Sensor device and method for manufacturing same

Abstract

[Problem] To provide a sensor device with which it is possible to ensure stable oscillation characteristics in a piezoelectric resonance device, and a method for manufacturing the sensor device. [Solution] The sensor device according to an embodiment of the present invention comprises a circuit substrate and a sensor device. The sensor device has a support substrate, a piezoelectric film provided on the support substrate, lower and upper electrodes facing each other across at least a part of the piezoelectric film, and a sensitive film provided on the upper electrode. The sensor device is flip-chip-connected to the circuit substrate.

Description

Technical Field

[0001] The present invention relates to a sensor device using a piezoelectric thin film resonator such as an FBAR (Film Bulk Acoustic Resonator) and a method for manufacturing the same.

Background Art

[0002] FBAR is a piezoelectric thin film resonator used in filters, duplexers, etc. of mobile communication devices. Development of sensors has been underway to apply a sensitive film to which a specific gas adsorbs to piezoelectric resonators such as FBAR, QCM (Quartz Crystal Microbalance), and SAW (Surface Acoustic Wave), and detect the frequency change corresponding to the mass change (see Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Piezoelectric resonance type sensors are typically configured by mounting a sensor device on a circuit board equipped with an oscillation circuit. However, depending on the mounting form of the sensor device on the circuit board, it may not oscillate at the original resonance frequency and may not operate as a sensor. For example, when connecting between a sensor device and a circuit board by a wire bonding method, if the inductance of the bonding wire increases, the dielectric region of the resonance characteristics becomes wider, and there is a concern that it may oscillate at a frequency other than the original oscillation frequency.

[0005] In view of the above circumstances, an object of the present invention is to provide a sensor device capable of ensuring stable oscillation characteristics of a piezoelectric resonance device and a method for manufacturing the same.

Means for Solving the Problems

[0006] To achieve the above object, a sensor device according to one embodiment of the present invention includes a circuit board and A plurality of a sensor device. A plurality of The sensor device includes a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode facing each other with at least a part of the piezoelectric film interposed therebetween, and a sensitive film provided on the upper electrode each and is flip-chip connected to the circuit board. The circuit board is provided to extend along the arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices, and has a through hole through which the gas to be detected flows. To achieve the above object, a sensor device according to an aspect of the present invention includes a circuit board and a plurality of sensor devices. The plurality of sensor devices each have a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode facing each other with at least a part of the piezoelectric film interposed therebetween, and a sensitive film provided on the upper electrode, and are flip-chip connected to the circuit board. The circuit board is provided to extend along the arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices, and has a recess through which the gas to be detected flows.

[0007] In the above sensor device, since the sensor device is mounted on the circuit board by a flip-chip connection method, the wiring length between the sensor device and the circuit board is shortened, thereby ensuring stable oscillation characteristics of the sensor device.

[0008] The sensitive films of the plurality of sensor devices may be formed of different materials from each other.

[0010] The sensitive film may be provided in a resonance region of the upper electrode where the lower electrode and the upper electrode face each other with the piezoelectric film interposed therebetween.

[0011] The piezoelectric film, the lower electrode, and the upper electrode may have a convex curved surface shape that forms a gap between the support substrate and the lower electrode in the resonance region.

[0012] The circuit board may have a first electrode connected to the lower electrode and a second electrode connected to the upper electrode. The sensor device may further have joints provided on the lower electrode and the upper electrode, respectively, and electrically connected to the first electrode and the second electrode, respectively.

[0013] The joint may be a solder bump, a gold bump, or an anisotropic conductive film.

[0014] The sensing film may be an inorganic film, an organic polymer film, or an organic dye film.

[0015] The sensing film may be a cellulose-based resin, a fluorine-based resin, an acrylic-based resin, or a conductive polymer.

