JPWO2017159593A1 - Raman scattered light measuring device, probe, and method of manufacturing the probe - Google Patents

Abstract

Provided are a Raman scattered light measuring device, a probe, and a method of manufacturing a probe that make it possible to measure Raman scattered light with high sensitivity.
By irradiating the tip of the probe (12) with a focused ion beam, the tip of the probe (12) is removed to form the tip surface (14). Next, the probe (12) is immersed in a chloroauric acid aqueous solution (metal ion-containing solution). Au is deposited on the tip surface (14), and an aggregate (13) of Au nanostructures (metal nanostructures) is formed. The probe (12) is used to measure tip enhanced Raman scattering. In the Raman scattered light measurement device, the tip surface (14) of the probe (12) is non-perpendicular to the perpendicular (53) of the sample mounting surface (51), and the optical axis (41) of the lens (4). Is tilted. There are few portions of the probe (12) between the portion where the Raman scattered light is generated on the sample (52) and the lens (4), and the generated Raman scattered light is absorbed or reflected by the probe (12). A ratio is low and the efficiency which condenses Raman scattered light with a lens (4) is high.

Description

  The present invention relates to a Raman scattered light measurement device, a probe, and a probe manufacturing method for measuring tip-enhanced Raman scattering.

  Tip-enhanced Raman scattering is a method in which a metal tip of a probe is brought close to or in contact with a sample, light is irradiated to the tip of the probe, and enhanced Raman scattered light is generated from the sample. Irradiation of light to the tip of the probe made of metal induces localized plasmons, generates a locally enhanced electric field, and enhances Raman scattered light. By utilizing the tip-enhanced Raman scattering, Raman spectroscopic analysis of a minute region of the sample becomes possible. As the probe, a probe having a metal nanostructure formed at the tip of a probe for SPM (Scanning Probe Microscope) such as AFM (Atomic Force Microscope) is used. The probe is formed in a pyramid shape at the end of the cantilever. Patent Document 1 discloses a technique for irradiating the tip of a probe with light and realizing tip-enhanced Raman scattering.

JP 2006-90715 A

  When measuring the tip-enhanced Raman scattering, a lens for collecting light at the tip of the probe and collecting the generated Raman scattered light is required. In a measurement apparatus in which a lens is arranged on the same side as the probe with respect to the surface of the sample, a part of the probe may be located between the lens and the portion where the Raman scattered light is generated. For this reason, the generated Raman scattered light is absorbed or reflected by a part of the probe, the efficiency of collecting the Raman scattered light with the lens is lowered, and it becomes difficult to measure the Raman scattered light with high sensitivity. is there. There is also a measuring device in which a lens is arranged on the back side of the sample. In this measuring device, the efficiency of condensing Raman scattered light with the lens is not reduced by the probe. However, since it is necessary for light to pass through the sample, it is difficult to measure Raman scattered light for samples that are difficult to transmit light, such as opaque samples or thick samples. Therefore, there is a problem that it is difficult to measure Raman scattered light with high sensitivity for a sample that is difficult to transmit light.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a Raman scattered light measurement apparatus and probe that can measure Raman scattered light with high sensitivity for any sample. And it is providing the manufacturing method of a probe.

  The Raman scattered light measurement apparatus according to the present invention includes a sample placement surface on which a sample is placed, a semiconductor probe, and an irradiation unit that irradiates light to the tip of the probe that is close to or in contact with the sample. And a Raman scattered light measuring apparatus comprising: a lens that collects Raman scattered light generated from the sample; and a detection unit that detects the Raman scattered light collected by the lens. The lens is disposed at a position facing the sample mounting surface, the lens is disposed with an optical axis inclined with respect to a normal to the sample mounting surface, and the probe has a tip that is not perpendicular to the normal It has the surface and the metal structure protruded from this front end surface, It is characterized by the above-mentioned.

  In the present invention, the Raman scattered light measuring device brings the tip of the probe close to or in contact with the sample placed on the sample placement surface, irradiates the tip of the probe with light, and emits the Raman scattered light to the lens. The light is collected by and detected by the detection unit. The lens tilts the optical axis with respect to the normal of the sample mounting surface. A tip surface is formed on the probe, and the tip surface is non-perpendicular to the normal to the sample mounting surface. The metal structure protruding from the tip surface approaches or contacts the sample, and tip-enhanced Raman scattering is generated by light irradiation. The portion of the probe located between the lens and the portion where the Raman scattered light is generated on the sample is small, and the ratio of the generated Raman scattered light being absorbed or reflected by a portion of the probe is low. For this reason, the efficiency which condenses Raman scattered light with a lens is high.

  In the Raman scattered light measurement apparatus according to the present invention, the longer the distance to the sample placement surface in the direction perpendicular to the sample placement surface, the longer the distance to the tip surface in the direction. The lens and the probe are arranged so as to pass in a direction in which the sum of the length of the lens and the probe increases.

  In the present invention, as the distance of the optical axis of the lens in the direction perpendicular to the sample mounting surface from the optical axis to the sample mounting surface increases, this distance and the sample mounting surface from the optical axis to the tip surface The probe and the lens are arranged so that the total distance with the distance in the direction orthogonal to the direction becomes longer. The further away from the sample along the optical axis, the wider the distance between the sample mounting surface and the tip surface, and the portion of the probe located between the portion where the Raman scattered light is generated on the sample and the lens. Few.

