Substance detection element

Abstract

A through-hole (3) is provided in a support substrate (2). A plate-like beam (4(4A, 4B)) having a piezoelectric element extends from an edge of the through-hole (3) toward an opposite edge to block a part of the through-hole (3), and supports a substance adsorption film to which a constituent substance of a detection object adheres. The vibration frequency of the beam (4) changes when the constituent substance adheres to the substance adsorption film. A drive electrode (16) is used to apply a voltage to the piezoelectric element to cause the beam (4) to vibrate and deform. A detection electrode (17) is used to detect information related to the vibration frequency of the beam (4).

Description

[0001] This application is a divisional application of an application with an application date of March 16, 2018, an application number of 201880020078.6 (international application number PCT / JP2018 / 010449), and an invention title of "substance detection element". Technical Field

[0002] The present invention relates to a substance detection element. Background Art

[0003] In Patent Document 1, a chemical sensor device is disclosed for identifying a substance based on a change amount of a resonance frequency of an oscillator generated when a substance is adsorbed or desorbed. The chemical sensor device includes a plurality of oscillators representing desorption-adsorption characteristics of different substances, and each oscillator has a piezoelectric substrate. When an alternating voltage is applied to the plurality of oscillators, they are excited due to deformation of the piezoelectric substrate. By identifying the oscillator whose resonance frequency has changed, a substance can be identified.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2009-204584 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In the chemical sensor device disclosed in Patent Document 1 above, only a plurality of oscillators are simply arranged two-dimensionally on a flat plate, and they are not efficiently arranged in a manner that makes it easy for each oscillator to adsorb substances contained in the air. In such a structure, there is also a possibility that the flat plate itself blocks the flow of air, resulting in a decrease in the adsorption efficiency of the adsorbed substances on each oscillator.

[0009] The present invention has been completed in view of the above actual situation, and an object thereof is to provide a substance detection element capable of detecting a substance more efficiently.

[0010] Solutions to Solve the Problems

[0011] To achieve the above object, the substance detection element of the present invention includes:

[0012] A support substrate provided with a through hole;

[0013] A plate-shaped beam having a piezoelectric element, the beam extending from an edge of the through hole toward an opposite edge to block a part of the through hole, and supporting a substance adsorption film to which a substance to be detected adheres, and the vibration frequency of the beam changes when the substance adheres to the substance adsorption film;

[0014] A drive electrode for applying a voltage to the piezoelectric element to cause the beam to vibrate and deform; and

[0015] A detection electrode for detecting information related to the vibration frequency of the beam.

[0016] In this case, it is also possible that the beam is fixed to the edge of the through hole at at least two positions.

[0017] It is also possible that the beam is formed by a plate-shaped first beam having the drive electrode provided at at least one end fixed to the edge of the through hole and a plate-shaped second beam having the detection electrode provided at at least one end fixed to the edge of the through hole and intersecting the first beam.

[0018] It is also possible that the drive electrodes are provided at both ends of the first beam fixed to the edge of the through hole.

[0019] The detection electrodes are provided at both ends of the second beam fixed to the edge of the through hole.

[0020] The first beam and the second beam are joined together at their respective centers.

[0021] It is also possible that the width of the joining portion of the first beam and the second beam is set wider than the width of other portions of the first beam and the second beam except the joining portion.

[0022] It is also possible that the width of the first beam is set wider than the width of the second beam.

[0023] It is also possible that the first beam and the second beam are orthogonal.

[0024] It is also possible that a wire connecting the detection electrodes formed at both ends of the second beam to each other is formed on the second beam, and a wire electrically connected to one of the detection electrodes is led out of the second beam.

[0025] It is also possible that wires electrically connected to the drive electrodes formed at both ends of the first beam are respectively led out of the first beam and gathered into one wire.

[0026] It is also possible that a plurality of through holes are provided in the support substrate.

[0027] A beam is provided for each of the through holes.

[0028] The types of the substance adsorption films supported by the respective beams are different.

[0029] Effects of the Invention

[0030] According to the present invention, a substance adsorption film is provided in the through-hole through which the gas containing the substance passes, and the gas containing the substance to be detected easily passes around the substance adsorption film, so that the substance can be detected more efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 FIG. 6 is a perspective view of the substance detection element according to Embodiment 1 of the present invention.

[0032] Figure 2 FIG. 10 is a perspective view Figure 1 observed from the opposite side of the substance detection element.

[0033] Figure 3 FIG. 16 is a perspective view showing partial destruction of the periphery of the through-hole.