[0017] A method for manufacturing a sensor device according to an aspect of the present invention includes a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode facing each other with at least a part of the piezoelectric film interposed therebetween, and a sensing film provided on the upper electrode each having A plurality of preparing a sensor device in which a sensor device is flip-chip connected to a circuit board, providing the sensor device on a mother board 、 The circuit board is provided to extend along the arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices, and has a through hole through which the gas to be detected flows. A method for manufacturing a sensor device according to an aspect of the present invention prepares a sensor device in which a plurality of sensor devices each having a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode facing each other with at least a part of the piezoelectric film interposed therebetween, and a sensitive film provided on the upper electrode are flip-chip connected to a circuit board, provides the sensor device on a mother board, The circuit board is provided to extend along the arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices, and has a recess through which the gas to be detected flows. The sensitive films of the plurality of sensor devices may be formed of different materials from each other.

Advantages of the Invention

[0018] According to the present invention, stable oscillation characteristics of a piezoelectric resonance device can be ensured.

Brief Description of the Drawings

[0019]

FIG. 1

FIG. 2

FIG. 3

FIG. 4

FIG. 5

FIG. 6

FIG. 7

FIG. 8

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] [Sensor Device] FIG. 1 is a side cross-sectional view schematically showing the configuration of a sensor device 1 according to an embodiment of the present invention, and FIG. 2 is a plan view of the sensor device 1. The sensor device 1 includes a circuit board 50 and a sensor device 100 mounted on the circuit board 50.

[0022] The sensor device 1 is for identifying (detecting) the type of gas or measuring the amount of the gas. In the present embodiment, a plurality of sensor devices 100 are mounted on the circuit board 50, and each sensor device 100 is typically configured to be able to detect different gases individually. Note that the number of sensor devices 100 is not limited to a plurality and may be a single one. Details of the circuit board 50 and the mounting form of the sensor device 100 will be described later.

[0023] (Configuration of Sensor Device) The configuration of the sensor device 100 will be described. On the circuit board 50, a drive circuit 54 including an oscillation circuit for driving each sensor device 100 is mounted. The drive circuit 54 is commonly configured for each sensor device 100, but a plurality of oscillation circuits are provided corresponding to each sensor device 100.

[0024] Subsequently, the details of the sensor device 100 will be described. FIG. 3 is a diagram showing the configuration of the sensor device 100, where (a) is a plan view and (b) is a cross-sectional view taken along line A-A in (a).

[0025] The sensor device 100 of the present embodiment includes a support substrate 10, a piezoelectric film 22, and a lower electrode 21 and an upper electrode 23 that face each other with at least a part of the piezoelectric film 22 interposed therebetween, and further includes a sensitive film 30 provided at a position corresponding to the resonance region 24 of the upper electrode 23, and is configured as an FBAR type piezoelectric resonator.

[0026] As the support substrate 10, for example, in addition to semiconductor substrates such as a silicon (Si) substrate and a gallium arsenide (GaAs) substrate, a ceramic substrate such as a quartz substrate, a glass substrate, or an alumina substrate can be used.

[0027] The lower electrode 21 is formed on the support substrate 10 in a predetermined shape. Here, the lower electrode 21 is formed in a polygonal shape in which the width dimension along the vertical direction in FIG. 3(a) increases as it approaches the resonance region 24. The thickness of the lower electrode 21 is, for example, 240 nm. The lower electrode 21 is composed of a single metal layer of aluminum (Al), copper (Cu), chromium (Cr), molybdenum (Mo), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), or iridium (Ir), or a laminated film in which a plurality of materials are selected from these.

[0028] The piezoelectric film 22 is formed in a predetermined shape on the support substrate 10 so as to cover a part of the lower electrode 21. Here, the piezoelectric film 22 is formed in a polygonal shape whose width dimension along the vertical direction in FIG. 3(a) increases as it goes toward the resonance region 24, similar to the lower electrode 21. The thickness of the piezoelectric film 22 is, for example, 500 nm. The piezoelectric film 22 is composed of a piezoelectric material mainly containing aluminum nitride (AlN) with the (002) direction as the main axis. In addition to the AlN film, for example, a ZnO film can also be used for the piezoelectric film 22.

