JP2006145230A - Specimen carrier and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a specimen carrier of high sensitivity which does not limit the substrate. <P>SOLUTION: The specimen carrier comprises the substrate, a porous thin film having a plurality of pores that are arranged on the substrate and formed substantially perpendicularly with respect to the substrate, and a coating metal for covering the surface of the porous thin film and the surface of the pores. The main component except for oxygen of the porous thin film is silicon, germanium, or a mixture of silicon and germanium. The specimen carrier is manufactured in a process of forming a structure thin film on the substrate where a columnar material containing a first component is dispersed in a member containing a second component, namely a semiconductor material capable of forming eutectic crystal with the first component, a process of removing the columnar material and forming the porous thin film, a process of introducing a solution containing metal compound into the pores of the porous thin film, and a process of depositing metal on the surface of the porous thin film and the surface of the pores by chemically changing the metal compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an analyte carrier used for Raman spectroscopic analysis (a carrier for carrying an analyte used for Raman spectroscopic analysis) and a method for producing the same, and more specifically, for performing microanalysis in Raman spectroscopic analysis. The present invention relates to an analyte carrier and a method for producing the same. In particular, an analyte carrier that increases the specific surface area of a metal thin film by coating the surface of a porous thin film with a high specific surface area and the surface of a pore to increase the specific surface area of the metal thin film and enhances the surface enhancement action that occurs during Raman spectroscopic analysis. And a simple method for producing an analyte carrier.

In recent years, single-molecule spectroscopy using surface-enhanced Raman scattering (SERS: Surface-enhanced Raman Scattering) has attracted attention (see Non-Patent Document 1). This refers to a phenomenon in which the Raman scattering intensity of a substance adsorbed on the surface of a metal electrode, sol, crystal and vapor deposition film, semiconductor, etc. is remarkably enhanced as compared to when the substance is in a single state. In comparison, the scattering intensity is about 10 ⁵ to 10 ⁶ times. The characteristics of SERS are as follows: 1) An enhancement effect appears in metals that can generate localized plasmons, such as gold, silver, copper, platinum, nickel, and the like, and the effect is particularly remarkable in gold and silver. 2) The roughness of the metal surface is involved in the development of SERS, and the effect is enhanced by using a metal with a high specific surface area. It is considered that the excitation of surface plasmons on the metal surface plays an important role. ing.

As an example of sensing by SERS, there is one using a porous silicon substrate produced by anodization (see Non-Patent Document 2). This is because the high specific surface area of anodized porous silicon is utilized to deposit silver on the surface of the pores to produce a device having a metal thin film with a high specific surface area, further enhancing the signal enhancement effect of SERS. It enables detection of a very small amount of molecules. A method for manufacturing this element will be described. First, a silicon substrate is made porous by anodization using hydrofluoric acid (HF) to produce a porous silicon substrate. When an aqueous silver nitrate solution is introduced without any treatment on the porous silicon, the pore surface of the porous silicon anodized with hydrofluoric acid is terminated with hydrogen, so the reactivity with silver nitrate is high, and the silver is spontaneously generated. Will be deposited. In order to prevent this reaction, it is necessary to perform a process of reducing the activity by plasma oxidizing the porous silicon pores to silicon dioxide (SiO ₂ ). Silver nitrate aqueous solution is introduced into the surface-oxidized porous silicon, and then dried to deposit silver nitrate on the surface of the porous silicon pores. Finally, the silver nitrate is reduced by heating to reduce the silver nitrate on the surface of the pores. An analyte carrier in which silver is coated on the porous silicon surface without depositing the pores is obtained. It has been reported that the analyte sensitivity prepared in this way significantly increases the sensitivity of detection of trace molecules. Further, in this element, the sensitivity at the time of Raman scattering measurement is improved as the porosity at the time of producing porous silicon is increased.

In addition, an example has been reported in which metal fine particles are deposited on a substrate such as a slide glass using a reactive sputtering method, and a trace amount of molecules is detected by SERS (see Patent Document 1). In this method, silver oxide (Ag ₂ O) is produced by sputtering and then reduced by irradiation with electromagnetic waves to produce silver fine particles, which are used as an analyte carrier. The intensity of the Raman scattered light is increased by the localized plasmons generated near the surface of the metal fine particles, and the sensitivity of the Raman spectroscopic analysis is improved. In the case of an element of this form, the sensitivity varies depending on the particle size of the metal fine particles, and the sensitivity is improved as the particle size is decreased. The particle size is controlled by the film thickness of silver oxide produced by reactive sputtering, and the smaller the film thickness, the smaller the particle size. Also, if a total reflection prism is arranged on the back side of the substrate of the analyte carrier and a Raman scattering light detection element is arranged on the molecule-carrying film side, excitation light is incident from the molecule-carrying film side and Raman scattered light is emitted from the same side. Significantly higher sensitivity is realized compared to the case of detection (see Non-Patent Document 3).
Hyundai Chemistry September 2003 p20-27 Adv. Mater. , 2003, 15, no. 19, p 1595-1598 J. et al. Appl. Phys. , Vol. 88, no. 11, 2000, p6187-6191 JP 2002-277397 A

However, in the method of Non-Patent Document 2, the substrate is limited to silicon, and it is necessary to use an anodizing apparatus and hydrofluoric acid (HF) at the time of anodizing. Further, in porous silicon anodized with hydrofluoric acid (HF), the silicon on the surface of the pores is hydrogen-terminated, so that it reacts with the aqueous silver nitrate solution used when silver is deposited on the surface of the pores. In order to reduce the reactivity, plasma oxidation is required to make the surface of the pores made of silicon oxide (SiO ₂ ).

