure.

[0003] Currently, there is no research on forming regular array-type nanoslits on the surface of PDMS thin films. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned problems in the prior art and provide a method for preparing a strip-shaped nano-slit structure. This preparation method is stable and reliable and can be used repeatedly.

[0005] A second objective of this invention is to provide a material having a strip-shaped nanoslit structure obtained by the above method.

[0006] A third objective of this invention is to provide applications of the aforementioned materials.

[0007] To achieve the above objectives, the present invention provides a method for preparing a material with a strip-shaped nano-slit structure, characterized by comprising the following steps: S1. Prepare a (110) single-crystal silicon wafer covered with a thin layer of silicon nitride, and coat its surface with a photosensitive material to form a photosensitive thin film coating. S2. A strip array pattern is formed on the surface of a photosensitive material thin film coating using photolithography; S3. The patterned array of the photosensitive thin film coating is transferred to the silicon nitride layer by etching with concentrated phosphoric acid solution, and the single crystal silicon material is exposed. S4. After etching the naturally oxidized silicon dioxide layer on the exposed monocrystalline silicon surface using hydrofluoric acid solution, the monocrystalline silicon wafer is directly placed into an alkaline solution for anisotropic etching to obtain a silicon wafer with a micron-sized vertical wall structure on the surface of the monocrystalline silicon. S5. Place the silicon wafer obtained in S4 into a high-temperature muffle furnace and introduce a mixed gas of oxygen and nitrogen. At a high temperature of 650℃-900℃, oxidize the exposed single crystal silicon to form a silicon dioxide film. By controlling the oxidation time, the thickness of the silicon dioxide film is controlled between 5-50 nm. S6. The silicon wafer oxidized in S5 is placed in a concentrated phosphoric acid solution to etch away the silicon nitride portion. Then, it is placed in an alkaline solution to etch the single-crystal silicon while retaining the oxidized silicon dioxide, thereby forming a silicon wafer with a nano-silica vertical wall array structure; and S7. Coat the surface of the silicon wafer with the nano-silica vertical wall array structure of S6 with a polymer film. After curing, peel it off to form a material with a strip-shaped nano-slit structure.

[0008] In a specific embodiment, in step S1, the photosensitive material is a photosensitive polymer material that is sensitive to ultraviolet light, such as PMMA photosensitive material or SU8 series photosensitive material.

[0009] In a specific embodiment, in step S2, a strip array patterned structure is constructed on the surface of the photosensitive thin film coating using UV light, and then developed using an IPA solution to form a line array on the surface of the photosensitive thin film coating. The spacing between the lines can be adjusted. In a specific embodiment, in steps S3 and S6, the etching temperature range of concentrated phosphoric acid is 90-130 °C. The concentration of concentrated phosphoric acid is independently between 80-100%.

[0010] In a specific embodiment, in step S4, the concentration of hydrofluoric acid is 1%-10%.

[0011] In a specific embodiment, in steps S4 and S6, the alkaline solutions used are each independently 10-50% KOH solutions.

[0012] In a specific implementation, in step S5, the flow rate ratio of nitrogen to oxygen is 70:30-30:70, and the oxidation time is 10-20 minutes.

[0013] In a specific embodiment, in step S7, the width of the formed strip-shaped nanoslit is 10-100 nm.

[0014] In a specific embodiment, in step S7, the polymer film is a PDMS film or a PMMA film.

[0015] This method allows for the repeated preparation of relevant structures on PDMS.

[0016] On the other hand, the present invention provides a material having a strip-shaped nanoslit structure prepared by the above method.

[0017] In a specific implementation, the material is a PDMS thin film or a PMMA thin film with a slit structure having a width of 10 nm.

[0018] The application of the nanoscale slit structure in this application is not specifically limited and can be applied to any field that requires a nanoscale structure. For example, it can be applied to various different application fields after a metal layer is deposited, sputtered, or surface modified onto the surface of the material.

[0019] In another aspect, the present invention provides the application of the above-mentioned materials in surface-enhanced Raman spectroscopy, biomolecular analysis, small molecule filtration, or DNA sequencing.

[0020] Beneficial effects: This invention provides a method for preparing a material with a strip-like nanoslit structure and the material prepared therefrom. The method of this application has the advantages of being stable, reliable, and reusable. The prepared nanoslits are in the size range of 10-100 nm, therefore, it has broad application prospects in surface-enhanced Raman spectroscopy, biomolecular analysis, small molecule filtration, or DNA sequencing. Attached Figure Description

[0021] Figure 1 The image shows a scanning electron microscope (SEM) image of a silicon wafer with a micron-sized, vertically walled structure prepared in step S4 of Example 1.

