JP2017040609A - Sensor chip and manufacturing method therefor, and automatic analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor chip having a high density hot site for absorbing target substance and a high electric field enhancement at the hot site.SOLUTION: The disclosed sensor chip comprises: a substrate; a structure formed above the substrate; and metal particles disposed side surface of the structure. Assuming a plane parallel to a substrate crossing the structure, and when the plane is displaced in a direction away from the substrate, the structure on the plane has a bent portion, the centroid in a cross section thereof regularly shifts, and at least a part of the metal particles are disposed at a position where side face in the bent portion of the structure is oriented upward.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a sensor chip, a manufacturing method thereof, and an analysis apparatus.

  In recent years, demand for medical diagnosis, food inspection, and the like has been increasing, and development of a small and high-speed sensing technology has been demanded. Various types of sensors, including electrochemical techniques, have been studied. However, surface plasmon resonance (SPR) is used because it can be integrated, is low-cost, and does not choose the measurement environment. There is growing interest in sensors.

  For example, a device that detects the presence or absence of target substance adsorption, such as the presence or absence of antigen adsorption in an antigen-antibody reaction, using SPR generated on a metal thin film provided on the surface of a total reflection prism is known. This technique senses the presence of a molecule to be detected by detecting that the extinction wavelength due to SPR shifts before and after the adsorption of the molecule to be detected (target substance).

As one of high-sensitivity spectroscopic techniques for detecting a low concentration target substance, attention is focused on surface enhanced Raman scattering (SERS) using SPR. SERS is a phenomenon in which Raman scattered light is enhanced by 10 ² to 10 ¹⁴ times on a metal surface having a nanometer-scale uneven structure.

  When a molecule such as a laser is irradiated with excitation light having a single wavelength, light having a wavelength slightly shifted from the wavelength of the excitation light by the vibration energy of the molecule (Raman scattered light) is scattered. When the scattered light is spectrally processed, a spectrum (fingerprint spectrum) unique to the molecular species is obtained. By analyzing the shape of this fingerprint spectrum, it becomes possible to identify the molecule.

  On the other hand, in Raman spectroscopy, since the Raman scattered light is very weak, various sensor chips that exhibit strong enhancement using SERS have been proposed for detecting very low concentrations of substances. For example, Patent Document 1 and Patent Document 2 propose a chip having a structure in which metal nanoparticle layers are arranged on a mirror layer via a gap layer made of a dielectric. Such a structure is also reported in Non-Patent Document 1, in which the Gap type Surface Plasmon (GSP) model is referred to.

  Electric field enhancing spots, so-called hot sites, generated around the metal particles due to the surface plasmon phenomenon enhance the Raman scattered light. Therefore, in order to strongly enhance the Raman scattered light, it is advantageous to increase the electric field enhancement and increase the number and density of hot sites.

  When forming a sensor with the above-mentioned GSP structure, the number of hot sites and the density of arrangement are limited because the metal particles are arranged in a plane. From this point of view, in Patent Document 3, metal nanoparticles are formed on the side walls of the dielectric pillars, and a strong electric field enhancement is generated between the particles, thereby increasing the number (density) of hot sites per area of the substrate. Attempts have been proposed.

Special table 2007-538264 gazette JP 2008-014933 A US Patent Application Publication No. 2014/0045209

OPTICS EXPRESS Vol.34, No.3 (2009) pp.244-246

  In the technique described in Patent Document 3, the density of hot sites is improved by arranging metal nanoparticles in a direction perpendicular to the substrate (the normal direction of the substrate). However, the spacing and arrangement of the metal particles in the normal direction of the substrate cannot be controlled, and are not necessarily effective enough to generate SPR. That is, in the technique described in Patent Document 3, metal particles are arranged in the normal direction of the substrate to separate the upper and lower metal particles, but the distance between the metal particles at this time is not controlled. It was difficult to obtain a hot site with high electric field strength.

  One of the objects according to some embodiments of the present invention is to provide a sensor chip, an analysis apparatus, and a method for manufacturing the sensor chip that have a high hot site density for adsorbing a target substance and a high hot field electric field strength. There is to do.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

  One aspect of the sensor chip according to the present invention includes a substrate, a structure formed above the substrate, and metal particles disposed on a side surface of the structure, and the structure includes the structure. Assuming a plane parallel to the substrate that cuts the substrate, and when the plane is moved in a direction away from the substrate, the center of gravity of the cross section of the structure in the plane has a bent portion that periodically moves, At least a part of the metal particles is disposed on the side surface of the bent portion of the structure, and the side surface faces upward.

  In such a sensor chip, metal particles are arranged at predetermined positions in the normal direction of the substrate. That is, in such a sensor chip, the position where the metal particles are present is controlled in the normal direction of the substrate. Thereby, a strong localized surface plasmon (LSP: Localized Surface Plasmon) can be generated between the metal particles, and a hot site with a high electric field enhancement can be formed in the vicinity of the metal particles. For this reason, the sensor chip has a high number (density) of hot sites per substrate area for adsorbing a target substance, and the electric field enhancement intensity of the hot sites is also high. Thereby, for example, a high enhancement of the SERS signal can be obtained.

  In the sensor chip according to the present invention, when the plane is moved away from the substrate in the bent portion, the locus of the center of gravity in the plane is a circle, an ellipse, a polygon, a line segment, or a combination thereof. It may be a shape.

  Such a sensor chip is easy to manufacture.

  In the sensor chip according to the present invention, a metal layer may be provided between the substrate and the structure.

