JP2011075348A - Method for manufacturing test piece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a test piece which can effectively perform analysis with good measuring sensitivity. <P>SOLUTION: The method for manufacturing the test piece having a nano-structure surface wherein a large number of minute columnar bodies are formed has the first step being the step of vapor-depositing a transparent metal oxide or metal fluoride on a substrate from an oblique direction and forming a large number of column parts having anisotropy on the substrate by reversing a vapor deposition direction at each predetermined membrane thickness obtained by vapor deposition and a second step of vapor-depositing a noble metal on the apex parts of the formed column parts in a thickness of 20-40 nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing the test strip with a nanostructured surface that serves as an optical sensor for analyzing a liquid sample.

  Conventionally, molecular measurement using light such as surface enhanced Raman scattering (SERS) method, surface enhanced infrared absorption spectroscopy (SEIRA) method, surface plasmon resonance (SPR) method, and localized surface plasmon resonance (LPR) method The method is known. When performing such molecular measurements, the solution to be analyzed is dropped on the surface of the optical sensor (test piece), and the measurement light is irradiated under conditions according to each measurement method to reflect or scattered light from the optical sensor. The substance contained in the solution can be identified by receiving and analyzing the light. In such an optical sensor, an optical sensor in which a noble metal nanostructure is formed on the sensor surface in order to further increase the sensitivity of the sensor is known (see Patent Document 1).

International Publication No. 2006/073117

  Such an optical sensor having a mesoscopic structure and having a nano-sized structure as an active part has a large electric field enhancement effect because the nanostructures of noble metals are close to each other. Measurement sensitivity (measurement intensity) is improved as compared with the sensor. However, even in such an optical sensor (test piece), there is a need for a test piece that has higher measurement sensitivity and exhibits sufficient performance for effective analysis.

    In view of the above-described problems of the prior art, it is an object of the present invention to provide a method for manufacturing the test piece that can be analyzed effectively with high measurement sensitivity.

In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) In a method of manufacturing a test piece having a nanostructure surface on which a large number of microcolumnar bodies are formed, a step of depositing a transparent metal oxide or metal fluoride on a substrate from an oblique direction, obtained by the deposition. A first step of forming a large number of pillars having anisotropy on the substrate by reversing the deposition direction for each predetermined film thickness, and a noble metal having a thickness of 20 nm or more on the top of the pillars formed. And a second step of vapor deposition at 40 nm or less.
(2) In the method for manufacturing a test piece according to (1), the column part is 100 nm or more and 1000 nm or less.
(3) In the method for manufacturing a test piece according to (2), the noble metal portion is made of Au and the column portion is made of SiO ₂ .

  According to the present invention, the performance of the test piece can be sufficiently exhibited, and the analysis can be performed effectively with good measurement sensitivity.

  Embodiments of the present invention will be described below. First, the configuration of the test piece (optical sensor) used in the present embodiment and the manufacturing method will be described.

FIG. 1 is a schematic view showing details of a surface 2 having a nanorod structure in the test piece of the present embodiment. For example, the nanorod structure formed on the substrate 1 includes a large number of micro-columnar bodies 3 formed on the substrate 1 with a predetermined interval. For the substrate 1, materials that can be used as substrates for optical sensors such as various glass materials, transparent resins, semiconductors, and metals can be used. The minute columnar body 3 includes a column portion 3a and a noble metal portion 3b formed on the top of the column portion 3a. The column part 3a may be any material that is transparent to the wavelength of the measurement light (probe light) used for sample analysis and causes plasmon resonance. For example, a metal oxide such as SiO ₂ or TiO ₂ or LiF A metal fluoride such as is preferably used. Further, the columnar portion 3a is formed with a surface irregularity shape having self-organized anisotropy. The surface irregularity having such anisotropy is formed by, for example, depositing a material for forming the column portion 3a obliquely on the substrate 1 using a vacuum deposition method, and inverting the substrate surface every predetermined film thickness. Can be formed.

  The noble metal portion 3b is made of a noble metal necessary for obtaining a highly sensitive optical sensor, preferably Au, Ag, Cu, or the like. In addition, since a test piece may be normally stored for a long period of time, it is especially preferable to use Au which is not easily oxidized as a material for forming the noble metal portion 3b. Further, as a result of intensive studies by the present inventors, in such a test piece having the minute columnar body 3 on the substrate 1, the thickness of the noble metal portion 3b formed on the top of the column portion 3a is obtained at the time of measurement. It has been found that the measurement strength (measurement sensitivity) does not improve, and the measurement strength varies greatly depending on the thickness of the noble metal portion 3b. The thickness range of the noble metal portion 3b is about 20 nm or more and about 40 nm or less if the measurement intensity is reduced to about 30% with respect to the condition that the highest measurement intensity can be obtained. In addition, if a reduction in measurement intensity of about 15% is allowed with respect to the condition for obtaining the highest measurement intensity, the thickness range of the noble metal portion 3b is about 25 nm or more and about 35 nm or less.

