Measuring device

Abstract

To prevent the response characteristics of a measuring device from deteriorating.SOLUTION: A measuring device according to the present invention includes a semiconductor substrate that transmits light of a predetermined wavelength and has a diffraction grating formed on one plate surface, an intermediate layer laminated on a grating surface of the diffraction grating of the semiconductor substrate, and a metal layer that is laminated on a surface of the intermediate layer, forms a Schottky barrier with the semiconductor substrate via the intermediate layer, and causes surface plasmon resonance when irradiated with light of a predetermined wavelength.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measurement device. [Background technology]

[0002] Surface plasmon resonance (SPR) is known as a phenomenon in which evanescent waves generated by the total reflection of light at a dielectric-metal interface couple to the resonant vibration of free electrons on the metal surface. The SPR resonance conditions depend on the incident angle and wavelength of the light, the dielectric constant of the metal, and the dielectric constant of the dielectric in contact with the metal, and are particularly sensitive to changes in the dielectric constant of the dielectric. In recent years, chemical and biological sensors based on SPR have been widely studied. Current-detection SPR sensors do not require an optical system to detect reflected light and respond only to changes in the refractive index of the object being measured, making them easily miniaturized.

[0003] For example, Patent Document 1 discloses a chip for local SPR measurement in which organic molecule immobilization sections having nanopatterns of a number of non-light-transmitting materials such as metals are arranged on a substrate made of a light-transmitting material. The chip for local SPR measurement in Patent Document 1 detects changes in light absorption due to local SPR, and the state of the object to be measured can be imaged based on the light absorption detection results. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-222401 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional SPR sensors, including the chip for local SPR measurement disclosed in Patent Document 1, silicon (Si), a semiconductor material, is used as the substrate material, and gold (Au), for example, may be used as a suitable material for the metal layer that induces SPR. In such cases, the adhesion between the substrate and the metal layer formed on the surface of the substrate is poor, which can cause interdiffusion of Au with Si, potentially resulting in a decrease in the response characteristics of the SPR sensor. [Means for solving the problem]

[0006] The measuring device of this embodiment comprises a semiconductor substrate having a diffraction grating formed on one surface thereof, an intermediate layer laminated on the grating surface of the diffraction grating of the semiconductor substrate, and a metal layer laminated on the surface of the intermediate layer, which forms a Schottky barrier between the semiconductor substrate and the intermediate layer and which generates surface plasmon resonance when irradiated with light of a predetermined wavelength. [Effects of the Invention]

[0007] According to the present invention, it is possible to prevent a decrease in the response characteristics of a measuring device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a measuring device according to an embodiment of the present invention. [Figure 2] FIG. 2 is an energy band diagram of the measuring device shown in FIG. [Figure 3] 2A to 2C are perspective views of a manufacturing process of the measuring device shown in FIG. [Figure 4] 2A to 2C are perspective views of a manufacturing process of the measuring device shown in FIG. [Figure 5] 2A to 2C are perspective views of a manufacturing process of the measuring device shown in FIG. [Figure 6] 2A to 2C are perspective views of a manufacturing process of the measuring device shown in FIG. [Figure 7] 2A to 2C are perspective views of a manufacturing process of the measuring device shown in FIG. [Figure 8] 2A to 2C are perspective views of a manufacturing process of the measuring device shown in FIG. [Figure 9] FIG. 2 is a schematic diagram of an evaluation optical system for a measurement device prototyped in an example. [Figure 10] 1 is a graph showing response characteristics measured for a measurement device prototyped in an example. [Figure 11] 10 is a graph showing response characteristics measured for a measurement device prototyped in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a measurement device and a measurement sensor according to the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the ratios of length, width, and thickness may not be the same as those in the actual devices and may be changed as appropriate.

[0010] First, the configuration of the measuring device 100 of this embodiment will be described. As shown in Fig. 1, the measuring device 100 of this embodiment includes a semiconductor substrate 5, an intermediate layer 60, and a metal layer 10. A diffraction grating is formed on one plate surface 5b of the semiconductor substrate 5. The intermediate layer 60 is stacked with a substantially constant thickness on the grating surface 50 of the diffraction grating formed on the semiconductor substrate 5. The metal layer 10 is stacked with a substantially constant thickness on one surface 60b of the intermediate layer 60 opposite to the other surface in contact with the semiconductor substrate 5.