  Such a sensor chip can generate localized surface plasmons (LSP) between metal particles using propagating surface plasmons (PSP) generated near the surface of the metal layer. Hot sites with even higher electric field enhancement can be formed at positions in the direction perpendicular to the substrate.

  In the sensor chip according to the present invention, the material of the metal layer is at least one metal selected from gold, silver, copper, aluminum, platinum, nickel, palladium, tungsten, rhodium and ruthenium, or a plurality of these alloys. It may be.

  Such a sensor chip can generate stronger PSP in the vicinity of the surface of the metal layer, so that hot sites with higher electric field enhancement can be formed in the vicinity of the metal particles.

In the sensor chip according to the present invention, the metal particles may be disposed apart from the plurality of bent portions.
Such a sensor chip can arrange the metal particles closer to each other at a more controlled distance, and can obtain a higher electric field enhancement strength.

  One aspect of a method for manufacturing a sensor chip according to the present invention includes a step of forming a dielectric layer above a substrate, a step of patterning the dielectric layer to form a base portion, and a dynamic gradient deposition method. Forming a structure by depositing a dielectric on the base portion under a first tilt condition, and further depositing a dielectric under a second tilt condition different from the first tilt condition; Depositing a metal on the side of the body by a gradient deposition method.

  In this case, it is assumed that the substrate includes a substrate, a structure formed above the substrate, and metal particles disposed on a side surface of the structure, and a plane parallel to the substrate that cuts the structure. When the plane is moved in a direction away from the substrate, the center of gravity of the cross section of the structure in the plane is periodically moved, and at least a part of the metal particles has the center of gravity. It is possible to easily manufacture a sensor chip which is a moving section and is disposed at a position where the side surface faces upward.

  The sensor chip manufacturing method according to the present invention may include a step of heating the substrate after depositing the metal.

  In this way, it is possible to easily manufacture a sensor chip in which a plurality of metal particles are arranged and separated from each other.

  One aspect of the analyzer according to the present invention includes the above-described sensor chip, a light source that irradiates the sensor chip with excitation light, and a detector that detects light emitted from the sensor chip.

  Since such an analysis apparatus includes a sensor chip in which hot sites with high electric field enhancement are arranged at high density, the light enhancement based on plasmons is very large, and the target substance can be analyzed with extremely high sensitivity. it can.

The schematic diagram of the structure of the sensor chip concerning an embodiment. The schematic diagram of the structure of the sensor chip concerning an embodiment. The schematic diagram of the structure and arrangement of a sensor chip concerning an embodiment. The schematic diagram of the structure and arrangement of a sensor chip concerning an embodiment. Schematic of the principal part of the sensor chip concerning an embodiment. The schematic diagram of the principal part of the sensor chip concerning an embodiment. The schematic diagram which shows the example of the formation method of the structure which concerns on embodiment. The schematic diagram which shows the example of the formation method of the metal particle which concerns on embodiment. The schematic diagram which shows the example of the formation method of the metal particle which concerns on embodiment. The schematic diagram which shows an example of the analyzer which concerns on embodiment.

  Several embodiments of the present invention will be described below. Embodiment described below demonstrates an example of this invention. The present invention is not limited to the following embodiments, and includes various modified embodiments that are implemented within a range that does not change the gist of the present invention. Note that not all of the configurations described below are essential configurations of the present invention.

1. Sensor Chip A sensor chip 100 according to the present embodiment includes a substrate 1, a structure 20, and metal particles 30. 1 and 2 are schematic views showing an example of the structure 20 of the sensor chip 100 according to this embodiment. 3 and 4 are schematic views of the structure 20 and the arrangement of the sensor chip 100 according to the present embodiment, respectively. 5 and 6 are schematic views of the main part of the sensor chip 100 according to the present embodiment, respectively.

1.1. Substrate The substrate 1 is a base of the sensor chip 100. Examples of the substrate 1 include a silicon substrate, a glass substrate, and a resin substrate. The substrate 1 has a flat shape. In the present specification, the thickness direction of the substrate 1 may be referred to as a normal direction, a thickness direction, a height direction, or the like. In this embodiment, since the board | substrate 1 is flat form, the thickness direction and the normal line direction of the surface of the board | substrate 1 correspond.

  In the present specification, the word “upper” is formed (arranged), for example, another specific thing (hereinafter referred to as “B”) in “above” of the “specific thing (hereinafter referred to as“ A ”). ) "And the like include the case where B is directly formed (arranged) on A and the case where B is formed (arranged) on A via another or space, The word “upward” is used. Further, the terms “upper”, “lower”, and the like are not intended to be a vertical relationship depending on the installation state of the sensor chip 100, but the state in which the substrate 1 exists below regardless of the installation state of the sensor chip 100. This is a word intended for the vertical relationship when viewed in (when the field of view is taken so that the substrate 1 comes down). Therefore, for example, if the sensor chip 100 is installed so that the substrate 1 is on the upper side and the structure 20 is on the lower side when the direction in which gravity acts acts is lower, the upper side of the substrate 1 is higher. Means that the field of view is selected so that the substrate 1 is located below (that is, in this case, the direction in which the gravity acts is upward) It will be understood that the structure 20 is located above.

  The board | substrate 1 may be integral with the base part 22 of the structure 20 mentioned later. Further, the substrate 1 and the structure 20 may be separate. In this case, the structure 20 may be provided directly on the substrate 1 or a dielectric layer (not shown) may be provided on the substrate 1. ) And / or the metal layer 10 or the like, the structure 20 may be provided. Further, a dielectric layer or the like may be formed above the substrate 1, and the structure 20 may be provided above the dielectric layer. In this case, the metal layer 10 may be further provided between the substrate 1 and the dielectric layer or between the dielectric layer and the structure 20.