  On the other hand, the measured strength of the test piece tends to increase as the thickness (height) of the column portion 3a increases, but the production efficiency is reduced accordingly. Therefore, the thickness (height) of the column part 3a is preferably 100 nm or more and 1000 nm or less, and more preferably 300 nm or more and 900 nm or less.

Next, the manufacture example of the test piece of this embodiment is shown below using FIG.
After cleaning the substrate 1, the substrate 1 and the vapor deposition material are set in a vacuum vapor deposition apparatus. As shown in the figure, the vacuum vapor deposition apparatus 20 is provided above the apparatus main body 21, the exhaust part 22 for making the inside of the apparatus a vacuum state, the base 23 for placing the vapor deposition material, the electron beam generating part 24, and the base 23. A substrate holding unit 25 for attaching the substrate and a detection unit 26 for detecting the film thickness during vapor deposition are provided. These components are connected to a control unit (not shown) and are driven and controlled by signals from the control unit. Further, the substrate holding unit 25 can hold the substrate 1 and can appropriately change the vapor deposition angle α (an angle formed between the incident direction of the vapor deposition flow and the normal line at the center of the substrate) on the substrate 1, thereby enabling oblique vapor deposition. It has become. The vapor deposition angle α is preferably 45 ° to 88 °. Further, the substrate holding unit 24 can be turned 180 ° while holding the substrate 1 at a predetermined angle. Moreover, as the detection part 26, the mechanism which detects the existing film thickness, such as a crystal vibration type film thickness meter, can be used.

  The substrate 1 and the vapor deposition material 26 are set on the substrate holding unit 25 and the base 23, respectively, and the inside of the apparatus is evacuated using the exhaust unit 22. After confirming that the inside of the apparatus is in a vacuum state, the electron beam generator 24 irradiates an electron beam toward the vapor deposition material 26, evaporates the evaporation material, and obliquely deposits on the surface of the substrate 1. The film thickness detected by the detection unit 26 is set to a film thickness formed on the substrate 1, and when an appropriate film thickness is obtained, the in-plane angle of the substrate 1 is reversed by 180 degrees by the substrate holding unit 25. After the substrate 1 is inverted, the vapor deposition operation is continued until an appropriate film thickness is obtained as described above, and the substrate 1 is inverted again. The inversion cycle (timing) is preferably performed when the film thickness is 5 nm to 100 nm and the same film thickness is obtained at each inversion. By repeating such vapor deposition, reversal, vapor deposition, reversal,..., Many micro-columnar bodies (column portions 3a in FIG. 1) having an anisotropic shape are formed on the substrate 1. It will be. In addition, the column part 3a is formed so that it may have a height with which a suitable sensitivity can be obtained with respect to the wavelength of the measurement light used in the analysis. Further, a noble metal is vapor-deposited on the top of the column portion 3a having the required height to form a noble metal portion 3b as shown in FIG. The vapor deposition operation may be performed by the same method as described above by changing the vapor deposition material. In the case of depositing the noble metal portion 3b, it is preferable that the angle of the oblique deposition is the same as or similar to that for forming the column portion 3a.

After introducing air into the apparatus, the substrate 1 having a nanorod structure (microcolumnar body 3) formed on the surface is taken out and cut into a size suitable for use as an optical sensor.
Test specimens obtained by the above method include surface enhanced Raman scattering (SERS) method, surface enhanced infrared absorption spectroscopy (SEIRA) method, surface plasmon resonance (SPR) method, and localized surface plasmon resonance (LPR) method. , And used as an optical sensor in a measuring apparatus that performs molecular measurement using light.

A more specific experimental example is shown below.
<Experimental example 1>
In Experimental Example 1, the measurement intensity (sensitivity) by changing the height of the column part (300 nm, 450 nm, 600 nm, 900 nm) while keeping the film thickness of the noble metal part of the micro-columnar body formed on the test piece constant (60 nm). Sought the impact on. A SiO ₂ pellet made by Canon Optron Co., Ltd. is set as a deposition material in the vacuum deposition apparatus described above, a glass plate (57 mm × 57 mm, thickness 0.25 mm) is set as a substrate, and the inside of the apparatus is 1.33 × 10 ⁻⁴ Pa. In a vacuum state of about (1.00 × 10 ⁻⁶ Torr), the deposition material was irradiated with an electron beam, and the deposition angle α was set to 82 °. When the SiO ₂ film had a thickness of 50 nm as measured by the detection unit, the substrate in-plane angle was inverted by 180 °, and vapor deposition was similarly performed until the thickness became 25 nm. XTC / 2 manufactured by INFICON Co., Ltd. was used as a detection unit used for film formation detection.