[0029] The upper electrode 23 is formed in a predetermined shape on the support substrate 10 so as to cover at least a part of the piezoelectric film 22. Here, the upper electrode 23 is formed in a polygonal shape whose width dimension along the vertical direction in FIG. 3(a) increases as it goes toward the resonance region 24, similar to the lower electrode 21 and the piezoelectric film 22. The thickness of the upper electrode 23 is, for example, 240 nm. The upper electrode 23 is composed of a single-layer film of the metal materials listed for the lower electrode 21, or a laminated film in which a plurality of these materials are selected.

[0030] The sensor device 100 has a resonance region 24. The resonance region 24 is a region where the lower electrode 21 and the upper electrode 23 overlap. In the resonance region 24, a gap G is provided between the support substrate 10 and the lower electrode 21. In the present embodiment, in the resonance region 24, the piezoelectric film 22, the lower electrode 21, and the upper electrode 23 are convex curved surfaces that form the gap G between the support substrate 10 and the lower electrode 21. The planar shape of the convex curved surface of the upper electrode 23 is, for example, a substantially elliptical shape with a major axis of 270 μm and a minor axis of 180 μm. The resonance region 24 is a region that resonates in the thickness longitudinal vibration mode when an AC voltage of the resonance frequency is input between the lower electrode 21 and the upper electrode 23. The resonance frequency of the resonance region 24 is not particularly limited and is typically a frequency in the GHz band, which is 2.4 GHz in the present embodiment.

[0031] Note that the planar shape of the resonance region 24 may be formed into other shapes such as a circular shape or a polygonal shape having five or more sides. In particular, by setting the planar shape of the resonance region 24 to an ellipse or a polygonal shape having five or more sides, the generation of vibration modes propagating in the lateral direction can be suppressed compared to the case where the planar shape of the resonance region 24 is rectangular (square or rectangle), so that good resonance characteristics can be maintained.

[0032] In the resonance region 24, the gap G is a dome-shaped bulge formed between the flat upper surface of the support substrate 10 and the lower electrode 21. The dome-shaped bulge is, for example, a bulge having a shape such that the height of the gap G is low around the periphery of the gap G and the height of the gap G is higher toward the inside of the gap G. Below the lower electrode 21, an introduction path 25 formed by introducing an etchant when forming the gap G is provided. The vicinity of the tip of the introduction path 25 is not covered with the piezoelectric film 22 or the like, and the tip of the introduction path 25 is a hole portion 26. The two hole portions 26 are inlets for introducing the etchant when forming the gap G and are also outlets.

[0033] The formation position of the hole portion 26 is not particularly limited, but is preferably provided near the resonance region 24. After the formation of the gap G, the hole portion 26 is closed using an appropriate material such as resin, adhesive, or the constituent material of the sensitive film 30. Thereby, communication between the gap G and the outside air can be blocked, so that deterioration of the resonance characteristics due to the gas invading the gap G can be prevented.

[0034] The sensitive film 30 is made of a material capable of adsorbing the gas to be detected. The material constituting the sensitive film can be arbitrarily selected according to the type of the gas to be detected, and typically, an organic polymer film (organic high molecular film, organic low molecular film), an organic dye film, an inorganic film, or the like can be used. More specifically, examples of the sensitive film 30 include a cellulose-based resin, a fluorine-based resin, an acrylic-based resin, or a conductive polymer, but are not limited thereto. As a method for forming the sensitive film 30, in addition to the method of dissolving the material of the sensitive film in a solvent and applying it, a vapor deposition method, a sputtering method, or a CVD (Chemical Vapor Deposition) method can be used.

[0035] Examples of organic polymer materials include homopolymers composed of a single structure such as polystyrene, polymethyl methacrylate, 6-nylon, cellulose acetate, poly-9,9-dioctylene fluorene, polyvinyl alcohol, polyvinyl carbazole, polyethylene oxide, polyvinyl chloride, poly-p-phenylene ether sulfone, poly-1-butene, polybutadiene, polyphenylmethylsilane, polycaprolactone, polybisphenoxyphosphazene, polypropylene, etc., copolymers which are copolymers of two or more homopolymers, blend polymers obtained by mixing these, and the like can be used.