  1 to 6, the structure 20 is formed on the metal layer 10, and the upper surface of the metal layer 10 is exposed in a region where the structure 20 does not exist. Moreover, in the example shown in FIGS. 1-6, although it has the metal layer 10, the metal layer 10 is not an essential structure and the metal layer 10 does not need to exist. In addition, when the material of the base part 22 of the board | substrate 1 or the structure 20 is a silicon | silicone, since it is transparent in an infrared region, it uses as a dielectric material layer or a translucent layer by selecting the excitation light mentioned later appropriately. be able to.

1.2. Structure The structure 20 is formed above the substrate 1. The structure 20 may be formed in contact with the substrate 1, or the base portion 22 of the structure 20 may be formed integrally with the substrate 1. Further, other layers such as a dielectric layer, a light transmissive layer, and a metal layer may be disposed between the structure 20 and the substrate 1.

  The structure 20 assumes a plane parallel to the substrate 1 that cuts the structure 20, and when the plane is moved away from the substrate 1, the center of gravity of the cross section of the structure 20 in the plane is within the plane. It has the shape which has the area (for example, bending part 21) which moves periodically.

  FIG. 1 is a diagram schematically illustrating an example of the structure 20 of the sensor chip 100 according to the present embodiment. In FIG. 1, the metal particles 30 are omitted. Moreover, although a two-dot chain line is drawn in FIG. 1, the line indicates a virtual plane parallel to the substrate 1.

  As shown in FIG. 1, the structure 20 has a base portion 22 and a bent portion 21. The base portion 22 is not an essential configuration when the bent portion 21 can be formed with respect to the substrate 1 (the metal layer 10 is present in this example). The base portion 22 is used to provide a shadow for forming the pattern of the structure 20 when the bent portion 21 is formed by an inclined vapor deposition method to be described later. Accordingly, the function of the base portion 22 includes forming a planar shape of the bent portion 21 (pattern formation). The material of the base portion 22 is not particularly limited as long as patterning is possible. In the illustrated example, the base portion 22 is formed on the metal layer 10, but may be integrated with the metal layer 10 or may be integrated with the substrate 1 when the metal layer 10 is not present. May be.

  Unevenness is formed on the side surface of the bent portion 21. In the example of FIG. 1, the bent portion 21 of the structure 20 has a coil spring-like shape extending along the normal direction of the substrate 1, and in the example of FIG. 2, along the normal direction of the substrate 1. It has the shape of an extending zigzag column. A plurality of the bent portions 21 may be formed on the base portion 22. Even in this case, if the plurality of bent portions 21 are enveloped, irregularities are formed on the side surfaces of the structure 20.

  A case where the structure 20 is cut along a virtual plane parallel to the substrate 1 will be described. Consider the transition of the center of gravity of the cross section of the structure 20 that appears on the virtual plane when the structure 20 is cut by the virtual plane and moved (scanned) away from the substrate 1.

  The sensor chip 100 of the present embodiment has a section (bent portion 21) in which the center of gravity of the cross section moves while the virtual plane moves. Therefore, in the structure 20 of this embodiment, a part of the side surface of the structure 20 faces upward (the normal direction of a part of the side surface faces the direction opposite to the substrate 1). In the example of FIGS. 1 and 2, the section where the center of gravity periodically moves corresponds to the entire bent portion 21. Further, when the bent portion 21 is formed by a dynamic gradient deposition method to be described later, even if a plurality of bent portions 21 are formed, each bent portion 21 is bent in the same manner. The center of gravity of the cross section will move.

  The section where the center of gravity moves periodically may move continuously or discontinuously. That is, the side surface of the structure 20 in the section in which the center of gravity moves may be, for example, a plane substantially parallel to the substrate 1. In such a section where the center of gravity moves, a part of the side surface of the structure 20 faces upward, so that the metal particles 30 can be disposed at this position. The size of the side surface facing upward formed by bending the bent portion 21 is arbitrary as long as the metal particles 30 can be disposed.

Further, when the virtual plane is moved in the direction away from the substrate 1 in the section where the center of gravity moves (bent portion 21), the locus of the center of gravity in the virtual plane viewed from the normal direction of the substrate 1 is a circle, an ellipse, and many The shape may be a square, a line segment, or a combination thereof. For example, in the example of FIG. 1, the locus of the center of gravity is a circle and the bent portion 21 has a spiral column shape. In the example of FIG. 2, the locus of the center of gravity is a line segment, and the bent portion 21 has a zigzag column shape. It has become. Although not shown, the bent portion 21 may have a polygonal spiral column shape in which the locus of the center of gravity is a polygon, or an elliptic column shape in which the locus is an ellipse. In this way, since the size of the bent portion 21 protruding from the side surface of the structure 20 is constant, the metal particles 30 can be arranged efficiently. Furthermore, if it does in this way, it will be easy to form the bending part 21 using the below-mentioned dynamic gradient evaporation method, and manufacture of the sensor chip 100 can be made easy.

  In addition, when the virtual plane moves in a direction away from the substrate 1, the center of gravity periodically moves from the normal direction of the substrate 1 when the virtual plane advances twice the appropriate unit distance. This means that the center of gravity in the observed virtual plane appears three times at the same position. That is, as shown in FIG. 1 and FIG. 2, when the distance between adjacent protruding portions of the side surface of the bent portion 21 (between A and C or C and B in the figure) is defined as a unit distance, When the virtual plane is moved from the position A to the position B in the figure, the centers of gravity in the virtual plane viewed from the normal direction of the substrate 1 overlap at the positions A, C, and B. In this specification, such a state is expressed as that the center of gravity of the cross section of the structure 20 in the virtual plane moves periodically.