This vapor deposition operation was performed a plurality of times, and repeated until the thickness (height) of SiO ₂ finally reached 300 nm. After the desired column height is obtained, the deposition material is changed to Au wire, and Au (gold) is deposited on the top of the column at a deposition angle of 72 °, thereby depositing gold on the tip of the nanorod. The obtained substrate was obtained. The deposition of Au on the top was performed until a film thickness of 60 nm was obtained at the detection part. A test piece was obtained by taking out the substrate having a micro-columnar body formed on the surface by such vapor deposition from the apparatus and cutting it to 5 mm × 7 mm. Moreover, the test piece (all the film thickness of a noble metal part is 60 nm) from which the height of a pillar part is set to 450 nm, 600 nm, and 900 nm was obtained by the same manufacturing method.
A microscope equipped with a laser having a wavelength of 785 nm as measurement light after 15 μL of 10 μM of 4,4′-bipyridine aqueous solution was dropped on four types of test pieces having different column heights obtained by the above-described method and air-dried. Raman spectrometer Microscopic Raman analysis was performed using MicroRAM-200 manufactured by Lambda Vision. Measurement conditions were as follows: exposure time 1 second, number of integrations 1 time, power 20 mW, magnification 10 times, diffraction grating 600 Gr / 750 nm, focal length 200 mm.
Analysis of 4,4'-bipyridine solution, to appear the highest peak near 1600 cm ^-1 (Kayser), the peak value of 1600 cm ^-1 (measured intensity) as a measurement point in each specimen, plotting (plot point: A diamond is shown in FIG.

<Experimental example 2>
Four types of test pieces (300 nm, 450 nm, 600 nm, 900 nm) having different column heights were obtained under the same conditions as in Experimental Example 1, except that the thickness of the noble metal portion was 30 mm. Similarly to Experimental Example 1, 15 μL of 10 μM of 4,4′-bipyridine aqueous solution was dropped on each test piece, air-dried, and microscopic Raman analysis was performed. FIG. 3 shows a plot (plot point: square) of a peak value (measured intensity) of 1600 cm ⁻¹ in each test piece.

<Result 1>
As shown in FIG. 3, the measured strength obtained tends to increase as the height of the pillar (SiO ₂ ) increases. The change in the measurement intensity due to the difference in the height of the column part is moderate when the column part height is in the range of 300 nm to 900 nm. Therefore, the height of the column part may be about 100 nm to 1000 nm. . Further, it was found that the measurement strength greatly differs depending on the thickness of the noble metal part (Au).

<Experimental example 3>
Next, the influence on the measurement intensity (sensitivity) by changing the thickness of the noble metal part while keeping the height of the column part constant was obtained.
The method for producing the test piece is the same as in Experimental Example 1, the height of the column part (SiO2) is uniformly 600 nm, and the thickness of the noble metal part (Au) is 7.5 nm, 15 nm, 20 nm, 30 nm, 40 nm, Microscopic Raman analysis was performed under the same conditions as in Experimental Example 1 (15 μL of 10 μM of 4,4′-bipyridine aqueous solution was dropped) using a total of 8 types of test pieces of 50 nm, 60 nm, and 120 nm. FIG. 4 shows a plot (plot point: round shape) of the peak value (measured intensity) of 1600 cm ⁻¹ in each test piece.

<Result 2>
As shown in FIG. 4, the strongest measurement intensity was obtained when the thickness of the noble metal was around 30 nm. Therefore, the thickness of the noble metal portion is about 20 nm or more and about 40 nm or less if a decrease in measurement intensity of about 30% is allowed with respect to the condition that the highest measurement intensity can be obtained. In addition, if a reduction in measurement intensity of about 15% is allowed with respect to the condition for obtaining the highest measurement intensity, the thickness range of the noble metal portion is about 25 nm or more and about 35 nm or less. Further, as shown in FIG. 3, the tendency of change in the measured intensity due to the difference in height of the column section, since it is the same tendency regardless of the thickness of the noble metal portion, the height of the column portion made of SiO ₂ It is considered that the tendency shown in FIG. 4 can be obtained even when the height is other than 600 nm. Further, in this experimental example, SiO ₂ is used as the column part and Au is used as the noble metal part, but it is considered that the same tendency can be obtained also in the other usable materials described above.

It is the figure which showed schematic structure of the test piece in this embodiment. It is the figure which showed the outline | summary of the vacuum evaporation system used in order to manufacture a test piece. It is the figure which showed the measurement sensitivity change when the thickness of a noble metal part is fixed and the height of a pillar part is changed. It is the figure which showed the measurement sensitivity change when the height of a pillar part is made constant and the thickness of a noble metal part is changed.

DESCRIPTION OF SYMBOLS 1 Substrate 3 Micro columnar body 3a Column part 3b Precious metal part 20 Vacuum deposition apparatus

Claims (3)

In a method of manufacturing a test piece having a nanostructure surface on which a large number of microcolumnar bodies are formed, a step of depositing a transparent metal oxide or metal fluoride on a substrate from an oblique direction, the predetermined obtained by the deposition A first step of forming a large number of anisotropic pillars on the substrate by reversing the deposition direction for each film thickness, and a noble metal having a thickness of 20 nm to 40 nm on the top of the pillars formed. And a second step of vapor deposition. 2. The method of manufacturing a test piece according to claim 1, wherein the column part is 100 nm or more and 1000 nm or less. The test piece according to claim 2, wherein the noble metal portion is made of Au and the column portion is made of SiO ₂ .

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