JP6164053B2 - Lamb wave sensing device - Google Patents

Description

  The present invention relates to a lamb wave sensing device.

  Conventionally, a Lamb wave type sensing device includes a diaphragm made of a piezoelectric material such as ALN and a comb-like electrode disposed on the diaphragm, and is excited to the diaphragm by an AC voltage applied to the comb-like electrode. There is one that detects a pressure received by a diaphragm using a generated Lamb wave (see Patent Document 1 and Non-Patent Document 1).

  In this, a Lamb wave type sensing device is operated as a resonator. And when a diaphragm receives a pressure, a diaphragm will bend and deform | transform and the space | interval between a pair of comb-tooth part which comprises a comb-tooth shaped electrode will change. Along with this, the resonance frequency of the resonator changes. By detecting the amount of change in the resonance frequency, the pressure received by the diaphragm 2 can be detected.

Japanese Patent No. 5138246 Lamb wave resonant pressure micro-sensor utilizing a thin-film aluminum nitride membrane Author (s): Anderas E, Katardjiev I, Yantchev VSource: JOURNAL OF MICROMECHANICS AND MICROENGINEERING Volume: 21 Issue: 8 Article Number: 085010 DOI: 10.1088 / 0960- 1317/21/8/085010 Published: AUG 2011

  As a result of intensive studies on the Lamb wave type sensing device, the inventors of the present application have found that the following problems occur.

  14 and 15 show the Lamb wave sensing device 1 studied by the present inventors. FIG. 14 is a top view of the Lamb wave type sensing device 1, and FIG. 15 is a side view of the Lamb wave type sensing device 1.

  The Lamb wave sensing device 1 is composed of a diaphragm 2 made of a piezoelectric material and a comb-like electrode 3 disposed on the diaphragm 2. The Lamb wave type sensing device 1 is configured to form a resonator, and the stress is detected by a change in the resonance frequency, similarly to the Lamb wave type sensing device described above.

  Specifically, when the back surface of the diaphragm 2 of the Lamb wave type sensing device 1 receives the pressure P (see FIG. 15), the diaphragm 2 is bent and deformed. At this time, stress acts on the surface of the diaphragm 2 in the radial direction and the circumferential direction, and a stress distribution is formed substantially concentrically with respect to the center of the diaphragm 2. The front surface is a surface formed on one side in the thickness direction of the diaphragm 2 (upper side in FIG. 15), and the back surface is a surface formed on the other side in the thickness direction of the diaphragm 2 (lower side in FIG. 15). It is.

  The stress can be divided into a stress component P1 in the Lamb wave propagation direction and a stress component P2 in a direction perpendicular to the Lamb wave propagation direction. Therefore, the resonance frequency change when the diaphragm 2 receives pressure is, as in the following formulas (1) and (2), a change in the interval between the comb-like electrodes 3 and a change in the sound speed due to the stress in the propagation direction of the Lamb wave. The amount of change in resonance frequency due to each change in sound velocity due to stress in the direction perpendicular to the propagation direction of the Lamb wave is added.

f = v / 2L (1)
Δf / f = ΔL / L + ΔV1 / V + ΔV2 / V (2)
L is the interval between the comb electrodes, V is the sound speed (propagation speed) of the Lamb wave, ΔV1 is the sound speed change due to the stress in the Lamb wave propagation direction, and ΔV2 is the sound speed change due to the stress perpendicular to the Lamb wave propagation direction. , Δf, and ΔL are amounts of change in f and L, respectively.

  However, depending on the diaphragm material, propagation direction, Lamb wave mode, etc., the change direction of the resonance frequency due to the change in the sound speed due to the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave is the change in the sound speed due to the stress P1 in the Lamb wave propagation direction There is a case in which the direction of change in the resonance frequency due to the change in the tooth electrode interval has an inverse relationship. In this case, the change in the sound speed due to the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave is the change in the resonance frequency due to the change in the interval between the comb-like electrodes 3, and the change in the sound speed due to the stress P1 in the propagation direction of the Lamb wave. It has been found that the pressure detection sensitivity of the Lamb wave type sensing device 1 is lowered in a direction that cancels out the amount of change in the resonance frequency due to.

  Specifically, the stress on the surface of the diaphragm 2 on the opposite side to the pressure-receiving surface is a direction perpendicular to the Lamb wave propagation direction stress P1 and the Lamb wave propagation direction when the thickness of the diaphragm 2 is more than a certain level. The stress P2 is a tensile stress in the entire area of the diaphragm 2.

  Due to the tensile stress P1 in the propagation direction of the Lamb wave, the interval between the comb-like electrodes 3 is widened and the resonance frequency is lowered. Further, the resonance frequency may also be lowered by changing the sound velocity in the propagation direction of the Lamb wave in the direction of lowering by the tensile stress P1 in the propagation direction of the Lamb wave. On the other hand, due to the tensile stress P2 in the direction perpendicular to the propagation direction of the Lamb wave, the sound velocity in the propagation direction of the Lamb wave changes in a direction that increases, and the resonance frequency may increase. For this reason, the resonance frequency change is canceled out, and the stress detection sensitivity is lowered.

  In addition, here, as an example of the pressure detection method, the case where the Lamb wave sensing device 1 is used as a resonator and the pressure is detected from a change in the resonance frequency has been described as an example. However, the Lamb wave sensing device 1 is used as a filter element. The same problem occurs when the pressure is detected from the change in the delay time. This is because, as described above, the change in sound speed due to the stress P1 in the propagation direction of the Lamb wave and the change in sound speed due to the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave change in opposite directions.

  In view of the above points, an object of the present invention is to provide a Lamb wave type sensing device that suppresses a decrease in detection sensitivity.

In order to achieve the above object, in the first aspect of the present invention, a first diaphragm (41) made of a piezoelectric material and a back surface side of the first diaphragm are formed on the opposite side to the first diaphragm. A first diaphragm structure (40) including an open space (44) and a support portion (42) for supporting the periphery of the first diaphragm from its back surface side, and so as to mesh with each other on the surface side of the first diaphragm A device chip (30) comprising a pair of interdigitated electrodes (50a, 50b) disposed;
A second diaphragm (21) having a device chip mounted on the front surface side, and a second diaphragm structure (20) including a support portion (22) for supporting the periphery of the second diaphragm from the back surface side; An alternating voltage applied between the pair of comb-like electrodes causes Lamb waves to propagate in the diaphragm in one direction, and the device chip detects a force applied through the second diaphragm.
A slit (46a, 46b) is provided in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes are arranged in the first diaphragm. .

  According to the first aspect of the present invention, the slit is provided in the first diaphragm in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region. For this reason, it can reduce that the stress of the direction perpendicular | vertical to the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. Therefore, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  Here, the surface of the first diaphragm is a surface formed on one side in the thickness direction of the first diaphragm, and the back surface of the first diaphragm is formed on the other side of the first diaphragm in the thickness direction. It is a surface. The surface of the second diaphragm is a surface formed on one side in the thickness direction of the second diaphragm, and the back surface of the second diaphragm is a surface formed on the other side in the thickness direction of the second diaphragm. is there. The slit is a cut formed in the first diaphragm.

  In the third aspect of the present invention, the first diaphragm (41) made of a piezoelectric material and the void (44) formed on the back surface side of the first diaphragm and opening on the opposite side to the first diaphragm. A first diaphragm structure (40) including a support portion (42) for supporting the periphery of the first diaphragm from the back surface side thereof, and a pair of the first diaphragm structure arranged to mesh with each other on the surface side of the first diaphragm A device chip (30) having comb-like electrodes (50a, 50b), a second diaphragm (21) formed by mounting the device chip on the front surface side, and a support portion for supporting the periphery of the second diaphragm from the back surface side And a second diaphragm structure (20) comprising (22), so that a Lamb wave propagates in the diaphragm in one direction by an alternating voltage applied between a pair of comb-like electrodes. The device chip detects a force applied through the second diaphragm, the first diaphragm is subjected to compressive stress, and a pair of comb-like electrodes of the first diaphragm are arranged. And first and second films (80a, 80b) that are disposed on both sides of the Lamb wave propagation direction and act on tensile stress with respect to the device region (45) to be formed, In the first region (48) in which the second film and the pair of comb-like electrodes are disposed, buckling based on the compressive stress is released by the tensile stress, and the first diaphragm other than the first region is removed. The two regions (49a, 49b) are characterized in that buckling remains.

  According to invention of Claim 3, buckling remains in 2nd area | regions other than a 1st area | region among 1st diaphragms. For this reason, the amount of buckling in the second region is increased or decreased by the stress in the direction perpendicular to the propagation direction of the Lamb wave, and the stress in the direction perpendicular to the propagation direction of the Lamb wave is absorbed in the second region. Therefore, it can reduce that the stress of a direction perpendicular | vertical to the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  In the invention according to claim 4, the first diaphragm (41) made of a piezoelectric material and the void (44) formed on the back surface side of the first diaphragm and opening on the opposite side to the first diaphragm. A first diaphragm structure (40) including a support portion (42) for supporting the periphery of the first diaphragm from the back surface side thereof, and a pair of the first diaphragm structure arranged to mesh with each other on the surface side of the first diaphragm A device chip (30) having comb-like electrodes (50a, 50b), a second diaphragm (21) formed by mounting the device chip on the front surface side, and a support portion for supporting the periphery of the second diaphragm from the back surface side And a second diaphragm structure (20) comprising (22), so that a Lamb wave propagates in the diaphragm in one direction by an alternating voltage applied between a pair of comb-like electrodes. The device chip detects a force applied through the second diaphragm, the first diaphragm is subjected to compressive stress, and a pair of comb-like electrodes of the first diaphragm are arranged. The first diaphragm is provided with first and second films (80a, 80b) disposed on both sides in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) to be applied and acting on a tensile stress. In the first region (48) in which the first and second films and the pair of comb-like electrodes are disposed, the buckling based on the compressive stress is released by the tensile stress, and the first diaphragm among the first diaphragms. The second region (49c, 49d) other than the region is characterized in that buckling remains.