[0034] Figure 4 FIG. 20 is an enlarged perspective view of the vicinity of the through-hole.

[0035] Figure 5 FIG. 24 is a top view of the vicinity of the through-hole.

[0036] Figure 6A FIG. 28 is a cross-sectional view taken along the longitudinal direction of the drive beam.

[0037] Figure 6B FIG. 32 is a cross-sectional view taken along the longitudinal direction of the detection beam.

[0038] Figure 7A FIG. 36 is a view showing a state (No. 1) of deformation of the drive beam.

[0039] Figure 7B FIG. 40 is a view showing a state (No. 2) of deformation of the drive beam.

[0040] Figure 8A FIG. 44 is a view showing a state (No. 1) of deformation of the detection beam.

[0041] Figure 8B FIG. 48 is a view showing a state (No. 2) of deformation of the detection beam.

[0042] Figure 9 FIG. 52 is a perspective view showing the wiring of the substance detection element.

[0043] Figure 10 FIG. 56 is a view showing the substance detection element inserted into an electronic device.

[0044] Figure 11A FIG. 60 is a view showing a reference pattern (No. 1) of the constituent substances of a chemical substance.

[0045] Figure 11B FIG. 64 is a view showing a reference pattern (No. 2) of the constituent substances of a chemical substance.

[0046] Figure 12 This is a diagram showing the situation where gas passes through the through-holes.

[0047] Figure 13A This is a diagram showing a deformation example (No. 1) of the piezoelectric element formed on the beam.

[0048] Figure 13B This is a diagram showing a deformation example (No. 2) of the piezoelectric element formed on the beam.

[0049] Figure 13C This is a diagram showing a deformation example (No. 3) of the piezoelectric element formed on the beam.

[0050] Figure 14A This is a diagram showing a deformation example (No. 1) of the beam.

[0051] Figure 14B This is a diagram showing a deformation example (No. 2) of the beam.

[0052] Figure 14C This is a diagram showing a deformation example (No. 3) of the beam. Detailed implementation mode

[0053] Hereinafter, the implementation mode of the present invention will be described in detail. The substance detection element of this implementation mode is manufactured using MEMS (Micro Electro Mechanical Systems), which is a semiconductor manufacturing technology for realizing microfabrication.

[0054] As Figure 1 shown, the substance detection element 1 of this implementation mode includes a support substrate 2 in a substantially rectangular flat plate shape. For example, the support substrate 2 is manufactured using an SOI (Silicon on Insulator) substrate. The SOI substrate is a semiconductor substrate having a stacked structure including a BOX layer as a buried oxide film and a silicon (SOI) layer as a semiconductor layer on the BOX layer, and is a wafer with an oxide film encapsulated therein.

[0055] As Figure 1 and Figure 2 shown, the support substrate 2 is constituted by laminating an Si support layer 11 formed of a base wafer and a BOX layer on a base portion 10 formed of resin, and the BOX layer is formed of a buried oxide film. An Si active layer 12 as an active layer of the element wafer is laminated on the Si support layer 11 (refer to Figure 6A , Figure 6B ).

[0056] A circular opening 13 is provided locally in the base portion 10 of the support substrate 2, and the Si support layer 11 is exposed at the portion of the opening 13. Seven through-holes 3 are provided in the Si support layer 11 and the Si active layer 12 at the portion of the opening 13. The through-holes 3 are circular and have the same diameter as each other.

[0057] As Figure 3 and Figure 4 shown, a pair of plate-like beams 4 are respectively provided in each through-hole 3. The pair of beams 4 includes a linear plate-like drive beam (first beam) 4A and a linear plate-like detection beam (second beam) 4B. The beams 4 (the drive beam 4A and the detection beam 4B) respectively have portions extending from an edge formed by the Si active layer 12 toward opposite edges.

[0058] The drive beam 4A and the detection beam 4B are orthogonal and are connected together at the center. In the present embodiment, the widths of the drive beam 4A and the detection beam 4B are the same. This width represents the length in the width direction of the drive beam 4A and the length in the width direction of the detection beam 4B. The pair of beams 4 does not block the whole of the through-hole 3, but blocks a part of the through-hole 3. Thus, the beams 4 can prevent gas from staying in the through-hole 3 and make the gas easily pass through the through-hole 3.

