Acoustic conversion device

Abstract

To improve sensitivity.SOLUTION: An acoustic conversion device 100 includes a fixed frame 10 and a cantilever 20 having one end which is a fixed end 22 fixed to the fixed frame 10 and the other end which is a free end 21, and extending from the fixed frame 10 to the inside of the fixed frame 10, and the cantilever 20 has a detection region 23 which can detect a physical quantity and a non-detection region 24 which does not detect a physical quantity.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an acoustic transducer. [Background technology]

[0002] For example, a piezoelectric element is known that includes a piezoelectric film having one end supported and the other end free, and a pair of electrodes disposed on either side of the piezoelectric film (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-140638 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION An object of the present disclosure is to provide an acoustic transducer that can improve sensitivity, in which an acoustic transducer having a piezoelectric element is required. [Means for solving the problem]

[0005] The acoustic transducer according to the present disclosure comprises a fixed frame and a cantilever having one end fixed to the fixed frame and the other end free, the cantilever extending from the fixed frame to the inside of the fixed frame, the cantilever having a detection region capable of detecting a physical quantity and a non-detection region not capable of detecting a physical quantity. [Effects of the Invention]

[0006] The present disclosure can provide an acoustic transducer capable of improving sensitivity. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view illustrating an acoustic transducer according to a first embodiment. [Figure 2] 1 is a plan view illustrating an acoustic transducer according to a first embodiment. [Figure 3] 1 is a cross-sectional view illustrating an acoustic transducer according to a first embodiment. [Figure 4] FIG. 10 is a plan view illustrating an acoustic transducer according to a second embodiment. [Figure 5] 10 is a graph showing the relationship between the ratio of the detection area to the total length of the cantilever and the signal level. [Figure 6] FIG. 10 is a cross-sectional view illustrating an acoustic transducer according to a third embodiment. [Figure 7] FIG. 10 is a cross-sectional view illustrating an acoustic transducer according to a fourth embodiment. [Figure 8] FIG. 10 is a perspective view illustrating an acoustic transducer according to a fifth embodiment. [Figure 9] 1 is a circuit diagram of an acoustic transducer according to an embodiment. [Figure 10] FIG. 10 is a plan view illustrating an acoustic transducer according to a sixth embodiment. [Figure 11] FIG. 13 is a cross-sectional view illustrating an acoustic transducer according to a seventh embodiment. [Figure 12] FIG. 13 is a plan view illustrating an acoustic transducer according to an eighth embodiment. [Figure 13] FIG. 13 is a perspective view illustrating an acoustic transducer according to an eighth embodiment. [Figure 14] FIG. 13 is a perspective view illustrating an acoustic transducer according to an eighth embodiment, viewed from the bottom side. [Figure 15] FIG. 13 is a cross-sectional view illustrating an acoustic transducer according to an eighth embodiment. [Figure 16] FIG. 2 is a partially enlarged cross-sectional view illustrating an enlarged example of a diaphragm (piezoelectric film). [Figure 17] 10A and 10B are side views illustrating the distribution of electric charges generated on a diaphragm that is deformed by receiving sound pressure. [Figure 18] FIG. 13 is a plan view illustrating an acoustic transducer according to a ninth embodiment. [Figure 19] 18. FIG. 19 is a cross-sectional view illustrating the acoustic transducer according to the ninth embodiment, taken along line IX-IX in FIG. [Figure 20] FIG. 10 is a circuit diagram of an acoustic transducer according to a sixth embodiment. [Figure 21] 10 is a graph showing the relationship between the sensing area diameter ratio and the normalized SNR. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an acoustic transducer according to an embodiment will be described with reference to the accompanying drawings. In this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description. In addition, in this specification, the terms "upper" and "lower" may be used. These refer to the "upper" and "lower" in the state shown in FIG. 3, where the side where the upper electrode 30 is arranged in the Z-axis direction is the "upper" and the side where the lower electrode 40 is arranged is the "lower". The actual arrangement of the acoustic transducer 100 is not limited to this.

[0009] [Sound transducer 100 according to the first embodiment] FIG. 1 is a perspective view illustrating an acoustic transducer 100 according to the first embodiment. FIG. 2 is a plan view illustrating an acoustic transducer 100 according to the first embodiment. FIG. 3 is a cross-sectional view illustrating an acoustic transducer according to the first embodiment. In each drawing, an X-axis direction, a Y-axis direction, and a Z-axis direction that are orthogonal to each other may be illustrated. The X-axis direction, the Y-axis direction, and the Z-axis direction do not have to be orthogonal to each other. The X-axis direction, the Y-axis direction, and the Z-axis direction may be any direction. The X-axis direction is an example of a first direction. The Y-axis direction is an example of a direction intersecting the first direction.

[0010] The acoustic transducer 100 shown in Figs. 1 to 3 is a piezoelectric acoustic transducer having a piezoelectric element (piezoelectric film). The acoustic transducer 100 may be, for example, a microphone (MEMS microphone). The acoustic transducer 100 may be used for noise cancellation purposes. The acoustic transducer 100 may be a TWS (Ture wireless stereo) or an in-vehicle device installed in an automobile. The acoustic transducer 100 may be used, for example, as a hearing aid. The acoustic transducer 100 may be any device capable of detecting a physical quantity, and its use is not particularly limited. The physical quantity may be, for example, sound pressure.

[0011] [Fixed Frame 10] The acoustic transducer 100 includes a fixed frame 10 and a cantilever 20. The fixed frame 10 is a rectangular frame when viewed in the Z-axis direction. The length of the fixed frame 10 in the X-axis direction is shorter than the length of the fixed frame 10 in the Y-axis direction. The fixed frame 10 has a first base 11 and a second base 12. The first base 11 may be a substrate. The second base 12 is formed on the first base 11.

[0012] [Cantilever 20] The cantilever 20 has a piezoelectric film. The cantilever 20 extends from the fixed frame 10 toward the inside of the fixed frame 10 in the X-axis direction. One end of the cantilever 20 is a fixed end 22, and the other end is a free end 21. As shown in FIGS. 1 and 2 , a pair of slits 71 and 72 are formed around the periphery of the cantilever 20. The slits 71 and 72 are gaps formed between the fixed frame 10 and the cantilever 20 and penetrate the substrate in the Z-axis direction. The pair of slits 71 extend in the X-axis direction and are spaced apart in the Y-axis direction. The slit 72 is a gap formed between the free end 21 and the fixed frame 10. The fixed end 22 of the cantilever 20 is connected to the fixed frame 10. The width of the slits 71 and 72 may be, for example, 100 nm or more and 5 μm or less. The width of the slits 71 and 72 may be, for example, 0.5 μm.

[0013] Fig. 3 shows a cross section taken along line III-III in Fig. 2. The piezoelectric film of the cantilever 20 has a lower electrode 40, a first piezoelectric layer 61, an intermediate electrode 50, a second piezoelectric layer 62, and an upper electrode 30, as shown in Fig. 3.

[0014] [Lower electrode 40] The lower electrode 40 is a thin electrode film and includes a first lower electrode 41 and a second lower electrode 42. The first lower electrode 41 and the second lower electrode 42 are spaced apart in the X-axis direction. Between the first lower electrode 41 and the second lower electrode 42, there is an electrode-free region 82 where no electrode is formed. After the lower electrode 40 is formed, etching is performed to remove the electrode, thereby forming the electrode-free region 82. The electrode-free region 82 may be formed using a lift-off method.

[0015] The first lower electrode 41 is formed closer to the fixed end 22 in the X-axis direction. The second lower electrode 42 is formed closer to the free end 21 in the X-axis direction.