[0011] The semiconductor substrate 5 contains silicon (Si) and is made of, for example, n-type Si, which is an n-type semiconductor. The semiconductor substrate 5 determines the SPR resonance conditions between the semiconductor substrate 5 and the metal layer 10 in the measuring device 100. The semiconductor substrate 5 forms a Schottky barrier between the semiconductor substrate 5 and the metal layer 10 via the intermediate layer 60. The semiconductor substrate 5 also plays a role in forming the electrode section 30.

[0012] The intermediate layer 60 is interposed at the interface between the semiconductor substrate 5 and the metal layer 10. The intermediate layer 60 is made of a metal with a low diffusion coefficient and high heat resistance. The intermediate layer 60 suppresses interdiffusion between the semiconductor material of the semiconductor substrate 5 and the metal material of the metal layer 10.

[0013] The metal layer 10 has an antenna part that generates SPR when light L is irradiated onto the metal layer 10 from the surface opposite to the surface 10b through the semiconductor substrate 5. The antenna part is formed on the surface 10b side of the metal layer 10. A reactive layer 20 is provided on one surface of the metal layer 10 opposite the other surface that contacts the intermediate layer 60. The antenna part functions as an antenna that captures SPR generated between the reactive layer 20 and the metal layer 10, and is formed on the part of the metal layer 10 on the reactive layer 20 side.

[0014] The metal layer 10 has resonating portions 11 formed at intervals s in the D1 direction along the plate surface 5b of the semiconductor substrate 5, and current collecting portions connected to the resonating portions 11 and formed at intervals s. In this configuration, electrons inside the resonating portions are excited by irradiation with light L, causing resonance along the D1 direction, and SPR occurring between the antenna portion and the reaction layer 20 is coupled.

[0015] The material of the metal layer 10 is not particularly limited as long as it is a metal that can generate a surface current due to SPR as described above. A suitable material for the metal layer 10 is gold (Au). Gold has excellent conductivity, and there is mature technology for depositing a film of a substance that constitutes the reaction layer 20, such as an antibody (not shown), on the surface 10b. Other materials for the metal layer 10 include silver (Ag), aluminum (Al), and copper (Cu).

[0016] The reactive layer 20 is configured to be capable of reacting with a specific detection substance. The substance or material constituting the reactive layer 20 is appropriately selected to be compatible with the specific detection substance and capable of being formed into a film on the surface 10b of the metal layer 10.

[0017] An example of a specific detection substance is an antigen. The reaction layer 20 is composed of an antibody (not shown) that undergoes an antigen-antibody reaction with the antigen. One end of the antibody is fixed to the surface 10b of the metal layer 10, i.e., the antenna portion, and the other end of the antibody is open. Specifically, at least one antibody is fixed in a line along the surface 10b of the metal layer 10, with the constant region at one end of the antibody abutting the surface 10b of the metal layer 10, and the variable region at the other end of the antibody is open. The variable region is a region that recognizes and specifically binds to the antigen, causing an antigen-antibody reaction.

[0018] In the above-described configuration, for example, if a liquid sample is dropped onto the reaction layer 20 and the sample contains an antigen, the antigen binds to the variable region of the antibody, causing an antigen-antibody reaction. The refractive index of the antibody and the antenna unit that have undergone the antigen-antibody reaction changes, affecting resonance and SPR in the resonator 11. In this way, the antenna unit detects the change in refractive index.

[0019] The electrode section 30 has a metal layer 10, a conductive layer 34 laminated on the surface 5a of the semiconductor substrate 5, and a circuit 36 ​​connecting the terminal of the metal layer 10 to the conductive layer 34. The current I collected in the current collecting section of the metal layer 10 can be displayed on an ammeter 38 provided on the circuit 36 ​​or on a monitor (not shown). The conductive layer 34 is made of, for example, aluminum (Al).

[0020] Next, the principle of the measuring device 100 of this embodiment will be described. In the measuring device 100 of this embodiment, a conductive layer 34, a semiconductor substrate 5, and a metal layer 10 that also serves as a terminal of the electrode portion 30 are sequentially stacked along the D2 direction, thereby forming the energy band structure shown in FIG. 2. In FIG. 2, energy Ev represents the energy level of the valence band. Energy Ef represents the Fermi level. Energy Ec represents the energy level of the conduction band.