[0059] As Figure 3 shown, the beam 4 supports a substance adsorption film 5 for adsorbing a substance to be detected. The substance adsorption film 5 is located at the center of the beam 4, i.e., the center in the through-hole 3, and is disposed at the connecting portion of the drive beam 4A and the detection beam 4B. The center of the beam 4, i.e., the portion where the pair of beams 4 are connected to each other and the substance adsorption film 5 is formed, is set to be wider in the width direction of one beam 4 and the width direction of the other beam 4 than other portions except the connecting portion. And the substance adsorption film 5 has a dome shape (hemispherical shape). Therefore, the surface area exposed to the gas can be increased, and thus it is easy to adsorb the substance to be detected contained in the gas (e.g., in the air).

[0060] The substance to be detected is, for example, a gaseous substance (hereinafter referred to as "constituent substance") in a chemical substance group (odor causative agent) constituting an odor, for example, a chemical substance constituting the substance to be detected contained in the air. As the chemical substance to be detected, for example, there are odor causative substances such as ammonia, mercaptan, aldehyde, hydrogen sulfide, and amine having a peculiar odor. For the substance adsorption film 5, after a certain time has passed since the constituent substance constituting the odor causative substance is adsorbed, the adsorbed constituent substance is separated, and thus it can be reused.

[0061] The beam 4 is configured such that its vibration frequency (e.g., resonance frequency) changes due to the adsorption of the constituent substance to the substance adsorption film 5. Since the substance adsorption film 5 is disposed in the through-hole 3 which is the opening of the gas containing the constituent substance, the substance adsorption film 5 is easy to adsorb the constituent substance contained in the gas. In addition, in order to prevent the vibration of the beam 4 from being affected by the vibration of the device (e.g., the electronic device 50 described later) on which the substance detection element 1 is installed, it is desirable to set the vibration frequency of the beam 4 to be higher so as to be different from the vibration frequency of the device.

[0062] AsFigure 4 As shown, a pair of drive electrodes 16 are formed at both ends of the drive beam 4A, and a pair of detection electrodes 17 are formed at both ends of the detection beam 4B. In addition, drive signal lines 21, inter-electrode signal lines 22, and detection signal lines 23 serving as conductors are formed on the support substrate 2 and the beam 4. The drive signal line 21 is connected to the drive electrode 16. In addition, the inter-electrode signal line 22 connects the detection electrodes 17 to each other on the detection beam 4B. The detection signal line 23 is connected to one detection electrode 17.

[0063] A voltage signal for driving the beam 4 is applied to the drive electrode 16 via the drive signal line 21. In addition, a voltage signal from one detection electrode 17 generated due to the vibration of the beam 4 is transmitted to the other detection electrode 17 via the inter-electrode signal line 22. Then, the voltage signals from the pair of detection electrodes 17 are collectively output via the detection signal line 23.

[0064] As shown in Figure 5 the A-A line cross-sectional view of Figure 6A As shown, the drive beam 4A is mainly formed by the Si active layer 12 of the support substrate 2. A lower electrode layer 14 is formed on the Si active layer 12, and a piezoelectric element 15 is formed on the lower electrode layer 14. At the center of the drive beam 4A, the lower electrode layer 14 and the piezoelectric element 15 are removed to allow the inter-electrode signal line 22 to pass through. In addition, an insulating layer (not shown) is provided between the inter-electrode signal line 22 and the Si active layer 12. In addition, Figure 6A the illustration of the BOX layer is omitted in

[0065] The lower electrode layer 14 is formed of a conductive material (such as a metal like aluminum or copper). The same applies to the drive electrode 16 and the detection electrode 17. The piezoelectric element 15 is formed of a material such as PZT (lead zirconate titanate) (a material exhibiting piezoelectric characteristics). The piezoelectric element 15 has the property of expanding and contracting in the length direction (a direction orthogonal to the thickness direction) when a voltage of a predetermined polarity is applied in the thickness direction.

[0066] As Figure 6A shown, the pair of drive electrodes 16 are formed on the piezoelectric element 15 at the edge portion of the through hole 3. The piezoelectric layer is formed by the lower electrode layer 14, the piezoelectric element 15, and the drive electrode 16. The drive electrode 16 and the lower electrode layer 14 are used to apply a voltage to the piezoelectric element 15 to cause the drive beam 4A to vibrate and deform.

[0067] More specifically, as Figure 7AAs shown, when a voltage with the driving electrode 16 being positive and the lower electrode layer 14 being negative (hereinafter referred to as the positive polarity) is applied, a stress is applied to the piezoelectric layer in a direction that elongates in the length direction (the direction along the x-axis) and elongates in the plane direction (the direction along the y-axis). As a result, the surface of the Si active layer 12 where the lower electrode layer 14 is formed elongates, and the driving beam 4A bends in a convex manner upward (in the +z direction).