[0016] [First piezoelectric layer 61] The first piezoelectric layer 61 is a piezoelectric thin film, and is formed on the lower electrode 40. The first piezoelectric layer 61 is formed continuously in the X-axis direction.

[0017] [Intermediate electrode 50] The intermediate electrode 50 is a thin electrode film and includes a first intermediate electrode 51 and a second intermediate electrode 52. The first intermediate electrode 51 and the second intermediate electrode 52 are spaced apart in the X-axis direction. Between the first intermediate electrode 51 and the second intermediate electrode 52, there is an electrode-free region 83 where no electrode is formed. After the intermediate electrode 50 is formed, etching is performed to remove the electrode, thereby forming the electrode-free region 83. The electrode-free region 83 may be formed using a lift-off method.

[0018] The first intermediate electrode 51 is formed closer to the fixed end 22 in the X-axis direction. The second intermediate electrode 52 is formed closer to the free end 21 in the X-axis direction.

[0019] [Second piezoelectric layer 62] The second piezoelectric layer 62 is a piezoelectric thin film, and is formed on the intermediate electrode 50. The first piezoelectric layer 61 is formed continuously in the X-axis direction.

[0020] [Top electrode 30] The upper electrode 30 is a thin electrode film and includes a first upper electrode 31 and a second upper electrode 32. The first upper electrode 31 and the second upper electrode 32 are spaced apart in the X-axis direction. Between the first upper electrode 31 and the second upper electrode 32, there is an electrode-free region 81 where no electrode is formed. After the upper electrode 30 is formed, etching is performed to remove the electrode, thereby forming the electrode-free region 81. The electrode-free region 81 may be formed using a lift-off method.

[0021] The first upper electrode 31 is formed closer to the fixed end 22 in the X-axis direction. The second upper electrode 32 is formed closer to the free end 21 in the X-axis direction.

[0022] [Material and thickness of piezoelectric thin film] The material of the first piezoelectric layer 61 and the second piezoelectric layer 62 may be, for example, ScAlN. The material of the first piezoelectric layer 61 may be AlN. Sc may be 0 at % or more and 50 at % or less. The thickness of the first piezoelectric layer 61 and the second piezoelectric layer 62 may be, for example, 100 nm or more and 1 μm or less. The thickness of the first piezoelectric layer 61 and the second piezoelectric layer 62 may be, for example, 500 nm.

[0023] The first piezoelectric layer 61 and the second piezoelectric layer 62 may have a fluorite structure (hafnium oxide, zirconium oxide, cesium oxide) or a wurtzite structure (zinc oxide).

[0024] [Electrode thin film material and thickness] The upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may be made of materials such as Al, Mo, Pt, or Ti. The thickness of the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may be, for example, 5 nm or more and 100 nm or less. The thickness of the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may be, for example, 50 nm.

[0025] [Detection area 23 and non-detection area 24] The cantilever 20 has a detection region 23 where a physical quantity can be detected, and a non-detection region 24 where no physical quantity is detected. The physical quantity is, for example, sound pressure. The detection region 23 may be a region where the first upper electrode 31, the first intermediate electrode 51, and the first lower electrode 41 are arranged to overlap in the Z-axis direction. The first upper electrode 31, the first intermediate electrode 51, and the first lower electrode 41 are electrically connected. The acoustic transducer 100 can detect a piezoelectric output charge between the first upper electrode 31 and the first intermediate electrode 51. The acoustic transducer 100 can detect a piezoelectric output charge between the first lower electrode 41 and the first intermediate electrode 51.

[0026] The detection region 23 is disposed closer to the fixed end 22 than the non-detection region 24. In other words, the non-detection region 24 is disposed closer to the free end 21 than the detection region 23.

[0027] The non-detection region 24 is a region of the cantilever 20 excluding the detection region 23. The second upper electrode 32, the second intermediate electrode 52, and the second lower electrode 42 are not electrically connected.

[0028] [Length L21 of detection area 23] The length L21 of the detection region 23 is the length in the X-axis direction. The length L21 of the detection region 23 may be the length of the first upper electrode 31, which is the shortest among the lengths of the first upper electrode 31, the first intermediate electrode 51, and the first lower electrode 41.

[0029] The length L21 of the detection region 23 may be 20% or more and 75% or less of the total length L20 of the cantilever 20. The total length L20 of the cantilever 20 is the length in the X-axis direction, and is the length from the fixed end 22 to the free end 21. The length L21 of the detection region 23 may be 30% or more and 60% or less of the total length L20 of the cantilever 20. The length L21 of the detection region 23 may be 40% or more and 45% or less of the total length L20 of the cantilever 20. The length of the non-detection region 24 is the remaining length obtained by subtracting the length L21 of the detection region 23 from the total length L20 of the cantilever 20.

[0030] The first upper electrode 31 is shorter in the X-axis direction than the first intermediate electrode 51 and the first lower electrode 41. The first lower electrode 41 is longer in the X-axis direction than the first upper electrode 31 and the first intermediate electrode 51.

[0031] The second upper electrode 32 is longer in the X-axis direction than the second intermediate electrode 52 and the first piezoelectric layer 61. The second lower electrode 42 is shorter in the X-axis direction than the second upper electrode 32 and the second intermediate electrode 52.

[0032] [Split position] As described above, the electrode-free region 81 is formed between the first upper electrode 31 and the second upper electrode 32. The electrode-free region 81 may also be referred to as a division position. The division position, which is the electrode-free region 81, may be formed within a range of 20% to 75% of the total length L20 of the cantilever 20 from the fixed end 22. The division position, which is the electrode-free region 81, may be formed within a range of 30% to 60% of the total length L20 of the cantilever 20 from the fixed end 22. The division position, which is the electrode-free region 81, may be formed within a range of 40% to 45% of the total length L20 of the cantilever 20 from the fixed end 22.

[0033] In the X-axis direction, the end of detection region 23 closer to free end 21 may be located at a position that is 20% to 75% of the total length L20 of cantilever 20 from fixed end 22. The end of detection region 23 closer to free end 21 is the end that is farther from fixed end 22. In the X-axis direction, the end of detection region 23 closer to free end 21 may be located at a position that is 30% to 60% of the total length L20 of cantilever 20 from fixed end 22. In the X-axis direction, the end of detection region 23 closer to free end 21 may be located at a position that is 40% to 45% of the total length L20 of cantilever 20 from fixed end 22.

[0034] The division positions of the upper electrode 30 (electrode non-forming region 81), the division positions of the intermediate electrode 50 (electrode non-forming region 83), and the division positions of the lower electrode 40 (electrode non-forming region 82) in the X-axis direction do not overlap one another. A first intermediate electrode 51 and a first lower electrode 41 are formed below the electrode non-forming region 81. A second intermediate electrode 52 and a second upper electrode 32 are formed above the electrode non-forming region 82. A second upper electrode 32 is formed above the electrode non-forming region 83, and a first lower electrode 41 is formed below the electrode non-forming region 83. This makes it possible to suppress a decrease in the mechanical strength of the cantilever 20. A piezoelectric thin film is formed in the electrode non-forming regions 81 to 83.