  The overall shape of the structure 20 is not particularly limited as long as the structure 20 has a side surface. The shape of the structure 20 can be a lattice shape as shown in FIG. 3, a rectangular parallelepiped shape (grating shape) as shown in FIG. Although not shown, the structure 20 may have a mesh shape in which a plurality of holes are provided. In addition, the space | interval and height of the base part 22 in FIG. 3, FIG. 4 are drawn differently from actuality for convenience of explanation.

  In the present specification, the type (type) of the sensor chip 100 may be referred to depending on the arrangement or shape of the structure 20, for example, a type in which the columnar structures 20 as shown in FIG. 3 are arranged. A pillar array, a type in which linear structures 20 are arranged as shown in FIG. 4 may be referred to as a grating, and a type in which holes formed in the structure 20 are arranged (not shown) is referred to as a hole array.

  As a function of the structure 20, at least a part of the metal particles 30 is placed on a surface facing upward formed on the side surface of the bent portion 21. With such a function, the metal particles 30 can be arranged apart from the substrate 1 by a predetermined distance. In addition, as a function of the structure 20, a plurality of metal particles 30 are arranged at a controlled interval so as to be separated along the height direction (normal direction of the substrate 1). Furthermore, as a function of the structure 20, a plurality of metal particles 30 can be arranged at the same position in the height direction (normal direction of the substrate 1). Thereby, since it can approach between the some metal particles 30 along the plane parallel to the board | substrate 1, the intensity | strength of LSP which generate | occur | produces in the metal particles 30 can be raised more.

  The material of the structure 20 is arbitrary as long as at least the bent portion 21 exhibits a property as a dielectric. For example, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, polysilicon, And a mixture thereof. The structure 20 does not need to be a homogeneous material as a whole. For example, the structure 20 may be made of a material different between the vicinity of the surface and the inside.

1.3. Metal Particle The metal particle 30 is disposed on the side surface of the structure 20. The number in which the metal particles 30 are arranged is arbitrary. The metal particles 30 can be disposed on at least a portion where the side surface of the bent portion 21 of the structure 20 faces upward. The metal particles 30 may be disposed at a site other than the bent portion 21 of the structure 20. By disposing the metal particles 30 on the bent portion 21, the distance (height) from the substrate 1 on which the metal particles 30 are disposed can be controlled. A plurality of metal particles 30 may be disposed on the bent portion 21.

  The shape of the metal particle 30 is not particularly limited. For example, the shape of the metal particles 30 is a circle, an ellipse, a polygon, an indeterminate shape, or a combination thereof when projected in the thickness direction of the substrate 1 (in plan view from the thickness direction). Even when projected in a direction orthogonal to the thickness direction, it may be a circle, an ellipse, a polygon, an indeterminate shape, or a combination thereof. The plurality of metal particles 30 may have different shapes. 5 and 6, the metal particles 30 are both drawn in a spherical shape, but the shape of the metal particles 30 is not limited to this.

  When the shape of the metal particle 30 is a sphere, the diameter of the metal particle 30 is 5 nm to 300 nm, preferably 20 nm to 100 nm, more preferably 30 nm to 50 nm. Further, when the shape of the metal particle 30 is irregular or the like, the average diameter of a sphere having the same volume as the metal particle 30 is 5 nm to 300 nm, preferably 20 nm to 100 nm, more preferably 30 nm to 50 nm. The following is preferable. Further, the average dimension of the metal particles 30 is preferably such that the average value of the maximum span of the metal particles 30 is smaller than ½ (half wavelength) of the wavelength of the excitation light.

  In the case where the passing of the metal particles 30 has a dimension of about half a wavelength or less of the excitation light, when the excitation light is incident on the metal particles 30, electric field polarization occurs in the metal particles 30 and LSP is likely to occur. When the passing of the metal particles 30 is about the wavelength of the excitation light, when the excitation light enters the metal particles 30, the polarization of the electric field in the metal particles 30 becomes a quadrupole state, and the half wavelength LSP can be generated although the strength is small compared to the case of a dimension of about or less.

  The material of the metal particles 30 is at least one metal selected from gold, silver, copper, aluminum, platinum, nickel, palladium, tungsten, rhodium and ruthenium, or a plurality of these alloys, or a plurality of these It can be a composite of a metal or an alloy. With such a material, localized plasmons are likely to be generated by light in the vicinity of visible light. Among these, as a material of the metal particle 30, it is more preferable that it is gold or silver, stronger LSP resonance can be obtained, and the enhancement of the entire chip can be increased.

  The metal particles 30 can be formed by selecting conditions for forming islands under conditions for forming a thin film by sputtering, vapor deposition, or the like. The metal particles 30 can also be formed by a method in which a thin film is formed and then granulated by heating, a method in which a thin film is formed by sputtering, vapor deposition, or the like, followed by patterning.

  The metal particles 30 have a function of generating localized plasmons (LSP) in the sensor chip 100 of the present embodiment. Therefore, even when the metal layer 10 is not provided, localized plasmons can be generated around the metal particles 30 by irradiating the metal particles 30 with excitation light. In this embodiment, since the height of the metal particles 30 is controlled and arranged, LSP (lateral direction: direction along the plane of the substrate 1) can be generated more efficiently.