[0068] In contrast, as Figure 7B shown, when a voltage with the driving electrode 16 being negative and the lower electrode layer 14 being positive (hereinafter referred to as the negative polarity) is applied, a stress is applied to the piezoelectric layer in a direction that contracts in the length direction (the direction along the x-axis) and contracts in the plane direction (the direction along the y-axis). As a result, the surface of the Si active layer 12 where the lower electrode layer 14 is formed contracts, and the driving beam 4A bends in a convex manner downward (in the -z direction).

[0069] It goes without saying that such a piezoelectric element having the following properties can also be used: when a voltage is applied between the two electrodes with the driving electrode 16 side being positive and the lower electrode layer 14 side being negative, the piezoelectric element contracts in the length direction. On the other hand, when a voltage is applied between the two electrodes with the driving electrode 16 side being negative and the lower electrode layer 14 side being positive, the piezoelectric element elongates in the length direction. In this case, when a positive-polarity voltage is applied, the driving beam 4A bends in a convex manner downward, and when a negative-polarity voltage is applied, the driving beam 4A bends in a convex manner upward. Thus, the driving beam 4A only needs to flexibly vibrate under the action of the expansion and contraction of the piezoelectric layer.

[0070] In short, by applying a voltage of a predetermined polarity between the driving electrode 16 and the lower electrode layer 14, it is possible to generate Figure 7A or Figure 7B the deformation shown. The degree of deformation becomes a quantity corresponding to the applied voltage value. In addition, due to the difference in the materials constituting the piezoelectric element (such as the difference between a bulk material and a thin film), the polarization effect is different, so the relationship between the voltage polarity and the expansion and contraction may sometimes be opposite to the above situation.

[0071] On the other hand, as in the Figure 5 B - B line cross-sectional view of Figure 6B shown, a pair of detection electrodes 17 are formed to be in contact with the piezoelectric element 15 at the edge of the through-hole 3 of the detection beam 4B. The piezoelectric layer is formed by the lower electrode layer 14, the piezoelectric element 15, and the detection electrodes 17. When the detection beam 4B vibrates along with the vibration of the above-mentioned driving beam 4A, the piezoelectric element 15 constituting the detection beam 4B deforms, and a potential difference is generated between the detection electrodes 17 and the lower electrode layer 14. In addition, in Figure 6A the illustration of the BOX layer is omitted.

[0072] More specifically, if Figure 8A As shown, when the detection beam 4B bends in a convex upward manner (toward the +z direction), stress is applied to the piezoelectric layer in a direction extending in the length direction (along the y-axis direction) and in the plane direction (along the x-axis direction). As a result, a voltage with a polarity (hereinafter referred to as positive polarity) is generated in which the detection electrode 17 is positive and the lower electrode layer 14 is negative.

[0073] In contrast, Figure 8B As shown, when the detection beam 4B is bent in a downward convex manner (in the -z direction), stress is applied to the piezoelectric layer in the direction of contraction in the length direction (in the direction of the y axis) and in the direction of contraction in the plane direction (in the direction of the x axis). As a result, a voltage of a polarity (hereinafter referred to as negative polarity) is generated in which the detection electrode 17 is negative and the lower electrode layer 14 is positive.

[0074] It goes without saying that a piezoelectric element having the following properties may be used: when the piezoelectric element contracts in the longitudinal direction, a potential difference is generated in which the detection electrode 17 side is positive and the lower electrode layer 14 side is negative, and when the piezoelectric element extends in the longitudinal direction, a potential difference is generated in which the detection electrode 17 side is negative and the lower electrode layer 14 side is positive. In this case, a voltage of positive polarity is generated when the detection beam 4B is bent in a downward convex manner, and a voltage of negative polarity is generated when the detection beam 4B is bent in an upward convex manner. In this way, the detection beam 4B only needs to be able to expand and contract the piezoelectric layer by bending and generate a voltage.

[0075] In short, in the production Figure 8A or Figure 8B When deformed as shown, a voltage of a predetermined polarity can be generated between the detection electrode 17 and the lower electrode layer 14. The magnitude of the voltage becomes an amount corresponding to the detection beam 4B. In addition, since the difference in the material constituting the piezoelectric element (for example, the difference in the block and the film) leads to the difference in polarization, the relationship between the expansion and contraction and the polarity of the voltage is sometimes opposite to the above case.

[0076] For example, when a voltage that changes in a sinusoidal manner is applied between the drive electrode 16 and the lower electrode layer 14, the drive beam 4A vibrates in a sinusoidal manner. The detection beam 4B also vibrates in coordination with the vibration of the drive beam 4A. When the detection beam 4B vibrates, a potential difference that changes in a sinusoidal manner is generated between the drive electrode 16 and the lower electrode layer 14.