[0035] No-electrode region 81 is located closer to fixed end 22 than no-electrode regions 82 and 83. No-electrode region 82 is located farther from fixed end 22 than no-electrode regions 81 and 83. The crystallinity of the piezoelectric thin film above the boundary between no-electrode region 82 and the end of first lower electrode 41 is lower than the crystallinity of the piezoelectric thin film above lower electrode 40. Similarly, the crystallinity of the piezoelectric thin film above the boundary between no-electrode region 82 and the end of second lower electrode 42 is lower than the crystallinity of the piezoelectric thin film above lower electrode 40. In cantilever 20, no-electrode region 82 is located farther from fixed end 22 than no-electrode regions 81 and 83, and therefore the boundaries with the ends of first lower electrode 41 and second lower electrode 42 are also located farther away, which does not hinder the crystal growth of the piezoelectric thin film that generates charge. The piezoelectric thin film that generates a charge includes a first piezoelectric layer 61 between the first lower electrode 41 and the first intermediate electrode 51, and a second piezoelectric layer 62 between the first upper electrode 31 and the first intermediate electrode 51. In the cantilever 20, the crystallinity of the piezoelectric thin film in the detection region 23 that generates a charge is high.

[0036] [Shape of cantilever 20] As described above, the shape of the cantilever 20 is rectangular when viewed in the Z-axis direction. When the cantilever 20 is rectangular, the area of ​​the cantilever 20 within the chip can be increased, making it possible to increase the sensitivity of the cantilever 20. In other words, for the same sensitivity, the acoustic transducer 100 can be made smaller than conventional devices. The acoustic transducer 100 can be made smaller and less expensive.

[0037] [Total length of cantilever 20: L20] In the acoustic transducer 100, the resonant frequency of the cantilever 20 can be easily changed by changing the overall length L20 of the cantilever 20. At the time of design, the resonant frequency can be lowered by increasing the overall length L20 of the cantilever 20. The resonant frequency when the overall length L20 is long is lower than the resonant frequency when the overall length L20 is short.

[0038] [Cantilever 20 width W20] FIG. 2 shows the width W20 of the cantilever 20. The width W20 of the cantilever 20 is the width along the Y-axis direction, and is the width of the detection area 23. In the acoustic transducer 100, by changing the width W20 of the cantilever 20, the sensitivity of the cantilever 20 can be changed regardless of the resonant frequency. The sensitivity of the cantilever 20 is the sensitivity of the detection area 23. At the time of design, the sensitivity can be increased by widening the width W20 of the cantilever 20. The sensitivity when the width W20 is wide is higher than when the width W20 is narrow.

[0039] [Electrode end shape] The end of the electrode in the X-axis direction may be tapered. The electrodes include an upper electrode 30, a lower electrode 40, and an intermediate electrode 50. The thickness of the end of the electrode in the X-axis direction may be thinner than the thickness of the central part of the electrode in the X-axis direction. The end of the electrode may be formed to form an acute angle. The tapered shape may be inclined so that the lower end is positioned outward in the X-axis direction relative to the upper end.

[0040] The end of the electrode may be disposed more inward than the free end 21 in the X-axis direction. The first piezoelectric layer 61 and the second piezoelectric layer 62 may be formed more outward than the end of the electrode in the X-axis direction. The first piezoelectric layer 61 and the second piezoelectric layer 62 may be connected in the Z-axis direction in a region more outward than the end of the electrode. In this way, by tapering the end of the electrode, it is possible to suppress a decrease in the crystallinity of the first piezoelectric layer 61 and the second piezoelectric layer 62. Therefore, it is possible to stably generate electric charges in the first piezoelectric layer 61 and the second piezoelectric layer 62.

[0041] [Actions and Effects of the Sound Converter 100 According to the First Embodiment] The acoustic transducer 100 of the first embodiment comprises a fixed frame 10, and a cantilever 20 having one end which is a fixed end 22 fixed to the fixed frame 10 and the other end which is a free end 21, and extending from the fixed frame 10 to the inside of the fixed frame 10, and the cantilever 20 has a detection region 23 in which a physical quantity can be detected, and a non-detection region 24 in which a physical quantity is not detected.

[0042] In the acoustic transducer 100 of this embodiment, the cantilever 20 deforms, and the deformation of the cantilever 20 is detected to detect a physical quantity. In the acoustic transducer 100, the electrodes are separated in the longitudinal direction (X-axis direction) of the cantilever 20, thereby forming a detection region 23 and a non-detection region 24, thereby improving sensitivity.

[0043] In the cantilever 20, stress concentrates at the base portion near the first base 11 on the fixed end 22 side, generating a large amount of charge. On the other hand, almost no stress occurs on the free end 21 side of the cantilever 20, generating little charge. Therefore, by electrically separating the base portion of the first base 11 on the fixed end 22 side from the tip portion on the free end 21 side and using only the base portion for the detection region 23, it is possible to increase the amount of charge generated per unit area. This increases the signal level, thereby improving sensitivity.

[0044] Furthermore, in the acoustic transducer 100, the cantilever 20 has a piezoelectric film, which includes a lower electrode 40, a first piezoelectric layer 61 formed on the lower electrode 40, an intermediate electrode 50 formed on the first piezoelectric layer 61, a second piezoelectric layer 62 formed on the intermediate electrode 50, and an upper electrode 30 formed on the second piezoelectric layer 62, and has electrode-free regions 82, 83, and 81 between the detection region 23 and the non-detection region 24, in which at least one of the lower electrode 40, the intermediate electrode 50, and the upper electrode 30 is not formed.

[0045] In the acoustic transducer 100 having this configuration, the cantilever 20, which is a piezoelectric film, is deformed, and piezoelectric output charges generated between the first upper electrode 31 and the first intermediate electrode 51 and between the first lower electrode 41 and the first intermediate electrode 51 in the detection region 23 are connected to the first intermediate electrode 51. In the acoustic transducer 100, the detection region 23 and the non-detection region 24 can be separated by forming electrode-free regions 82, 83, and 81 in which no electrode is formed on at least one of the lower electrode 40, the intermediate electrode 50, and the upper electrode 30.

[0046] In the acoustic transducer 100, the electrode-free region 82 where the lower electrode 40 is not formed is located farther from the fixed end 22 than the electrode-free region 81 where the upper electrode 30 is not formed. This makes it possible to avoid a decrease in the crystallinity of the first piezoelectric layer 61 between the first lower electrode 41 and the intermediate electrode 50, and the crystallinity of the second piezoelectric layer 62 between the intermediate electrode 50 and the first upper electrode 31. Therefore, electric charges can be generated stably in the first piezoelectric layer 61 and the second piezoelectric layer 62.

[0047] Furthermore, the acoustic transducer 100 is a piezoelectric acoustic transducer, and is more resistant to dust and water droplets than conventional electrostatic acoustic transducers.

[0048] Furthermore, because the acoustic transducer 100 has a rectangular shape, the area of ​​the cantilever 20 within the chip can be increased, enabling higher sensitivity. Since the acoustic transducer 100 can achieve high sensitivity, it can be made smaller. In the acoustic transducer 100, the resonant frequency can be easily changed by changing the overall length 20L of the cantilever 20. In the acoustic transducer 100, the sensitivity can be changed regardless of the resonant frequency by changing the width W20 of the detection region 23.

[0049] [Sound transducer 100B according to the second embodiment] Next, an acoustic transducer 100B according to a second embodiment will be described. Fig. 4 is a plan view illustrating the acoustic transducer 100B according to the second embodiment. The acoustic transducer 100B according to the second embodiment shown in Fig. 4 differs from the acoustic transducer 100 according to the first embodiment shown in Fig. 2 in that the acoustic transducer 100B according to the second embodiment shown in Fig. 4 includes a pair of cantilevers 20. Note that in the description of the acoustic transducer 100B according to the second embodiment, explanations that are the same as those in the description of the acoustic transducer 100 according to the first embodiment may be omitted.