In the method of Patent Document 1, the film thickness is about 100 nm in order to optimize the particle size of silver oxide (AgO ₂ ) fine particles, and the intensity of Raman scattered light in this case is improved by several hundred to one thousand times. Therefore, further improvement in sensitivity is demanded.

  Accordingly, an object of the present invention is to provide a highly sensitive analyte carrier that does not limit the substrate. In particular, the surface of the pores of an oxide nanoporous material thin film produced on an arbitrary substrate is coated with silver to produce a metal thin film with a high specific surface area, and the analyte whose Raman scattered light intensity is further improved A carrier is provided.

  Another object of the present invention is to provide a method for producing a highly sensitive analyte carrier without limiting the substrate. In particular, the present invention provides a method for producing an analyte carrier using a simpler process that does not use an anodic oxidation process using hydrofluoric acid and does not require an inactivation process by plasma oxidation on the surface of pores.

  The above objective is solved by the analyte carrier of the present invention.

That is, the present invention is a carrier for carrying an analyte used for Raman spectroscopic analysis,
A substrate, a porous thin film having a plurality of pores disposed on the substrate and substantially perpendicular to the substrate, and the surface of the porous thin film and the surface of the pores are coated It is made of a coating metal, and the material of the porous thin film is silicon, germanium, or a mixture of silicon and germanium as a component excluding oxygen.

  In particular, the porous thin film is preferably an oxide.

  Further, the coating metal is preferably Au, Ag, Cu, Pt, Ni, W, or Ti, and more preferably Ag.

  The present invention is also an analyzer comprising the above-mentioned analyte carrier and means for irradiating the analyte on the carrier with light.

  The present invention also provides a method for producing an analyte carrier having the above structure.

That is, the present invention is a method for producing an analyte carrier for use in Raman spectroscopy,
A structure in which a columnar substance including a first component is dispersed in a member including a second component that is a semiconductor material capable of forming a eutectic with the first component on a substrate. Forming a body thin film;
Removing the columnar material to form a porous thin film; and
Introducing a solution containing a metal compound into the pores of the porous thin film; and
And a step of chemically changing the metal compound to deposit a metal on the surface of the porous thin film and the surface of the pores.

Further, the present invention is a method for producing an analyte carrier used for Raman spectroscopic analysis,
A structure in which a columnar substance including a first component is dispersed in a member including a second component that is a semiconductor material capable of forming a eutectic with the first component on a substrate. Forming a body thin film;
Removing the columnar material to form a porous thin film; and
Oxidizing the porous thin film;
Introducing a solution containing a metal compound into the pores of the porous thin film; and
And a step of chemically changing the metal compound to deposit a metal on the surface of the porous thin film and the surface of the pores.

  In particular, the step of chemically changing a metal compound to deposit metal on the surface of the porous thin film and the surface of the pores includes drying the solution containing the metal compound to form the surface of the porous thin film and the fine film. A step of depositing a metal compound on the surface of the pores, and a step of depositing a metal on the surface of the porous thin film and the surface of the pores by reducing the metal compound deposited on the surface of the pores. Is preferred.

  Moreover, it is preferable that the porous thin film is oxidized by a step of removing the columnar substance using an aqueous solution.

  Moreover, it is preferable that the said metal compound is a compound containing Ag.

  An analyte carrier capable of detecting a very small amount of molecules by Raman spectroscopic analysis can be provided.

  Embodiments of the present invention will be described below.

  The analyte carrier according to this embodiment is a metal having an effect of enhancing Raman scattered light without blocking pores on the surface of a porous oxide thin film having a plurality of pores produced on an arbitrary substrate. By coating, the specific surface area of the metal thin film is increased. By this, molecules are adsorbed on the surface of the porous thin film and on the surface of the pores, and by performing Raman spectroscopy using surface-enhanced Raman scattering (SERS), a small amount of the small amount present in the solution is present. Molecules can be detected with high sensitivity.

  In addition, the method for producing an analyte carrier according to the present embodiment can be produced on an arbitrary substrate, and does not require a step such as anodization using hydrofluoric acid or oxygen plasma treatment. This is a manufacturing method that facilitates the production of a material thin film. This makes it possible to produce an analyte carrier simply and at low cost without using an anodizing device or a dangerous solution such as hydrofluoric acid.

  Next, the configuration of the analyte carrier and the manufacturing method thereof will be described below.

<About the structure of the analyte carrier>
First, the configuration of the analyte carrier of the present invention will be described.

  FIG. 1 shows a configuration example of an analyte carrier of the present invention. In FIG. 1, 11 is a substrate, 12 is a porous thin film, 13 is a coated metal, and 14 is a pore.