[0077] Further, when increasing or decreasing the frequency of the sine-wave voltage applied between the drive electrode 16 and the lower electrode layer 14, the frequencies of the vibrations of the drive beam 4A and the detection beam 4B also increase or decrease, and the frequency of the voltage signal generated between the detection electrode 17 and the lower electrode layer 14 also increases or decreases. As the frequencies of the vibrations of the drive beam 4A and the detection beam 4B approach the resonance frequency of the beam 4, the amplitude of the beam 4 increases, and when the frequencies of the vibrations of the drive beam 4A and the detection beam 4B become the resonance frequency of the beam 4, the amplitude of the beam 4 becomes maximum.

[0078] As described above, the beam 4 is configured such that the vibration frequency (e.g., resonance frequency) changes due to the constituent substance being adsorbed on the substance adsorption film 5. In addition, the vibration frequency of the beam 4 changes corresponding to the adsorption degree of the constituent substance adsorbed on the substance adsorption film 5. Thus, the frequency at which the amplitude of the beam 4 becomes maximum also changes. Conversely, it is possible to detect the case where the state changes from the state where the constituent substance is not adsorbed on the substance adsorption film 5 to the state where the constituent substance is adsorbed on the substance adsorption film 5 by obtaining the change in the vibration frequency at which the amplitude of the voltage signal between the detection electrode 17 and the lower electrode layer 14 becomes maximum.

[0079] The potential difference generated between the detection electrode 17 and the lower electrode layer 14 becomes a voltage signal, and this voltage signal is output via the inter-electrode signal line 22 and the detection signal line 23. If the output voltage signal is regarded as information related to the vibration frequency of the beam 4 and the change in the vibration frequency of the beam 4 is detected based on this information, it is possible to detect the case where the gas passing through the through-hole 3 contains the substance adsorbed on the substance adsorption film 5.

[0080] As Figure 6A and Figure 6B shown, in the support substrate 2, the lower electrode layer 14 is formed on the Si active layer 12, and the insulating layer 18 is formed on the lower electrode layer 14. However, as Figure 5 shown, the lower electrode layer 14 and the insulating layer 18 are removed around the through-hole 3. However, the lower electrode layer 14 constituting the drive beam 4A and the detection beam 4B is not removed and is connected to the lower electrode layer 14 on the support substrate 2.

[0081] In addition, in the region S on the support substrate 2 where the drive signal line 21 and the detection signal line 23 are wired, the lower electrode layer 14 is removed. The purpose is to prevent the generation of parasitic capacitance between the drive signal line 21, the detection signal line 23 and the lower electrode layer 14, and to prevent the case where the voltage signal cannot be properly input to the piezoelectric layers of the drive beam 4A and the detection beam 4B.

[0082] As Figure 9As shown, a signal processing circuit 20 is provided in the substance detection element 1. The signal processing circuit 20 connects one drive signal line 21 and seven detection signal lines 23 together. One drive signal line 21 led out from the signal processing circuit 20 branches into 14 and is connected to a pair of drive electrodes 16 of each through hole 3. That is, the drive signal lines 21 respectively conducting with the drive electrodes 16 formed at both ends of the drive beam 4A are led out to the outside of the drive beam 4A and gathered into one. In addition, the seven detection signal lines 23 led out from each through hole 3 are independently connected to the signal processing circuit 20. The signal processing circuit 20 inputs and outputs a voltage signal with the potential of the lower electrode layer 14 as a reference.

[0083] The signal processing circuit 20 outputs a voltage signal such as a sine wave shape to the drive electrodes 16 corresponding to each through hole 3 through the drive signal line 21, and inputs the voltage signal output from the detection electrodes 17 corresponding to each through hole 3 to the signal processing circuit 20 through the detection signal line 23. The signal processing circuit 20 detects the change in the vibration frequency (such as the resonance frequency) of the beam 4 based on the input voltage signal. In the substance detection element 1, for example, the adsorption of the constituent substances can be detected in units of 1 ng.

[0084] In the substance detection element 1, a beam 4 is provided for each through hole 3, and the types of the substance adsorption films 5 respectively supported by the beams 4 are different. For the signal processing circuit 20, the voltage signals output from the detection electrodes 17 of each through hole 3 are input through the detection signal lines 23, and the change in the vibration frequency of each beam 4 is detected based on the input voltage signals, that is, the situation where the constituent substances are adsorbed on the substance adsorption film 5 corresponding to the beam 4 is detected. The signal processing circuit 20 has a memory, and stores the detection results of the constituent substances of each substance adsorption film 5 in the memory.