[0050] The acoustic transducer 100B includes a pair of cantilevers 20. The pair of cantilevers 20 includes cantilevers 20A and 20B arranged opposite each other in the X-axis direction. The cantilever 20A is an example of a first cantilever, and the cantilever 20B is an example of a second cantilever. The free ends 21 of the pair of cantilevers 20 face each other. The cantilevers 20A and 20B have the same structure as the cantilever 20 described above. The capacitance element of the cantilever 20A and the capacitance element of the cantilever 20B are connected in series.

[0051] [Actions and Effects of the Sound Converter 100B According to the Second Embodiment] The acoustic transducer 100B according to the second embodiment also has the same effects as the acoustic transducer 100 according to the first embodiment. The acoustic transducer 100B according to the second embodiment is provided with a pair of cantilevers 20 facing each other in the X-axis direction, thereby improving sensitivity.

[0052] [Relationship between the ratio of detection area 23 and signal level] Next, the relationship between the ratio of the detection area 23 and the signal level will be described with reference to FIG. 5. FIG. 5 is a graph showing the relationship between the ratio of the detection area 23 to the total length L10 of the cantilever 20 and the signal level. In FIG. 5, the horizontal axis represents the ratio [%] of the detection area 23, and the vertical axis represents the signal level [%]. The ratio of the detection area 23 is the ratio of the length L21 of the detection area 23 to the total length L20 of the cantilever 20. When the ratio of the detection area 23 was in the range of 40% to 45% inclusive, the signal level was 125% or higher. By setting the ratio of the detection area 23 to 40% to 45% inclusive, the S / N ratio (signal-to-noise ratio) can be improved by approximately 1.5 dB. The graph shown in FIG. 5 may be a calculation result for, for example, the acoustic transducer 100B.

[0053] [Sound transducer 100C according to the third embodiment] Next, an acoustic transducer 100C according to a third embodiment will be described. Fig. 6 is a cross-sectional view illustrating the acoustic transducer 100C according to the third embodiment. The acoustic transducer 100C shown in Fig. 6 differs from the acoustic transducer 100 according to the first embodiment shown in Fig. 3 in that the upper electrode 30 and the lower electrode 40 are not separated. In the description of the acoustic transducer 100C according to the third embodiment, explanations that are the same as those of the acoustic transducer 100 according to the first embodiment may be omitted.

[0054] The cantilever 20 of the acoustic transducer 100C includes an upper electrode 30, an intermediate electrode 50, and a lower electrode 40. The upper electrode 30 is formed continuously from the fixed end 22 to the free end 21. The lower electrode 40 is formed continuously from the fixed end 22 to the free end 21. The intermediate electrode 50 includes a first intermediate electrode 51 and a second intermediate electrode 52. An electrode-free region 83 is formed between the first intermediate electrode 51 and the second intermediate electrode 52.

[0055] The cantilever 20 has a detection area 23 and a non-detection area 24. The detection area 23 is an area where the lower electrode 40, the first intermediate electrode 51, and the upper electrode 30 are arranged to overlap in the Z-axis direction. The acoustic transducer 100C can detect the capacitance between the upper electrode 30 and the first intermediate electrode 51. The acoustic transducer 100C can detect the capacitance between the lower electrode 40 and the first intermediate electrode 51. The length L21C of the detection area 23 is the length of the first intermediate electrode 51 in the X-axis direction.

[0056] [Actions and Effects of the Sound Converter 100C According to the Third Embodiment] The acoustic transducer 100C according to the third embodiment also has the same effects as the acoustic transducer 100 according to the first embodiment. In the acoustic transducer 100C, the intermediate electrode 50 is divided, and the upper electrode 30 and the lower electrode 40 do not have to be divided.

[0057] [Sound transducer 100D according to the fourth embodiment] Next, an acoustic transducer 100D according to a fourth embodiment will be described. Fig. 7 is a cross-sectional view illustrating the acoustic transducer 100D according to the fourth embodiment. The acoustic transducer 100D shown in Fig. 7 differs from the acoustic transducer 100 according to the first embodiment shown in Fig. 3 in that the intermediate electrode 50 is not divided. In the description of the acoustic transducer 100C according to the third embodiment, the same description as that of the acoustic transducer 100 according to the first embodiment may be omitted.

[0058] The cantilever 20 of the acoustic transducer 100D includes an upper electrode 30, an intermediate electrode 50, and a lower electrode 40. The upper electrode 30 has a first upper electrode 31 and a second upper electrode 32. An electrode-free region 81 is formed between the first upper electrode 31 and the second upper electrode 32. The lower electrode 40 has a first lower electrode 41 and a second lower electrode 42. An electrode-free region 82 is formed between the first lower electrode 41 and the second lower electrode 42. The intermediate electrode 50 is formed continuously from the fixed end 22 to the free end 21.

[0059] The cantilever 20 has a detection region 23 and a non-detection region 24. The detection region 23 is a region where the first lower electrode 41, the intermediate electrode 50, and the first upper electrode 31 are arranged to overlap in the Z-axis direction. In the acoustic transducer 100D, a piezoelectric output charge is generated between the first upper electrode 31 and the intermediate electrode 50. In the acoustic transducer 100D, a piezoelectric output charge is generated between the first lower electrode 41 and the intermediate electrode 50. A length L21 of the detection region 23 is the length of the first upper electrode 31 in the X-axis direction.

[0060] [Actions and Effects of the Sound Converter 100D According to the Fourth Embodiment] The acoustic transducer 100D according to the fourth embodiment also has the same effects as the acoustic transducer 100 according to the first embodiment. In the acoustic transducer 100D, the upper electrode 30 and the lower electrode 40 are divided, but the intermediate electrode 50 does not have to be divided.

[0061] In the acoustic transducer 100, at least one of the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may be divided. In the acoustic transducer 100, the upper electrode 30 may be divided, and the lower electrode 40 and the intermediate electrode 50 may not be divided. In the acoustic transducer 100, the lower electrode 40 may be divided, and the upper electrode 30 and the intermediate electrode 50 may not be divided.

[0062] [Sound transducer 100E according to the fifth embodiment] Next, an acoustic transducer 100E according to a fifth embodiment will be described. Fig. 8 is a perspective view illustrating the acoustic transducer 100E according to the fifth embodiment. The acoustic transducer 100E according to the fifth embodiment shown in Fig. 8 differs from the acoustic transducer 100B according to the second embodiment shown in Fig. 4 in that it includes four cantilevers 20 and that the shape of the fixing frame 10 is different. Note that in the description of the acoustic transducer 100E according to the fifth embodiment, explanations that are the same as those of the acoustic transducers 100 and 100B according to the above embodiments may be omitted.

[0063] The acoustic transducer 100E includes a fixed frame 10. The fixed frame 10 has a plurality of frame portions 10B. The frame portions 10B are aligned in the X-axis direction. The frame portions 10B include a common portion 10E. The common portion 10E extends in the Y-axis direction at the center of the fixed frame 10. A pair of cantilevers 20 is formed inside each of the frame portions 10B. The free ends 21 of the pair of cantilevers 20 are arranged to face each other. The cantilevers 20 extending from the common portion 10E extend in opposite directions.

[0064] [Actions and Effects of the Sound Converter 100E According to the Fifth Embodiment] The acoustic transducer 100E according to the fifth embodiment also achieves the same effects as the acoustic transducer 100 according to the first embodiment. The acoustic transducer 100E according to the fifth embodiment is provided with four cantilevers 20, thereby improving sensitivity. The acoustic transducer 100E may be provided with multiple pairs of cantilevers 20. The acoustic transducer 100E may be provided with four or more cantilevers 20.