  In the Raman scattered light measurement apparatus according to the present invention, the point farthest from the sample mounting surface on the tip surface is closer to the lens than the point closest to the sample mounting surface on the tip surface. As described above, the lens and the probe are arranged.

  In the present invention, the point farthest from the sample placement surface on the tip surface is closer to the lens than the point closest to the sample placement surface on the tip surface. For this reason, the portion of the probe located between the portion where the Raman scattered light is generated on the sample and the lens is small.

  In the Raman scattered light measurement apparatus according to the present invention, the tip surface is a non-cleavage surface.

  In the present invention, the tip surface is a non-cleavage surface. For this reason, the front end surface is formed with a necessary inclination irrespective of the crystal plane.

  The probe according to the present invention protrudes from one surface of a cantilever having two surfaces which are in a relation of front and back, and in a semiconductor probe used in proximity to or in contact with a sample, the probe is perpendicular to the other surface of the cantilever. It has a tip surface that is non-perpendicular or non-perpendicular to a perpendicular to the surface on which the sample is placed, and a metal structure protruding from the tip surface.

  In the present invention, the tip surface is formed on the probe provided on the cantilever, and the metal structure protrudes from the tip surface. Tip enhanced Raman scattering occurs when the metal structure is close to or in contact with the sample. The front end surface is formed so as to be non-perpendicular to the normal line on the back surface of the cantilever or the normal line of the sample mounting surface. As a result, the ratio of the generated Raman scattered light absorbed or reflected by a part of the probe is low.

  The probe according to the present invention is characterized in that the tip surface is a non-cleavage surface.

  In the present invention, the tip surface is a non-cleavage surface. For this reason, the front end surface is formed with a necessary inclination irrespective of the crystal plane.

  A probe manufacturing method according to the present invention is a method for manufacturing a probe used in proximity to or in contact with a sample, and is a semiconductor needle-like body projecting from one surface of a cantilever having two surfaces that are front and back. By removing the tip from the tip, a tip surface that is not perpendicular to the perpendicular to the other surface of the cantilever or perpendicular to the surface on which the sample is placed is formed. A metal structure is grown on the tip surface by contacting with a metal.

  In the present invention, a tip surface is formed on the probe and brought into contact with a metal ion-containing solution. A metal deposits and grows on the front end surface, and a metal structure is formed. A probe having a metal structure projecting from the tip surface is manufactured.

  The probe manufacturing method according to the present invention is characterized in that the tip of the needle-like body is removed by irradiation with an energy beam.

  In the present invention, an energy beam is applied to the tip of the probe. By irradiating the energy beam, the tip of the probe is removed, and the tip surface is easily formed.

  The probe manufacturing method according to the present invention is characterized in that a depression is formed in the tip surface by irradiation of an energy beam, and a metal structure is grown in the depression.

  In the present invention, an energy beam is irradiated to form a depression on the tip surface. When the metal ion-containing solution comes into contact, a metal structure grows in the depression. The metal structure adheres to the recess and is securely fixed to the probe.

  The probe manufacturing method according to the present invention is characterized in that after the metal ion-containing solution is brought into contact with the tip surface, the tip surface is dried, and the metal ion-containing solution is again brought into contact with the tip surface. To do.

  In the present invention, after the metal ion-containing solution is brought into contact with the tip surface of the probe, it is once dried and the metal ion-containing solution is brought into contact with the tip surface again. The seed of the metal structure is formed by the first contact, and the metal structure grows efficiently by the second contact.

  The probe manufacturing method according to the present invention is characterized in that the metal ion-containing solution contains ions containing Au, Ag, Pt, Pd, or Cu.

  In the present invention, a metal ion-containing solution containing ions containing Au, Ag, Pt, Pd or Cu is used. A probe in which these metal structures protrude from the tip surface is manufactured, and tip-enhanced Raman scattering can be measured by using this probe.

  In the present invention, the efficiency of condensing the Raman scattered light is improved, and the Raman scattered light can be measured with high sensitivity regardless of the sample, and thus excellent effects are exhibited.