[0085] As Figure 10 shown, the substance detection element 1 of the present embodiment has an interface 30 for a memory card of an electronic device 50 such as a smart phone. Here, as the substance detection element 1, there are substance detection elements 1A and 1B with different specific substances to be detected.

[0086] The substance detection element 1A is connected to the electronic device 50 through the interface 30. The electronic device 50 can read the detection results of the constituent substances stored in the memory of the signal processing circuit 20 of the substance detection element 1A. The electronic device 50 reads the data in the memory of the signal processing circuit 20 of the substance detection element 1A inserted into the interface 30, and analyzes the substance to be detected based on the read data.

[0087] For example, the constituent substances of the detection target of the substance detection element 1A are set as 1a to 1g. Moreover, the constituent substances of a certain chemical substance A are 1a, 1b, and 1c, and the constituent substances of another chemical substance B are 1a, 1d, 1e, and 1f. When the gas contains chemical substance A, the detection result is as shown in Figure 11A shown, indicating the detection of 1a, 1b, and 1c. When the gas contains chemical substance B, the detection result is as shown in Figure 11B shown, indicating the detection of 1a, 1d, 1e, and 1f. The electronic device 50 stores a reference pattern of the chemical substance to be detected, and performs pattern matching on the actual detection result and the reference pattern to determine the chemical substance contained in the gas.

[0088] In addition, in the present embodiment, pattern matching is performed using a pattern based on the presence or absence of constituent substances, but the present invention is not limited to this. It is also possible to obtain the adsorption degree of the constituent substance adsorbed on the substance adsorption film 5 corresponding to the change amount of the vibration frequency of the beam 4, form a pattern corresponding to the content ratio of the constituent substances of the chemical substance, and perform pattern matching using this pattern to determine the chemical substance.

[0089] Since the substance detection elements 1A and 1B are manufactured using MEMS, they can be manufactured in a very small size. Therefore, the substance detection elements 1A and 1B can conform to the specifications of, for example, a small miniSD card. Thus, for example, it is also possible to prepare substance detection elements 1A and 1B with different combinations of detectable constituent substances, and by replacing the substance detection element 1 installed in the electronic device 50 with the substance detection element 1B, the combination of chemical substances that can be detected can be increased.

[0090] The substance detection element 1 is used to detect various chemical substances contained in the gas. For example, the substance detection element 1 is placed in the gas flow as shown in Figure 12 shown, and is used to detect the constituent substances of the chemical substances contained in the gas passing through the through-hole 3. Here, the beam 4 that supports the substance adsorption film 5 that adsorbs the constituent substances does not block the entire through-hole 3, but blocks a part of the through-hole 3. Therefore, the beam 4 can prevent the gas containing the chemical substance to be detected from staying in the through-hole 3 and make the gas easily pass through the through-hole 3.

[0091] As described in detail above, according to the present embodiment, the substance adsorption film 5 is provided in the through-hole 3 through which the gas containing the chemical substance passes, and the gas containing the chemical substance to be detected easily passes around the substance adsorption film 5. Therefore, the chemical substance can be detected more efficiently.

[0092] In addition, in the above embodiment, as shown in Figure 13AAs shown, the width (length in the width direction) W1 of the drive beam 4A and the width (length in the width direction) W1 of the detection beam 4B are the same, but the present invention is not limited thereto. It may also be, as shown in Figure 13B shown, the width W2 of the drive beam 4A is set wider than the width W1 of the detection beam 4B. In addition, it may also be, as shown in Figure 13C shown, on the premise that the width of the drive beam 4A is W2 and the width of the detection beam 4B is W1, the diameter of the through hole 3 is shortened, so that the length L1 of the drive beam 4A is shortened to L2. In this way, not only can the vibration frequency of the entire beam 4 be set higher to reduce the influence of external vibrations, but also the change amount of the vibration frequency of the beam 4 corresponding to each unit weight of the adsorbed constituent substance can be increased, improving the detection accuracy of the adsorption of the constituent substance.

[0093] In addition, it is desirable to determine the width and length of the beam 4 according to the relationship between the beam 4 and the size of the through hole 3 required for the gas flow.

[0094] In addition, in the present embodiment, the beam 4 is fixed to the edge of the through hole 3 at at least two positions. In this way, compared with the cantilever beam 4, not only can the beam 4 be stably held, but also the vibration frequency of the beam 4 can be increased.