  According to invention of Claim 4, buckling remains in 2nd area | regions other than a 1st area | region among 1st diaphragms. For this reason, the buckling amount in the second region is increased or decreased by the stress in the propagation direction of the Lamb wave, and the stress in the propagation direction of the Lamb wave is absorbed in the second region. Therefore, it can reduce that the stress of the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  In the fifth aspect of the present invention, the first diaphragm (41) made of a piezoelectric material and the void (44) formed on the back surface side of the first diaphragm and opening on the opposite side to the first diaphragm. A first diaphragm structure (40) including a support portion (42) for supporting the periphery of the first diaphragm from the back surface side thereof, and a pair of the first diaphragm structure arranged to mesh with each other on the surface side of the first diaphragm A device chip (30) having comb-like electrodes (50a, 50b), a second diaphragm (21) formed by mounting the device chip on the front surface side, and a support portion for supporting the periphery of the second diaphragm from the back surface side And a second diaphragm structure (20) comprising (22), so that a Lamb wave propagates in the diaphragm in one direction by an alternating voltage applied between a pair of comb-like electrodes. The device chip is adapted to detect a force applied through the second diaphragm, the first diaphragm is subjected to tensile stress, and a pair of comb-like electrodes of the first diaphragm are arranged. The first diaphragm is provided with first and second films (80c, 80d) disposed on both sides in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) to be applied, and subjected to compressive stress. Of these, the regions (49a, 49b) in which the first and second films are disposed are buckled by compressive stress.

  According to the fifth aspect of the present invention, buckling occurs in a region of the first diaphragm where the first and second films are disposed. For this reason, the amount of buckling in the region is increased or decreased by the stress in the direction perpendicular to the propagation direction of the Lamb wave, and the stress in the direction perpendicular to the propagation direction of the Lamb wave is absorbed in the region. Therefore, it can reduce that the stress of a direction perpendicular | vertical to the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  According to the sixth aspect of the present invention, the first diaphragm (41) made of a piezoelectric material and the void (44) formed on the back surface side of the first diaphragm and opening on the opposite side to the first diaphragm. A first diaphragm structure (40) including a support portion (42) for supporting the periphery of the first diaphragm from the back surface side thereof, and a pair of the first diaphragm structure arranged to mesh with each other on the surface side of the first diaphragm A device chip (30) having comb-like electrodes (50a, 50b), a second diaphragm (21) formed by mounting the device chip on the front surface side, and a support portion for supporting the periphery of the second diaphragm from the back surface side And a second diaphragm structure (20) comprising (22), so that a Lamb wave propagates in the diaphragm in one direction by an alternating voltage applied between a pair of comb-like electrodes. The device chip is adapted to detect a force applied through the second diaphragm, the first diaphragm is subjected to tensile stress, and a pair of comb-like electrodes of the first diaphragm are arranged. And first and second films (80c, 80d) that are arranged on both sides of the Lamb wave propagation direction and act on the device region (45) to be compressed, The regions (49a, 49b) in which the second film is disposed are characterized by being buckled by compressive stress.

  According to the sixth aspect of the present invention, buckling occurs in the region of the first diaphragm where the first and second films are disposed. For this reason, the amount of buckling in the region increases or decreases due to the stress in the propagation direction of the Lamb wave, and the stress in the propagation direction of the Lamb wave is absorbed in the region. Therefore, it can reduce that the stress of the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  According to the ninth aspect of the present invention, the first diaphragm (41) made of a piezoelectric material, the support portion (25) for supporting the periphery of the first diaphragm from the back surface side, and the back surface side of the first diaphragm are formed. And a space (44a) that opens through the openings (46a, 46b) on the surface side of the first diaphragm, and is arranged to mesh with the first diaphragm structure (40A) on the surface of the first diaphragm. And a device chip (30) having a pair of comb-like electrodes (50a, 50b), and a lamb wave is applied to the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes. The device chip detects a force applied to the first diaphragm, and a device in which a pair of comb-like electrodes of the first diaphragm is arranged. Wherein the slits in a direction perpendicular to the propagation direction of the Lamb wave (46a, 46b) are provided for source region (45).

  According to the ninth aspect of the present invention, the slit is provided in the first diaphragm in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region. For this reason, it can reduce that the stress of the direction perpendicular | vertical to the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. Therefore, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  In the eleventh aspect of the present invention, the first diaphragm (41) made of a piezoelectric material, the support portion (25) for supporting the periphery of the first diaphragm from the back surface side, and the back surface side of the first diaphragm are formed. A first diaphragm structure (40A) having a cavity (44a) opened through an opening (90a, 90b, 90c, 90d) on the surface side of the first diaphragm and biting on the surface of the first diaphragm A device chip (30) having a pair of comb-like electrodes (50a, 50b) arranged so as to meet each other, and a Lamb wave is generated by an alternating voltage applied between the pair of comb-like electrodes. One diaphragm propagates in one direction, and the device chip detects a force applied to the first diaphragm. The first diaphragm is subjected to compressive stress. The first diaphragm is disposed on both sides in the Lamb wave propagation direction with respect to the device region (45) in which the pair of comb-like electrodes of the first diaphragm is disposed, and a tensile stress acts on the first, In the first region (48) that includes the second membrane (80a, 80b) and in which the first and second membranes and the pair of comb-like electrodes are arranged in the first diaphragm, buckling based on compressive stress is performed. Is released by the tensile stress, and buckling remains in the second region (49a, 49b) other than the first region of the first diaphragm.

  According to invention of Claim 11, buckling remains in 2nd area | regions other than a 1st area | region among 1st diaphragms. For this reason, the amount of buckling in the second region is increased or decreased by the stress in the direction perpendicular to the propagation direction of the Lamb wave, and the stress in the direction perpendicular to the propagation direction of the Lamb wave is absorbed in the second region. Therefore, it can reduce that the stress of a direction perpendicular | vertical to the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  In the invention described in claim 12, the first diaphragm (41) made of a piezoelectric material, the support portion (25) for supporting the periphery of the first diaphragm from the back side thereof, and the back side of the first diaphragm are formed. A first diaphragm structure (40A) having a cavity (44a) opened through an opening (90a, 90b, 90c, 90d) on the surface side of the first diaphragm and biting on the surface of the first diaphragm A device chip (30) having a pair of comb-like electrodes (50a, 50b) arranged so as to meet each other, and a Lamb wave is generated by an alternating voltage applied between the pair of comb-like electrodes. One diaphragm propagates in one direction, and the device chip detects a force applied to the first diaphragm. The first diaphragm is subjected to compressive stress. It is arranged on both sides in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes of the first diaphragm is arranged, and tensile stress acts Compressive stress in the first region (48) of the first diaphragm where the first and second films and the pair of comb-like electrodes are disposed. The buckling based on the above is released by the tensile stress, and buckling remains in the second region (49c, 49d) other than the first region of the first diaphragm.

  According to invention of Claim 12, buckling remains in 2nd area | regions other than a 1st area | region among 1st diaphragms. For this reason, the buckling amount in the second region is increased or decreased by the stress in the propagation direction of the Lamb wave, and the stress in the propagation direction of the Lamb wave is absorbed in the second region. Therefore, it can reduce that the stress of the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  In the invention described in claim 13, the first diaphragm (41) made of a piezoelectric material, the support portion (25) for supporting the periphery of the first diaphragm from the back surface side, and the back surface side of the first diaphragm are formed. A first diaphragm structure (40A) having a cavity (44a) opened through an opening (90a, 90b, 90c, 90d) on the surface side of the first diaphragm and biting on the surface of the first diaphragm A device chip (30) having a pair of comb-like electrodes (50a, 50b) arranged so as to meet each other, and a Lamb wave is generated by an alternating voltage applied between the pair of comb-like electrodes. One diaphragm propagates in one direction, the device chip detects a force applied to the first diaphragm, and the first diaphragm is subjected to tensile stress. It is arranged on both sides in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes of the first diaphragm is arranged, and compressive stress acts The regions (49a, 49b) of the first diaphragm where the first and second films are arranged are buckled by compressive stress. It is characterized by being.