It is a schematic diagram which shows the probe for tip-enhanced Raman scattering. FIG. 3 is a schematic diagram illustrating a method for manufacturing a probe for tip-enhanced Raman scattering according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a method for manufacturing a probe for tip-enhanced Raman scattering according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a method for manufacturing a probe for tip-enhanced Raman scattering according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a method for manufacturing a probe for tip-enhanced Raman scattering according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a method for manufacturing a probe for tip-enhanced Raman scattering according to Embodiment 1. It is an electron micrograph which shows the example of the probe which the aggregate | assembly of Au nanostructure protruded from the front end surface. It is a block diagram which shows the structure of a Raman scattered light measuring apparatus. It is a schematic diagram which shows the positional relationship of the front-end | tip part of a probe, a lens, and a sample mounting surface. FIG. 5 is a schematic diagram showing a probe manufacturing method according to Embodiment 2. FIG. 5 is a schematic diagram showing a probe manufacturing method according to Embodiment 2. FIG. 5 is a schematic diagram showing a probe manufacturing method according to Embodiment 2. FIG. 5 is a schematic diagram showing a probe manufacturing method according to Embodiment 2. It is a typical perspective view which shows an inkjet printer. FIG. 6 is a schematic diagram showing a probe manufacturing method according to Embodiment 3. FIG. 6 is a schematic diagram showing a probe manufacturing method according to Embodiment 3.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
(Embodiment 1)
FIG. 1 is a schematic diagram showing a tip for tip-enhanced Raman scattering. The probe holder 1 is formed of Si (silicon) in a flat plate shape. A cantilever 11 is provided at one end of the probe holder 1. In the figure, the cantilever 11 is shown enlarged. A probe 12 is provided at the end of the cantilever 11. The cantilever 11 has two surfaces that are in a front-back relationship, and the probe 12 protrudes from one surface of the cantilever 11. Hereinafter, the other surface of the cantilever 11, that is, the surface opposite to the surface on which the probe 12 is provided is referred to as the back surface. The probe 12 is made of Si in a pyramid shape. Furthermore, in the drawing, the tip portion of the probe 12 is shown enlarged. The tip of the probe 12 has a shape from which the tip of the pyramid is removed, and has a tip surface 14. An aggregate 13 in which a plurality of metal nanostructures are aggregated protrudes from the tip surface 14. The tip portion of the probe 12 is a portion including the tip surface 14 and the aggregate 13 of metal nanostructures. In the present embodiment, an example is shown in which the metal nanostructure is an Au nanostructure made of Au (gold). The size of each Au nanostructure is several nm or more and less than 1 μm, and the size of the aggregate 13 of Au nanostructures is several μm or less.

2A, 2B, 2C, 3A, and 3B are schematic diagrams illustrating a method for manufacturing the probe 12 for tip-enhanced Raman scattering according to the first embodiment. As the material of the probe 12, an AFM probe is used. The probe 12 in the middle of manufacture corresponds to the needle-shaped body in the present invention. In FIG. 2A and FIG. 2B, the perpendicular 15 with respect to the back surface of the cantilever 11 is shown with the dashed-dotted line. As shown in FIG. 2A, the tip of the probe 12 is irradiated with a FIB (Focused Ion Beam) 2. At this time, the irradiation axis of the FIB 2 is set to a non-right angle with respect to the perpendicular 15. An angle at which the irradiation axis of the FIB 2 is inclined with respect to the perpendicular 15 is defined as θ ₁ . As shown in FIG. 2B, the tip of the probe 12 is removed by irradiation with the FIB 2 to form the tip surface 14. The tip surface 14 is a non-cleavage surface. Since the tip surface 14 is a non-cleavage surface, the tip surface 14 having a necessary inclination can be formed regardless of the crystal plane of Si. In addition to the FIB 2, the tip surface 14 may be formed by irradiating other energy beam such as laser light. Alternatively, the tip surface 14 may be formed by a method other than energy beam irradiation, such as a method of cutting the tip of the probe 12 with diamond.

  Next, as shown in FIG. 2B, FIB2 is irradiated to the front end surface. As shown in FIG. 2C, a depression 16 is formed in the distal end surface 14 by irradiation with FIB 2. In FIG. 2C, the depression 16 is indicated by a broken line. The position where the recess 16 is formed is preferably a position closer to the tip in the tip surface 14. At the stage where the tip surface 14 is formed, no oxide film is formed on the tip surface 14. Further, in the vicinity of the recess 16, Si constituting the probe 12 is amorphized. The portion other than the amorphous portion is crystalline. In addition to FIB 2, recess 16 may be formed by irradiating other energy beam such as laser light.

  Next, as shown in FIG. 3A, the probe 12 is immersed in the chloroauric acid aqueous solution 3. The chloroauric acid aqueous solution 3 is a solution containing complex ions including Au. The complex ion containing a metal is included in the metal ion in the present invention. That is, the chloroauric acid aqueous solution 3 is an example of a metal ion-containing solution. Hereinafter, ions containing Au are referred to as Au ions. Further, NaCl (sodium chloride) is added to the chloroauric acid aqueous solution 3. By immersing the probe 12 in the chloroauric acid aqueous solution 3, Au is deposited on the tip surface 14 and an Au nanostructure grows. On the front end surface 14, there is no oxide film, and Si dangling bonds reduce Au ions in the chloroauric acid aqueous solution 3 to form Au nuclei. Si electrons are supplied to Au ions through the interface between Si and Au generated by Au nucleation, and Au nanostructures grow. In particular, since the vicinity of the depression 16 is amorphous, a lot of dangling bonds are generated, and Au nanostructures grow efficiently in the depression 16. After the probe 12 is immersed in the chloroauric acid aqueous solution 3 for an appropriate time, the probe 12 is taken out from the chloroauric acid aqueous solution 3 and washed. Cleaning is not essential. As shown in FIG. 3B, an aggregate 13 of Au nanostructures is formed on the tip surface 14. A part of the assembly 13 is fixed to a recess 16 formed in the tip surface 14, and thereby the assembly 13 of Au nanostructures is securely fixed to the probe 12.