  First, the substrate 11 will be described. As the substrate, any substrate can be used as long as a thin film can be formed on the upper surface of the substrate by a film forming method such as sputtering. An insulating substrate such as quartz glass or slide glass can be used. If the above structure can be formed on a silicon substrate, a semiconductor substrate such as gallium arsenide or indium phosphide, a metal substrate such as aluminum, or a substrate as a supporting member, a flexible substrate (for example, polyimide resin) may be used. it can. The substrate surface need not be smooth, and a substrate having a complicated surface shape may be used.

  When producing an analyte carrier that irradiates excitation light from the back side of the substrate, it is necessary to use a substrate through which the excitation light is transmitted. Further, a total reflection prism may be disposed on the back surface of the substrate. With this configuration, the excitation light introduced from the back surface of the substrate is totally reflected at the interface between the substrate and the total reflection prism, and only the Raman scattered light generated by the excitation light is detected from the film surface direction. This is because noise during measurement is reduced and detection with higher sensitivity becomes possible.

  Next, the porous thin film 12 will be described. The porous thin film 12 is a base material in which the columnar substance 21 including the first component shown in FIG. 2A includes the second component capable of forming a eutectic with the first component. The columnar substance 21 is removed from the structure thin film 23 dispersed in the substance 24. This is shown in FIG. In FIG. 2B, 25 is a porous thin film formed by removing the columnar substance 21, and 26 is a pore formed by removing the columnar substance 21.

  Here, the columnar substance 21 including the first component is made of, for example, a material mainly composed of aluminum. The base material 24 including the second component capable of forming a eutectic with the first component is made of, for example, germanium, silicon, or a mixture of germanium and silicon.

  The base material 24 is preferably composed mainly of silicon or germanium. It is also possible to use a mixture of silicon and germanium as a main component. The base material 24 is preferably composed mainly of silicon or germanium, but aluminum (Al), oxygen (O), argon (Ar), nitrogen (N) of several atomic% to several tens atomic%. Various elements such as hydrogen (H) may be contained.

  The base material 24 is preferably an oxide. However, if the surface of the porous thin film and the surface of the pores are oxidized, the inside of the base material may be non-oxide crystalline or amorphous silicon, germanium, or a mixture of silicon and germanium. .

  The shape of the pores 26 may be a circle as shown in FIG. 4A or an ellipse as shown in FIG. 4B, and if the mechanical strength is maintained, FIG. It may be an irregular pore as shown in (c). Such a pore shape can be changed by the mixing ratio of the first component and the second component when the structure thin film 23 is produced.

  The thickness of the porous thin film is not particularly limited as long as the porous thin film is formed, but is preferably 1 nm to 50 μm, and more preferably 100 nm to 10 μm.

  Next, the coated metal 13 coated on the porous thin film surface will be described. The covering metal 13 is formed on the surface of the porous thin film and the surface of the pores without blocking the pores. The material of the coating metal can be formed on the surface of the porous thin film and the surface of the pores, and any metal may be used as long as it does not block the pores. The coating metal 13 is preferably a metal capable of generating surface plasmon or localized plasmon, specifically Au, Ag, Cu, Pt, Ni, W, Ti, etc., more preferably Au, Ag, and more preferably Ag. is there.

  Further, the thickness of the coating metal 13 is desirably a film thickness that can cover the entire surface of the pores without blocking the pores. Specifically, in the case of a thin film, the thickness is preferably 10 nm or less. When the coating metal is composed of fine particles, the fine particle diameter is desirably 10 nm or less.

  An example of an analysis method performed using the analyte carrier having the above-described configuration is a configuration as shown in FIG. In FIG. 3, the laser beam 38 generated from the laser generator 35 is incident from the film surface of the porous thin film 32, and an enhancing action is generated between the coated metal 33 excited by the laser beam and the non-detection molecule 34, and the enhancement is performed. The Raman scattered light 39 is emitted. This Raman scattered light 39 is detected by the photodetector 36. When the substrate 31 transmits laser light, a total reflection prism is disposed on the back surface of the analyte carrier, and non-detected molecules are excited by the coating metal excited by the laser light incident from the substrate surface, thereby causing Raman scattered light. May be emitted and detected by a photodetector. With such a configuration, detection with higher sensitivity becomes possible.

<Configuration of Analyte Carrier Production Method>
Next, a method for producing the analyte carrier will be described in detail.

  The steps of one embodiment in the method for producing an analyte carrier are shown below. The method for producing an analyte carrier includes the following steps (a) to (d).

Step (a): A columnar substance including a first component on a substrate is dispersed in a member including a second component that is a semiconductor material capable of forming a eutectic with the first component. Step (b): removing the columnar substance to form a porous thin film Step (c): a solution containing a metal compound in the pores of the porous thin film Step (d): Step of reducing metal compound and depositing metal on the surface of the porous thin film and the surface of the pores Hereinafter, each step will be described with reference to FIG. FIGS. 5A to 5D correspond to the steps (a) to (d), and are cross-sectional views illustrating each configuration.

  Step (a): As shown in FIG. 5A, a columnar substance 52 including a first component on a substrate 51 is a semiconductor material capable of forming a eutectic with the first component. The structure thin film 54 dispersed in the base material 53 including the second component is formed. For example, aluminum and silicon (or germanium, or a mixture of silicon and germanium) that forms a columnar material (first component) are formed in a base material (second component), and a sputtering method, electron beam evaporation, etc. A mixed film (an aluminum silicon mixed film, an aluminum germanium mixed film, or an aluminum silicon germanium mixed film), which is a structural thin film, is formed on the substrate by a method capable of forming a substance in a non-equilibrium state.