  According to the thirteenth aspect of the present invention, buckling occurs in the region of the first diaphragm where the first and second films are disposed. For this reason, the amount of buckling in the region is increased or decreased by the stress in the direction perpendicular to the propagation direction of the Lamb wave, and the stress in the propagation direction of the Lamb wave is absorbed in the region. Therefore, it can reduce that the stress of a direction perpendicular | vertical to the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  In the invention described in claim 14, the first diaphragm (41) made of a piezoelectric material, the support portion (25) for supporting the periphery of the first diaphragm from the back surface side, and the back surface side of the first diaphragm are formed. A first diaphragm structure (40A) having a cavity (44a) opened through an opening (90a, 90b, 90c, 90d) on the surface side of the first diaphragm and biting on the surface of the first diaphragm A device chip (30) having a pair of comb-like electrodes (50a, 50b) arranged so as to meet each other, and a Lamb wave is generated by an alternating voltage applied between the pair of comb-like electrodes. One diaphragm propagates in one direction, the device chip detects a force applied to the first diaphragm, and the first diaphragm is subjected to tensile stress. A first diaphragm that is arranged on both sides of the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes of the first diaphragm is arranged, and on which a compressive stress acts; The second membrane (80c, 80d) is provided, and the regions (49a, 49b) of the first diaphragm where the first and second membranes are disposed are buckled by compressive stress. And

  According to the fourteenth aspect of the present invention, buckling occurs in a region of the first diaphragm where the first and second films are disposed. For this reason, the amount of buckling in the region increases or decreases due to the stress in the propagation direction of the Lamb wave, and the stress in the propagation direction of the Lamb wave is absorbed in the region. Therefore, it can reduce that the stress of the propagation direction of a Lamb wave acts on a device area | region among 1st diaphragms. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip. Thereby, the Lamb wave type sensing device which suppressed the fall of the pressure detection sensitivity can be provided.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a side view of the Lamb wave type sensing device in a 1st embodiment of the present invention. It is a top view of the Lamb wave type sensing device in a 1st embodiment. It is a figure which shows the manufacturing process of the Lamb wave type sensing device in 1st Embodiment. It is a side view of the Lamb wave type sensing device in the modification of a 1st embodiment. It is a figure which shows the manufacturing process of the Lamb wave type sensing device in the modification of 1st Embodiment. It is a top view of the Lamb wave type sensing device in a 2nd embodiment of the present invention. It is a top view of the Lamb wave type sensing device in a 3rd embodiment of the present invention. It is a top view of the Lamb wave type sensing device in a 4th embodiment of the present invention. It is a top view of the Lamb wave type sensing device in a 5th embodiment of the present invention. It is a top view of the Lamb wave type sensing device in a 6th embodiment of the present invention. It is a top view of the Lamb wave type sensing device in a 7th embodiment of the present invention. It is a top view of the Lamb wave type sensing device in an 8th embodiment of the present invention. It is a top view of the Lamb wave type sensing device in a 9th embodiment of the present invention. It is a figure for demonstrating the subject of this invention. It is a figure for demonstrating the subject of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
1 and 2 show a first embodiment of a Lamb wave sensing device 10 of the present invention.

  The Lamb wave type sensing device 10 of the present embodiment includes a diaphragm structure 20 and a device chip 30.

  The diaphragm structure 20 is made of a metal material, and includes a diaphragm 21 and a support portion 22. The diaphragm 21 is formed in a thin film shape. The support part 22 is arrange | positioned around the surface direction of the diaphragm 21, and supports the diaphragm 21 from the back surface side. That is, the support part 22 supports the periphery of the diaphragm 21 from the back surface side. A void 24 is formed on the back side of the diaphragm 21. The void 24 opens to the opposite side with respect to the diaphragm 21. The void 24 is formed so as to be surrounded by the support portion 22. The surface of the diaphragm 21 is a surface formed on one side in the thickness direction of the diaphragm 21, and the back surface of the diaphragm 21 is a surface formed on the other side in the thickness direction of the diaphragm 21.

  The device chip 30 is disposed on the surface of the diaphragm 21 of the diaphragm structure 20. The device chip 30 includes a diaphragm structure 40 and a pair of comb-like electrodes 50a and 50b. The diaphragm structure 40 includes a diaphragm 41 and a support portion 42. The diaphragm 41 is a thin film member made of a piezoelectric material such as aluminum nitride (ALN).

  The support part 42 is arrange | positioned around the surface direction of the diaphragm 41, and supports the diaphragm 41 from the back surface side. That is, the support part 42 supports the surface direction of the diaphragm 41 from the back surface side. A void 44 is formed on the back side of the diaphragm 41. The void 44 is open on the opposite side to the diaphragm 41. The void 44 is formed so as to be surrounded by the support portion 42.

  In the present embodiment, the thickness dimension of the diaphragm 21 is larger than that of the diaphragm 41 of the device chip 30. This makes it possible to receive and measure a higher pressure than when the device chip 30 directly receives pressure.

  The pair of comb-like electrodes 50 a and 50 b are disposed on the surface 41 a of the diaphragm 41. The surface 41 a of the diaphragm 41 is a surface formed on one side in the thickness direction of the diaphragm 41, and the back surface of the diaphragm 41 is a surface formed on the other side in the thickness direction of the diaphragm 41. The pair of comb-like electrodes 50a and 50b are each formed in a comb-like shape and arranged so as to mesh with each other.

  Specifically, the comb-like electrode 50a includes a plurality of comb-tooth portions 51a extending in parallel with each other, and a support portion 52a connected to one end side of the plurality of comb-tooth portions 51a. The comb-like electrode 50b includes a plurality of comb-tooth portions 51b extending in parallel with each other, and a support portion 52b connected to the other end side of the plurality of comb-tooth portions 51a. The plurality of comb teeth portions 51a and 51b are formed so as to mesh with each other. The extending directions of the plurality of comb-tooth portions 51a and 51b are parallel to each other.

  In this embodiment, when an alternating voltage is applied between the pair of comb-like electrodes 50a and 50b, a Lamb wave is excited by the diaphragm 41 and propagates through the diaphragm 41 in a certain direction, as will be described later. The propagation direction of the Lamb wave is a direction in which the plurality of comb teeth 51a and 51b are arranged (that is, a direction perpendicular to the extending direction of the plurality of comb teeth 51a and 51b).

  Lead wires 70a and 70b are connected to the pair of comb-like electrodes 50a and 50b, respectively. The lead-out wiring 70a is arranged on one side (right side in the drawing) perpendicular to the propagation direction of the Lamb wave with respect to the comb-like electrode 50a. The lead-out wiring 70a is arranged so as to extend from the comb-like electrode 50a side to one side (upper side in FIG. 2) in the Lamb wave propagation direction. The lead-out wiring 70b is arranged on the other side (left side in the figure) in the direction perpendicular to the propagation direction of the Lamb wave with respect to the comb-like electrode 50b. The lead wire 70b is disposed so as to extend from the comb-like electrode 50b side to the other side (the lower side in FIG. 2) in the Lamb wave propagation direction.

  In the present embodiment, the diaphragm 41 is provided with slits 46a and 46b. The slits 46a and 46b are arranged so as to sandwich the device region 45 from a direction perpendicular to the propagation direction of the Lamb wave. The device region 45 is a region on the diaphragm 41 where the comb-like electrodes 50a and 50b are mounted. The slit 46a is arranged on one side (right side in the figure) in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region 45. The slit 46b is disposed on the other side (left side in the drawing) in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region 45. The slits 46a and 46b are cuts that extend in the Lamb wave propagation direction and are formed so as to penetrate between the front surface 41a and the back surface of the diaphragm 41.

  Next, the manufacturing method of the lamb wave type sensing device 10 of this embodiment is demonstrated with reference to FIG.

  First, in the first step, the piezoelectric film 61 is formed on the surface of the substrate 60 made of silicon by a method such as vapor deposition or sputtering (see FIG. 3A). The piezoelectric film 61 is formed from a piezoelectric material in a thin film shape.

  In the next second step, the piezoelectric film 61 is patterned by photolithography to form slits 46a and 46b in the piezoelectric film 61 (see FIG. 3B).

  For example, a photoresist 62 is applied on the surface of the piezoelectric film 61. A predetermined area of the applied photoresist 62 is exposed. Then, the photoresist 62 and the piezoelectric film 61 are etched. For this reason, the exposed portion of the photoresist 62 and the region corresponding to the exposed portion of the piezoelectric film 61 are dissolved to form slits 46 a and 46 b in the piezoelectric film 61.

  As the etching of this embodiment, dry etching or wet etching using a chlorine-based gas as an etchant (corrosive agent) can be used.

  In the next third step, the photoresist 62 on the surface of the piezoelectric film 61 is removed, and an electrode layer 51 made of a conductive metal such as aluminum (AL), copper (Cu), or Au (gold) is formed into the piezoelectric film. It forms on the surface of 61 (refer FIG.3 (c)).

  In the next fourth step, the electrode layer 51 is patterned by photolithography to form a pair of comb-like electrodes 50a and 50b on the piezoelectric film 61 (see FIG. 3D).

  FIG. 3D shows a state in which the photoresist 63 remains on the upper side of the comb-like electrodes 50a and 50b after the electrode layer 51 is etched.

  In the patterning of the electrode layer 51, dry etching or wet etching can be used as the etching. As the etching material (etchant), a material suitable for the material of the electrode layer 51 is used.

  In the next fifth step, the support member 64 is fixed to the upper side of the pair of comb-like electrodes 50a and 50b and the piezoelectric film 61 (see FIG. 3E).

  Specifically, the photoresist 63 remaining on the upper side of the comb-like electrodes 50a and 50b is removed. Further, a photoresist 65 is applied on the upper side of the piezoelectric film 61. A support material 66 is disposed above the coated photoresist 65. At this time, the photoresist 65 joins the comb-like electrodes 50 a and 50 b and the piezoelectric film 61 and the support material 66.

  In the next sixth step, the portion of the back surface corresponding to the device region 45 in the substrate 60 is removed by etching. As a result, a void 44 is formed in the portion of the substrate 60 corresponding to the device region 45 that opens to the back surface side. That is, the support portion 42 is formed so as to surround the void 44 on the rear surface side of the diaphragm 41. In addition to this, the photoresist 65 and the support material 66 are removed. Thereby, the device chip 30 is completed (see FIG. 3F). Thereafter, the device chip 30 is fixed to the surface side of the diaphragm 21 of the diaphragm structure 20. Thereby, the Lamb wave type sensing device 10 is completed.

  Next, the operation of this embodiment will be described.

  The device chip 30 of the present embodiment detects the pressure received by the diaphragm 41 by operating the device chip 30 as a resonator based on the same principle as the Lamb wave type sensing device 1 described in the above section of the problem. It is.

  Specifically, a measuring device (not shown) is connected to the pair of comb-like electrodes 50a and 50b, and an alternating voltage is output between the comb-like electrodes 50a and 50b from the measuring device. By detecting a change in the resonance frequency of the device chip 30, the pressure received by the diaphragm 41 is detected.

Here, the interdigital electrodes 50a from the measuring device, with the output the AC voltage between the 50b, the diaphragm 4 1 and excited Lamb waves this Lamb wave propagates diaphragm 4 1 in one direction.