  FIG. 4 is an electron micrograph showing an example of the probe 12 in which the aggregate 13 of Au nanostructures protrudes from the tip surface 14. FIG. 4 shows the side surface of the tip of the probe 12. A tip surface 14 is formed on the probe 12, and an aggregate 13 of Au nanostructures is formed on the tip surface 14. In particular, a large number of Au nanostructure aggregates 13 are formed in the tip surface 14 where the depressions 16 are formed. In this manner, the probe 12 having the Au nanostructure aggregate 13 provided at the tip is manufactured. Using this probe 12, tip enhanced Raman scattering can be measured.

The size and shape of the Au nanostructure aggregate 13 can be controlled by adjusting the concentration of the chloroauric acid aqueous solution 3 or the time during which the probe 12 is immersed in the chloroauric acid aqueous solution 3. It is possible not to add NaCl to the chloroauric acid aqueous solution 3. However, by adding NaCl to the chloroauric acid aqueous solution 3, it becomes difficult for the Au nanostructure to grow in the portion other than the recess 16 on the tip surface 14, and it becomes easy to grow the Au nanostructure by concentrating on the recess 16. . In addition, by adding NaCl, the aggregate 13 of Au nanostructures easily grows in a rod shape. Therefore, by adding an appropriate amount of NaCl to the chloroauric acid aqueous solution 3, the Au nanostructure aggregates 13 are concentrated and formed in the depressions 16, and the Au nanostructure aggregates 13 are shaped like rods. can do. In addition to NaCl, KCl (potassium chloride), NaBr (sodium bromide), LiCl (lithium chloride) or CaCl ₂ (calcium chloride) may be added to the aqueous chloroauric acid solution 3.

  The chloroauric acid aqueous solution 3 may be brought into contact with the tip surface 14 by dropping the chloroauric acid aqueous solution 3 with a pipette or the like. Further, the chloroauric acid aqueous solution 3 may be brought into contact with the tip surface 14 by inserting the probe 12 into the droplet of the chloroauric acid aqueous solution 3. As described above, the probe 12 for tip-enhanced Raman scattering is manufactured.

  FIG. 5 is a block diagram showing the configuration of the Raman scattered light measurement apparatus. The Raman scattered light measurement apparatus includes a sample stage 5 on which a sample 52 is placed, a cantilever 11, a probe 12, an irradiation unit 61 that irradiates a laser beam, and laser light from the irradiation unit 61 to the sample 52. And a lens 4 that collects light on the tip of the probe 12 that is in close proximity or in contact with the probe. The probe 12 is provided at the end of the cantilever 11. The sample stage 5 has a sample placement surface 51. Moreover, although the granular sample 52 was shown in FIG. 5, the sample 52 can take arbitrary shapes, such as a flat plate.

  Further, the Raman scattered light measurement device includes a drive unit 66 that moves the cantilever 11, a laser light source 67, an optical sensor 68, a signal processing unit 69, and a control unit 65. The drive unit 66 moves the cantilever 11 to bring the probe 12 closer to the sample 52 on the sample placement surface 51. The laser light source 67 irradiates the back surface of the cantilever 11 with laser light, and the laser light is reflected on the back surface of the cantilever 11. The optical sensor 44 detects the laser beam reflected by the cantilever 11 and outputs a signal indicating the detection result to the signal processing unit 69. In FIG. 5, the laser beam is indicated by a broken-line arrow. When the tip of the probe 12 approaches or comes into contact with the sample 52, the cantilever 11 is deflected by the atomic force, the position where the optical sensor 68 detects the laser beam is shifted, and the signal processing unit 69 detects the deflection of the cantilever 11. . A change in the amount of deflection of the cantilever 11 corresponds to a change in the distance between the probe 12 and the surface of the sample 52. The signal processing unit 69 controls the operation of the driving unit 66 so that the deflection of the cantilever 11 is constant. The control unit 65 controls the movement of the probe 12 by controlling the operation of the signal processing unit 69. Note that the Raman scattered light measurement apparatus may be configured to measure the current flowing between the probe 12 and the sample 52 and control the movement of the probe 12 based on the measured current.

  The Raman scattered light measurement apparatus further includes a beam splitter 62, a spectroscope 63, a detection unit 64 that detects light, and a drive unit 50 that moves the sample stage 5 up and down or left and right. The laser beam irradiated by the irradiation unit 61 passes through the beam splitter 62, is collected by the lens 4, and is irradiated to the tip of the probe 12 that is in proximity to or in contact with the sample 52. Here, the proximity means that localized plasmon is induced on the surface of the sample 52 by the irradiated light, a locally enhanced electric field is generated, and tip-enhanced Raman scattering in which Raman scattered light is enhanced occurs. The tip of the probe 12 is close to the surface of the sample 52 up to the distance of. Tip-enhanced Raman scattering occurs in the portion of the sample 52 where the tip of the probe 12 approaches or contacts and is irradiated with laser light. The generated Raman scattered light is collected by the lens 4, reflected by the beam splitter 62, and enters the spectroscope 63. In FIG. 5, laser light and Raman scattered light irradiated on the sample 52 are indicated by solid arrows. The Raman scattered light measurement apparatus includes an optical system including a number of optical components such as a mirror, a lens, and a filter for guiding, condensing, and separating laser light and Raman scattered light. In FIG. 5, optical systems other than the lens 4 and the beam splitter 62 are omitted. The spectroscope 63 separates the incident Raman scattered light. The detection unit 64 detects the light of each wavelength dispersed by the spectroscope 63 and outputs a signal corresponding to the detection intensity of the light of each wavelength to the control unit 65. The control unit 65 controls the wavelength of light dispersed by the spectroscope 63 and receives a signal output from the detection unit 64, and based on the wavelength of the dispersed light and the detected intensity of light indicated by the input signal. Generate a spectrum. In this way, tip enhanced Raman scattering is measured. The control unit 65 controls the operation of the driving unit 50 to move the sample stage 5 and enables measurement of tip-enhanced Raman scattering at each part on the sample 52.