1.4. Metal Layer The sensor chip 100 of this embodiment has a metal layer 10. The metal layer 10 is not an essential component for generating the LSP in the metal particle 30, but the presence of the metal layer 10 may cause the metal particle 30 to generate a stronger LSP in the direction perpendicular to the substrate 1. it can. The metal layer 10 is not specifically limited, For example, it can be set as the shape of a film, a board, a layer, or a film | membrane. The metal layer 10 may be provided on the substrate 1, for example. In the example of FIGS. 1 to 6, a layered metal layer 10 is provided on the surface (plane) of the substrate 1.

  The metal layer 10 can be formed, for example, by a technique such as vapor deposition, sputtering, casting, or machining. When the metal layer 10 is provided on the substrate 1 in a thin film shape, it may be provided on the entire upper surface of the substrate 1 or may be provided on a part of the substrate 1. The thickness of the metal layer 10 is not particularly limited as long as propagating surface plasmons can be excited on the metal layer 10. For example, the thickness is 10 nm to 1 mm, preferably 20 nm to 100 μm, more preferably 30 nm to 1 μm. Can do.

  The metal layer 10 is a metal in which an electric field applied by light (for example, excitation light) and an electric field in which the polarization induced by the electric field oscillates in an opposite phase exists, that is, when a specific electric field is applied. In addition, the real part of the dielectric function has a negative value (has a negative dielectric constant) and the dielectric constant of the imaginary part can have a dielectric constant smaller than the absolute value of the dielectric constant of the real part. Composed. Examples of metals that can have such a dielectric constant in the visible light region include at least one metal selected from gold, silver, copper, aluminum, platinum, nickel, palladium, tungsten, rhodium, and ruthenium, or These multiple types of alloys can be mentioned. The metal layer 10 may be a laminate of a plurality of layers of these metals or alloys.

  When the metal layer 10 is provided in the sensor chip 100 of the present embodiment, it can generate a propagation surface plasmon (PSP). When light is incident on the metal layer 10 under specific conditions, propagation-type surface plasmons are generated near the surface (end surface in the thickness direction) of the metal layer 10. In the present specification, the quantum of vibration in which the vibration of electric charges near the surface of the metal layer 10 and the electromagnetic wave are combined may be referred to as surface plasmon polariton (SPP). Propagation type surface plasmons generated in the metal layer 10 may interact with localized surface plasmons generated in the metal particles 30.

  When the sensor chip 100 of the present embodiment has the metal layer 10, the localized plasmon (LSP) generated in the metal particle 30 interacts with the propagation plasmon generated in the metal layer 10 under a certain condition. (Hybrid) can be. Furthermore, in the sensor chip 100 of the present embodiment, the height of the metal particles 30 (the distance from the substrate 1 of the metal particles 30) is controlled, so that vibration along the normal direction of the substrate 1 due to the propagation type plasmon. An LSP (longitudinal direction: a direction perpendicular to the plane of the substrate 1) can be generated more efficiently by the electric field.

1.5. Arrangement of Structures The structures 20 may be regularly arranged above the substrate 1. For example, as shown in FIG. 3, a plurality of the structures 20 may be arranged to form a structure row. The structures 20 are arranged side by side in a first direction parallel to the substrate 1 in the structure row. In other words, the structure row has a structure in which a plurality of the structures 20 are arranged in the first direction orthogonal to the height direction. The number of the structures 20 arranged in one structure row may be plural, and is preferably 10 or more. In the illustrated example, a plurality of such structure rows are arranged in the height direction and the second direction orthogonal to the first direction. The number of structure rows arranged in the second direction may be plural, and is preferably ten or more.

  As shown in FIG. 5, when the structure 20 is a grating, a plurality of the structures 20 may be arranged in a lattice pattern. In the example of FIG. 5, the structures 20 are arranged side by side in a second direction parallel to the substrate 1. In other words, the structure 20 has a structure in which a plurality of structures 20 are arranged in a second direction orthogonal to the height direction. The number of the structures 20 constituting the grating may be plural, and is preferably ten or more.

1.6. Arrangement of Metal Particles in Structure FIG. 5 and FIG. 6 show examples of arrangement of metal particles 30 in the sensor chip 100. The metal particles 30 are arranged on the side of the bent portion 21 of the structure 20 that faces upward (the portion in which the side of the structure 20 faces upward) generated by the bending. Particles 30 are spaced apart from one another. Moreover, the number of the metal particles 30 arrange | positioned at the part concerned is not limited. When a plurality of metal particles 30 are arranged in such a portion, for example, they can be arranged in front or in the depth direction in FIGS. 5 and 6. Further, the metal particles 30 may be disposed on the upper surface of the structure 20 or may be disposed on the metal layer 10.

  Furthermore, when the bent portions 21 of the structure 20 are formed so that the metal particles 30 of the sensor chip 100 are spaced apart from each other in the normal direction of the substrate 1 so as to be closer to the wavelength of the excitation light. Can generate LSP more efficiently by the oscillating electric field formed by PSP.

1.7. Operational Effect In the sensor chip 100 of the present embodiment, the metal particles 30 are positively arranged at a predetermined position (height) in the normal direction of the substrate 1. That is, in such a sensor chip 100, the position where the metal particles 30 exist is controlled in the normal direction of the substrate 1. As a result, strong localized surface plasmons (LSP) can be generated between the metal particles 30, and hot sites with high electric field enhancement can be formed in the vicinity of the metal particles 30. Therefore, the sensor chip 100 has a high hot site density for adsorbing the target substance and a high electric field enhancement intensity of the hot site. Thereby, for example, a high enhancement of the SERS signal can be obtained.