  When an aluminum silicon mixed film (or aluminum germanium mixed film or aluminum silicon germanium mixed film) is formed by such a method, an eutectic structure in which aluminum and silicon (or germanium, or a mixture of silicon and germanium) are metastable. A columnar material made of aluminum forms a nanostructure (columnar structure) of several nanometers to several tens of nanometers in a base material made of amorphous silicon (or amorphous germanium, or a mixture of amorphous silicon and germanium). And self-organizing.

  Note that in a mixed film of aluminum and amorphous silicon (or amorphous germanium, or a mixture of amorphous silicon and germanium), the amount of silicon (or germanium, or a mixture of silicon and germanium) in the formed film is the same as that of aluminum. It is 20-70 atomic% with respect to the whole quantity of silicon (or germanium, or a mixture of silicon and germanium), and preferably 25-65 atomic%. If the amount of silicon (or germanium, or a mixture of silicon and germanium) is within such a range, the columnar material of aluminum is present in the matrix material of amorphous silicon (or amorphous germanium, or a mixture of silicon and germanium in an amorphous state). A dispersed aluminum silicon mixed film (or aluminum germanium mixed film or aluminum silicon germanium mixed film) is obtained. The shape of the columnar substance varies depending on the ratio of aluminum and silicon (or germanium, or a mixture of silicon and germanium) in the mixed film.

  The atomic% indicating the ratio of aluminum and silicon (or germanium, or a mixture of silicon and germanium) indicates the ratio of the number of atoms of silicon (or germanium, or a mixture of silicon and germanium) and aluminum, and atom% Alternatively, it is also described as at%. For example, silicon (or germanium, or silicon and germanium) in an aluminum silicon mixed film (or aluminum germanium mixed film or aluminum silicon germanium mixed film) by inductively coupled plasma emission spectrometry (ICP method). It is the value when the amount of aluminum is quantitatively analyzed.

  Step (b): Next, the columnar substance 52 is removed, and a porous thin film 55 is formed.

  For example, aluminum which is a columnar substance in the aluminum silicon mixed film (or aluminum germanium mixed film or aluminum silicon germanium mixed film) is etched with a solution, and pores are formed in the matrix (here, silicon, germanium or silicon germanium). 56 is formed. Thereby, a porous thin film as shown in FIG. 5B is formed. The pore shape of the porous thin film varies depending on the ratio of aluminum and silicon (or germanium or silicon and germanium) in the aluminum silicon mixed film (or aluminum germanium mixed film or aluminum silicon germanium mixed film), and is shown in FIG. It is a shape like this. As the proportion of aluminum increases, the pore shape changes from a circular shape to an elliptical shape and an irregular shape.

  The solution used for etching is preferably an acid that dissolves aluminum but hardly dissolves silicon (or germanium), and is preferably an acid such as phosphoric acid, sulfuric acid, hydrochloric acid, or chromic acid solution. However, if there is no problem in forming pores by etching, an alkali such as sodium hydroxide or ammonia can be used, and it is not particularly limited to the kind of acid or the kind of alkali, but several kinds of acid solutions or several kinds You may use what mixed the alkaline solution. In addition, for example, the etching conditions, solution temperature, concentration, time, etc. can be appropriately set according to the porous thin film to be produced.

  Step (c): Next, a solution 57 containing a metal compound is introduced into the pores of the porous thin film 55.

As long as the solution to be introduced is a metal compound capable of forming a coating metal without blocking the pores of the porous thin film during metal deposition in the step (d), any metal compound solution may be used. Good. For example, a metal may be deposited on the surface of the pores without blocking the pores using an electroless plating method, and in this case, a metal compound such as Ni, Cu, Ag, Pt, or Au is ionized and generated. A plating bath containing metal ions may be used. Among these, it is desirable to introduce a silver nitrate (AgNO ₃ ) aqueous solution. This is because by using a silver nitrate solution, an Ag thin film can be formed relatively easily without closing the pores of the porous thin film in the subsequent step (d). The concentration and temperature of the aqueous silver nitrate solution are not particularly limited as long as the Ag thin film can be formed without blocking pores of the porous thin film.

  FIG. 5C shows a state after the solution is introduced. After the introduction of the solution, it is preferable to remove the excess solution remaining on the top of the porous thin film. Any method may be used as the removing method, but a method (blowing) of blowing off the excessive solution on the surface with a gas such as air or nitrogen is preferable.

  Step (d): Next, a metal is deposited on the surface of the pores of the porous thin film to form a coated metal 58.

  As shown in FIG. 5D, a metal is deposited on the surface of the pores of the porous thin film to form an analyte carrier in which the porous thin film is covered with the metal thin film. When depositing a metal from a solution containing a metal compound, the metal may be deposited by any method as long as the deposited metal does not block the pores of the porous thin film. The metal may be deposited directly on the surface of the pores from inside.

  The deposited metal is preferably Ag. This is because the Ag thin film can be easily obtained by heating and reducing silver nitrate. When depositing a metal from a solution containing other metal compounds, the metal may be deposited by any method as long as the deposited metal does not block the pores of the porous thin film, such as electroless plating. The metal may be deposited directly on the surface of the pores from the solution by the method.