[0036] For example, examples of organic low-molecular materials include tris(8-quinolinolato)aluminum (Alq3), naphthyldiamine (α-NPD), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), CBP (4,4'-N,N'-dicarbazole-biphenyl), copper phthalocyanine, fullerene, pentacene, anthracene, thiophene, Ir(ppy(2-phenylpyridinato)) 3 , triazine thiol derivatives, dioctylfluorene derivatives, tetracosane, parylene, and the like can be used.

[0037] For example, examples of inorganic materials include alumina, titania, vanadium pentoxide, tungsten oxide, lithium fluoride, magnesium fluoride, aluminum, gold, silver, tin, indium tin oxide (ITO), carbon nanotubes, sodium chloride, magnesium chloride, and the like can be used.

[0038] As shown in FIG. 3, the sensing film 30 is selectively provided in the resonance region 24. In the present embodiment, the sensing film 30 is provided within the resonance region 24 of the upper electrode 23, and typically, it is provided at a site corresponding to the resonance region 24 on the upper electrode 23. The site corresponding to the resonance region 24 refers to the elliptical dome-shaped surface of the upper electrode 23, and the sensing film 30 is provided on the convex curved surface portion of the upper electrode 23. The resonance region 24 is formed in an elliptical shape having a major axis and a minor axis substantially the same as those of the dome portion. The thickness of the sensing film 30 is not particularly limited and can be arbitrarily set depending on the ease of adsorption or desorption of the gas to be detected. For example, it is 250 μm.

[0039] The sensing film 30 includes the above-described polymer material and is composed of a coating film selectively applied and dried to the resonance region 24 using a mask material (not shown). Depending on the opening accuracy or position accuracy of the mask, the sensing film 30 may be formed in a region wider or narrower than the resonance region 24, or may be provided at a position offset from the resonance region.

[0040] In a sensor device 100 in which a plurality of sensor devices 100 are mounted on a circuit board 50 as in the present embodiment, typically, the sensing films 30 of the respective sensor devices 100 are composed of different materials individually. Thereby, it becomes possible to detect a plurality of types of gas species with one sensor device 100.

[0041] (Method for manufacturing a sensor device) Next, a method for manufacturing the sensor device 100 of the present embodiment will be described. FIGS. 4(a) to (d) are cross-sectional views showing the method for manufacturing the sensor device 100.

[0042] As shown in FIG. 4(a), a sacrificial layer 40 is formed on a support substrate 10 using, for example, a sputtering method, an evaporation method, or a chemical vapor deposition method (CVD method). For the sacrificial layer 40, for example, a magnesium oxide (MgO) film can be used, and it is provided including at least a region where voids G are formed. The film thickness of the sacrificial layer 40 is, for example, about 20 nm.

[0043] Subsequently, for example, sputtering is performed in an argon (Ar) gas atmosphere to form a metal film on the support substrate 10 and the sacrificial layer 40. The metal film may be formed using a vapor deposition method or a CVD method. The metal film is selected from at least one of the materials (Al, Cu, Cr, Mo, W, Ta, Pt, Ru, Rh, or Ir) listed for the lower electrode 21. Thereafter, for example, using a photolithography method and an etching method, the metal film is formed into a desired shape to form the lower electrode 21. At this time, a part of the lower electrode 21 covers the sacrificial layer 40. Note that the lower electrode 21 may be formed by a lift-off method.

[0044] Subsequently, as shown in FIG. 4(b), a piezoelectric film 22 made of an AlN film is formed on the support substrate 10 and the lower electrode 21. The piezoelectric film 22 can be formed by a unipolar sputtering method using an aluminum metal target in an atmosphere containing nitrogen (for example, in a mixed gas atmosphere of nitrogen and a noble gas (such as Ar)).