  FIG. 6 is a schematic diagram showing the positional relationship between the tip of the probe 12, the lens 4 and the sample placement surface 51. As shown in FIG. In FIG. 6, the optical axis 41 of the lens 4 and the perpendicular line 53 of the sample placement surface 51 are indicated by a one-dot chain line. FIG. 6 shows a surface including the optical axis 41 and the perpendicular line 53. The lens 4 is disposed at a position facing the sample placement surface 51. That is, the probe 12 and the lens 4 are disposed at a position facing the sample placement surface 51. The position facing the sample placement surface 51 includes the sample 52 placed on the sample placement surface 51 when the space is divided into two partial spaces with the surface including the sample placement surface 51 as a boundary. A position in a subspace. The probe 12 is arranged so that the perpendicular 15 with respect to the back surface of the cantilever 11 substantially coincides with the perpendicular 53 of the sample placement surface 51. The lens 4 is disposed with the optical axis 41 inclined with respect to the normal 53 of the sample mounting surface 51. The tip surface 14 of the probe 12 is not perpendicular to the perpendicular 15 on the back surface of the cantilever 11 and is also not perpendicular to the perpendicular 53 of the sample placement surface 51. The aggregate 13 of Au nanostructures provided on the tip surface 14 contacts or approaches the sample 52. When the aggregate 13 of Au nanostructures protrudes from a portion closer to the tip in the tip surface 14, it can be easily brought into contact with or brought close to the sample 52.

  In the probe 12 and the lens 4, the longer the distance in the direction of the vertical line 53 from the optical axis 41 to the sample placement surface 51, the longer the distance 53 and the vertical line 53 from the optical axis 41 to the tip surface 14. Are arranged in such a direction that the total distance of these directions becomes longer. For this reason, within the plane including the optical axis 41 and the perpendicular line 53, the distance from the optical axis 41 to the sample mounting surface 51 increases as the distance from the tip surface 14 to the sample mounting surface 51 increases on a line orthogonal to the sample mounting surface 51. The distance to becomes longer. The farther from the sample 52 along the optical axis 41, the wider the distance between the sample placement surface 51 and the tip surface 14. The point farthest from the sample placement surface 51 on the tip surface 14 is closer to the lens 4 than the point closest to the sample placement surface 51 on the tip surface 14. By arranging the probe 12 and the lens 4 in this way, the Au nanostructure at the tip of the probe 12 is compared with the case where the probe without the tip surface 14 is arranged. The portion of the probe 12 located between the portion on the sample 52 and the lens 4 where the assembly 13 is in contact with or close to is reduced.

  In FIG. 6, the tip 17 of the probe when the tip surface 14 is not formed is indicated by a broken line. In the case where the tip surface 14 is not formed, the sample 52 in which the tip of the probe approaches or comes into contact with a part of the probe between the lens 4 and the portion on the sample 52 that contacts or approaches the tip of the probe. The Raman scattered light generated in the upper part is absorbed or reflected, and the efficiency of collecting the Raman scattered light by the lens 4 is lowered. On the other hand, in the present embodiment, the tip surface 14 is formed on the probe 12, so that the Au nanostructure aggregate 13 is positioned between the portion on the sample 52 that is in contact with or close to the lens 4 and the lens 4. The portion of the probe 12 that is being used is reduced. The ratio at which the Raman scattered light generated in the portion on the sample 52 that is close to or in contact with the Au nanostructure aggregate 13 is absorbed or reflected by a part of the probe 12 decreases, and the lens 4 collects the Raman scattered light. The efficiency of light is improved. Therefore, the Raman scattered light measurement apparatus can measure the generated Raman scattered light with high sensitivity. In addition, since it is not necessary for light to pass through the sample 52, the Raman scattered light measurement apparatus can detect Raman scattered light with high sensitivity even for a sample 52 that is difficult to transmit light, such as an opaque sample 52 or a thick sample 52. It is possible to measure. Therefore, the Raman scattered light measurement apparatus can measure Raman scattered light with high sensitivity for any sample.

The angle θ ₂ formed between the perpendicular 53 of the sample mounting surface 51 and the tip surface 14 is preferably equal to or smaller than the angle θ ₃ formed between the perpendicular 53 and the optical axis 41 of the lens 4. When the angle θ ₂ is equal to or smaller than the angle θ ₃ , the portion of the probe 12 positioned between the portion on the sample 52 and the lens 4 where the aggregate 13 of the Au nanostructures is in contact with or close to is reliably ensured. Decrease. For example, when the angle θ ₃ is 60 °, the range of the angle θ ₂ is 0 ° to 60 °, and when the angle θ ₃ is 70 °, the range of the angle θ ₂ is 0 ° to 70 °.