  When the device chip 30 receives pressure as shown by an arrow P in FIG. 1 through the diaphragm 21 of the diaphragm structure 20, an isotropic stress is applied to the diaphragm 41. At this time, the slits 46a and 46b can prevent the stress from acting on the device region 45 from the direction perpendicular to the Lamb wave propagation direction.

  According to the embodiment described above, the Lamb wave type sensing device 10 includes the diaphragm structure 20 and the device chip 30. The diaphragm structure 20 includes a diaphragm 21 and a support portion 22 that supports the periphery of the diaphragm 21 from the back surface side. The device chip 30 includes a diaphragm structure 40 and a pair of comb-like electrodes 50a and 50b. The diaphragm structure 40 includes a diaphragm 41 made of a piezoelectric material, and a support portion 42 that supports the periphery of the diaphragm 41 from its back side. The pair of comb-like electrodes 50 a and 50 b are arranged so as to bite on the surface 41 a of the diaphragm 41. A lamb wave propagates through the diaphragm 41 in one direction by an alternating voltage applied between the pair of comb-like electrodes 50a and 50b. The measuring device connected to the pair of comb-like electrodes detects the pressure applied to the back surface side of the diaphragm 44 through the diaphragm 21 by detecting the change in the resonance frequency of the device chip 30. The diaphragm 41 is provided with slits 46a and 46b in a direction perpendicular to the propagation direction of the Lamb wave with respect to the pair of comb-like electrodes 50a and 50b, respectively.

  Therefore, the slits 46 a and 46 b can prevent the stress in the direction perpendicular to the Lamb wave propagation direction from acting on the device region 45. For this reason, it can reduce that the stress P2 of the direction perpendicular | vertical to the propagation direction of a Lamb wave which is the cause of the fall of a pressure detection sensitivity acts on the device area | region 45. FIG. Therefore, a decrease in pressure detection sensitivity in the device chip 30 can be suppressed. Thereby, the Lamb wave type sensing device 10 which suppressed the fall of the pressure detection sensitivity can be provided.

  In the present embodiment, the device chip 30 is disposed on the surface side of the diaphragm structure 20. For this reason, it is possible to detect a high pressure without using the diaphragm structure 20 as compared with the case where the pressure is detected by the device chip 30. In this case, the pressure can be appropriately detected by adjusting the thickness dimension of the diaphragm 21 of the diaphragm structure 20 in accordance with the pressure range to be detected.

  Japanese Patent Application Laid-Open No. 2010-169607 proposes that the bonding surface is partial when bonding the SAW chip to the diaphragm. This method can also be applied to a Lamb wave sensing device, but a decrease in the adhesion area leads to a decrease in reliability. Further, in order to limit the bonding surface locally, the process becomes complicated, leading to an increase in cost. On the other hand, such a problem does not occur in the lamb wave sensing device 10 of the present embodiment.

(Modification)
In the said 1st Embodiment, although the device chip 30 demonstrated the example using the diaphragm structure 40 provided with the space 44 opened on the opposite side with respect to the diaphragm 41, it replaced with this and in this modification, An example in which the diaphragm structure 40A that opens the void 44a to the surface 41a side of the diaphragm 41 through the slits 46a and 46b in the device chip 30 will be described.

  FIG. 4 shows a side view of the Lamb wave type sensing device 10 of this modification. The Lamb wave type sensing device 10 of this modification includes a diaphragm structure 20 and a device chip 30. 4, the same reference numerals as those in FIG. 1 denote the same components, and the description thereof is omitted.

  The device chip 30 of this modification includes a diaphragm structure 40A and a pair of comb-like electrodes 50a and 50b. The diaphragm structure 40A includes a space 40a. The void 44a of the diaphragm structure 40A is not formed so as to open to the back surface side. A diaphragm 41 is formed on the surface 41a side with respect to the void 44a in the diaphragm structure 40A. A portion of the diaphragm structure 40 </ b> A other than the diaphragm 41 constitutes a support portion 25 that supports the diaphragm 41. That is, a void 44 a is formed between the diaphragm 41 and the support portion 25 on the back side of the diaphragm 41 in the diaphragm structure 40 </ b> A. On the surface 41a side of the diaphragm 41, slits 46a and 46b as openings are provided in the same manner as in the first embodiment. The slits 46a and 46b communicate with the space 44a. As a result, the void 44a opens to the surface 41a side of the diaphragm 41 through the slits 46a and 46b.

  Next, a method for manufacturing the Lamb wave sensing device 10 of the present modification will be described with reference to FIG.

  First, in the first step, as in the first embodiment, the piezoelectric film 61 is formed on the surface of the substrate 60 (see FIG. 5A).

  In the next second step, the electrode layer 51 is formed on the surface of the piezoelectric film 61 by a method such as vapor deposition or sputtering (see FIG. 5B). The electrode layer 51 is made of a conductive metal such as aluminum (AL), copper (Cu), or Au (gold).

  In the next third step, the electrode layer 51 is patterned by photolithography to form a pair of comb-like electrodes 50a and 50b on the piezoelectric film 61 (see FIG. 5C).

  FIG. 5C shows a state in which the photoresist 63 remains on the upper side of the comb-like electrodes 50a and 50b after the electrode layer 51 is etched. In the patterning of the electrode layer 51, dry etching or wet etching can be used as the etching. As the etchant, a material suitable for the material of the electrode layer 51 is used.

  In the next fourth step, the photoresist 63 remaining on the upper side of the comb-like electrodes 50a and 50b in the third step (see FIG. 5C) is removed. In addition to this, a photoresist 64 is applied so as to cover the piezoelectric film 61 and the pair of comb-like electrodes 50a and 50b. Further, the photoresist 64 is patterned by photolithography to form slits 47a and 47b in the photoresist 64 (see FIG. 5D).

  In the next fifth step, the piezoelectric film 61 is etched to form slits 46a and 46b (see FIG. 5E). The slit 46a communicates with the slit 47a, and the slit 46b communicates with the slit 47b. As the etching, dry etching or wet etching using a chlorine-based gas as an etchant (corrosive agent) can be used. As the etchant, a material suitable for the material of the piezoelectric film 61 is used.

  In the next sixth step, a void 44a is formed in the substrate 60 by dry etching.

  Specifically, XeF2 gas is supplied into the substrate 60 through the slits 47a and 46a and the slits 47b and 46b as an etchant (corrosive agent). That is, the etchant is supplied to the substrate 60 from the surface side and etched. At this time, the slits 46 a and 46 b constitute an etching window for supplying an etchant to the inside of the substrate 60. Thus, the void 44a is formed by the etchant supplied into the substrate 60 (see FIG. 5F).

  In the next seventh step, the photoresist 64 is removed. Thereby, the device chip 30 is completed (see FIG. 5G). Thereafter, the device chip 30 is fixed to the surface side of the diaphragm 21 of the diaphragm structure 20. Thereby, the Lamb wave type sensing device 10 is completed.

  In the present embodiment configured as described above, the pressure received by the diaphragm 41 is detected by operating the device chip 30 as a resonator as in the first embodiment.

  Specifically, a measuring device (not shown) is connected to the pair of comb-like electrodes 50a and 50b, and an AC voltage is output from the measuring device between the comb-like electrodes 50a and 50b. Along with this, a Lamb wave is excited in the diaphragm 21 and this Lamb wave propagates through the diaphragm 21.

  At this time, the pressure received by the diaphragm 41 is detected by detecting the change in the resonance frequency of the device chip 30 by the measuring device. Here, when the device chip 30 receives pressure as shown by an arrow P in FIG. 4 through the diaphragm 21 of the diaphragm structure 20, an isotropic stress is applied to the surface 41 a of the diaphragm 41. At this time, the slits 46a and 46b can prevent the stress from acting on the device region 45 from the direction perpendicular to the Lamb wave propagation direction. For this reason, it can reduce that the stress P2 of the direction perpendicular | vertical to the propagation direction of a Lamb wave which is the cause of the fall of pressure detection sensitivity acts on the device area | region 45. FIG. Therefore, similarly to the first embodiment, it is possible to suppress a decrease in pressure detection sensitivity in the device chip 30.

  In the above modification, an example in which the slits 46a and 46b are used as etching windows has been described. However, if only the slits 46a and 46b are insufficient, an etching window may be provided separately from the slits 46a and 46b.

(Second Embodiment)
In the first embodiment, the example in which the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave is applied to the device region 45 by the slits 46a and 46b of the diaphragm 41 has been described. In the embodiment, an example in which the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave is applied to the device region 45 by the buckled region of the diaphragm 41 will be described.

  In the Lamb wave type sensing device 10 of this embodiment, tensile stress films 80a and 80b are provided in the device chip 30 instead of the slits 46a and 46b of the diaphragm 41. FIG. 6 shows a top view of the device chip 30 of the Lamb wave type sensing device 10 in the present embodiment.

  The diaphragm 41 of this embodiment is composed of a piezoelectric film on which compressive stress acts. It is possible to give the piezoelectric film a compressive stress by adjusting the film formation conditions when forming the piezoelectric film by sputtering or the like.

  The tensile stress films 80 a and 80 b are disposed on the surface 41 a of the diaphragm 41. The tensile stress films 80a and 80b are disposed on both sides of the diaphragm 41 with respect to the device region 45 in the Lamb wave propagation direction (vertical direction in FIG. 6). The device region 45 is a region in the diaphragm 41 where the pair of comb-like electrodes 50a and 50b are disposed. The tensile stress films 80a and 80b are thin films on which tensile stress acts, and Si3N4 formed by LPCVD (Low Pressure CVD) method can be used.