[0045] Subsequently, for example, by performing sputtering in an Ar gas atmosphere, a metal film is formed on the piezoelectric film 22. The metal film may be formed using a vapor deposition method or a CVD method. This metal film is also selected from at least one of Al, Cu, Cr, Mo, W, Ta, Pt, Ru, Rh, or Ir as described above.

[0046] Thereafter, as shown in FIG. 4(c), using a photolithography method and an etching method, the metal film is formed into a desired shape to form the upper electrode 23. The upper electrode 23 may be formed by a lift-off method. Subsequently, for example, using a photolithography method and an etching method, the piezoelectric film 22 is formed into a desired shape. Further, the lower electrode 21 and the sacrificial layer 40 are selectively etched to form holes 26 (see FIG. 3(a)).

[0047] Subsequently, as shown in Fig. 4(d), an etchant is introduced from the hole 26 to etch the sacrificial layer 40. Here, the stress of the laminated film of the lower electrode 21, the piezoelectric film 22, and the upper electrode 23 is made to be a compressive stress in advance. As a result, when the etching of the sacrificial layer 40 is completed, the laminated film bulges upward, and a resonance region 24 having a dome-shaped bulge is formed between the support substrate 10 and the lower electrode 21. Also, an introduction path 25 connecting the void G and the hole 26 is formed. Then, by providing the sensing film 30 at a site corresponding to the resonance region 24 on the upper electrode 23, the sensor device 100 shown in Fig. 1 is fabricated.

[0048] As a method for forming the sensing film 30, for example, a cellulose-based resin, a fluorine-based resin, an acrylic-based resin, or a conductive polymer is dissolved in a solvent such as acetone, methanol, ethanol, toluene, THF, MEK, NMP, heptane, or water. Other liquids other than the above may be used, but among the above liquids, the solvent is preferably used because it has relatively high volatility, the sensing film 30 is likely to dry, and a uniform film can be formed. Subsequently, the dissolved sensing film described above is selectively applied onto the resonance region 24 by a printing method using a metal mask or a cast dispensing method, and then dried.

[0049] (Mounting Structure of Sensor Device) The sensor device 100 of the present embodiment configured as described above is surface-mounted on the circuit board 50 by flip-chip connection. Flip-chip connection is a mode of surface mounting method also called the face-down method. Here, a form in which the support substrate 10 or the piezoelectric functional layer (the lower electrode 21, the piezoelectric film 22, the upper electrode 23, and the sensing film 30) on the support substrate 10 is mounted facing the mounting surface 51 of the circuit board 50 is called flip-chip connection.

[0050] As shown in FIG. 1, one main surface of the circuit board 50 is configured as a mounting surface 51 on which the sensor device 100 is mounted. The circuit board 50 is typically a wiring board in which a wiring layer having a predetermined pattern is formed on the surface of a rigid organic material such as a glass epoxy substrate or the like. The circuit board 50 may be a multilayer board in which the wiring layers are formed in multiple layers.

[0051] On the mounting surface 51, a first electrode portion 52a electrically connected to the lower electrode 21 of the sensor device 100 and a second electrode 52b electrically connected to the upper electrode 23 of the sensor device 100 are provided. As shown in FIG. 2, one of the first electrode 52a and the second electrode 52b is connected to the drive circuit 54 via the wiring pattern 55, and the other is connected to the common ground terminal 57 via the wiring pattern 56.

[0052] Bonding portions 62a and 62b made of a conductive material are provided on the lower electrode 21 and the upper electrode 23 of the sensor device 100, respectively. The bonding portion 62a electrically connects the lower electrode 21 to the first electrode 52a of the circuit board 50, and the bonding portion 62b electrically connects the upper electrode 23 to the second electrode 52b of the circuit board 50. The bonding portions 62a and 62b are typically solder bumps, but in addition to this, gold bumps, anisotropic conductive films, etc. are also applicable. Note that since FIG. 1 schematically shows the sensor device 100, the sizes of the bonding portions 62a and 62b are different from each other, but actually they are almost the same size (the same also applies in FIG. 5).