[0095] In the above embodiment, the beam 4 is fixed to the edge of the through hole 3 at 4 positions. However, the present invention is not limited thereto. It may also be, as shown in Figure 14A shown, the beam 41 is a cantilever beam. In this case, it is desirable to widen the width or increase the thickness of the beam 41 to increase the vibration frequency of the beam 41. In addition, the drive electrode 16 and the detection electrode 17 may be provided together at one end of the beam 41 (the end fixed to the edge of the through hole 3).

[0096] In addition, it may also be, as shown in Figure 14B shown, the beam 42 fixed to the edge of the through hole 3 at two positions is used. In this case, the drive electrode 16 and the detection electrode 17 may be provided together at both ends of the beam 42.

[0097] In addition, it may also be, as shown in Figure 14C shown, the beam 43 fixed to the edge of the through hole 3 at three positions is used. In this case, a pair of drive electrodes 16 are arranged at both ends of the beam 43, and the detection electrode 17 is arranged at the remaining end.

[0098] In addition, in the above-described embodiment, the beam 4 is configured such that two fixed-ended beams, i.e., a drive beam 4A and a detection beam 4B, are connected together at the center. In this case, the entire beam 4 is vibrated by one drive beam 4A, and the vibration of the beam 4 is detected by the other detection beam 4B, thereby saving the wiring for the circuit for driving the beam 4 and the wiring for the circuit for detecting the vibration of the beam 4.

[0099] In addition, in the above-described embodiment, the drive beam 4A and the detection beam 4B are orthogonal to each other. In this case, the detection beam 4B can be prevented from interfering with the vibration of the drive beam 4A. However, the drive beam 4A and the detection beam 4B do not have to be orthogonal as long as they cross each other.

[0100] In addition, in the above-described embodiment, drive electrodes 16 are provided at both ends of the drive beam 4A, and detection electrodes 17 are provided at both ends of the detection beam 4B. However, the present invention is not limited thereto. Alternatively, in the substance detection element 1, a drive electrode 16 may be provided at one end of the drive beam 4A, and a detection electrode 17 may be provided at one end of the detection beam 4B. In other words, in the substance detection element 1, a drive electrode 16 may not be provided at the other end of the drive beam 4A, and a detection electrode 17 may not be provided at the other end of the detection beam 4B.

[0101] In addition, in the above-described embodiment, the inter-electrode signal lines 22 connect the detection electrodes 17 to each other. In this case, the detection signal lines 23 led out from the detection electrodes 17 can be collected into one, and thus the wiring on the support substrate 2 can be saved.

[0102] In addition, in the above-described embodiment, the drive signal line 21 connected to the drive electrode 16 is led out to the outside. The drive signal line 21 is led out from the signal processing circuit 20 and branched into a plurality of lines, and then input to the drive electrode 16. In this case, since the drive signal lines 21 led out from the signal processing circuit 20 are collected into one, the drive signal lines 21 connected to the drive electrode 16 can also be saved.

[0103] In addition, in the above-described embodiment, a plurality of through holes 3 are provided in the support substrate 2, and a beam 4 is provided for each through hole 3. The types of the substance adsorption films 5 supported by the beams 4 are different. In this case, the chemical substance can be determined based on a plurality of detection patterns of the constituent substances.

[0104] In the above-described embodiment, the number of the through holes 3 and the beams 4 is seven. However, the present invention is not limited thereto. The number of the through holes 3 and the beams 4 may be six or less, or may be eight or more. The number of the through holes 3 and the beams 4 can be determined according to the number of the constituent substances to be detected.

[0105] In the above-described embodiment, the through-hole 3 is circular. However, the present invention is not limited to this. The through-hole may be elliptical, square, or may have a shape that is a combination of a curve and a straight line.

[0106] In addition, in the above-described embodiment, the substance to be detected is set as the chemical substance constituting the odor, but the present invention is not limited to this. For example, it is also possible to detect the chemical substance contained in an odorless gas.

[0107] In addition, in the above-described embodiment, the chemical substance contained in the gas is detected, but the present invention is not limited to this. The present invention can also be applied to the detection of substances in liquids.

[0108] In addition, in the above-described embodiment, the SOI wafer is used to manufacture the substance detection element 1A, but the present invention is not limited to this. Other wafers can also be used to manufacture the substance detection element.

[0109] In the above-described embodiment, the lower electrode layer 14 and the piezoelectric element 15 are provided on substantially the entire surface of the beam 4, but the present invention is not limited to this. The lower electrode layer 14 and the piezoelectric element 15 may also be provided only in the portion where the drive electrode 16 and the detection electrode 17 are formed.