Even more preferably, the angle theta ₂ is smaller than the difference between the maximum angle theta ₄ with respect to the optical axis 41 of the light rays incident from the angle theta ₃ and the sample 52 to the lens 4. In FIG. 6, a straight line connecting a portion on the sample 52 that is in contact with or close to the aggregate 13 of Au nanostructures and an edge of the lens 4 is indicated by a broken line. The angle between the straight line and the optical axis 41 is the maximum angle θ ₄ with respect to the optical axis 41 of the light ray that enters the lens 4 from the sample 52. The angle θ ₄ is expressed by the following equation (1), where n is the refractive index of the medium between the sample 52 and the lens 4 and NA is the numerical aperture of the lens 4. When the medium is air, n = 1. The angle θ ₂ is preferably included in the range represented by the following formula (2).
θ ₄ = Arcsin (n * NA) (1)
θ ₂ <θ ₃ −θ ₄ (2)

When the angle θ ₂ formed by the perpendicular 53 and the tip surface 14 is included in the range represented by the expression (2), the portion on the sample 52 where the Au nanostructure aggregate 13 is in contact with or close to the lens 4 and the lens 4 There is no portion of the probe 12 positioned between the two. Thereby, the lens 4 can collect the Raman scattered light with the maximum efficiency, and the Raman scattered light measuring apparatus can measure the Raman scattered light with high sensitivity.

The angle θ ₁ formed by the perpendicular 15 on the back surface of the cantilever 11 and the irradiation axis of the FIB 2 as shown in FIG. 2A is determined so that the angle θ ₂ is included in the range described above. Actually, the range of the angle θ ₂ is 30 ° to 50 °, for example, the angle θ ₂ is 39 °. In order to make it easier to reduce the portion of the probe 12 located between the lens 4 and the portion on the sample 52 that is in contact with or close to the aggregate 13 of Au nanostructures, The shape of the aggregate 13 is preferably an elongated shape such as a rod.

  The size of the Au nanostructure aggregate 13 is preferably smaller than the portion removed from the tip of the probe 12 by the FIB 2. That is, the size of the Au nanostructure aggregate 13 is preferably a size included between the tip 17 and the tip surface 14 of the probe when the tip surface 14 is not formed. Since the Au nanostructure assembly 13 has such a size, the probe is located between the lens 4 and the portion on the sample 52 in contact with or close to the Au nanostructure assembly 13. Twelve portions are likely to decrease. Similarly, the height of the Au nanostructure aggregate 13 from the tip surface 14 is preferably equal to or less than the distance between the tip 17 and the tip surface 14 when the tip surface 14 is not formed. Similarly, the volume of the Au nanostructure aggregate 13 is equal to or less than the volume of the portion removed from the tip of the probe 12 by the FIB 2, that is, the tip 17 and tip of the probe when the tip surface 14 is not formed. The volume is preferably equal to or less than the volume of the portion surrounded by the surface 14.

  Further, as described above, in this embodiment, the tip surface 14 is formed on the probe 12, and the aggregate 13 of Au nanostructures is grown on the tip surface 14 by contacting the chloroauric acid aqueous solution 3. The probe 12 is manufactured. Since there is no oxide film on the tip surface 14 and the vicinity of the recess 16 is amorphized, an aggregate 13 of Au nanostructures necessary for tip-enhanced Raman scattering can be easily formed on the tip surface 14. The size and shape of the Au nanostructure aggregate 13 can be controlled by adjusting the concentration of the chloroauric acid aqueous solution 3 in which the probe 12 is immersed, the immersion time, or the type or amount of the additive. . For this reason, the aggregate | assembly 13 suitable for the wavelength of the laser beam for Raman spectroscopy can be formed. Therefore, when the tip-enhanced Raman scattering is measured using the probe 12, it is possible to effectively enhance the Raman scattered light. Further, by controlling the size and shape of the Au nanostructure aggregate 13, it is possible to manufacture the probe 12 that can obtain a desired enhancement when measuring tip-enhanced Raman scattering. .

  In the present embodiment, the vertical line 15 with respect to the back surface of the cantilever 11 is substantially coincident with the normal line 53 of the sample mounting surface 51. However, in the Raman scattered light measurement device, the tip end surface 14 of the sample mounting surface 51 is the same. What is necessary is just to be non-right angle with respect to the perpendicular 53. For example, even if the vertical line 15 on the back surface of the cantilever 11 is inclined with respect to the normal line 53 of the sample mounting surface 51, it is sufficient that the tip surface 14 is not perpendicular to the normal line 53. The probe 12 only needs to be manufactured such that the tip surface 14 is non-perpendicular to the perpendicular 53 of the sample mounting surface 51 when mounted on the Raman scattered light measurement device. In the present embodiment, the lens 4 for condensing the laser light emitted by the irradiating unit 51 and the lens for condensing the Raman scattered light are used as one lens 4. The measuring apparatus may have a configuration in which a lens for condensing the laser light irradiated by the irradiation unit 51 and a lens for condensing the Raman scattered light are separately provided.