[0022] Figure 2 The image shows a scanning electron microscope (SEM) image of a silicon wafer with a nanoscale vertical wall structure prepared in step S6 of Example 1.

[0023] Figure 3 The image shows a scanning electron microscope (SEM) image of the PDMS thin film with a strip-like nanoslit structure finally prepared in step S7 of Example 1.

[0024] Figure 4 The results show that the slit width after gold plating is controlled within 10nm.

[0025] Figure 5 The results of the Raman test in the test embodiment are shown. The red curve represents the Raman spectrum of the Rhodamine 6G molecule, showing a significant enhancement, while the black curve represents the peaks in the blank area, showing no enhancement. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Unless otherwise specified, the experimental methods used in the following embodiments and experimental examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified; and the equipment used are conventional experimental equipment unless otherwise specified.

[0028] the term: PMMA: Polymethyl methacrylate IPA: Isopropyl alcohol PDMS: Polydimethylsiloxane In this application, the solution concentration indicated by "%" represents the mass concentration.

[0029] Materials and Instruments High-temperature heating instrument: High-temperature muffle furnace, Test method: The following section uses scanning electron microscopy (SEM) to characterize the different microstructures obtained in different steps.

[0030] Example 1 The illustrative preparation method of the material with a slit structure in this application is as follows: S1. Prepare a single-crystal silicon wafer with a 50 nm silicon nitride thin layer (110) crystal phase on its surface, and coat its surface with a 50 nm thick PMMA photosensitive material to form a photosensitive thin film coating.

[0031] S2. Ultraviolet light passes through a pre-designed mask (here, a mask with a 10-micron linewidth and 10-micron spacing is used). The UV light shines through the mask onto the surface of the photosensitive material, creating a patterned array of stripes with a fixed spacing on the mask surface. This pattern is then transferred to the photosensitive material surface via photolithography (using ordinary UV light at a wavelength of 365nm). The photosensitive material used in this application is a forward-facing photosensitive material; the exposed areas are photolyzed by the ultraviolet light, while the unexposed areas are retained. Then, development is performed using an IPA solution to form a line array on the surface of the photosensitive film material. It should be noted that although a mask with the above parameters is used in this application, the line spacing can be adjusted by designing masks with different line spacings.

[0032] S3. The exposed silicon nitride layer of the photosensitive thin film material is completely etched by concentrated phosphoric acid etching at 130℃, and the array pattern of the photosensitive thin film material is transferred to the silicon nitride layer.

[0033] S4. After etching the naturally oxidized silicon dioxide layer on the exposed monocrystalline silicon surface using hydrofluoric acid (1%), the monocrystalline silicon wafer is directly placed into a 50% KOH solution for anisotropic etching, forming a micron-sized vertical wall structure on the monocrystalline silicon surface.

[0034] S5. Then, the silicon wafer with the vertical wall structure is placed into a high-temperature muffle furnace, and a mixture of oxygen and nitrogen (flow rate ratio of 70:30) is introduced. At a high temperature of 900℃, the exposed single crystal silicon is oxidized to form a silicon dioxide film. By controlling the oxidation time, the thickness of the silicon dioxide film can be controlled between 5-50 nm.

[0035] S6. The oxidized silicon wafer is placed in an 85% phosphoric acid solution at 130°C to etch away the silicon nitride portion. Then, it is placed in a 50% KOH solution to etch the single-crystal silicon while retaining the oxidized silicon dioxide vertical wall array, thereby forming a nano-silica vertical wall array structure.

[0036] S7. A thin layer of PDMS is cast on the surface of a silicon wafer with a nano-silica vertical wall array structure. After the PDMS has cured, the thin layer of PDMS is peeled off, and a nano-scale slit of about 10 nm is formed on the PDMS surface.

[0037] Scanning electron microscope (SEM) images of the inline vertical wall array structure (obtained in step S4), the nano-silica vertical wall array structure (obtained in step S6), and the nano-slit array structure (obtained in step S7) prepared according to the above steps are shown in the figure. Figure 1 , Figure 2 and Figure 3 middle.