  In the present embodiment, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side of the sheet) is a rectangle. The rectangle has a side extending in the Lamb wave propagation direction (vertical direction in the drawing) as a short side and a side extending in a direction perpendicular to the Lamb wave propagation direction (in the horizontal direction in the drawing) as a long side.

  In the present embodiment, the lead-out wirings 70a and 70b are arranged so as to extend in a direction perpendicular to the propagation direction of the Lamb wave (the left-right direction in the figure).

  In the device chip 30 of this embodiment configured as described above, a tensile stress is applied to the diaphragm 41 only in the propagation direction of the Lamb wave by the tensile stress films 80a and 80b. As a result, in the diaphragm 41, in the region 48 where the tensile stress films 80a and 80b and the pair of comb-like electrodes 50a and 50b are arranged (the region surrounded by the alternate long and short dash line in the figure), the buckling is released. In the regions 49a and 49b other than the region 48, buckling remains. The region 49 a of the diaphragm 41 is a region on one side (left side in the figure) in a direction perpendicular to the propagation direction of the Lamb wave with respect to the region 48. The region 49 b of the diaphragm 41 is a region on the other side (right side in the figure) in a direction perpendicular to the propagation direction of the Lamb wave with respect to the region 48.

  Thereby, in the diaphragm 41, the buckling amount of the regions 49a and 49b is increased or decreased by the stress P2 in the direction perpendicular to the Lamb wave propagation direction, and the stress P2 in the direction perpendicular to the Lamb wave propagation direction is applied to the region. It is absorbed by 49a and 49b. Therefore, as in the first embodiment, it is possible to reduce the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave from acting on the device region 45. Therefore, a decrease in pressure detection sensitivity in the device chip 30 can be suppressed.

  In the present embodiment, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side of the drawing) has a side extending in the Lamb wave propagation direction as a short side and a side extending in a direction perpendicular to the Lamb wave propagation direction. It is a rectangle with a long side. Therefore, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side of the drawing) has a side extending in the Lamb wave propagation direction as a long side and a side extending in a direction perpendicular to the Lamb wave propagation direction as a short side. Compared to the case of the rectangle, the ratio of the regions 49a and 49b in the diaphragm 41 is larger. Therefore, it is possible to obtain an effect that the stress P2 in a direction perpendicular to the propagation direction of the Lamb wave is reliably absorbed by the regions 49a and 49b.

  In the present embodiment, as the ratio of the length of the long side to the length of the short side (= long side length / short side length) increases, the ratio of the regions 49a and 49b in the diaphragm 41 increases. The above effect is increased.

  In this embodiment, the slits 46a and 46b of the diaphragm 41 are not provided. For this reason, the freedom degree of arrangement | positioning of extraction wiring 70a, 70b becomes large, and it is easy to enlarge the dimension of the width direction of extraction wiring 70a, 70b.

(Third embodiment)
In the second embodiment, the example in which the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave is applied to the device region 45 has been described. Instead, in this embodiment, the propagation of the Lamb wave is performed. An example in which the stress P1 in the direction is reduced from acting on the device region 45 will be described.

  FIG. 7 shows a top view of the device chip 30 of the Lamb wave sensing device 10 in the present embodiment. This embodiment is different from the second embodiment mainly in the arrangement of the tensile stress films 80a and 80b. For this reason, descriptions other than the arrangement of the tensile stress films 80a and 80b are simplified.

  In the present embodiment, the tensile stress films 80 a and 80 b are disposed on the surface 41 a of the diaphragm 41. The tensile stress films 80a and 80b are arranged on both sides of the diaphragm 41 in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region 45 (left and right direction in FIG. 6).

  In the device chip 30 of this embodiment configured as described above, the tensile stress is applied to the diaphragm 41 only in the direction perpendicular to the propagation direction of the Lamb wave by the tensile stress films 80a and 80b. As a result, in the diaphragm 41, in the region 48 where the tensile stress films 80a and 80b and the pair of comb-like electrodes 50a and 50b are arranged (the region surrounded by the alternate long and short dash line in the figure), the buckling is released. In the regions 49c and 49d other than the region 48, buckling remains. The region 49 c of the diaphragm 41 is a region on one side (upper side in the drawing) of the Lamb wave propagation direction with respect to the region 48. A region 49 d of the diaphragm 41 is a region on the other side (lower side in the drawing) in the Lamb wave propagation direction with respect to the region 48.

  Thereby, in the diaphragm 41, the buckling amount of the regions 49c and 49d is increased or decreased by the stress P1 in the propagation direction of the Lamb wave, and the stress P1 in the propagation direction of the Lamb wave is absorbed in the regions 49c and 49d. Therefore, it is possible to reduce the stress P1 in the propagation direction of the Lamb wave from acting on the device region 45.

Here, the change in the sound speed due to the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave is the change in the resonance frequency due to the change in the spacing between the comb-like electrodes 3, and the change in the sound speed due to the stress P1 in the propagation direction of the Lamb wave. Canceling the amount of change in the resonance frequency due to is the cause of the decrease in pressure detection sensitivity,
Therefore, as described above, the reduction in pressure detection sensitivity in the device chip 30 can be suppressed by reducing the effect of the stress P1 in the propagation direction of the Lamb wave on the device region 45.

  In the present embodiment, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side in the drawing) has a side extending in the Lamb wave propagation direction as a long side and a side extending in a direction perpendicular to the Lamb wave propagation direction. It is a rectangle with a short side. For this reason, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side of the drawing) has a side extending in the Lamb wave propagation direction as a short side and a side extending in a direction perpendicular to the Lamb wave propagation direction as a long side. Compared to the case of the rectangle, the ratio of the regions 49c and 49d in the diaphragm 41 is larger. Therefore, the effect that the stress P1 in the propagation direction of the Lamb wave is reliably absorbed by the regions 49c and 49d can be obtained.

(Fourth embodiment)
In the second embodiment, the example using the diaphragm 41 acting as the compressive stress has been described. Instead, in the present embodiment, the diaphragm 41 acting as the tensile stress acts as an example. To do.

  FIG. 8 shows a top view of the device chip 30 of the Lamb wave type sensing device 10 in the present embodiment.

  In the device chip 30 of the present embodiment, the diaphragm 41 is not a piezoelectric film to which a compressive stress acts, but a piezoelectric film to which a tensile stress acts. In the device chip 30 of this embodiment, compressive stress films 80c and 80d are disposed on the surface 41a of the diaphragm 41 in place of the tensile stress films 80a and 80b. In the present embodiment, the configuration other than the diaphragm 41 and the compressive stress films 80c and 80d is the same as that of the third embodiment, and thus the description thereof is omitted.

  The pair of comb-like electrodes 50 a and 50 b are arranged at the center of the surface 41 a of the diaphragm 41. The compressive stress film 80c is arranged on one side (the left side in the drawing) perpendicular to the Lamb wave propagation direction with respect to the device region 45 where the pair of comb-like electrodes 50a and 50b are arranged on the surface 41a of the diaphragm 41. Has been. The compressive stress film 80d is disposed on the other side (right side in the drawing) of the surface 41a of the diaphragm 41 in the direction perpendicular to the Lamb wave propagation direction with respect to the device region 45.

  In the present embodiment, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side of the drawing) has a short side extending in the Lamb wave propagation direction (vertical direction in the drawing) and is perpendicular to the Lamb wave propagation direction. It is a rectangle whose side is a long side extending in the right direction (left and right direction in the figure).

  In the device chip 30 of the present embodiment configured as described above, compressive stress is applied to the diaphragm 41 only in the Lamb wave propagation direction by the compressive stress films 80c and 80d. As a result, the regions 49a and 49b of the diaphragm 41 where the compressive stress films 80c and 80d are disposed are buckled by the compressive stress of the compressive stress films 80c and 80d. In the region 49g of the diaphragm 41 other than the regions 49a and 49b, no buckling occurs.

  As a result, as in the second embodiment, in the diaphragm 41, the buckling amount of the regions 49a and 49b is increased or decreased by the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave, and the propagation direction of the Lamb wave is increased. The stress P2 in the vertical direction is absorbed by the regions 49a and 49b. Accordingly, it is possible to reduce the stress P2 in the direction perpendicular to the propagation direction of the Lamb wave from acting on the device region 45. For this reason, it is possible to suppress a decrease in pressure detection sensitivity in the device chip 30.

  In the present embodiment, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side of the drawing) has a side extending in the Lamb wave propagation direction as a short side and a side extending in a direction perpendicular to the Lamb wave propagation direction. It is a rectangle with a long side. For this reason, the ratio occupied by the regions 49a and 49b in the diaphragm 41 increases. Therefore, it is possible to obtain an effect that the stress P2 in a direction perpendicular to the propagation direction of the Lamb wave is reliably absorbed by the regions 49a and 49b.

(Fifth embodiment)
In the third embodiment, the example using the diaphragm 41 acting as the compressive stress has been described. Instead, in the present embodiment, the diaphragm 41 acting as the tensile stress acts as an example. To do.

  FIG. 9 shows a top view of the device chip 30 of the Lamb wave sensing device 10 in the present embodiment.

  In the device chip 30 of the present embodiment, the diaphragm 41 is not a piezoelectric film to which a compressive stress acts, but a piezoelectric film to which a tensile stress acts. In the device chip 30 of this embodiment, compressive stress films 80c and 80d are disposed on the surface 41a of the diaphragm 41 in place of the tensile stress films 80a and 80b. In the present embodiment, the configuration other than the diaphragm 41 and the compressive stress films 80c and 80d is the same as that of the third embodiment, and thus the description thereof is omitted.

  The pair of comb-like electrodes 50 a and 50 b are arranged at the center of the surface 41 a of the diaphragm 41. The compressive stress film 80c is disposed on one side (upper side in the drawing) of the Lamb wave propagation direction with respect to the device region 45 where the pair of comb-like electrodes 50a and 50b are disposed on the surface of the diaphragm 41. The compressive stress film 80d is disposed on the other side (lower side in the drawing) of the Lamb wave propagation direction with respect to the device region 45 in the surface 41a of the diaphragm 41.