(Embodiment 2)
7A, 7B, 7C, and 7D are schematic views illustrating a method for manufacturing the probe 12 according to the second embodiment. Similar to the first embodiment, the tip surface 14 and the depression 16 are formed by irradiating the tip of the probe 12 with FIB 2. Next, as shown in FIG. 7A, the probe 12 is immersed in the chloroauric acid aqueous solution 3. Au is deposited on the tip surface 14 to form seeds of Au nanostructures. After the probe 12 is immersed in the chloroauric acid aqueous solution 3 for a certain period of time, as shown in FIG. 7B, the probe 12 is pulled up from the chloroauric acid aqueous solution 3, and the tip of the probe 12 is washed and dried. . After drying, as shown in FIG. 7C, the probe 12 is again immersed in the chloroauric acid aqueous solution 3. Au nanostructures grow from the seeds of Au nanostructures formed on the tip surface 14 of the probe 12. After the probe 12 is immersed in the chloroauric acid aqueous solution 3 for an appropriate time, the probe 12 is taken out from the chloroauric acid aqueous solution 3. As shown in FIG. 7D, an aggregate 13 of Au nanostructures is formed on the tip surface 14 of the probe 12. As in the first embodiment, the chloroauric acid aqueous solution 3 may be brought into contact with the probe 12 by a method other than immersion. The configuration of the Raman scattered light measurement apparatus provided with the probe 12 is the same as that of the first embodiment.

  As described above, in this embodiment, the chloroauric acid aqueous solution 3 is brought into contact with the probe 12 on which the tip surface 14 is formed, the probe 12 is once dried, and the chloroauric acid aqueous solution 3 is brought into contact with the probe 12 again. By doing so, the probe 12 for tip-enhanced Raman scattering is manufactured. Compared to the case where the probe 12 is immersed only once in the chloroauric acid aqueous solution 3 as in the first embodiment, an aggregate 13 of Au nanostructures having a sharper shape or a larger shape may be obtained. As a result, an aggregate 13 of Au nanostructures having a desired size and shape can be grown on the tip surface 14 of the probe 12, and a desired enhancement can be obtained when measuring tip-enhanced Raman scattering. It becomes possible to manufacture a simple probe 12. Also in the Raman scattered light measurement apparatus according to the present embodiment, the ratio of the Raman scattered light absorbed or reflected by a part of the probe 12 decreases. The efficiency of condensing the Raman scattered light with the lens 4 is improved, and the Raman scattered light measuring apparatus can measure the Raman scattered light with high sensitivity for any sample.

(Embodiment 3)
In the third embodiment, the tip 12 for tip-enhanced Raman scattering is manufactured using an inkjet printer. FIG. 8 is a schematic perspective view showing an ink jet printer, and FIGS. 9A and 9B are schematic views showing a method for manufacturing the probe 12 according to the third embodiment. Similar to the first embodiment, the tip surface 14 and the depression 16 are formed by irradiating the tip of the probe 12 with FIB 2. Next, as shown in FIG. 8, the probe holder 1 is mounted on the ink jet printer 7, and as shown in FIG. A droplet of the aqueous gold acid solution 3 is discharged. The droplet of the chloroauric acid aqueous solution 3 adheres to the tip surface 14, and Au precipitates on the tip surface 14 to form an Au nanostructure. The ink jet printer 7 can also repeatedly discharge droplets of the chloroauric acid aqueous solution 3. The droplets of the chloroauric acid aqueous solution 3 ejected a plurality of times adhere to the tip surface 14 each time it is ejected, and Au nanostructures grow. As shown in FIG. 9B, an aggregate 13 of Au nanostructures is formed on the tip surface 14 of the probe 12. In this manner, the probe 12 for tip-enhanced Raman scattering, in which the Au nanostructure aggregate 13 is provided at the tip, is obtained. The configuration of the Raman scattered light measurement apparatus provided with the probe 12 is the same as that of the first embodiment.

  The size and shape of the Au nanostructure aggregate 13 can be controlled by adjusting the concentration, the discharge amount, and the discharge frequency of the aqueous chloroauric acid solution 3. Further, by drying the tip surface 14 between a plurality of ejections, the Au nanostructure aggregate 13 can be efficiently grown on the tip surface 14 as in the second embodiment. In addition, the inkjet printer 7 includes a plurality of nozzles, and the tip surface 14 may be cleaned by the inkjet printer 7 by discharging the chloroauric acid aqueous solution 3 with one nozzle 71 and discharging the cleaning liquid with another nozzle. Is possible. Further, an additive such as ethylene glycol may be added to the chloroauric acid aqueous solution 3 so that the ink jet printer 7 can easily discharge an appropriate amount of droplets. In addition, the chloroauric acid aqueous solution 3 can be selectively brought into contact with the tip surface 14 by moving the droplet of the probe holder 1 or the chloroauric acid aqueous solution 3 by a three-dimensional stage.