[0065] [Circuit diagram of the acoustic transducer 100E according to the embodiment] Next, a circuit diagram of the acoustic transducer 100E according to the embodiment will be described. Fig. 9 is a circuit diagram of the acoustic transducer 100E according to the embodiment. In the description of the circuit diagram of the acoustic transducer 100E, explanations similar to those of the acoustic transducers 100, 100B to 100D according to the above embodiments may be omitted.

[0066] As shown in FIG. 9, the acoustic transducer 100E includes a MEMS microphone chip 101. The MEMS microphone chip 101 includes a plurality of cantilevers 20A, 20B, 20C, and 20D. The MEMS microphone chip 101 may include four or more cantilevers 20. The cantilevers 20A, 20B, 20C, and 20D include an upper electrode 30, a lower electrode 40, and an intermediate electrode 50. The acoustic transducer 100 can detect a piezoelectric output charge between the upper electrode 30 and the intermediate electrode 50, and a piezoelectric output charge between the lower electrode 40 and the intermediate electrode 50. The cantilevers 20A, 20B, 20C, and 20D are connected in series.

[0067] The MEMS microphone chip 101 also has pads 13 and 14. A cantilever 20A is connected to the pad 13, and a cantilever 20D is connected to the pad 14. The acoustic transducer 100E includes an IC 102 connected to the pad 13. The IC 102 is an amplifier that amplifies the output signal of the cantilever 20. The IC 102 may be provided with a function to perform AD (analog-to-digital) conversion after amplifying the output signal of the cantilever 20. The IC 102 may also perform solid-state adjustment of the output level of the amplified signal.

[0068] [Sound transducer 100F according to the sixth embodiment] Next, an acoustic transducer 100F according to a sixth embodiment will be described. Fig. 10 is a plan view illustrating the acoustic transducer 100F according to the sixth embodiment. The acoustic transducer 100F according to the sixth embodiment shown in Fig. 10 differs from the acoustic transducer 100B according to the second embodiment shown in Fig. 4 in that it includes a pair of cantilevers 20 (cantilevers 20A, 20F) having different widths W20, W20F, and that the shape of the fixing frame 10F is different. Note that in the description of the acoustic transducer 100F according to the sixth embodiment, descriptions that are the same as those of the acoustic transducers 100, 100B according to the above embodiments may be omitted.

[0069] The acoustic transducer 100F includes cantilevers 20A and 20F as a pair of cantilevers 20. As described above, the layered structure of the cantilevers 20A and 20F is the same as that of the cantilever 20, and includes an upper electrode 30, a lower electrode 40, an intermediate electrode 50, a first piezoelectric layer 61, and a second piezoelectric layer 62. The cantilever 20A has a detection region 23 and a non-detection region 24. The cantilever 20F has a detection region 23F and a non-detection region 24F.

[0070] The width W20F of the cantilever 20F is wider than the width W20 of the cantilever 20A (W20F>W20). The width W20F is the width of the first upper electrode 31 in the detection region 23F. The width W20 is the width of the first upper electrode 31 in the detection region 23. The capacitive element of the cantilever 20A and the capacitive element of the cantilever 20F are connected in series.

[0071] Furthermore, the length L20 of the cantilever 20A may be equal to the length L20F of the cantilever 20F (L20=L20F). The length L21 of the detection region 23 of the cantilever 20A may be approximately the same as the length L21F of the detection region 23F of the cantilever 20F (L21≈L21F).

[0072] The shape of the fixing frame 10F corresponds to the shapes of the cantilevers 20A and 20F. The slits 71 formed on both sides of the cantilever 20A and the slits 71 formed on both sides of the cantilever 20F are located at different positions in the Y-axis direction.

[0073] [Actions and Effects of the Sound Converter 100F According to the Sixth Embodiment] The acoustic transducer 100F according to the sixth embodiment also has the same effects as the acoustic transducer 100 according to the first embodiment. In the acoustic transducer 100F according to the sixth embodiment, the widths W20 and W20F along the Y-axis direction of the pair of opposing cantilevers 20A and 20F may be different.

[0074] [Sound transducer 100G according to the seventh embodiment] Next, an acoustic transducer 100G according to a seventh embodiment will be described. Fig. 11 is a cross-sectional view illustrating the acoustic transducer 100G according to the seventh embodiment. The acoustic transducer 100G according to the seventh embodiment shown in Fig. 11 differs from the acoustic transducer 100 shown in Fig. 3 in that the thickness of the intermediate electrode 50G is thicker than the thicknesses of the upper electrode 30 and the lower electrode 40. In the description of the acoustic transducer 100G according to the seventh embodiment, descriptions that are the same as those of the acoustic transducer 100 according to the above embodiments may be omitted.

[0075] The cantilever 20 of the acoustic transducer 100G has an upper electrode 30, a lower electrode 40, an intermediate electrode 50G, a first piezoelectric layer 61, and a second piezoelectric layer 62. The intermediate electrode 50G includes a first intermediate electrode 51 and a second intermediate electrode 52. The intermediate electrode 50G is thicker than the upper electrode 30. The intermediate electrode 50G is thicker than the lower electrode 40. The thickness of the intermediate electrode 50G may be the same as the thickness of the first intermediate electrode 51. In the detection region 23, the first intermediate electrode 51 is thicker than the first upper electrode 31 and the first lower electrode 41. The first upper electrode 31 may have the same thickness as the first lower electrode 41.

[0076] The intermediate electrode 50G is formed to include a neutral plane N20. The neutral plane N20 is an imaginary plane, and when no stress is applied to the cantilever 20, it may be, for example, a plane that is located at the center position between the upper electrode 30 and the lower electrode 40 in the Z-axis direction and that extends along the XY plane. When stress is applied to the cantilever 20, the neutral plane N may also be an imaginary plane on which no compressive stress or tensile stress acts.

[0077] [Actions and Effects of the Acoustic Converter 100G According to the Seventh Embodiment] The acoustic transducer 100G according to the seventh embodiment also achieves the same effects as the acoustic transducer 100 according to the first embodiment. In the acoustic transducer 100G according to the seventh embodiment, the intermediate electrode 50 is thicker than the upper electrode 30 and the lower electrode 40. The intermediate electrode 50 is disposed at a position including the neutral plane N20. This causes the first piezoelectric layer 61 and the second piezoelectric layer 62 to be disposed on the outer side in the thickness direction. Therefore, when stress is generated in the cantilever 20, the deformation amounts of the first piezoelectric layer 61 and the second piezoelectric layer 62 can be increased. As a result, the acoustic transducer 100G can achieve high sensitivity, miniaturization, and a high SNR (signal-to-noise ratio).

[0078] [Sound transducer 200 according to the eighth embodiment] Next, an acoustic transducer 200 according to an eighth embodiment will be described. FIG. 12 is a plan view illustrating the acoustic transducer 200 according to the eighth embodiment. FIG. 13 is a perspective view illustrating the acoustic transducer 200 according to the eighth embodiment. FIG. 14 is a perspective view illustrating the acoustic transducer 200 according to the eighth embodiment from the bottom side. FIG. 15 is a cross-sectional view illustrating the acoustic transducer 200 according to the eighth embodiment. Note that in each drawing, X-axis, Y-axis, and Z-axis directions, which are orthogonal to each other, may be illustrated. The X-axis, Y-axis, and Z-axis directions do not have to be orthogonal to each other. The X-axis, Y-axis, and Z-axis directions may be arbitrary directions. The X-axis direction is an example of a first direction. The Y-axis direction is an example of a direction intersecting the first direction. In the description of the acoustic transducer 200 according to the eighth embodiment, descriptions similar to those of the acoustic transducer 100 according to the above-described embodiments will be omitted.