  In the present embodiment, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side of the drawing) has a long side extending in the Lamb wave propagation direction (vertical direction in the drawing), and is perpendicular to the Lamb wave propagation direction. It is a rectangle whose side is a short side extending in the right direction (left-right direction in the figure).

  In the device chip 30 of the present embodiment configured as described above, compressive stress is applied to the diaphragm 41 only in the Lamb wave propagation direction by the compressive stress films 80c and 80d. As a result, the regions 49c and 49d in the diaphragm 41 where the compressive stress films 80c and 80d are disposed are buckled by the compressive stress of the compressive stress films 80c and 80d. In the region 49g other than the regions 49c and 49d in the diaphragm 41, no buckling occurs.

  As a result, as in the third embodiment, in the diaphragm 41, the buckling amounts of the regions 49c and 49d are increased or decreased by the stress P1 in the propagation direction of the Lamb wave, and the stress P1 in the propagation direction of the Lamb wave is in the region. It is absorbed by 49c and 49d. Therefore, it is possible to reduce the stress P1 in the propagation direction of the Lamb wave from acting on the device region 45. Therefore, a decrease in pressure detection sensitivity in the device chip 30 can be suppressed.

  In the present embodiment, the shape of the diaphragm 41 viewed from the thickness direction (that is, the front side in the drawing) has a side extending in the Lamb wave propagation direction as a long side and a side extending in a direction perpendicular to the Lamb wave propagation direction. It is a rectangle with a short side. For this reason, the ratio of the regions 49c and 49d in the diaphragm 41 is increased. Therefore, the effect of reliably absorbing the stress P2 in a direction perpendicular to the propagation direction of the Lamb wave in the regions 49c and 49d can be obtained.

(Sixth embodiment)
In the second embodiment, the example in which the diaphragm structure body in which the void 44 is opened on the opposite side to the diaphragm 41 is used as the diaphragm structure body 40 constituting the device chip 30 is described. In this embodiment, the device chip 30 is configured using a diaphragm structure having the following structure.

  That is, in the present embodiment, as the diaphragm structure constituting the device chip 30, the void 44a passes through the opening and the surface of the diaphragm 41 as in the diaphragm structure 40A (see FIG. 4) in the modification of the first embodiment. A diaphragm structure opened on the 41a side is used. In the present embodiment, since the configuration other than the diaphragm structure constituting the device chip 30 is the same as that of the modification of the first embodiment, the description thereof is omitted.

  FIG. 10 shows a top view of the device chip 30 of the Lamb wave sensing device 10 in the present embodiment.

  In the present embodiment, the device chip 30 is provided with etching windows 90 a, 90 b, 90 c, 90 d that open on the surface 41 a side of the diaphragm 41.

  The etching windows 90a, 90b, 90c, and 90d are openings for supplying an etchant to the inside of the diaphragm structure when the void 44a (not shown in FIG. 10) is formed inside the diaphragm structure constituting the device chip 30. is there. For this reason, the void 44a is opened to the surface 41a side of the diaphragm 41 through the etching windows 90a, 90b, 90c, 90d. Etching windows 90 a, 90 b, 90 c, and 90 d open to regions 49 a and 49 b other than the region 48 in the diaphragm 41. The region 48 is a region in the diaphragm 41 where the tensile stress films 80a and 80b and the pair of comb-like electrodes 50a and 50b are disposed. Thus, the etching windows 90 a, 90 b, 90 c, and 90 d are arranged in a region of the surface 41 a of the diaphragm 41 excluding the region in the Lamb wave propagation direction with respect to the device region 45.

  In the present embodiment described above, the openings of the etching windows 90a, 90b, 90c, and 90d are arranged in a region of the surface 41a of the diaphragm 41 excluding the region in the Lamb wave propagation direction with respect to the device region 45. Yes.

  For example, when the openings of the etching windows 90 a, 90 b, 90 c, 90 d are arranged in the Lamb wave propagation direction with respect to the device region 45 in the surface 41 a of the diaphragm 41, the etching windows 90 a, 90 b, 90 c, 90 d This prevents the stress in the propagation direction from acting on the device region 45. Therefore, the pressure detection sensitivity in the device chip 30 is lowered.

  On the other hand, in the present embodiment, the openings of the etching windows 90a, 90b, 90c, 90d are arranged in a region of the surface 41a of the diaphragm 41 excluding the region in the Lamb wave propagation direction with respect to the device region 45. Has been. Therefore, the etching windows 90a, 90b, 90c and 90d do not prevent the stress in the Lamb wave propagation direction from acting on the device region 45. Therefore, it is possible to prevent the pressure detection sensitivity from decreasing in the device chip 30.

(Seventh embodiment)
In the second embodiment, the tensile stress film 80a on both sides of the propagation direction of the Lamb wave to the device region 45 of the die off the ram 41 has been described as being arranged 80b, instead of this, the present embodiment in may be arranged stress film tension in a region other than the device region 45 of the die off the ram 41.

  FIG. 11 shows a top view of the device chip 30 of the Lamb wave type sensing device 10 in the present embodiment.

The device chip 30 of the Lamb wave type sensing device 10 in this embodiment is provided with a tensile stress film 80c instead of the tensile stress films 80a and 80b of FIG. Tensile stress film 80c is formed so as to surround a device region 45 of the die off the ram 41.

For example, the stress control of the piezoelectric thin film constituting the die-off ram 41 may not be always easy. When priority is given to necessary characteristics such as the piezoelectric characteristics of the piezoelectric thin film, it may not always be easy to make the film stress (weak). If the film stress of the piezoelectric thin film is inevitably a compressive stress, it is possible to eliminate the buckling of the die off the ram 41 by adding a stress film 80c tension as shown in Figure 11 to die off ram 41. By providing the slits 46a and 46b, it is possible to avoid the stress component P2 in the direction perpendicular to the propagation direction of the Lamb wave from acting on the device region 45. That is, the transverse acoustic elasticity effect can be avoided.

  Here, if the tensile stress film 80a is added to the device region 45, the propagation characteristics of the Lamb wave may deteriorate. As shown in FIG. 11, buckling can be sufficiently avoided only by adding the tensile stress film 80 c to the peripheral region of the device region 45.

(Eighth embodiment)
Aforementioned seventh embodiment, an example was described in which to place the tensile stress film 80c in a region other than the device region 45 of the die off the ram 41, instead of this, in the present embodiment, the device of the die off the ram 41 The tensile stress films 80a and 80b may be arranged on both sides of the region 45 in the propagation direction of the Lamb wave.

  FIG. 12 shows a top view of the device chip 30 of the Lamb wave sensing device 10 in the present embodiment.

  The Lamb wave sensing device 10 of the present embodiment and the Lamb wave sensing device 10 of the seventh embodiment are the same except for the arrangement of the tensile stress film, and the description thereof is omitted. To do.

(Ninth embodiment)
In the first to eighth embodiments, the example in which the pressure is detected by changing the resonance frequency of the device chip 30 according to the pressure received on the back surface of the diaphragm 41 has been described. In the embodiment, an example will be described in which the pressure is detected using the fact that the propagation path of the Lamb wave also changes according to the pressure received on the back surface of the diaphragm 41.

  FIG. 13 shows a top view of the device chip 30 of the Lamb wave type sensing device 10 of the present embodiment.

  In the present embodiment, in order to make the device chip 30 function as a filter element, the device chip 30 is provided with a pair of comb-like electrodes 50c and 50d in addition to the pair of comb-like electrodes 50a and 50b. . The pair of comb-like electrodes 50a and 50b and the pair of comb-like electrodes 50c and 50d are disposed between the tensile stress films 80a and 80b on the surface 41a of the diaphragm 41. The pair of comb-like electrodes 50a, 50b and the pair of comb-like electrodes 50c, 50d are arranged so that the propagation directions of the Lamb waves coincide with each other. The tensile stress films 80a and 80b are disposed on both sides in the Lamb wave propagation direction with respect to the pair of comb-like electrodes 50a and 50b and the pair of comb-like electrodes 50c and 50d.

  The pair of comb-like electrodes 50a and 50b and the pair of comb-like electrodes 50c and 50d are the same, but for the sake of convenience of description, different reference numerals are used.

  In the present embodiment configured as described above, the pair of comb-like electrodes 50a and 50b are caused to function as the comb-like electrodes on the transmission side that transmit Lamb waves. The pair of comb-like electrodes 50c and 50d are caused to function as receiving-side comb-like electrodes that receive Lamb waves.

  Here, since the propagation path of the Lamb wave also changes according to the pressure received on the back surface of the diaphragm 41, the propagation of the Lamb wave propagating from the pair of comb-like electrodes 50a, 50b to the pair of comb-like electrodes 50c, 50d. Time (ie, delay time) changes. Therefore, it is possible to detect the pressure received on the back surface of the diaphragm 41 by the change in the propagation time of the Lamb wave.

  In this case, as in the case where the pressure is detected by the change in the resonance frequency, the change in the propagation path length of the Lamb wave, the change in the tensile stress P1 in the propagation direction of the Lamb wave, and the tensile force in the direction perpendicular to the propagation direction of the Lamb wave. The change in the propagation time of the Lamb wave may be canceled due to the change in the stress P2.

  Therefore, as in the second embodiment, the tensile stress films 80a and 80b are provided, and the stress P2 in the direction perpendicular to the Lamb wave propagation direction is applied to the region 49a, leaving buckling in the regions 49a and 49b of the diaphragm 41. , 49b. Therefore, a decrease in pressure detection sensitivity in the device chip 30 can be suppressed.