  As described above, in the present embodiment, the chloroauric acid aqueous solution 3 is brought into contact with the tip surface 14 of the probe 12 by ejecting droplets of the chloroauric acid aqueous solution 3 by the ink jet printer 7, and tip enhanced Raman scattering. The probe 12 for manufacturing is manufactured. In the ink jet printer 7, a small amount of liquid droplets can be ejected and adhered to an arbitrary location, so that the chloroauric acid aqueous solution 3 can be selectively brought into contact with the front end surface 14. For this reason, the influence by the chloroauric acid aqueous solution 3 contacting parts other than the front end surface 14 of the cantilever 11 can be suppressed. Further, the size and shape of the Au nanostructure aggregate 13 can be controlled by adjusting the concentration, the discharge amount, and the number of discharges of the aqueous chloroauric acid solution 3. In addition, it is possible to easily manufacture the probe 12 that can obtain a desired increase in strength. Also in the Raman scattered light measurement apparatus according to the present embodiment, interference between the optical axis 41 of the lens 4 and the probe 12 is reduced. The ratio at which the Raman scattered light is absorbed or reflected by a part of the probe 12 is reduced, the efficiency of collecting the Raman scattered light with the lens 4 is improved, and the Raman scattered light measuring apparatus is highly sensitive to any sample. Raman scattered light can be measured.

  In the first to third embodiments, the chloroauric acid aqueous solution is used as the solution containing Au ions. However, the solution containing Au ions may be another solution. For example, a solution using a solvent other than water may be used. In the first to third embodiments, the aggregate 13 in which a plurality of Au nanostructures are aggregated is formed on the tip surface 14 of the probe 12. However, the probe 12 is a single piece on the tip surface 14. The form in which the Au nanostructure was formed. Moreover, in Embodiments 1-3, although the form which grows Au nanostructure on the front end surface 14 as metal nanostructure was shown, even if metal nanostructure is a nanostructure of metals other than Au Good. The metal may be, for example, Ag (silver), Pt (platinum), Pd (palladium), or Cu (copper). In this embodiment, a solution containing ions containing these metals is used. In the first to third embodiments, the tip-enhanced Raman scattering probe 12 is manufactured from the AFM probe. However, in the present invention, the tip-enhancing Raman probe is used from the SPM probe other than the AFM. It is also possible to manufacture the scattering probe 12. In the first to third embodiments, the probe holding body 1 including the cantilever 11 and the probe 12 is made of Si. However, the probe holding body 1 is made of a semiconductor other than Si. May be. For example, the probe holder 1 may be made of SiC (silicon carbide) or diamond.

DESCRIPTION OF SYMBOLS 1 Probe holder 11 Cantilever 12 Probe 13 Ag nanostructure (metal nanostructure) aggregate 14 Tip surface 15 Normal to back 16 Depression 2 FIB (focused ion beam)
3 Chloroauric acid aqueous solution (metal ion-containing solution)
4 Lens 5 Sample Stand 51 Sample Placement Surface 52 Sample 53 Perpendicular 61 Irradiation Unit 64 Detection Unit 7 Inkjet Printer 71 Nozzle

Claims (11)

A sample placement surface on which a sample is placed, a semiconductor probe, an irradiation unit that irradiates light to the tip of the probe that is close to or in contact with the sample, and Raman scattered light generated from the sample In a Raman scattered light measurement device comprising a condensing lens and a detection unit for detecting the Raman scattered light collected by the lens,
The lens and the probe are arranged at positions facing the sample mounting surface,
The lens is disposed with the optical axis inclined with respect to the normal of the sample mounting surface,
The probe has a tip surface that is non-perpendicular to the perpendicular and a metal structure projecting from the tip surface. The optical axis is passed in a direction in which the total of the distance and the distance to the tip surface in the direction becomes longer as the distance to the sample placement surface in the direction orthogonal to the sample placement surface becomes longer. The Raman scattered light measuring apparatus according to claim 1, wherein the lens and the probe are arranged. The lens and the probe are arranged so that a point farthest from the sample mounting surface on the tip surface is closer to the lens than a point closest to the sample mounting surface on the tip surface. The Raman scattered light measuring device according to claim 1, wherein The Raman scattered light measurement apparatus according to claim 1, wherein the tip surface is a non-cleavage surface. In a semiconductor probe that protrudes from one surface of a cantilever having two surfaces that are front and back, and is used in proximity to or in contact with a sample,
A tip surface that is not perpendicular to the perpendicular to the other surface of the cantilever or perpendicular to the surface on which the sample is placed;
And a metal structure protruding from the tip surface. The probe according to claim 5, wherein the tip surface is a non-cleavage surface. In a method for producing a probe used in proximity to or in contact with a sample,
By removing the tip from a semiconductor needle protruding from one surface of a cantilever having two surfaces that are front and back, the surface on which the sample is placed non-perpendicular to the perpendicular to the other surface of the cantilever Forming a tip surface that is non-perpendicular to the normal to
A method for manufacturing a probe, comprising: bringing a metal ion-containing solution into contact with the tip surface to grow a metal structure on the tip surface. The probe manufacturing method according to claim 7, wherein the tip of the needle-like body is removed by irradiation with an energy beam. The method for manufacturing a probe according to claim 7 or 8, wherein a recess is formed in the tip surface by irradiation with an energy beam, and a metal structure is grown in the recess. The metal ion-containing solution is brought into contact with the tip surface, and then the tip surface is dried, and the metal ion-containing solution is again brought into contact with the tip surface. A method for manufacturing the probe according to claim 1. The method for producing a probe according to any one of claims 7 to 10, wherein the metal ion-containing solution contains ions containing Au, Ag, Pt, Pd, or Cu.

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