[0053] When the bonding portions 62a and 62b are composed of solder bumps, the sensor device 100 is mounted on the circuit board 50 by the reflow soldering method. In this case, a plurality of sensor devices 100 can be mounted on the circuit board 50 collectively. Also, when the bonding portions 62a and 62b are composed of gold bumps, the sensor device 100 is mounted on the circuit board 50 by a welding method with ultrasonic and thermocompression bonding applied. Furthermore, when the joints 62a and 62b are made of an anisotropic conductive film, the sensor device 100 is mounted on the circuit board 50 by a pressure heating method.

[0054] The positions and numbers of the joints 62a and 62b are not particularly limited and can be arbitrarily set according to the shape and size of the electrodes. For example, the joints 62a and 62b may be provided at a plurality of locations on the lower electrode 21 and the upper electrode 23, respectively.

[0055] A recess 53 is provided on the mounting surface 51 of the circuit board 50. The recess 53 is provided in a region where the sensitive film 30 of the sensor device 100 faces between the first electrode 52a and the second electrode 52b. The recess 53 is configured as a flow path through which the gas to be detected flows or a reservoir of the gas.

[0056] In the present embodiment, the recess 53 is configured by, for example, a groove portion linearly formed along the arrangement direction of the sensor devices 100 as shown in FIG. 2. Here, the recess 53 is linearly provided between a gas inlet 53a formed near one side of the circuit board 50 and a gas outlet 53b provided near the opposite side. The plurality of sensor devices 100 are arranged adjacent to each other so as to block the recess 53. Thereby, one recess 53 can be shared by the plurality of sensor devices 100. Of course, the recess 53 is not limited to the example where it is provided in common for the plurality of sensor devices 100, and a plurality of recesses 53 may be provided corresponding to the individual sensor devices 100. Further, instead of the recess 53, a through hole 58 provided in the circuit board 50 as shown in FIG. 5 may be used.

[0057] Note that the plurality of sensor devices 100 may be configured as a wafer level package. That is, the plurality of sensor devices 100 may be a multi-sensor module in which a plurality of sensor elements each having a piezoelectric film 22, a lower electrode 21, an upper electrode 23, and a sensitive film 30 are arranged on a common support substrate 10. Thereby, the plurality of sensor devices 100 can be mounted on the circuit board 50 collectively.

[0058] The recess 53 functions as a flow path through which gas flows. When the recess 53 is provided in common for a plurality of sensor devices 100 as shown in FIG. 2, by introducing gas from the gas inlet 53a toward the gas outlet 53b, the components of the gas can be individually detected based on the outputs of the respective sensor devices 100.

[0059] Here, in the case of a piezoelectric resonance type sensor device, depending on the mounting form on the circuit board, there may be a case where the desired sensitivity cannot be obtained due to unstable oscillation or the like. For example, as a comparative example, FIG. 6 shows a sensor device 2 in which the sensor device 100 is mounted on a circuit board 50 by a wire bonding method. In the sensor device 2, the support substrate 10 of the sensor device 100 is fixed to the mounting surface 51 of the circuit board 50 with an adhesive or the like. Then, the lower electrode 21 and the upper electrode 23 of the sensor device 100 are electrically connected to the first electrode 52a and the second electrode 52b of the circuit board 50 via a bonding wire (gold wire) W.

[0060] FIG. 7(a) is an equivalent circuit of the sensor device 1 (sensor device 100) of the present embodiment, and (b) is an equivalent circuit of the sensor device 2 of the comparative example. Comparing FIGS. 7(a) and (b), the sensor device 2 of the comparative example is different from the sensor device 1 in that an inductor component (Lw) of the wire W is added to both ends of the sensor device 100.

[0061] FIG. 8 is a simulation result showing an example of the resonance characteristics of the sensor device 1 of the present embodiment and the sensor device 2 of the comparative example. In the figure, the horizontal axis represents frequency (unit: Hz), and the vertical axis represents impedance (unit: Ω). Also, the waveform A1 shown by the solid line in the figure represents the resonance characteristics of the sensor device 1 of the present embodiment (FIG. 1), and the waveform A2 shown by the two-dot chain line represents the resonance characteristics of the sensor device 2 of the comparative example (FIG. 6).