  In addition, it is preferable to oxidize the porous thin film 55 after the step (b) to make the porous thin film an oxide. After the etching in the step (b), the porous thin film is oxidized, for example, in an oxygen atmosphere. An annealing treatment or the like is preferably performed. By performing such treatment, the mechanical strength of the porous thin film increases. In addition, the porous thin film is transparent to visible light, thereby increasing the wavelength selectivity of the laser used for Raman spectroscopic analysis. The annealing temperature and time are not particularly limited as long as the annealing temperature is such that the pore structure of the porous thin film is not destroyed. This oxidation step may be performed during step (b). Further, the oxidation of the porous thin film occurs when an aqueous solution is used in the steps (b) and (c), etc., or during the heating step in the atmosphere in the step (d) without providing a separate step. sell. For example, the surface of the pores of the porous thin film prepared by etching in the step (b) is oxidized with water in the solution to become silicon oxide (or germanium oxide, or a mixture of silicon oxide and germanium oxide).

  Hereinafter, the case where the coating metal is Ag will be described with reference to FIG.

  Steps (a ′) and (b ′) in FIG. 6 are the same steps as steps (a) and (b), and are not particularly limited even when the coating metal is Ag.

  A step of oxidizing the porous thin film may be added after the step (b ′).

  In the step (c ′), an aqueous silver nitrate solution is used as the aqueous solution containing the metal compound, and the aqueous silver nitrate solution 61 is introduced into the pores of the porous thin film. The concentration of the aqueous silver nitrate solution is not particularly limited, but is preferably 0.01 mol / l or more and 10 mol / l or less, more preferably 0.1 mol / l or more and 5 mol / l or less, and 0.5 mol / l or less. More preferably, it is 1 or more, and further 2 mol / l or less.

  In the step (d ′), the aqueous silver nitrate solution is dried to deposit solid silver nitrate 62 on the surfaces of the pores of the porous thin film. Precipitation conditions require drying and precipitation at a temperature at which silver nitrate is not reduced. Further, it is preferable that the solid silver nitrate precipitated at this time does not block the pores. Specifically, drying and precipitation at 300 ° C. or lower are preferable, and drying and precipitation at 200 ° C. or lower is more preferable. Moreover, what is necessary is just to set the time of drying and precipitation corresponding to drying and precipitation temperature, and optimal time.

In the step (e ′), heat treatment is performed, and silver 63 is precipitated by the following reaction.
AgNO ₃ (solid) → Ag (solid) + NO ₂ (gas) + 1 / 2O ₂ (gas)
When reducing silver nitrate deposited on the surface of the pores, it should be above the temperature at which silver nitrate is reduced and silver is produced, and below the temperature at which the produced silver diffuses and aggregates to block the pores, Specifically, heating is preferably performed at a temperature of 300 ° C. or higher and 800 ° C. or lower, and more preferably heated at a temperature of 400 ° C. or higher and 600 ° C. or lower. The heating time may be set to an optimum time corresponding to the heating temperature.

  In this example, an analyte carrier prepared by forming a porous thin film structure on a glass substrate and coating Ag and the surfaces thereof and pores will be described.

  An aluminum silicon mixed film containing 65 atomic% of aluminum with respect to the total amount of aluminum and silicon was formed to a thickness of about 1 μm on a glass substrate by magnetron sputtering. A circular aluminum silicon mixed target having a diameter of 4 inches (101.6 mm) was used as the target. As the aluminum silicon mixed target, an aluminum powder and a silicon powder sintered at a ratio of 65 atomic%: 35 atomic% were used. Sputtering conditions were as follows: RF flow rate, Ar flow rate: 30 sccm, discharge pressure: 0.15 Pa, input power: 100 W. The substrate temperature was 100 ° C.

  In addition, the aluminum silicon mixed film was observed with FE-SEM (field emission scanning electron microscope). As shown in FIG. 5A, the shape of the surface viewed from the diagonally upward direction of the substrate was a circular array of aluminum columnar structures surrounded by silicon regions. The average diameter of the aluminum columnar structure portion was 12 nm. Moreover, when the cross section was observed with FE-SEM, each aluminum columnar structure was mutually independent.

  The aluminum silicon mixed film thus prepared was immersed in a 5 wt% phosphoric acid solution for 24 hours as shown in FIG. 5B, and only aluminum columnar structure portions were selectively etched to form pores. As a result, a porous film composed of a member whose main component excluding oxygen was silicon was produced. Note that silicon in the porous thin film is oxidized.

  Next, an aluminum silicon mixed film etched with 5 wt% phosphoric acid (a porous thin film composed of a material whose main component excluding oxygen is silicon) was observed with an FE-SEM (field emission scanning electron microscope). did. As shown in FIG. 5B, the shape of the surface viewed from the diagonally upward direction of the substrate was that pores surrounded by silicon members were two-dimensionally arranged. The pore diameter was 12 nm. Further, it was confirmed that the produced porous thin film was in an amorphous state from the diffraction peak shape by X-ray diffraction, and that the silicon in the porous thin film was oxidized from the peak shape in the microscopic Raman scattering measurement.