[0021] A Schottky barrier W1 is formed at the interface formed by the junction between the metal layer 10 and the intermediate layer 60. As shown in Fig. 2, unexcited free electrons e in the metal layer 10 cannot cross the Schottky barrier W1 and remain inside the metal layer 10. When an antigen binds to an antibody and SPR occurs between the reaction layer 20 and the metal layer 10 as described above, the free electrons e inside the metal layer 10 are excited, overcome the Schottky barrier W1, and diffuse from the metal layer 10 through the intermediate layer 60 toward the semiconductor substrate 5.

[0022] A Schottky barrier W2 is formed at the interface between the semiconductor substrate 5 and the conductive layer 34. Free electrons e that are excited by SPR and overcome the Schottky barrier W1 diffuse toward the Schottky barrier W2. Basically, the free electrons e cannot overcome the Schottky barrier W2 as shown by the arrow unless they are excited with energy corresponding to the height of the Schottky barrier W2. For this reason, it is preferable that the surface 5a of the semiconductor substrate 5 opposite the surface 5b that contacts the intermediate layer 60 be doped with impurities.

[0023] If the semiconductor substrate 5 is heavily doped with impurities, the width of the Schottky barrier W2 is narrow for the free electrons e. By selecting a material for the conductive layer 34 that reduces the Schottky barrier W2 between the conductive layer 34 and the semiconductor substrate 5, the free electrons e can tunnel through the Schottky barrier W2 as indicated by the arrow.

[0024] In response to the diffusion of the free electrons e, holes h diffuse from the valence band of the semiconductor substrate 5 through the intermediate layer 60 toward the interior of the metal layer 10. Due to this principle, when SPR occurs, a surface current is generated in the metal layer 10. By measuring the increase or decrease in the surface current extracted by the electrode unit 30, the presence or absence of the above-mentioned antigen-antibody reaction, and the presence or absence and concentration of antigens in the sample, etc. can be detected.

[0025] The magnitude of the surface current of the metal layer 10 varies depending on the wavelength of the light L, depending on the presence or absence of an antigen-antibody reaction, the presence or absence and concentration of antigens in the sample, the SPR resonance conditions, etc. Note that the magnitude of the surface current for each wavelength can be predicted by numerical simulation or the like, taking into account the above-mentioned conditions, etc., and the wavelength of the light L can be adjusted. In other words, the wavelength of the light L (predetermined wavelength) can be adjusted, taking into account the results of the above-mentioned numerical simulation, etc., and the change in the surface current can be measured.

[0026] In the measuring device 100 of this embodiment, based on the above-mentioned principle, an antibody is selected according to the measurement target, such as an antigen, and a metal for the metal layer 10 is selected that can form a film of the antibody and cause SPR. As described above, Au is preferred as the metal for the metal layer 10 because the antibody that constitutes the reaction layer 20 can be easily formed into a film on the surface 10b of the metal layer 10. When the material of the metal layer 10 is Au, the antenna section and the metal layer 10 can be made of the same Au.

[0027] The width d of the resonating portion 11 of the metal layer 10 is preferably, for example, 0.2 μm or more and 5 μm or less. When the width d of the resonating portion 11 is within the above-mentioned range, the SPR excitation conditions and the degree of resonance coupled with SPR become favorable. The thickness of the metal layer 10 is preferably 50 nm or more and 200 nm or less, for example, 100 nm. The period of the diffraction grating formed on the semiconductor substrate 5 and the metal layer 10, i.e., the sum of the width d and the spacing s, is, for example, about 470 nm.

[0028] In the measuring device 100 of this embodiment, the wavelength of light L that induces SPR between the reaction layer 20, i.e., the antibody, and the antenna portion is set. A material is selected for the semiconductor substrate 5 that induces SPR via the metal constituting the metal layer 10 and the intermediate layer 60 and forms a Schottky barrier W1. The wavelength (predetermined wavelength) of light L is preferably, for example, 1 μm or more and 10 μm or less. The wavelength of light L is not particularly limited as long as it can induce SPR between the reaction layer 20 and the antenna portion, as described above. A suitable material for the semiconductor substrate 5 is Si, which is an n-type semiconductor. When light L is incident on the semiconductor substrate 5 from the plate surface 5a side, the semiconductor substrate 5 is capable of transmitting light L.