[0062] Here, the resistance R0 is 0.310709 Ω, the resistance Rs is 0.345748 Ω, the resistance Rp is 0.0861 Ω, the capacitor Cs is 278.0687 fF, the capacitor Cp is 3.803729 pF, the inductor Ls is 15.7646 nH, the inductor Lw is 0.47 nH, and the resonance frequency of the resonance region 24 is 2.4 GHz.

[0063] As shown in FIG. 8, the sensor device 2 (waveform A2) of the comparative example is, in terms of the equivalent circuit, in a form in which the inductor component (Lw) of the wire W is inserted in series at both ends (lower electrode and upper electrode) of the sensor device 100. Therefore, compared with the sensor device 1 (waveform A1) of the present embodiment without the inductor component (Lw), the inductive region is broadened, and there is a possibility of oscillation at an unintended frequency.

[0064] On the other hand, according to the sensor device 1 of the present embodiment, compared with the sensor device 2, the sharpness (Q value) of resonance at the resonance frequency (2.4 GHz) is sharp, abnormal oscillation can be suppressed, and stable resonance characteristics can be obtained. This is because the sensor device 100 is flip-chip connected to the circuit board 50, so the wiring length between the sensor device 100 and the circuit board 50 is shortened, thereby reducing the inductor component. Furthermore, by increasing the contact area of the electrically connected portion, the electrical connection reliability between the sensor device 100 and the circuit board 50 can be improved.

[0065] As described above, according to the sensor device 1 of the present embodiment, since the sensor device 100 is mounted on the circuit board 50 by the flip-chip connection method, the wiring length between the sensor device 100 and the circuit board 50 is shortened, thereby ensuring stable oscillation characteristics of the sensor device.

[0066] According to this embodiment, by means of face-down mounting, the wire components in the wire bonding method can be eliminated, so that stable oscillation characteristics can be obtained. When the circuit board 50 is mounted on the mother board of the sensor device 1 or in the transportation process, the circuit board 50 can realize mechanical protection of the sensor. For example, some sensors are provided with a protective cap on the reaction part (for example, a probe). However, with this face-down mounting, this cap is unnecessary. The size of the through hole 58 only needs to be large enough for the sensitive film to be exposed, and it only needs to be smaller than the support substrate 10 of the sensor device 100.

[0067] In addition, since the recesses 53 and 58 on the circuit board 50 function as gas reservoirs, gas with suppressed flow fluctuations can be supplied to the sensor device 100. Furthermore, the distance between the mounting surface 51 of the circuit board 50 and the sensitive film 30 may become narrow, making it difficult for gas to pass through. In this case, it can be solved by forcing the gas to flow. By using the recess 58 as a through hole as shown in FIG. 5, the gas can penetrate from the surface of the circuit board 50 and reach the sensor device 100 through a short path.

[0068] Note that when the circuit board 50 functions as mechanical protection during the mounting of the sensor device 1 on the mother board or in the transportation process, the recess 53 is not necessarily required. This is because the circuit board 50 covering the surface mechanically protects the electrodes and sensitive film of the sensor device.

[0069] By using the recess 53 or the through hole 58 as a flow path as in this embodiment, the gas can be supplied stably to a certain extent, and its output can be stabilized. The formation of the recess 53 and the through hole 58 on the circuit board 50 is mainly realized by laser processing or mechanical processing. In this case, the side surfaces of the recess and the through hole become rough, and in the case of a resin substrate, there is also a problem that the detected gas is adsorbed and held on the side surface as it is. In this case, if a film that is difficult for gas to adsorb is formed on the inner wall of the recess and the side wall of the through hole, the adsorption can be eliminated, and the gas for the next detection can be made more accurate. Also, if a heater, for example, a heater formed by wiring on the surface or inner layer of a substrate, is provided around the concave portion or the through hole, it becomes possible to desorb the adsorbed gas by the heat generated thereby.