  Further, in the case where the metal layer 10 is provided as in the sensor chip 100 of the present embodiment, when the sensor chip 100 is irradiated with excitation light, PSP is generated in the metal layer 10, and the substrate 1 is caused by the PSP. An oscillating electric field in the normal direction can be generated. Thereby, it is easier to generate LSP at the end of the metal particle 30 in the normal direction of the substrate 1. Thereby, the sensor chip 100 has a very high density of hot sites for adsorbing the target substance, and the electric field enhancement of the hot sites is also high. Thereby, for example, a high enhancement of the SERS signal can be obtained.

1.8. First, (1) Localized surface plasmon resonance (LSPR) will be described. This is a phenomenon in which when light is incident on metal particles (metal fine particles), the vibration of free electrons inside the metal and the electric field of the light resonate, and a strong enhanced electric field is formed around the metal fine particles.

Next, (2) excitation of propagation type plasmons will be described. The dispersion relation of the surface plasmon propagating through the interface between the metal having the dielectric function ε (ω) and the medium having the dielectric function ε _m (ω) is given by the following formula (1).

Here, ω is the angular frequency, k _spp is the magnitude of the wave number vector of the surface plasmon propagating along the metal-medium interface, and c is the speed of light. On the other hand, the dispersion relationship between the light incident at the incident angle θ and the light diffracted by the structure (period P) is given by the following equations (2) and (3).

At this time, k ₀ is always larger than k _spp and does not have an intersection, so that surface plasmons cannot be directly excited by incident light. However, k _n has an intersection with k _spp , so surface plasmons Can be excited.

Therefore, by setting the period of the hole array, the pillar array, the grating structure, etc. in the structure 20 of the present embodiment so that k _n = k _{spp at} the wavelength of the excitation light, the propagation surface plasmon resonance (PSP) is achieved. In addition, it can be expressed in a superimposed manner with the LSP of the metal particles 30, and a very strong electric field enhancement can be obtained.

2. Sensor Chip Manufacturing Method The sensor chip 100 according to the present embodiment may be manufactured in any manner as long as the above-described structure can be formed. Can be manufactured. As an example, the sensor chip manufacturing method of the present embodiment includes a step of forming a dielectric layer above the substrate 1, a step of patterning the dielectric layer to form the base portion 22, and a dynamic gradient deposition method. A step of forming a structure 20 by depositing a dielectric on the base portion 22 under a first tilt condition and further depositing a dielectric under a second tilt condition different from the first tilt condition; And depositing a metal on the side surface of the body 20 by an inclined vapor deposition method.

  FIG. 7 is a diagram schematically showing the state of dynamic gradient deposition. Dynamic gradient deposition is performed by the following method. In vacuum deposition, the substrate 1 is rotated at a predetermined rotation speed about a rotation axis perpendicular to the substrate 1. On the other hand, the vapor deposition material comes from the vapor deposition source, but the direction of the flight is inclined at a predetermined angle with respect to the rotation axis.

  When the substrate 1 is rotated at a predetermined rotational speed, the vapor deposition material is allowed to fly from the vapor deposition source and deposited on the substrate 1, and depending on the vapor deposition conditions such as the rotational speed and the degree of vacuum at the time of vapor deposition, A structure 20 having a columnar structure (bending portion 21) such as an elliptical column and a zigzag column is formed on the substrate 1.

  FIG. 7 shows an example of formation of the structure 20 by dynamic gradient deposition. In this example, the substrate 1 is formed with a structure that becomes the base portion 22 of the structure 20 in advance. The base portion 22 has a structure such as a hole array, a pillar array, or a grating having a predetermined period.

Dynamic gradient deposition is performed on the substrate 1 on which such a base portion 22 is formed. As dynamic gradient deposition, for example, the deposit is made of SiO ₂ , the substrate temperature is 45 ° C., the substrate tilt angle is 60 degrees (an example of the first tilt condition), the 10 nm deposition film is formed, and the film formation direction is rotated by 90 degrees. An amount equivalent to 15 nm is further vapor-deposited at a substrate inclination angle of 80 degrees (an example of the second inclination condition), and then the vapor deposition orientation is rotated by 180 degrees each time an amount equivalent to 15 nm is vapor-deposited until the vapor deposition reaches 700 nm thickness. I do.

One or a plurality of bent portions 21 can be formed on the base portion 22 through the dynamic gradient deposition. At this time, the height T of the base portion 22 and the substrate inclination angle θ of the dynamic gradient deposition are ensured to the extent that no deposit is deposited on the bottom of the structure during the dynamic gradient deposition. Assuming the arrangement as shown in FIG. 7A, the metal flow from the vapor deposition source is set so as to be incident on the substrate at an incident angle of θ to 90 degrees. Here, θ is θ = cos ⁻¹ {T / (A ² + T ² ) ^1/2 } (A: interval of the base portion 22, T: height of the base portion 22).

  When a columnar dielectric (bent portion 21) is formed by dynamic gradient deposition satisfying the above conditions, a structure 20 as shown in FIG. 7B is obtained. It will be understood that the shape of the bent portion 21 can be changed by changing the mode of rotation of the substrate 1.