[0079] [Support substrate 211] The acoustic transducer 200 includes a support substrate (fixed frame) 211 and a diaphragm (piezoelectric element) 220. The support substrate 211 may be rectangular when viewed in the Z-axis direction. The plate thickness direction of the support substrate 211 is along the Z-axis direction. The support substrate 211 has an upper surface 211a and a lower surface 211b that face each other in the Z-axis direction. An opening 221 is formed in the support substrate 211. The opening 221 is formed so as to penetrate the support substrate 211 in the Z-axis direction. The support substrate 211 is formed from, for example, a silicon wafer. The opening 221 is formed so as to form a circle when viewed in the Z-axis direction.

[0080] [Diaphragm 220] The diaphragm 220 has a piezoelectric film. The diaphragm 220 is formed so as to cover the opening 221. The diaphragm 220 is formed so as to have a circular shape when viewed in the Z-axis direction. An outer periphery 222 of the diaphragm 220 is a fixed end of the diaphragm 220, and is fixed to the upper surface 211a of the support substrate 211. As will be described later, the diaphragm 220 has a first detection area 324, a non-detection area 325, and a second detection area 326. The diaphragm 220 is also called a "diaphragm." Note that the shape of the opening 221 is not limited to a circle, and may be an ellipse or another shape.

[0081] [Piezoelectric film] The piezoelectric film, which is diaphragm 220, deforms in response to sound pressure and generates an electric charge. Fig. 16 is an enlarged cross-sectional view illustrating an example of the piezoelectric film. The piezoelectric film has a lower electrode layer 440, a lower piezoelectric layer (first piezoelectric layer) 460, an intermediate electrode layer 250, an upper piezoelectric layer (second piezoelectric layer) 360, and an upper electrode layer 330. The lower electrode layer 440, the lower piezoelectric layer 460, the intermediate electrode layer 250, the upper piezoelectric layer 360, and the upper electrode layer 330 are laminated in this order.

[0082] [Lower electrode layer 440] Lower electrode layer 440 has lower electrodes 441 to 443 which are thin electrode films. Lower electrode layer 440 is disposed at a position close to opening 221 in the Z-axis direction. Lower electrodes 441 to 443 are disposed apart in the X-axis direction. Lower electrode 441 has a circular shape. Lower electrode 441 is disposed at a position close to center C11 of diaphragm 220 as viewed in the Z-axis direction. Lower electrode 442 has a ring shape as viewed in the Z-axis direction. Lower electrode 442 is disposed outside lower electrode 441 in the radial direction. Lower electrode 443 has a ring shape as viewed in the Z-axis direction. Lower electrode 443 is disposed outside lower electrode 442 in the radial direction.

[0083] [No-electrode formation area 483,484] In the radial direction of diaphragm 220, there is an electrode-free region 483 where no electrode is formed between lower electrode 441 and lower electrode 442. In the radial direction of diaphragm 220, there is an electrode-free region 484 where no electrode is formed between lower electrode 442 and lower electrode 443.

[0084] [Lower piezoelectric layer 460] The lower piezoelectric layer 460 is a piezoelectric thin film, and is formed on the lower electrode layer 440. The lower piezoelectric layer 460 is formed continuously in the radial direction of the vibration plate 220.

[0085] [Intermediate electrode layer 250] The intermediate electrode layer 250 has intermediate electrodes 251 to 253 which are thin electrode films. The intermediate electrode layer 250 is formed on the lower piezoelectric layer 460. The intermediate electrodes 251 to 253 are arranged to be spaced apart in the X-axis direction. The intermediate electrode 251 has a circular shape. The intermediate electrode 251 is arranged at a position close to the center C11 of the vibration plate 220 when viewed in the Z-axis direction. The intermediate electrode 252 has a ring shape when viewed in the Z-axis direction. The intermediate electrode 252 is arranged radially outward of the intermediate electrode 251. The intermediate electrode 253 has a ring shape when viewed in the Z-axis direction. The intermediate electrode 253 is arranged radially outward of the intermediate electrode 252.

[0086] [Electrode non-formation area 281,282] In the radial direction of diaphragm 220, there is an electrode-free region 281 where no electrode is formed between intermediate electrode 251 and intermediate electrode 252. In the radial direction of diaphragm 220, there is an electrode-free region 282 where no electrode is formed between intermediate electrode 252 and intermediate electrode 253.

[0087] [Upper piezoelectric layer 360] The upper piezoelectric layer 360 is a piezoelectric thin film, and is formed on the intermediate electrode layer 250. The upper piezoelectric layer 360 is formed continuously in the radial direction of the vibration plate 220.

[0088] [Top electrode layer 330] The upper electrode layer 330 has upper electrodes 331 to 333 which are thin electrode films. The upper electrode layer 330 is formed on the upper piezoelectric layer 360. The upper electrodes 331 to 333 are arranged to be spaced apart in the X-axis direction. The upper electrode 331 has a circular shape. The upper electrode 331 is arranged at a position close to the center C11 of the vibration plate 220 when viewed in the Z-axis direction. The upper electrode 332 has a ring shape when viewed in the Z-axis direction. The upper electrode 332 is arranged radially outward of the upper electrode 331. The upper electrode 333 has a ring shape when viewed in the Z-axis direction. The upper electrode 333 is arranged radially outward of the upper electrode 332.

[0089] [Material and thickness of piezoelectric thin film] The piezoelectric material used for the lower piezoelectric layer 460 and the upper piezoelectric layer 360 may be, for example, aluminum nitride (AlN) or scandium aluminum nitride (ScAlN (Sc: 1 to 60 at%)), or may be, for example, a piezoelectric material having a fluorite structure (hafnium oxide, zirconium oxide, cesium oxide) or a piezoelectric material having a wurtzite structure (zinc oxide, gallium nitride).

[0090] The thickness of the lower piezoelectric layer 460 may be, for example, 100 nm to 1 μm The material of the lower piezoelectric layer 460 may be, for example, ScAlN (Sc: 40 at %), and the thickness of the lower piezoelectric layer 460 may be, for example, 500 nm.

[0091] The thickness of the upper piezoelectric layer 360 may be, for example, 100 nm to 1 μm The material of the upper piezoelectric layer 360 may be, for example, ScAlN (Sc: 40 at %), and the thickness of the upper piezoelectric layer 360 may be, for example, 500 nm.

[0092] [Electrode thin film material and thickness] The thickness of the electrode thin film in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be, for example, 5 nm or more and 100 nm or less. The thickness of the electrode thin film may be, for example, 20 nm. The electrode thin films in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be formed to different thicknesses.

[0093] The material of the electrode thin films in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be formed from, for example, at least one of gold, platinum, tungsten, aluminum, copper, molybdenum, ruthenium, titanium, chromium, and nickel, or an alloy containing one of these. The electrode thin films in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be formed from the same material or different materials.

[0094] [First detection area, non-detection area, and second detection area] As shown in Figures 15 and 16, diaphragm 220 includes first detection areas 323, 423, non-detection areas 324, 424, and second detection areas 325, 425. First detection areas 323, 423 and second detection areas 325, 425 are areas where a physical quantity can be detected. Non-detection areas 324, 424 are areas where a physical quantity is not detected. The physical quantity is, for example, sound pressure.