[0029] The conductive layer 34 forms a Schottky barrier W2 at the interface with the semiconductor substrate 5. From the viewpoint of enabling tunneling of free electrons e to the semiconductor substrate 5 made of n-type Si and enabling smooth extraction of the surface current of the metal layer 10, examples of the material for the conductive layer 34 include Al, Ti, Cr, etc.

[0030] As described above, the surface 5a side of the semiconductor substrate 5 is doped with impurities to enable tunneling of free electrons e and to smoothly extract the surface current of the metal layer 10. The impurities are known dopants for n-type semiconductors, such as phosphorus (P), arsenic (As), and antimony (Sb). The doping concentration is, for example, 10 20 atoms / cm 3 This is adjusted appropriately taking into consideration the height of the Schottky barrier W2, etc. When the thickness of the semiconductor substrate 5 is about several hundred μm, the depth to which the impurities penetrate from the plate surface 5a may be, for example, about 100 nm.

[0031] In the measuring device 100 of this embodiment, SPR occurs when the coupling condition of the following equation (1) is satisfied.

[0032]

number

[0033] In equation (1), ω represents the angular frequency of the light L incident on the measuring device 100. c represents the speed of light in a vacuum. θ M represents the angle of incidence of light L. m represents the diffraction order. α represents the period of the diffraction grating formed on the metal layer 10 and the semiconductor substrate 5, and corresponds to the sum of the width d and the spacing s. ε m represents the dielectric constant of the dielectric material such as the sample. M represents the dielectric constant of the metal material of the metal layer 10.

[0034] In the measuring device 100 of this embodiment, when the SPR coupling condition is satisfied, the energy of the incident light L is absorbed, generating SPR, as described above. Free electrons e in the metal layer 10, such as Au, are excited and overcome the Schottky barrier W1 at the interface between the intermediate layer 60 and the semiconductor substrate 5, generating a photocurrent signal, i.e., current I. Even if the metal layer 10 and the semiconductor substrate 5 are in direct contact as in the past, the metallic bond at the interface between the material, such as Au, of the metal layer 10 and the material, such as Si, of the semiconductor substrate 5 is weak, resulting in interdiffusion. On the other hand, metals with high melting points do not easily diffuse with Si. Here, a high melting point means a melting point of, for example, 1500°C or higher. Therefore, it is preferable that the material of the intermediate layer 60 has a melting point of 1500°C or higher.

[0035] When the material of the metal layer 10 is Au and the semiconductor substrate 5 is made of Si, suitable materials for the intermediate layer 60 are, for example, molybdenum (Mo), chromium (Cr), titanium (Ti), and the like.

[0036] Next, a method for manufacturing the measuring device 100 of this embodiment will be described. As shown in Fig. 3, a resist 150 is applied to the entire surface 5b of the semiconductor substrate 5. Then, the resist 150 is patterned by, for example, electron beam lithography to form a plurality of resists 150, each having a width d in the D1 direction, spaced apart by a distance s, as shown in Fig. 4. Then, as shown in Fig. 5, the resist 150 is removed and the exposed semiconductor substrate 5 is etched using the resist 150 as a mask by, for example, dry reactive ion etching (RIE), to form a diffraction grating.

[0037] Next, as shown in Fig. 6, the resist 150 remaining on the surface 5b of the semiconductor substrate 5 is removed. Thereafter, as shown in Fig. 7, the material for the intermediate layer 60 is deposited on the grating surface 50 of the diffraction grating, i.e., on the surface 5b of the semiconductor substrate 5 having the uneven shape that is parallel to the surface 5a, to form the intermediate layer 60. Next, as shown in Fig. 8, the material for the metal layer 10 is deposited on the surface 60b of the intermediate layer 60 to form the metal layer 10. Furthermore, the material for the conductive layer 34 is deposited on the other surface 5a of the semiconductor substrate 5 to form the conductive layer 34.

[0038] The measuring device 100 of this embodiment is manufactured through the above-mentioned steps. The techniques used in the above-mentioned steps may be changed as appropriate depending on the materials used, etc.