A metal is deposited on the structure 20 by a method such as vacuum vapor deposition or sputtering (gradient vapor deposition method) (FIG. 8A). Also in the inclined vapor deposition method, the inclination angle may be changed in the same manner as the above-described dynamic gradient vapor deposition method. The metal flow from the evaporation source or the target is incident on the substrate at an incident angle of 0 to θ and is deposited on the side wall of the structure. Here, θ is given by θ = cos ⁻¹ {T / (A ² + T ² ) ^1/2 } (A: the interval between the structures 20, T: the height of the structures 20). As described above, the side surface of the structure 20 has irregularities, and metal is deposited on the surface of the side surface facing upward, but it is difficult for the metal to deposit in the shadowed concave portion, so-called shadowing phenomenon. Occurs. Thereby, island-like metal particles 30 separated by the unevenness on the side surface of the structure 20 are obtained (FIG. 8B).

  More specifically, it is performed as follows. Using a quartz glass substrate (substrate 1), an electron beam resist ZEP-520A is applied on the substrate, and lines and spaces having a period of 600 nm and a duty ratio of 0.5 are drawn by an electron beam drawing apparatus. Thereafter, development is performed with a developer ZED-N50 to obtain a resist pattern. Thereafter, the resist pattern is transferred to the quartz substrate by reactive ion etching (RIE) to obtain the substrate 1 on which the base portion 22 having a height of 30 nm is formed. An amount equivalent to 15 nm is vapor-deposited at a substrate temperature of 45 ° C. and a substrate tilt angle of 85 degrees. Thereafter, every time an equivalent amount of 15 nm is vapor-deposited, the vapor deposition direction is rotated by 180 degrees, and film formation is performed until the vapor deposition reaches 700 nm thickness. Thereafter, metal particles 30 are adhered by depositing gold in an island shape by vacuum vapor deposition.

  Further, by controlling the deposition amount, the metal does not lead to film formation, and an island-like structure can be obtained. Thereby, island-like metal particles 30 separated by the unevenness on the side surface of the structure 20 are obtained (FIG. 8B). In addition, if it vapor-deposits, rotating the board | substrate 1 like Fig.8 (a), the metal particle 30 can be arrange | positioned over the perimeter of the structure 20. FIG. Further, in the case of the grating structure as shown in FIG. 4, the substrate 1 does not need to be rotated, and if the substrate 1 is tilted so as to be deposited on the two side surfaces of the structure 20. The metal particles 30 can be disposed on the entire side surface.

  Further, when the metal particles 30 are formed by deposition of a metal flow, if the amount of deposited metal is large, the island-like structure may be connected beyond the unevenness on the side surface of the structure 20 (bending portion 21). . In such a case, it is effective to perform heat treatment after depositing the metal. In this way, the metal deposited in a film shape can be aggregated to form particles. FIG. 9A is an SEM image showing the result of heat treatment at 500 ° C. on 5 nm gold deposited in a thin film. It can be confirmed that the gold thin film, which was a film before the heat treatment, is turned into particles and formed into islands. By applying such a technique, as shown in FIG. 9B, after depositing a metal in a film shape (gold thin film M) on the side surface of the structure 20, heat treatment is performed to separate the metal by unevenness. A structure in which the metal particles 30 are arranged can be obtained. The temperature of the heat treatment depends on the metal species and amount, but is preferably about 500 ° C. when the deposited metal is gold.

  When the size of the island-shaped metal particles 30 is sufficiently smaller than the wavelength of incident light, localized surface plasmons (LSP) are developed and an enhanced electric field is generated around the metal particles 30. As a result, SERS, which is an enhanced phenomenon of Raman scattered light, is expressed, and a very small amount of substance can be detected. The expression wavelength of LSP varies depending on the size and interval of the metal particles 30, and these can be appropriately set depending on the height and size of the bent portion 21 of the structure 20 and the amount of deposited metal.

3. Analysis Device FIG. 10 is a diagram schematically illustrating an analysis device 200 according to the present embodiment. For example, the analysis device 200 is a Raman spectroscopic device, and the analysis device 200 will be described below as a Raman spectroscopic device. As shown in FIG. 10, the analyzer 200 includes a gas sample holding unit 110, a detection unit 120, a control unit 130, and a housing 140 that houses the detection unit 120 and the control unit 130. The gas sample holder 110 includes a sensor chip according to the present invention. Below, the example containing the above-mentioned sensor chip 100 is explained.

  The gas sample holding unit 110 includes a sensor chip 100, a cover 112 that covers the sensor chip 100, a suction channel 114, and a discharge channel 116. The detection unit 120 includes a light source 210, lenses 122a, 122b, 122c, and 122d, a half mirror 124, and a photodetector 220. The control unit 130 includes a detection control unit 132 that processes a signal detected by the photodetector 220 and controls the photodetector 220, and a power control unit 134 that controls power and voltage of the light source 210 and the like. doing. As shown in FIG. 10, the control unit 130 may be electrically connected to a connection unit 136 for connection to the outside.

  In the analyzer 200, when the suction mechanism 117 provided in the discharge flow path 116 is operated, the suction flow path 114 and the discharge flow path 116 become negative pressure, and the target substance to be detected from the suction port 113 is contained. The gas sample is aspirated. The suction port 113 is provided with a dust removal filter 115, which can remove relatively large dust, some water vapor, and the like. The gas sample passes through the suction flow path 114 and the discharge flow path 116 and is discharged from the discharge port 118. The gas sample contacts the metal particle body 32 of the sensor chip 100 when passing through the path.

  The shapes of the suction channel 114 and the discharge channel 116 are such that light from the outside does not enter the sensor chip 100. Thereby, since the light which becomes noise other than a Raman scattered light does not inject, the S / N ratio of a signal can be improved. The material constituting the suction flow path 114 and the discharge flow path 116 is, for example, a material or a color that hardly reflects light.