[0095] The first detection region 323 is a region where the intermediate electrode 251, the upper piezoelectric layer 360, and the upper electrode 331 are arranged to overlap in the Z-axis direction. The first detection region 423 is a region where the lower electrode 441, the lower piezoelectric layer 460, and the intermediate electrode 251 are arranged to overlap in the Z-axis direction. The acoustic transducer 200 can detect the piezoelectric output charge between the lower electrode 441 and the intermediate electrode 251. The acoustic transducer 200 can detect the piezoelectric output charge between the intermediate electrode 251 and the upper electrode 331.

[0096] The non-detection region 324 includes a region where the intermediate electrode 252, the upper piezoelectric layer 360, and the upper electrode 332 are overlapping in the Z-axis direction. The non-detection region 424 includes a region where the lower electrode 442, the lower piezoelectric layer 460, and the intermediate electrode 252 are overlapping in the Z-axis direction. The acoustic transducer 200 cannot detect the piezoelectric output charge between the lower electrode 442 and the intermediate electrode 252. The acoustic transducer 200 cannot detect the piezoelectric output charge between the intermediate electrode 252 and the upper electrode 332.

[0097] The second detection region 325 is a region where the intermediate electrode 253, the upper piezoelectric layer 360, and the upper electrode 333 are arranged to overlap in the Z-axis direction. The second detection region 425 is a region where the lower electrode 443, the lower piezoelectric layer 460, and the intermediate electrode 253 are arranged to overlap in the Z-axis direction. The acoustic transducer 200 can detect the piezoelectric output charge between the lower electrode 443 and the intermediate electrode 253. The acoustic transducer 200 can detect the piezoelectric output charge between the intermediate electrode 253 and the upper electrode 333.

[0098] The first detection regions 323, 423 are formed at positions close to the center of the diaphragm 220. The non-detection regions 324, 424 are formed further outward than the first detection regions 323, 423 in the radial direction of the diaphragm 220. The second detection regions 325, 425 are formed further outward than the non-detection regions 324, 424 in the radial direction of the diaphragm 220.

[0099] [Outer diameters of first detection area 323, non-detection area 324, and second detection area 325] 12, the outer diameter Φ323 of the first detection region 323 is, for example, 0.59 mm, the outer diameter Φ324 of the non-detection region 324 is, for example, 0.81 mm, and the outer diameter Φ325 of the second detection region 325 is 1 mm.

[0100] [Split position] 16, the lower electrode layer 440 has no-electrode regions 483 and 484. The intermediate electrode layer 250 has no-electrode regions 281 and 282. The upper electrode layer 330 has no-electrode regions 381 and 382.

[0101] The electrode-free regions 281, 282, 381, 382, ​​483, and 484 may be referred to as “division positions.” These electrode-free regions 281, 282, 381, 382, ​​483, and 484 are arranged at different positions in the radial direction of the diaphragm 220.

[0102] The electrode-free region 381 is disposed more inward than the electrode-free region 281 in the radial direction of the diaphragm 220. The electrode-free region 281 is disposed more inward than the electrode-free region 483 in the radial direction of the diaphragm 220.

[0103] The electrode-free region 382 is disposed further outward than the electrode-free region 282 in the radial direction of the diaphragm 220. The electrode-free region 282 is disposed further outward than the electrode-free region 484 in the radial direction of the diaphragm 220.

[0104] In diaphragm 220, multiple electrode-free regions 281, 282, 381, 382, ​​483, and 484 are formed in positions that do not overlap one another when viewed in the Z-axis direction, thereby preventing a decrease in strength of diaphragm 220. Note that piezoelectric thin films are formed in electrode-free regions 281, 282, 483, and 484.

[0105] The crystallinity of the piezoelectric thin film above the boundary between the end of the lower electrode 441 and the electrode-free region 483 is lower than the crystallinity of the piezoelectric thin film above the lower electrode 441. Similarly, the crystallinity of the piezoelectric thin film above the boundary between the electrode and the electrode-free region is lower than the crystallinity of the piezoelectric thin film above the electrode.

[0106] The division position of electrode-free region 483 is located outside first detection region 423 in the radial direction of diaphragm 220. The division position of electrode-free region 484 is located inside second detection region 425 in the radial direction of diaphragm 220. This does not hinder the crystal growth of the piezoelectric thin film that generates electric charge. In acoustic transducer 200, the crystallinity of the piezoelectric thin film is high in first detection region 423 and second detection region 425 that generate electric charge.

[0107] The division position of electrode-free region 281 is located outside first detection region 323 in the radial direction of diaphragm 220. The division position of electrode-free region 282 is located inside second detection region 325 in the radial direction of diaphragm 220. This does not hinder crystal growth of the piezoelectric thin film that generates electric charge. In acoustic transducer 200, the crystallinity of the piezoelectric thin film is high in first detection region 323 and second detection region 325 that generate electric charge.

[0108] [Piezoelectric film connection] In vibration plate 220, which is a piezoelectric film (piezoelectric element), the electrodes of first detection regions 323, 423 are electrically connected in parallel. The electrodes of first detection region 323 include upper electrode 331 and intermediate electrode 251. The electrodes of first detection region 423 include lower electrode 441 and intermediate electrode 251. The electrodes of second detection regions 325, 425 are electrically connected in parallel. The electrodes of second detection region 325 include upper electrode 333 and intermediate electrode 253. The electrodes of second detection region 425 include lower electrode 443 and intermediate electrode 253.

[0109] The electrodes in the first and second detection regions are electrically connected in series: specifically, upper electrode 331 and upper electrode 333 are connected in series, and lower electrode 441 and lower electrode 443 are connected in series, or intermediate electrode 251 and intermediate electrode 253 are connected in series.

[0110] [Actions and Effects of the Acoustic Converter 200 According to the Eighth Embodiment] Acoustic transducer 200 according to the eighth embodiment includes support substrate (fixed frame) 211 and diaphragm 220, which is a piezoelectric element fixed to support substrate 211. Diaphragm 220 has first detection regions 323, 423 and second detection regions 325, 425, which are multiple detection regions capable of detecting physical quantities, and non-detection regions 324, 424, which do not detect physical quantities. Electrodes in the multiple detection regions are electrically connected in series.

[0111] In the acoustic transducer 200 of this embodiment, the physical quantity can be detected by detecting the deformation of the diaphragm 220 due to deformation of the diaphragm 220. In the acoustic transducer 200, first detection areas 323, 423 and second detection areas 325, 425 are formed, and the electrodes of these multiple detection areas are electrically connected in series, thereby improving the sensitivity of the diaphragm 220.

[0112] In the acoustic transducer 200, the piezoelectric element is a vibration plate (diaphragm) 220, and an outer periphery 222 of the vibration plate 220 (outer periphery of the diaphragm) is a fixed end fixed to a support substrate 211.

[0113] In the acoustic transducer 200, the multiple detection regions include first detection regions 323 and 423 which are inner detection regions arranged at positions close to the center C11 of the diaphragm 220 in the radial direction of the diaphragm 220, and second detection regions 325 and 425 which are outer detection regions arranged at positions far from the center C11 of the diaphragm 220 in the radial direction of the diaphragm 220. Non-detection regions 324 and 424 are formed between the inner detection regions and the outer detection regions in the circumferential direction of the diaphragm 220.

[0114] In the acoustic transducer 200 of this embodiment, as the diaphragm 220 deforms, charges are generated in response to the diaphragm 220, and the charges generated are detected in the first detection areas 323, 423 and the second detection areas 325, 425. In the acoustic transducer 200, the electrodes are divided in the radial direction of the diaphragm 220, thereby forming the first detection areas 323, 423, the non-detection areas 324, 424, and the second detection areas 325, 425. In such an acoustic transducer 200, the sensitivity for detecting charges in response to sound pressure can be improved.