[0039] The measuring device 100 of this embodiment described above includes a semiconductor substrate 5 having a diffraction grating formed on one surface 5b, an intermediate layer 60 laminated on the grating surface 50 of the diffraction grating formed on the semiconductor substrate 5, and a metal layer 10 laminated on the surface 60b of the intermediate layer 60. The metal layer 10 forms a Schottky barrier W1 between itself and the semiconductor substrate 5 via the intermediate layer 60, and generates SPR when irradiated with light L of a predetermined wavelength.

[0040] In the measuring device 100 of this embodiment, an intermediate layer 60 is provided on at least the grating surface 50 of the diffraction grating formed on the semiconductor substrate 5, and the intermediate layer 60 is interposed between the semiconductor substrate 5 and the metal layer 10 in the D2 direction, thereby suppressing interdiffusion between the metal material of the metal layer 10 and the semiconductor material of the semiconductor substrate 5, and in particular effectively suppressing diffusion of the semiconductor material of the semiconductor substrate 5 toward the metal layer 10, thereby stabilizing the Schottky barrier W1 and its action over the long term and preventing a decrease in response performance.

[0041] The measuring device 100 of this embodiment includes an electrode portion 30 and a conductive layer 34 electrically connected to the metal layer 10 and the other surface 5a opposite to the one surface 5b of the semiconductor substrate 5.

[0042] In the measuring device 100 of this embodiment, the electrode section 30 is provided, so that the surface current generated in the metal layer 10 can be extracted to the circuit 36 ​​and easily measured using an ammeter 38 or a monitor device (not shown) provided on the circuit 36. Furthermore, in the measuring device 100 of this embodiment, the electrode section 30 connecting the metal layer 10 and the plate surface 5a of the semiconductor substrate 5 can perform operations from irradiating light L to measuring antigens by itself.

[0043] In the measuring device 100 of this embodiment, the specified wavelength is 1 μm or more and 10 μm or less, the semiconductor substrate 5 is made of n-type silicon, and the period of the diffraction grating formed on the semiconductor substrate 5 and the metal layer 10 is 0.4 μm or more and 5 μm or less.

[0044] In the measuring device 100 of this embodiment, by using suitable design conditions and combinations of a predetermined wavelength and the period of the diffraction grating, the diffracted light from the diffraction grating and SPR can be well coupled, thereby improving sensitivity and suppressing deterioration of response characteristics.

[0045] In the measuring device 100 of this embodiment, the semiconductor substrate 5 contains Si, the intermediate layer 60 contains Mo, Cr or titanium (Ti), and the metal layer 10 contains Au.

[0046] In the measuring device 100 of this embodiment, the material of the intermediate layer 60 is suitably selected for the semiconductor material of the semiconductor substrate 5 and the metal material of the metal layer 10, so that the diffusion of the semiconductor material of the semiconductor substrate 5 into the metal layer 10 is effectively suppressed and the metal layer 10 is prevented from peeling or detaching from the semiconductor substrate 5.

[0047] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as set forth in the claims.

[0048] For example, although not shown, in the measuring device 100 of the above-described embodiment, the intermediate layer 60 may be laminated on the entire surface 5b of the semiconductor substrate 5, rather than only on the grating surface 50 of the diffraction grating on one surface 5b of the semiconductor substrate 5. In other words, the intermediate layer 60 may also be formed on the side surface of the uneven structure that forms the diffraction grating of the semiconductor substrate 5. [Example]

[0049] Next, examples will be described to confirm the usefulness of the measuring device of the above-described embodiment. Note that the configuration and effects of the measuring device according to the present invention are not limited to the following examples.

[0050] As an example, the measuring device 100 shown in FIG. 1 was fabricated by the manufacturing method described with reference to FIGS. 3 to 8. In this example, the material of the semiconductor substrate 5 was n-type Si, the period of the diffraction grating was 470 nm, and the height of the uneven structure of the diffraction grating was 30 nm. The material of the intermediate layer 60 was Mo, and the thickness of the intermediate layer 60 was 5 nm. The material of the metal layer 10 was Au, and the thickness of the metal layer 10 was 100 nm. The energy Φ of the Schottky barrier W1 of the fabricated measuring device 100 was 0.70 eV.