(Other embodiments)
In the first and second embodiments, the example in which the diaphragm 41 is provided with the two slits 46 a and 46 b has been described. However, instead of this, one of the slits 46 a and 46 b may be provided in the diaphragm 41. That is, a slit may be provided only on one side of the diaphragm 41 in the device region 45 in the direction perpendicular to the Lamb wave propagation direction.

  In the modification of the first embodiment, the example using the Lamb wave sensing device 10 including the diaphragm structure 20 and the device chip 30 has been described, but instead of this, the diaphragm structure 20 is not used. The Lamb wave sensing device 10 may be configured with only the device chip 30.

  This is because in the diaphragm structure 40 </ b> A constituting the device chip 30, the diaphragm 41 receives pressure from the back side through the support portion 25. For this reason, the pressure P is not directly applied to the diaphragm 41, and the support portion 25 having a thickness larger than that of the diaphragm 41 functions in the same manner as the diaphragm 21.

  In the modification of the first embodiment, the device chip 30 is not limited to detecting the pressure applied from the back surface side of the diaphragm 41, but may detect the pressure applied from the front surface 41a side of the diaphragm 41. In the modification of the first embodiment, since the slits 46a and 46b are open on the surface 41a of the diaphragm 41, even if pressure is applied from the surface 41a side of the diaphragm 41, the pressure is not applied to the diaphragm 41. . And since the support part 25 and the diaphragm 21 receive a pressure and deform | transform, it carries out sensing operation | movement like the case where a pressure is applied from the back surface side (lower side in FIG. 4) as the diaphragm 41. FIG.

  Similarly, in the first embodiment, the device chip 30 is not limited to detecting the pressure applied from the back surface side of the diaphragm 41, but may detect the pressure applied from the front surface 41a side of the diaphragm 41. In the first embodiment, since the slits 46a and 46b are open on the surface 41a of the diaphragm 41, even if pressure is applied from the surface 41a side of the diaphragm 41, a modification of the first embodiment. This is because it operates in the same manner as in the above case.

  In the second, third, fourth, fifth, seventh, eighth, and ninth embodiments, as the diaphragm structure constituting the device chip 30, an example in which the diaphragm structure 40 having the void 24 opened on the back surface side is used. As described above, instead of this, as the diaphragm structure constituting the device chip 30, the diaphragm structure 40 </ b> A having the void 44 a that opens through the opening on the surface 41 a side of the diaphragm 41 is used as in the above modification. May be.

  As described above, in the second, third, fourth, fifth, seventh, eighth, and ninth embodiments, when the diaphragm structure 40A having the space 44a that opens through the opening on the surface 41a side of the diaphragm 41 is used. The lamb wave sensing device 10 may be configured by mounting the device chip 30 on the diaphragm structure 20. Alternatively, the Lamb wave sensing device 10 may be configured with only the device chip 30 without adopting the diaphragm structure 20.

  In the second and third embodiments, the example in which the tensile stress films 80a and 80b are disposed on the surface 41a side of the diaphragm 41 has been described. Instead, the tensile stress films 80a and 80b are disposed on the back surface side of the diaphragm 41. You may arrange.

  In the fourth and fifth embodiments, the example in which the tensile stress films 80c and 80d are disposed on the front surface 41a side of the diaphragm 41 has been described, but instead, the tensile stress films 80c and 80d are disposed on the rear surface side of the diaphragm 41. You may arrange.

  In the sixth embodiment, in the device chip 30 in which the tensile stress films 80a and 80b are arranged on both sides in the Lamb wave propagation direction with respect to the device region 45, the Lamb wave is applied to the device region 45 of the surface 41a of the diaphragm 41. Although the example in which the etching windows 90a, 90b, 90c, and 90d are arranged in the region excluding the region in the propagation direction has been described, the following may be used instead.

  That is, as in the third embodiment, in the device chip 30 in which the tensile stress films 80 a and 80 b are arranged on both sides of the device region 45 in the direction perpendicular to the Lamb wave propagation direction, the diaphragm 41 has the device region 45. Etching windows 90a, 90b, 90c, and 90d are disposed in regions excluding the region perpendicular to the Lamb wave propagation direction. For example, the etching windows 90a, 90b, 90c, and 90d are arranged in the propagation direction of the Lamb wave with respect to the device region 45 in the surface 41a of the diaphragm 41.

  Furthermore, in the fourth embodiment, as in the modification of the first embodiment, the device chip 30 is formed using the diaphragm structure 40A having the void 44a that opens through the opening on the surface 41a side of the diaphragm 41. In the same manner as in the sixth embodiment, the etching windows 90a and 90b serving as openings are formed in the diaphragm 41 other than the area in the Lamb wave propagation direction with respect to the device area 45. , 90c, 90d may be arranged.

  In the fifth embodiment, as in the modification of the first embodiment, the device chip 30 is configured using a diaphragm structure 40A having a space 44a that opens through the opening on the surface 41a side of the diaphragm 41. In some cases, the etching windows 90a, 90b, 90c, and 90d as openings may be arranged in other regions of the diaphragm 41 except for the region perpendicular to the propagation direction of the Lamb wave with respect to the device region 45. Good.

  In the ninth embodiment, the pair of comb-like electrodes 50a and 50b function as the comb-like electrodes on the transmission side, while the pair of comb-like electrodes 50c and 50d are used on the receiving-side comb teeth that receive Lamb waves. However, instead of this, Lamb waves transmitted from the pair of comb-like electrodes 50a and 50b are reflected by the pair of comb-like electrodes 50c and 50d, and the reflected lamb is reflected. A reflection delay device that receives waves by the pair of comb-like electrodes 50a and 50b may be configured.

  In the ninth embodiment, the example in which the form of the Lamb wave sensing device 10 in the second embodiment is modified from the resonator type to the filter type has been described. However, the same modification can be applied to all other than the second embodiment. You may apply to each embodiment.

  For example, in the ninth embodiment, the following (1), (2), (3), and (4) may be used.

  (1) The diaphragm 41 is configured not with the tensile stress films 80a and 80b but with the slits 46a and 46b of the first embodiment.

  (2) In the diaphragm 41, as in the third embodiment, the tensile stress films 80a and 80b are disposed on both sides of the device region 45 in the direction perpendicular to the Lamb wave propagation direction.

  (3) As in the fourth embodiment, the diaphragm 41 is composed of a piezoelectric film on which tensile stress acts. In the diaphragm 41, compressive stress is applied to both sides of the device region 45 in the direction perpendicular to the propagation direction of the Lamb wave. Films 80c and 80d are disposed.

  (4) Similar to the fifth embodiment, the diaphragm 41 is formed from a piezoelectric film on which tensile stress acts. In the diaphragm 41, compressive stress films 80c and 80d are formed on both sides of the device region 45 in the Lamb wave propagation direction. Place.

  In the first to ninth embodiments, the example in which the pressure applied to the Lamb wave type sensing device 10 is detected has been described, but instead, the load applied to the Lamb wave type sensing device 10 may be detected.

  In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible.

DESCRIPTION OF SYMBOLS 10 Lamb wave type sensing device 20 Diaphragm structure 30 Device chip 40 Diaphragm structure 41 Diaphragm 45 Device area | region 50a, 50b Comb-like electrode 70a, 70b Lead wiring 46a, 46b Slit 80a, 80b Tensile stress film 80c, 80d Compression stress film

Claims (19)