  Next, the porous thin film made of silicon oxide formed on the glass substrate was immersed in a 1 mol / l silver nitrate aqueous solution for 20 minutes, then removed from the solution, and excess aqueous solution adhering to the surface was removed by blowing with nitrogen gas. Next, the porous thin film into which the silver nitrate solution had been introduced was dried in air at 100 ° C. for 20 minutes to precipitate solid silver nitrate on the surface of the pores. Next, this porous thin film was heated in air at 500 ° C. for 30 minutes, and silver was deposited on the surface of the pores of the porous thin film to produce the target analyte carrier.

  The surface shape of the analyte carrier was observed with an FE-SEM (field emission scanning electron microscope). The shape of the surface seen from the diagonally upward direction of the substrate was that pores surrounded by silver were two-dimensionally arranged. The pore diameter was 4 nm. Further, when observed with a cross-sectional FE-SEM, it was observed that the surface of the pores was covered with silver and reached the vicinity of the interface between the substrate and the porous thin film without being blocked. In order to confirm that the silver has reached the bottom of the pores, the composition distribution in the depth direction of the film thickness is examined while etching the porous thin film with Ar ions using an XPS (photoelectron spectrometer). It was. As a result, a peak derived from silver was detected until the analysis depth was about 1 μm, which was the film thickness, and the intensity did not change greatly. However, when the analysis depth was 1 μm or more, the peak derived from silver rapidly decreased and almost disappeared. From this, it was confirmed that silver was present to a depth of about the film thickness, and the silver was covered to the bottom of the pores.

A rhodamine 6G dye molecule solution having a concentration of 100 μmol / l is dropped on the analyte carrier, and a titanium-sapphire laser with a wavelength of 785 nm is irradiated from the surface of the analyte carrier as shown in FIG. Raman scattered light was detected by a detector installed on the surface side of the analyte carrier. At this time, for comparison, the same experiment was performed on a film in which a silver thin film was formed to a thickness of about 10 nm on a flat glass substrate as shown in FIG. 7B, and the analyte carrier using the porous thin film 82 was used. And compared. As a result, in the analyte carrier using a porous thin film, is the peak intensity of a Raman spectrum derived in comparison with the device fabricated on a flat glass substrate Rhodamine 6G dye molecules strongly about 10 ⁶ times It was confirmed that

  When Raman scattering measurement is performed using an analyte carrier in which silver is coated on a porous thin film as described above, surface-enhanced Raman scattering (SERS) is generated by a silver thin film having a high specific surface area. The detection sensitivity of this molecule is remarkably improved, and it becomes possible to detect a very small amount of molecules in the solution. In addition to the dye molecules as described above, trace amounts of biomolecules such as adenine and guanine and DNA can also be detected.

  In this example, an analyte carrier prepared by forming a porous thin film structure on a glass substrate and coating Ag and the surfaces thereof and pores will be described.

  An aluminum silicon mixed film containing 75 atomic% of aluminum with respect to the total amount of aluminum and silicon was formed to a thickness of about 1 μm on a glass substrate by magnetron sputtering. A circular aluminum silicon mixed target having a diameter of 4 inches (101.6 mm) was used as the target. As the aluminum silicon mixed target, an aluminum powder and silicon powder sintered at a ratio of 75 atomic%: 25 atomic% was used. Sputtering conditions were as follows: Ar flow rate: 20 sccm, discharge pressure: 0.075 Pa, input power: 80 W using an RF power source. The substrate temperature was 100 ° C.

  In addition, the aluminum silicon mixed film was observed with FE-SEM (field emission scanning electron microscope). As shown in FIG. 5A, the shape of the surface viewed from the obliquely upward direction of the substrate was an elliptical shape surrounded by a silicon region or a bent elliptical aluminum columnar structure two-dimensionally arranged. Moreover, when the cross section was observed with FE-SEM, each aluminum columnar structure was mutually independent.

  The aluminum silicon mixed film thus prepared was immersed in a 5 wt% phosphoric acid solution for 24 hours as shown in FIG. 5B, and only aluminum columnar structure portions were selectively etched to form pores. As a result, a porous thin film composed of a member whose main component excluding oxygen was silicon was produced. Note that silicon in the porous thin film is oxidized.

  Next, an aluminum silicon mixed film etched with 5 wt% phosphoric acid (a porous film composed of a member whose main component excluding oxygen is silicon) was observed with an FE-SEM (field emission scanning electron microscope). . As shown in FIG. 5 (b), the shape of the surface viewed obliquely upward from the substrate was such that elliptical pores surrounded by silicon members were two-dimensionally arranged. The produced porous thin film was in an amorphous state from the diffraction peak shape by X-ray diffraction, and it was confirmed that the silicon in the porous thin film was oxidized from the peak shape in microscopic Raman scattering measurement. .

  Next, the porous thin film made of silicon oxide formed on the glass substrate was immersed in a 1 mol / l silver nitrate aqueous solution for 20 minutes, then taken out from the solution, and the excess aqueous solution adhering to the surface was removed by blowing with nitrogen gas. . Next, the porous thin film into which the silver nitrate solution was introduced was dried by heating at 100 ° C. for 20 minutes in air to deposit solid silver nitrate on the surface of the pores. Next, this porous thin film was heated in air at 500 ° C. for 30 minutes, and silver was deposited on the surface of the pores of the porous thin film to produce the target analyte carrier.