[0110] In the above-described embodiment, the detection electrodes 17 formed at both ends of the detection beam 4B are connected together by the inter-electrode signal line 22, but the present invention is not limited to this. It may also be configured such that each detection signal line 23 is led out from the detection electrode 17 and each voltage signal is output.

[0111] The present invention can form various embodiments and variations without departing from the broad spirit and scope of the present invention. In addition, the above-described embodiments are used to illustrate the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is represented by the claims rather than by the embodiments. Moreover, various variations implemented within the scope of the claims and within the meaning of the invention equivalent thereto are considered to be included within the scope of the present invention.

[0112] In addition, this application claims priority based on Japanese Patent Application No. 2017-70353 filed on March 31, 2017, and the entire specification, claims, and drawings of Japanese Patent Application No. 2017-70353 are incorporated herein by reference.

[0113] Industrial Applicability

[0114] The present invention can be applied to the detection of chemical substances contained in fluids.

[0115] Explanation of Reference Numerals

[0116] 1, 1A, 1B, substance detection elements; 2, support substrate; 3, through hole; 4, beam; 4A, drive beam (first beam); 4B, detection beam (second beam); 5, substance adsorption film; 10, base; 11, Si support layer; 12, Si active layer; 13, opening; 14, lower electrode layer; 15, piezoelectric element (piezo element); 16, drive electrode; 17, detection electrode; 18, insulating layer; 20, signal processing circuit; 21, drive signal line; 22, inter-electrode signal line; 23, detection signal line; 30, interface; 41, 42, 43, beam; 50, electronic device.

Claims

1. A substance detection element, wherein, the substance detection element includes: a support substrate provided with a through-hole; and a plate-shaped beam having a piezoelectric element, the beam extending from an edge of the through-hole toward an opposite edge to block a part of the through-hole, and supporting a substance adsorption film to which a substance to be detected adheres, and the vibration frequency of the beam changes due to the substance adhering to the substance adsorption film, drive signal lines, inter-electrode signal lines, and detection signal lines serving as conductors are formed on the support substrate and the beam, the beam has a first beam in the shape of an elongated plate fixed at both ends to the edge of the through-hole and a second beam in the shape of an elongated plate fixed at both ends to the edge of the through-hole and intersecting with the first beam, the electrodes provided on the first beam and the lower electrode layer are used to apply a voltage to the piezoelectric element to cause the beam to vibrate and deform, and the drive signal line is connected to the electrode provided on the first beam, the electrodes provided on the second beam and the lower electrode layer are used to detect information related to the vibration frequency of the beam, and the detection signal line is connected to the electrode provided on the second beam, electrodes are formed at both ends of one of the first beam and the second beam, and electrodes are formed at at least one end of the other of the first beam and the second beam, an inter-electrode signal line connecting the electrodes formed at both ends of the one beam is formed on the one beam, and the drive signal line or the detection signal line conducting with one of the electrodes is led out to the outside of the one beam, a plurality of the through-holes are provided in the support substrate, a beam is provided for each of the through-holes, the lower electrode layer is removed from the area on the support substrate where the drive signal line and the detection signal line are wired.

2. The substance detection element according to claim 1, wherein, electrodes are formed at both ends of the other beam.

3. The substance detection element according to claim 1, wherein, the width of the connecting portion of the first beam and the second beam is set wider than the widths of the other portions of the first beam and the second beam except the connecting portion.

4. The substance detection element according to claim 1, wherein, the width of the first beam is set wider than the width of the second beam.

5. The substance detection element according to claim 1, wherein, the first beam and the second beam are orthogonal.

6. The substance detection element according to claim 2, wherein, the drive signal line or the detection signal line conducting with the electrodes formed at both ends of the other beam is led out to the outside of the one beam and gathered into one.

7. The substance detection element according to claim 1, wherein, the types of the substance adsorption films supported by the beams are different.

8. The substance detection element according to claim 3, wherein, the width of the electrode formed on the first beam along the width of the first beam is set wider than the width of the electrode formed on the second beam along the width of the second beam.

9. The substance detection element according to claim 1, wherein, The plurality of through holes include through holes having different hole sizes from each other.

10. The substance detection element according to claim 1, wherein, The electrode provided on the first beam and the electrode provided on the second beam are formed across the edge of the through hole.

11. The substance detection element according to claim 2, wherein, Any one of the electrodes formed at both ends of the other beam is connected to the drive signal line or the detection signal line led out to the outside of the other beam.

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