[0038] Test Implementation Example: The structure obtained in Example 1 was surface-modified with a nano-gold thin film using magnetron sputtering. After gold particles were deposited from top to bottom, the thickness of the thin film was controlled within 10 nm, which did not directly change the original slit structure. However, it could further reduce the slit size and improve uniformity within a 10% range. Simultaneously, the slit interface was transformed from the original organic material to a metallic interface, forming a gold-based slit structure smaller than 10 nm. The scanning electron microscope image of this structure is shown in [image missing]. Figure 4 .

[0039] The structure was placed in the solution of the rhodamine 6G molecule to be detected (concentration: 10). -10 The results, using a Raman spectrometer from Zolihan Optoelectronics, under a detection environment of 3% laser intensity, 0.1 seconds integration time, and 532 nm laser wavelength, showed that the Raman spectral signal of the molecule to be detected could be obtained at the nano-slit, while no signal could be detected in the part without this structure (the blank area). Figure 5 ).

[0040] In summary, the methods described in this application can successfully form various materials with nano-slits of 10-100 nm width, which have broad application prospects in surface-enhanced Raman spectroscopy, biomolecular analysis, small molecule filtration, or DNA sequencing.

[0041] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a material having a strip-like nano-slit structure, characterized by, Includes the following steps: S1. Prepare a (110) single-crystal silicon wafer covered with a thin layer of silicon nitride, and coat its surface with a photosensitive material to form a photosensitive thin film coating. S2. A strip array pattern is formed on the surface of a photosensitive material thin film coating using photolithography; S3. The patterned array of the photosensitive thin film coating is transferred to the silicon nitride layer by etching with concentrated phosphoric acid solution, and the single crystal silicon material is exposed. S4. After etching the naturally oxidized silicon dioxide layer on the exposed monocrystalline silicon surface using hydrofluoric acid solution, the monocrystalline silicon wafer is directly placed into an alkaline solution for anisotropic etching to obtain a silicon wafer with a micron-sized vertical wall structure on the surface of the monocrystalline silicon. S5. Place the silicon wafer obtained in S4 into a high-temperature muffle furnace and introduce a mixed gas of oxygen and nitrogen. At a high temperature of 650℃-900℃, oxidize the exposed single crystal silicon to form a silicon dioxide film. By controlling the oxidation time, the thickness of the silicon dioxide film is controlled between 5-50 nm. S6. The silicon wafer oxidized in S5 is placed in a concentrated phosphoric acid solution to etch away the silicon nitride portion. Then it is placed in an alkaline solution to etch the single crystal silicon while retaining the oxidized silicon dioxide, thereby forming a silicon wafer with a nano-silica vertical wall array structure. as well as S7. Coat the surface of the silicon wafer with the nano-silica vertical wall array structure of S6 with a polymer film. After curing, peel it off to form a material with a strip-shaped nano-slit structure.

2. The method of claim 1, wherein, In step S1, the photosensitive material is an ultraviolet light-sensitive photosensitive polymer material, such as PMMA photosensitive material or SU8 series photosensitive material.

3. The method of claim 1, wherein, In step S2, a strip array patterned structure is constructed on the surface of the photosensitive thin film coating using UV light, and then developed using IPA solution to form a line array on the surface of the photosensitive thin film coating.

4. The method of claim 1, wherein, In steps S3 and S6, the etching temperature range of concentrated phosphoric acid is 90-130 °C, and the concentration of concentrated phosphoric acid is independently between 80-100%; and / or In steps S4 and S6, the alkaline solutions used are each independently 10-50% KOH solutions.

5. The method of claim 1, wherein, In step S4, the concentration of hydrofluoric acid is 1%-10%.

6. The method of claim 1, wherein, In step S5, the flow rate ratio of nitrogen to oxygen is between 70:30 and 30:70, and the oxidation time is 10-20 minutes.

7. The method of claim 1, wherein, In step S7, the width of the formed strip-shaped nanoslit is 10-100 nm; The polymer film is a PDMS film or a PMMA film.

8. A material having a strip-shaped nanoslit structure prepared by the method according to any one of claims 1-7.

9. The material of claim 8, wherein, The material is a PDMS thin film or a PMMA thin film with a slit structure having a width of 10 nm.

10. The application of the material as described in claim 8 or 9 in surface-enhanced Raman spectroscopy, biomolecular analysis, small molecule filtration, or DNA sequencing, for example, by depositing, sputtering, or surface modification of the material surface to form a metal layer, such as a gold layer, which is then applied to the surface-enhanced Raman spectroscopy, biomolecular analysis, small molecule filtration, or DNA sequencing.

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