  The surface shape of the analyte carrier was observed with an FE-SEM (field emission scanning electron microscope). The shape of the surface seen from the diagonally upward direction of the substrate was that pores surrounded by silver were two-dimensionally arranged. Further, when observed with a cross-sectional FE-SEM, it was observed that the surface of the pores was covered with silver and reached the vicinity of the interface between the substrate and the porous thin film without being blocked. In order to confirm that the silver has reached the bottom of the pores, the composition distribution in the depth direction of the film thickness is examined while etching the porous thin film with Ar ions using an XPS (photoelectron spectrometer). It was. As a result, a peak derived from silver was detected until the analysis depth was about 1 μm, which was the film thickness, and the intensity did not change greatly. However, when the analysis depth was 1 μm or more, the peak derived from silver rapidly decreased and almost disappeared. From this, it was confirmed that silver was present to a depth of about the film thickness, and the silver was covered to the bottom of the pores.

A rhodamine 6G dye molecule solution having a concentration of 100 μmol / l is dropped on the analyte carrier, and a titanium: sapphire laser with a wavelength of 785 nm is irradiated from the surface of the analyte carrier as shown in FIG. Raman scattered light was detected by a detector installed on the surface side of the analyte carrier. For comparison, a similar experiment was also conducted on a film in which a silver thin film was formed to a thickness of about 10 nm on a flat glass substrate as shown in FIG. 7B, and the analyte carrier using the porous thin film was A comparison was made. As a result, in the analyte carrier using the porous thin film, the peak intensity of the Raman spectrum derived from the rhodamine 6G dye molecule is about 10 ¹⁰ times stronger than that of the element produced on the flat glass substrate. It was confirmed that

  When Raman scattering measurement is performed using an analyte carrier in which silver is coated on a porous thin film as described above, surface-enhanced Raman scattering (SERS) is generated by a silver thin film having a high specific surface area. The detection sensitivity of this molecule is remarkably improved, and it becomes possible to detect a very small amount of molecules in the solution.

  In this example, an analyte carrier prepared by forming a porous thin film structure on a glass substrate and coating Ag and the surfaces thereof and pores will be described.

  An aluminum germanium mixed film containing 70 atomic% of aluminum with respect to the total amount of aluminum and germanium was formed to a thickness of about 1 μm on a glass substrate by magnetron sputtering. As a target, a circular aluminum germanium mixed target having a diameter of 4 inches (101.6 mm) was used. Sputtering conditions were as follows: Ar flow rate: 15 sccm, discharge pressure: 0.06 Pa, input power: 60 W using an RF power source. The substrate temperature was 100 ° C.

  In addition, the aluminum germanium mixed film was observed with an FE-SEM (field emission scanning electron microscope). As shown in FIG. 5A, the shape of the surface viewed from the obliquely upward direction of the substrate was a circular aluminum columnar structure surrounded by a germanium region two-dimensionally arranged. The average diameter of the aluminum columnar structure was 15 nm. Moreover, when the cross section was observed with FE-SEM, each aluminum columnar structure was mutually independent.

  The aluminum germanium mixed film thus prepared was immersed in a 5 wt% phosphoric acid solution for 10 hours as shown in FIG. 5B, and only aluminum columnar structure portions were selectively etched to form pores. As a result, a porous thin film composed of a member whose main component excluding oxygen was germanium was produced. Note that germanium in the porous thin film is oxidized.

  Next, using an FE-SEM (field emission scanning electron microscope), an aluminum germanium mixed film etched with 5 wt% phosphoric acid (a porous thin film composed of a member containing germanium as a main component excluding oxygen) was observed. did. As shown in FIG. 5 (b), the shape of the surface viewed from the obliquely upward direction of the substrate was circular pores surrounded by germanium members arranged two-dimensionally. The average diameter of the pores was 15 nm. Moreover, it was confirmed that the produced porous thin film was in an amorphous state from the diffraction peak shape by X-ray diffraction, and germanium in the porous thin film was oxidized from the peak shape in microscopic Raman scattering measurement.

  Next, the porous thin film made of germanium oxide formed on the glass substrate was immersed in a 1 mol / l silver nitrate aqueous solution for 20 minutes, then taken out from the solution, and the excess aqueous solution adhering to the surface was removed by blowing with nitrogen gas. . Next, the porous thin film into which the silver nitrate solution was introduced was dried by heating at 100 ° C. for 20 minutes in air to deposit solid silver nitrate on the surface of the pores. Next, this porous thin film was heated in air at 500 ° C. for 30 minutes, and silver was deposited on the surface of the pores of the porous thin film to produce the target analyte carrier.

  The surface shape of the analyte carrier was observed with an FE-SEM (field emission scanning electron microscope). The shape of the surface seen from the diagonally upward direction of the substrate was that pores surrounded by silver were two-dimensionally arranged. Further, when observed with a cross-sectional FE-SEM, it was observed that the surface of the pores was covered with silver and reached the vicinity of the interface between the substrate and the porous thin film without being blocked. In order to confirm that the silver has reached the bottom of the pores, the composition distribution in the depth direction of the film thickness is examined while etching the porous thin film with Ar ions using an XPS (photoelectron spectrometer). It was. As a result, a peak derived from silver was detected until the analysis depth was about 1 μm, which was the film thickness, and the intensity did not change greatly. However, when the analysis depth was 1 μm or more, the peak derived from silver rapidly decreased and almost disappeared. From this, it was confirmed that silver was present to a depth of about the film thickness, and the silver was covered to the bottom of the pores.