  The shape of the suction channel 114 and the discharge channel 116 is such that the fluid resistance to the gas sample is reduced. Thereby, highly sensitive detection becomes possible. For example, the shape of the suction channel 114 and the discharge channel 116 is made as smooth as possible by eliminating the corners as much as possible, thereby preventing the gas sample from staying in the corners. As the suction mechanism 117, for example, a fan motor or a pump having a static pressure and an air volume corresponding to the flow path resistance is used.

In the analyzer 200, the light source 210 irradiates the sensor chip 100 with light (for example, laser light having a wavelength of 633 nm, excitation light). As the light source 210, for example, a semiconductor laser or a gas laser can be used. The light emitted from the light source 210 is collected by the lens 122a and then enters the sensor chip 100 through the half mirror 124 and the lens 122b. SERS light is emitted from the sensor chip 100, and the light reaches the photodetector 220 via the lens 122b, the half mirror 124, and the lenses 122c and 122d. That is, the light detector 220 detects light emitted from the sensor chip 100. Since the SERS light includes Rayleigh scattered light having the same wavelength as the incident wavelength from the light source 210, the Rayleigh scattered light may be removed by the filter 126 of the photodetector 220. The light from which the Rayleigh scattered light has been removed is received by the light receiving element 128 via the spectroscope 127 of the photodetector 220 as Raman scattered light. For example, a photodiode is used as the light receiving element 128.

  The spectroscope 127 of the photodetector 220 is formed of, for example, an etalon using Fabry-Perot resonance, and the pass wavelength band can be made variable. The light receiving element 128 of the light detector 220 obtains a Raman spectrum peculiar to the target substance. For example, the signal intensity of the target substance can be detected by collating the obtained Raman spectrum with data stored in advance. it can.

  The analysis apparatus 200 includes the sensor chip 100, the light source 210, and the photodetector 220, and is not limited to the above example as long as the target substance can be adsorbed on the sensor chip 100 and the Raman scattered light can be acquired.

  As described above, the analysis apparatus 200 includes the sensor chip 100 having a high density per unit area of the hot site and a high electric field enhancement intensity of the hot site. Therefore, the intensity of Raman scattered light can be increased. Therefore, the analyzer 200 can have high detection sensitivity.

  The above-described embodiments and modifications are merely examples, and the present invention is not limited to these. For example, it is possible to appropriately combine each embodiment and each modification.

  For example, the sensor chip according to the present invention can be used as an affinity sensor for detecting the presence or absence of substance adsorption, such as the presence or absence of antigen adsorption in an antigen-antibody reaction. The affinity sensor makes white light incident on the sensor, measures the wavelength spectrum with a spectroscope, and detects the amount of shift of the surface plasmon resonance wavelength due to adsorption, thereby making the absorption of the detection substance to the sensor chip highly sensitive. Can be detected.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 10 ... Metal layer, 20 ... Structure, 21 ... Bending part, 22 ... Base part, 30 ... Metal particle, 100 ... Sensor chip, 110 ... Gas sample holding part, 112 ... Cover, 113 ... Suction port, DESCRIPTION OF SYMBOLS 114 ... Suction flow path, 115 ... Dust removal filter, 116 ... Discharge flow path, 117 ... Suction mechanism, 118 ... Discharge port, 120 ... Detection part, 122a, 122b, 122c, 122d ... Lens, 124 ... Half mirror, 126 ... Filter DESCRIPTION OF SYMBOLS 127 ... Spectroscope, 128 ... Light receiving element, 130 ... Control part, 132 ... Detection control part, 134 ... Power control part, 136 ... Connection part, 140 ... Case, 200 ... Raman spectroscopy apparatus, 210 ... Light source, 220 ... Photodetector

Claims (8)

A substrate,
A structure formed above the substrate;
Metal particles disposed on a side surface of the structure;
Including
The structure assumes a plane parallel to the substrate that cuts the structure, and when the plane is moved away from the substrate, the center of gravity of the cross section of the structure on the plane periodically moves. Has a bent part,
At least a part of the metal particles is a sensor chip disposed on a side surface of the bent portion of the structure, the side surface facing upward. In claim 1,
When the plane is moved away from the substrate in the bent portion,
The sensor chip, wherein the locus of the center of gravity in the plane is a circle, an ellipse, a polygon, a line segment, or a combination thereof. In claim 1 or claim 2,
A sensor chip having a metal layer between the substrate and the structure. In claim 3,
The sensor chip, wherein the material of the metal layer is at least one metal selected from gold, silver, copper, aluminum, platinum, nickel, palladium, tungsten, rhodium, and ruthenium, or a plurality of these alloys. In any one of Claims 1 thru | or 4,
The sensor chip, wherein the metal particles are arranged apart from each other in the plurality of bent portions. Forming a dielectric layer above the substrate;
Patterning the dielectric layer to form a base,
A dielectric is deposited on the base portion under a first tilt condition by a dynamic tilt vapor deposition method, and a dielectric is further deposited under a second tilt condition different from the first tilt condition. Forming, and
Depositing metal on the side surface of the structure by a gradient deposition method;
A method for manufacturing a sensor chip. In claim 6,
A method of manufacturing a sensor chip, comprising: heating the substrate after depositing the metal. The sensor chip according to any one of claims 1 to 7,
A light source for irradiating the sensor chip with excitation light;
A detector for detecting light emitted from the sensor chip;
Analytical device equipped with.