[0070] [Modification Example] As described above, the embodiments of the present invention have been described. However, the present invention is not limited only to the above-described embodiments, and it goes without saying that various modifications can be made.

[0071] For example, in the above embodiments, the sensor device having an air gap structure in which the resonance region 24 is configured by forming a gap G between the support substrate 10 and the lower electrode 21 has been described as an example. However, a cavity may be provided in the support substrate 10, and a sensor device having a cavity structure in which the laminated region of the lower electrode, the piezoelectric film, and the upper electrode formed on the cavity is used as the resonance region may be used. Alternatively, a sensor device having an acoustic reflection film structure may be adopted.

Description of Reference Numerals

[0072] 1, 3... Sensor device 10... Support substrate 21... Lower electrode 22... Piezoelectric film 23... Upper electrode 24... Resonance region 30... Sensing film 50... Circuit board 51... Mounting surface 52a... First electrode 52b... Second electrode 62a, 62b... Joint portion 53... Concave portion 58... Through hole 100... Sensor device G... Gap

Claims

1. A circuit board; a plurality of sensor devices each including a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode opposed to each other with at least a part of the piezoelectric film interposed therebetween, and a sensitive film provided on the upper electrode, the sensor devices being flip-chip connected to the circuit substrate; Equipped with The circuit board is disposed along an arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices, and has a through hole through which a gas to be detected flows.

2. A circuit board, a plurality of sensor devices each including a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode opposed to each other with at least a part of the piezoelectric film interposed therebetween, and a sensitive film provided on the upper electrode, the sensor devices being flip-chip connected to the circuit substrate; Equipped with The circuit board is disposed along an arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices, and has a recess through which a gas to be detected flows.

3. A sensor device according to claim 1 or 2, The sensitive films of the plurality of sensor devices are formed of different materials. Sensor device.

4. The sensor device according to any one of claims 1 to 3, The sensitive film is provided in a resonance region of the upper electrode where the lower electrode and the upper electrode face each other with the piezoelectric film interposed therebetween. Sensor device.

5. The sensor device according to claim 4, The piezoelectric film, the lower electrode, and the upper electrode have a convex curved surface shape that forms a gap between the support substrate and the lower electrode in the resonance region. Sensor device.

6. The sensor device according to any one of claims 1 to 5, the circuit board has a first electrode connected to the lower electrode and a second electrode connected to the upper electrode; The sensor device further includes a junction provided on the lower electrode and the upper electrode, and electrically connected to the first electrode and the second electrode, respectively. Sensor device.

7. The sensor device according to claim 6, The joints are solder bumps, gold bumps or anisotropic conductive films. Sensor device.

8. The sensor device according to any one of claims 1 to 6, The sensitive film is an inorganic film, an organic polymer film, or an organic dye film. Sensor device.

9. The sensor device according to claim 8, The sensitive film is a cellulose-based resin, a fluorine-based resin, an acrylic resin, or a conductive polymer. Sensor device.

10. a sensor device is provided in which a plurality of sensor devices, each of which has a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode opposed to each other with at least a part of the piezoelectric film therebetween, and a sensitive film provided on the upper electrode, are flip-chip connected to a circuit substrate; The sensor device is provided on a motherboard; The circuit board has a through hole extending along an arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices and through which a gas to be detected flows. A method for manufacturing a sensor device.

11. A sensor apparatus is provided in which a plurality of sensor devices, each of which has a support substrate, a piezoelectric film provided on the support substrate, a lower electrode and an upper electrode facing each other with at least a portion of the piezoelectric film therebetween, and a sensitive film provided on the upper electrode, are flip-chip connected to a circuit board; The sensor device is provided on a motherboard; The circuit board has a recessed portion extending along an arrangement direction of the plurality of sensor devices so as to face the sensitive films of the plurality of sensor devices and through which a gas to be detected flows. A method for manufacturing a sensor device.

12. A method for manufacturing a sensor device according to claim 10 or 11, comprising: The sensitive films of the plurality of sensor devices are formed of different materials. A method for manufacturing a sensor device.

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