A rhodamine 6G dye molecule solution having a concentration of 100 μmol / l is dropped on the analyte carrier, and a titanium: sapphire laser with a wavelength of 785 nm is irradiated from the surface of the analyte carrier as shown in FIG. Raman scattered light was detected by a detector installed on the surface side of the analyte carrier. For comparison, a similar experiment was also conducted on a film in which a silver thin film was formed to a thickness of about 10 nm on a flat glass substrate as shown in FIG. 7B, and the analyte carrier using the porous thin film was A comparison was made. As a result, in the analyte carrier using the porous thin film, the peak intensity of the Raman spectrum derived from the rhodamine 6G dye molecule is about 10 ⁷ times stronger than that of the element produced on the flat glass substrate. It was confirmed that

  In this example, an aluminum germanium mixed film was prepared using a mixed target of aluminum and germanium at the time of preparation of the porous thin film, and then the aluminum was removed to use the porous thin film of germanium oxide. A similar analyte carrier can be produced using a mixed target of aluminum, silicon, and germanium optimized for.

  The analyte carrier and the method for producing the same of the present invention can be used in an analysis apparatus for detecting an extremely small amount of molecules.

It is the schematic which shows the structure of the analyte carrier of this invention. Outline of a structure thin film composed of a columnar substance and a base material constituting a porous thin film used for the analyte carrier of the present invention, and a porous thin film formed by removing the columnar substance from the structure thin film FIG. It is an example of the analysis method using the analyte carrier of the present invention. It is an example of the pore shape of the porous body thin film used for the analyte carrier of the present invention. It is a structural example of the manufacturing method of the analyte carrier of this invention. It is a structural example of the manufacturing method of the analyte carrier of this invention. The analysis method using the analyte carrier of the present invention and the analysis method used for comparison.

Explanation of symbols

11, 22, 31, 51, 71, 81 Substrate 12, 25, 32, 41, 43, 46, 55, 72, 82 Porous thin film 13, 33, 58, 73, 83 Coated metal 14, 26, 56 Fine Holes 21 and 52 Columnar substances 23 and 54 Structure thin films 24 and 53 Base material substances 34, 74, 84 Detected molecules 35, 75, 85 Laser generators 36, 76, 86 Photo detector 38 Laser light 39 Raman scattered light 42 Circular pore 43 Elliptical pore 45 Amorphous pore 57 Solution containing metal compound 61 Silver nitrate aqueous solution 62 Silver nitrate 63 Deposited silver 77, 87 Metal thin film

Claims (10)

A carrier for carrying an analyte used for Raman spectroscopy,
A substrate, a porous thin film having a plurality of pores disposed on the substrate and substantially perpendicular to the substrate, and the surface of the porous thin film and the surface of the pores are coated An analyte carrier comprising a coating metal, wherein the material of the porous thin film is silicon, germanium, or a mixture of silicon and germanium as a component excluding oxygen.   2. The analyte carrier according to claim 1, wherein the porous thin film is an oxide.   The analyte carrier according to claim 1, wherein the coating metal is any one of Au, Ag, Cu, Pt, Ni, W, and Ti.   4. The analyte carrier according to claim 1, wherein the coated metal is Ag.   An analyzer comprising the carrier according to claim 1 and means for irradiating the analyte on the carrier with light. A method for producing an analyte carrier for use in Raman spectroscopy, comprising:
A structure in which a columnar substance including a first component is dispersed in a member including a second component that is a semiconductor material capable of forming a eutectic with the first component on a substrate. Forming a body thin film;
Removing the columnar material to form a porous thin film; and
Introducing a solution containing a metal compound into the pores of the porous thin film; and
And a step of chemically changing the metal compound to deposit metal on the surface of the porous thin film and the surface of the pores. A method for producing an analyte carrier for use in Raman spectroscopy, comprising:
A structure in which a columnar substance including a first component is dispersed in a member including a second component that is a semiconductor material capable of forming a eutectic with the first component on a substrate. Forming a body thin film;
Removing the columnar material to form a porous thin film; and
Oxidizing the porous thin film;
Introducing a solution containing a metal compound into the pores of the porous thin film; and
And a step of chemically changing the metal compound to deposit a metal on the surface of the porous thin film and the surface of the pores. The step of chemically changing the metal compound according to claim 6 or 7 to deposit a metal on the surface of the porous thin film and the surface of the pores,
Drying the solution containing the metal compound to deposit the metal compound on the surface of the porous thin film and the surface of the pores; and
And a step of reducing the metal compound deposited on the surface of the pores to deposit metal on the surface of the porous thin film and the surface of the pores.   The method for producing an analyte carrier according to any one of claims 6 to 8, wherein the porous thin film is oxidized by a step of removing a columnar substance using an aqueous solution.   The method for producing an analyte carrier according to any one of claims 6 to 9, wherein the metal compound is a compound containing Ag.