[0051] The response characteristics of the prototype measuring device 100 were measured using the evaluation optical system shown in Fig. 9. As shown in Fig. 9, in the evaluation optical system, the laser light LA ​​emitted from the light source 202 passes through the polarizing element 204 to be converted into linearly polarized light, passes through the opening 206, and is incident at an angle θ with respect to the normal to the plate surface 5a of the semiconductor substrate 5 of the measuring device 100 or the grating surface 50 of the diffraction grating, as shown by the dashed line. M The wavelength of the laser light LA ​​emitted from the light source 202 was 635 [nm]. The ambient temperature was 22 [°C].

[0052] The prototype measuring device 100 is supported in a fixed state by a support member 210. The support member 210 is formed in a box shape. The prototype measuring device 100 is housed inside the support member 210. The support member 210 has an opening formed therein whose size matches the optical path of the laser light LA ​​incident on the metal layer 10 of the measuring device 100 at an incident angle θM.

[0053] In order to examine the change over time in the response characteristics of the prototype measuring device 100, the incident angle θ M 10, in the measuring device 100 of the example, the intermediate layer 60 is interposed between the semiconductor substrate 5 and the metal layer 10, and therefore the current I detected at the incident angle θ M The peak of current I, which indicates responsiveness to the temperature, remained almost unchanged from 1 day after prototyping to 10 days after prototyping, demonstrating high stability. The intensity of current I at the peak decreased slightly from 1 day after prototyping to 10 days after prototyping. It is believed that the decrease in current I can be reduced by providing intermediate layer 60 over the entire surface 5b of semiconductor substrate 5 and also on the side surfaces of the concave-convex structure of the diffraction grating, as described in the above-mentioned modified example.

[0054] Although not shown, as a comparative example, a measuring device was fabricated in which the intermediate layer 60 in the measuring device 100 of the embodiment was removed and the metal layer 10 was laminated directly on the surface 5b of the semiconductor substrate 5 as in the conventional case. The materials and dimensions of each component of the measuring device of the comparative example were the same as those of the measuring device 100 of the embodiment.

[0055] The change over time in the response characteristics of the measurement device of the comparative example was evaluated using the evaluation optical system shown in Fig. 9, as in the example. As shown in Fig. 11, in the measurement device of the comparative example, the intermediate layer 60 is not interposed between the semiconductor substrate 5 and the metal layer 10, so that the incident angle θ M The peak of current I, which indicates the responsiveness to the angle, shifted toward 0° every day from 1 day after prototyping to 10 days after prototyping. The intensity of current I at the peak of the responsiveness characteristic of the comparative example measurement device significantly decreased compared to the measuring device 100 of the example from 1 day after prototyping to 10 days after prototyping. From these results, it was clear that the comparative example measurement device, which has the same concept as the conventional one, showed a significant decrease in responsiveness after prototyping.

[0056] From the above results, it was confirmed that in the measuring device 100 of the above embodiment, the presence of the intermediate layer 60 between the semiconductor substrate 5 and the metal layer 10 prevents a decrease in response characteristics. [Explanation of symbols]

[0057] 5. Semiconductor substrate 5a,5b plate surface 10 metal layer 50 lattice planes 60 Middle Class 60b surface

Claims

1. a semiconductor substrate having a diffraction grating formed on one surface thereof; an intermediate layer laminated on the grating surface of the diffraction grating of the semiconductor substrate; a metal layer laminated on a surface of the intermediate layer, forming a Schottky barrier between the metal layer and the semiconductor substrate via the intermediate layer, and causing surface plasmon resonance when irradiated with light of a predetermined wavelength; Equipped with Measuring devices.

2. an electrode portion electrically connected to the metal layer and to the other surface of the semiconductor substrate opposite to the one surface; The measuring device according to claim 1 .

3. the predetermined wavelength is 1 μm or more and 10 μm or less, the semiconductor substrate is made of n-type silicon; The period of the diffraction grating is 0.4 μm or more and 5 μm or less. The measuring device according to claim 1 or 2.

4. the semiconductor substrate comprises silicon; the intermediate layer comprises molybdenum, chromium, or titanium; the metal layer comprises gold; The measuring device according to claim 1 or 2.

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