A first diaphragm (41) made of a piezoelectric material, a space (44) formed on the back side of the first diaphragm and opened to the opposite side of the first diaphragm, and the first diaphragm A first diaphragm structure (40) provided with a support portion (42) that supports the periphery from the back surface side thereof, and a pair of comb-like electrodes (a pair of comb-like electrodes arranged so as to be engaged with each other on the surface side of the first diaphragm) 50a, 50b) a device chip (30),
A second diaphragm (21) having the device chip mounted on the front surface side; and a second diaphragm structure (20) including a support portion (22) for supporting the periphery of the second diaphragm from the back surface side. ,
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied through the second diaphragm;
A slit (46a, 46b) is provided in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes are arranged in the first diaphragm. Lamb wave sensing device that features The first diaphragm has a compressive stress,
A film (80a, 80b, 80c) having tensile stress disposed in a region other than the region (45) for mounting the pair of comb-like electrodes of the first diaphragm;
The Lamb wave sensing device according to claim 1, wherein buckling based on the compressive stress is released by the tensile stress in the other region of the first diaphragm. A first diaphragm (41) made of a piezoelectric material, a space (44) formed on the back side of the first diaphragm and opened to the opposite side of the first diaphragm, and the first diaphragm A first diaphragm structure (40) provided with a support portion (42) that supports the periphery from the back surface side thereof, and a pair of comb-like electrodes (a pair of comb-like electrodes arranged so as to be engaged with each other on the surface side of the first diaphragm) 50a, 50b) a device chip (30),
A second diaphragm (21) having the device chip mounted on the front surface side; and a second diaphragm structure (20) including a support portion (22) for supporting the periphery of the second diaphragm from the back surface side. ,
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied through the second diaphragm;
The first diaphragm is subjected to compressive stress,
First and second elements that are disposed on both sides of the propagation direction of the Lamb wave and that are subjected to tensile stress with respect to a device region (45) in which the pair of comb-like electrodes are disposed in the first diaphragm. The film (80a, 80b)
In the first region (48) of the first diaphragm where the first and second films and the pair of comb-like electrodes are disposed, buckling due to the compressive stress is released by the tensile stress. The Lamb wave type sensing device characterized in that buckling remains in second regions (49a, 49b) other than the first region of the first diaphragm. A first diaphragm (41) made of a piezoelectric material, a space (44) formed on the back side of the first diaphragm and opened to the opposite side of the first diaphragm, and the first diaphragm A first diaphragm structure (40) provided with a support portion (42) that supports the periphery from the back surface side thereof, and a pair of comb-like electrodes (a pair of comb-like electrodes arranged so as to be engaged with each other on the surface side of the first diaphragm) 50a, 50b) a device chip (30),
A second diaphragm (21) having the device chip mounted on the front surface side; and a second diaphragm structure (20) including a support portion (22) for supporting the periphery of the second diaphragm from the back surface side. ,
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied through the second diaphragm;
The first diaphragm is subjected to compressive stress,
The first diaphragm is disposed on both sides in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) where the pair of comb-like electrodes are disposed, and tensile stress acts on the first diaphragm. 1 and a second film (80a, 80b),
In the first region (48) of the first diaphragm where the first and second films and the pair of comb-like electrodes are disposed, buckling due to the compressive stress is released by the tensile stress. The lamb wave sensing device, wherein buckling remains in the second region (49c, 49d) other than the first region of the first diaphragm. A first diaphragm (41) made of a piezoelectric material, a space (44) formed on the back side of the first diaphragm and opened to the opposite side of the first diaphragm, and the first diaphragm A first diaphragm structure (40) provided with a support portion (42) that supports the periphery from the back surface side thereof, and a pair of comb-like electrodes (a pair of comb-like electrodes arranged so as to be engaged with each other on the surface side of the first diaphragm) 50a, 50b) a device chip (30),
A second diaphragm (21) having the device chip mounted on the front surface side; and a second diaphragm structure (20) including a support portion (22) for supporting the periphery of the second diaphragm from the back surface side. ,
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied through the second diaphragm;
The first diaphragm is subjected to tensile stress,
The first diaphragm is disposed on both sides in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) where the pair of comb-like electrodes are disposed, and compressive stress acts on the first diaphragm. 1 and a second film (80c, 80d),
A Lamb wave type sensing device characterized in that buckling is given to the regions (49a, 49b) in which the first and second films are arranged in the first diaphragm by the compressive stress. A first diaphragm (41) made of a piezoelectric material, a space (44) formed on the back side of the first diaphragm and opened to the opposite side of the first diaphragm, and the first diaphragm A first diaphragm structure (40) provided with a support portion (42) that supports the periphery from the back surface side thereof, and a pair of comb-like electrodes (a pair of comb-like electrodes arranged so as to be engaged with each other on the surface side of the first diaphragm) 50a, 50b) a device chip (30),
A second diaphragm (21) having the device chip mounted on the front surface side; and a second diaphragm structure (20) including a support portion (22) for supporting the periphery of the second diaphragm from the back surface side. ,
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied through the second diaphragm;
The first diaphragm is subjected to tensile stress,
First and second elements that are arranged on both sides of the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes are arranged in the first diaphragm and on which compressive stress acts. The film (80c, 80d)
A Lamb wave type sensing device, wherein a region ( 49c, 49d ) in which the first and second films are disposed in the first diaphragm is buckled by the compressive stress. The first diaphragm is formed in a rectangular shape as viewed from the thickness direction,
6. The Lamb wave sensing device according to claim 3, wherein the first diaphragm is formed such that both sides parallel to the propagation direction of the Lamb wave are short sides. The first diaphragm is formed in a rectangular shape as viewed from the thickness direction,
The Lamb wave sensing device according to claim 4 or 6, wherein the first diaphragm is formed such that both sides parallel to the propagation direction of the Lamb wave are long sides. A first diaphragm (41) made of a piezoelectric material; a support portion (25) for supporting the periphery of the first diaphragm from its back surface; and a back surface of the first diaphragm. A pair of voids (44a) opening through the openings (46a, 46b) on the surface side and arranged to mesh with the first diaphragm structure (40A) on the surface of the first diaphragm. A device chip (30) comprising a comb-like electrode (50a, 50b)
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied to the first diaphragm,
A slit (46a, 46b) is provided in a direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes are arranged in the first diaphragm. Lamb wave sensing device that features The first diaphragm has a compressive stress,
A film (80a, 80b, 80c) having a tensile stress disposed in a region other than the region where the pair of comb-like electrodes of the first diaphragm is mounted;
The lamb wave sensing device according to claim 9, wherein buckling based on the compressive stress is released by the tensile stress in the other region of the first diaphragm. A first diaphragm (41) made of a piezoelectric material; a support portion (25) for supporting the periphery of the first diaphragm from its back surface; and a back surface of the first diaphragm. A first diaphragm structure (40A) having a cavity (44a) that opens through an opening (90a, 90b, 90c, 90d) on the surface side, and is arranged to mesh with the surface of the first diaphragm. A device chip (30) comprising a pair of comb-like electrodes (50a, 50b),
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied to the first diaphragm,
The first diaphragm is subjected to compressive stress,
First and second elements that are disposed on both sides of the propagation direction of the Lamb wave and that are subjected to tensile stress with respect to a device region (45) in which the pair of comb-like electrodes are disposed in the first diaphragm. The film (80a, 80b)
In the first region (48) of the first diaphragm where the first and second films and the pair of comb-like electrodes are disposed, buckling due to the compressive stress is released by the tensile stress. The Lamb wave type sensing device characterized in that buckling remains in second regions (49a, 49b) other than the first region of the first diaphragm. A first diaphragm (41) made of a piezoelectric material; a support portion (25) for supporting the periphery of the first diaphragm from its back surface; and a back surface of the first diaphragm. A first diaphragm structure (40A) having a cavity (44a) that opens through an opening (90a, 90b, 90c, 90d) on the surface side, and is arranged to mesh with the surface of the first diaphragm. A device chip (30) comprising a pair of comb-like electrodes (50a, 50b),
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied to the first diaphragm,
The first diaphragm is subjected to compressive stress,
The first diaphragm is disposed on both sides in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) where the pair of comb-like electrodes are disposed, and tensile stress acts on the first diaphragm. 1 and a second film (80a, 80b),
In the first region (48) of the first diaphragm where the first and second films and the pair of comb-like electrodes are disposed, buckling due to the compressive stress is released by the tensile stress. The lamb wave sensing device, wherein buckling remains in the second region (49c, 49d) other than the first region of the first diaphragm. A first diaphragm (41) made of a piezoelectric material; a support portion (25) for supporting the periphery of the first diaphragm from its back surface; and a back surface of the first diaphragm. A first diaphragm structure (40A) having a cavity (44a) that opens through an opening (90a, 90b, 90c, 90d) on the surface side, and is arranged to mesh with the surface of the first diaphragm. A device chip (30) comprising a pair of comb-like electrodes (50a, 50b),
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied to the first diaphragm,
The first diaphragm is subjected to tensile stress,
The first diaphragm is disposed on both sides in the direction perpendicular to the propagation direction of the Lamb wave with respect to the device region (45) where the pair of comb-like electrodes are disposed, and compressive stress acts on the first diaphragm. 1 and a second film (80c, 80d),
A Lamb wave type sensing device characterized in that buckling is given to the regions (49a, 49b) in which the first and second films are arranged in the first diaphragm by the compressive stress. A first diaphragm (41) made of a piezoelectric material; a support portion (25) for supporting the periphery of the first diaphragm from its back surface; and a back surface of the first diaphragm. A first diaphragm structure (40A) having a cavity (44a) that opens through an opening (90a, 90b, 90c, 90d) on the surface side, and is arranged to mesh with the surface of the first diaphragm. A device chip (30) comprising a pair of comb-like electrodes (50a, 50b),
A lamb wave propagates in one direction through the first diaphragm by an alternating voltage applied between the pair of comb-like electrodes,
The device chip is adapted to detect a force applied to the first diaphragm,
The first diaphragm is subjected to tensile stress,
First and second elements that are arranged on both sides of the propagation direction of the Lamb wave with respect to the device region (45) in which the pair of comb-like electrodes are arranged in the first diaphragm and on which compressive stress acts. The film (80c, 80d)
A Lamb wave type sensing device, wherein a region ( 49c, 49d ) in which the first and second films are disposed in the first diaphragm is buckled by the compressive stress. The first diaphragm is formed in a rectangular shape as viewed from the thickness direction,
The lamb wave sensing device according to claim 11 or 13, wherein the first diaphragm is formed such that both sides parallel to the propagation direction of the lamb wave are short sides. The first diaphragm is formed in a rectangular shape as viewed from the thickness direction,
15. The Lamb wave sensing device according to claim 12, wherein the first diaphragm is formed such that both sides parallel to the propagation direction of the Lamb wave are long sides. Etching windows (90a, 90b, 90c, 90d) as the openings for supplying an etchant from the surface side of the first diaphragm to the inside of the first diaphragm structure are opened in the first diaphragm,
The void is formed by etching a member constituting the first diaphragm structure using an etchant supplied through the etching window.
The etching window is disposed in a region other than the regions on both sides of the Lamb wave propagation direction with respect to the device region (45) where the pair of comb-like electrodes are disposed in the first diaphragm. The lamb wave sensing device according to claim 11 or 13, Etching windows (90a, 90b, 90c, 90d) as the openings for supplying an etchant from the surface side of the first diaphragm to the inside of the first diaphragm structure are opened in the first diaphragm,
The void is formed by etching a member constituting the first diaphragm structure using an etchant supplied through the etching window.
The etching window is formed in a region other than the regions on both sides of the first diaphragm in a direction perpendicular to the propagation direction of the Lamb wave with respect to a device region (45) where the pair of comb-like electrodes are disposed. The lamb wave sensing device according to claim 12 or 14, wherein the lamb wave sensing device is arranged.   A second diaphragm structure (20) including a second diaphragm (21) having the device chip mounted on the front surface side and a support portion (22) supporting the periphery of the second diaphragm from the back surface side thereof. The lamb wave sensing device according to any one of claims 9 to 18.

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