[0115] 17 is a side view illustrating the distribution of electric charges generated on diaphragm 220 as it deforms under sound pressure. Diaphragm 220 has outer periphery 222 fixed to support substrate 211 in the radial direction. As shown in FIG. 17, the area near inflection point P12 is less likely to deform, and the amount of electric charge generated is small. Inflection point P12 and the area nearby, where the amount of electric charge generated is small, are included in second detection areas 325, 425.

[0116] In contrast, the area close to the center C11 of the diaphragm 220 and near the outer periphery 222 of the diaphragm 220 are largely deformed and generate a large amount of electric charge. The center C11 of the diaphragm 220 and the area around it are included in the first detection areas 323, 423. The area near the outer periphery 222 of the diaphragm 220 is included in the second detection areas 325, 425. In the acoustic transducer 200, the area including the inflection point P12 where little electric charge is generated is not included in the first detection areas 323, 423 and the second detection areas 325, 425. This makes it possible to improve the signal-to-noise ratio in the acoustic transducer 200 and to detect electric charge with high sensitivity.

[0117] [Electrode end shape] Next, the shape of the electrode end portions will be described. As shown in Fig. 16, the end portions of the upper electrodes 331-333, the lower electrodes 441-443, and the intermediate electrodes 251-253 may be tapered. The electrode end portions are end portions that face each other in the radial direction of the diaphragm 220. The tapered shape of the electrode end portions is formed so that the lower side protrudes more than the upper side.

[0118] In this way, by tapering the ends of the lower electrodes 441 to 443, it is possible to make the steps gentler at the boundaries between the lower electrodes 441 to 443 and the electrode-free regions 483, 484. This makes it possible to suppress deterioration in the crystallinity of the piezoelectric layer 460. The same applies to the boundaries between the other electrodes and the electrode-free regions.

[0119] [Sound transducer 200B according to the ninth embodiment] Next, an acoustic transducer 200B according to a ninth embodiment will be described. FIG. 18 is a plan view illustrating the acoustic transducer 200B according to the ninth embodiment. FIG. 19 is a cross-sectional view illustrating the acoustic transducer according to the ninth embodiment, taken along line IX-IX in FIG. 18. The acoustic transducer 200B according to the ninth embodiment shown in FIGS. 18 and 19 differs from the acoustic transducer 200 according to the eighth embodiment shown in FIG. 12 in that the acoustic transducer 200B according to the ninth embodiment includes a plurality of upper electrodes 331B, 333B divided in the circumferential direction, a plurality of lower electrodes 441B, 443B divided in the circumferential direction, a plurality of intermediate electrodes 251B, 253B divided in the circumferential direction, and electrode-free regions 385, 386 extending in the radial direction. Note that, in the description of the acoustic transducer 200B according to the ninth embodiment, descriptions similar to those of the acoustic transducer 200 according to the eighth embodiment may be omitted.

[0120] [Laminate 300B] As shown in Fig. 19, the acoustic transducer 200B includes laminates 300B and 400B. The laminate 300B includes an upper electrode layer 330B, a piezoelectric layer 360, and an intermediate electrode layer 250B. The upper electrode layer 330B includes a plurality of upper electrodes 331B divided in the circumferential direction, a circumferentially continuous upper electrode 332, and a plurality of upper electrodes 333B divided in the circumferential direction. The intermediate electrode layer 250B includes a plurality of intermediate electrodes 251B divided in the circumferential direction, a circumferentially continuous intermediate electrode 252, and a plurality of intermediate electrodes 253B divided in the circumferential direction.

[0121] [First detection area 323B] The laminate 300B has a first detection region 323B, a non-detection region 324B, and a second detection region 325B. The first detection region 323B has a plurality of upper electrodes 331B, a piezoelectric layer 360, and a plurality of intermediate electrodes 251B. The first detection region 323B includes a plurality of piezoelectric elements. In the first detection region 323B, the piezoelectric elements have an upper electrode 331B, a piezoelectric layer 360, and an intermediate electrode 251B.

[0122] [Second detection area 325B] The second detection region 325B includes a plurality of upper electrodes 333B, a piezoelectric layer 360, and a plurality of intermediate electrodes 253B. The second detection region 325B includes a plurality of piezoelectric elements. In the second detection region 325B, the piezoelectric elements include the upper electrodes 333B, the piezoelectric layer 360, and the intermediate electrodes 253B.

[0123] As shown in FIG. 18, the upper electrode layer 330B has electrode-free regions 381 and 383 and electrode-free regions 385 and 386 formed therein.

[0124] [Electrode non-formation area 385] The electrode-free regions 385 divide the upper electrode into multiple regions in the first detection region 323B. The electrode-free regions 385 extend radially from the center of the diaphragm 220B. The multiple electrode-free regions 385 are arranged at equal intervals in the circumferential direction. The multiple upper electrodes 331B have approximately the same area. The sound transducer 200B has, for example, ten upper electrodes 331B.

[0125] [Electrode non-formation area 386] The electrode-free regions 386 divide the upper electrode into multiple sections in the second detection region 325B. The electrode-free regions 386 extend radially from the electrode-free regions 382 toward the outer circumferential edge 222 of the diaphragm 220. The multiple electrode-free regions 386 are arranged at equal intervals in the circumferential direction.

[0126] [Laminate 400B] 19, the laminate 400B has an intermediate electrode layer 250B, a piezoelectric layer 460, and a lower electrode layer 440B. The intermediate electrode layer 250B serves as both the laminate 300B and the laminate 400B. The lower electrode layer 440B has a plurality of lower electrodes 441B divided in the circumferential direction, a lower electrode 442 that is continuous in the circumferential direction, and a plurality of lower electrodes 443B divided in the circumferential direction.

[0127] [First detection area 423B] The laminate 400B has a first detection region 423B, a non-detection region 424, and a second detection region 425B. The first detection region 423B has a plurality of intermediate electrodes 251B, a piezoelectric layer 460, and a plurality of lower electrodes 441B. The first detection region 423B includes a plurality of piezoelectric elements. In the first detection region 423B, the piezoelectric elements have an intermediate electrode 251B, a piezoelectric layer 460, and a lower electrode 441B. In the first detection region 423B, the areas of the plurality of lower electrodes 441B are approximately equal to each other.

[0128] [Second detection area 425B] The second detection region 425B has an intermediate electrode 253B, a piezoelectric layer 460, and a plurality of lower electrodes 443B. The second detection region 425B includes a plurality of piezoelectric elements. In the second detection region 425B, the piezoelectric elements have an intermediate electrode 253B, a piezoelectric layer 460, and a lower electrode 443B. In the second detection region 425B, the areas of the plurality of lower electrodes 443B are approximately equal to each other.

[0129] The lower electrode layer 440B and the intermediate electrode layer 250B of the stack 400B include a radially extending electrode-free region, similar to the upper electrode layer 330B of the stack 300B.

[0130] [Capacitance of piezoelectric element] In the laminate 300B, the capacitances of the plurality of piezoelectric elements aligned in the circumferential direction of the diaphragm 220 are approximately equal to each other. In the laminate 400B, the capacitances of the plurality of piezoelectric elements aligned in the circumferential direction of the diaphragm 220 are approximately equal to each other.

[0131] [Series connection of multiple piezoelectric elements] In the vibration plate 220B, the plurality of piezoelectric elements arranged in the circumferential and radial directions are electrically connected in series.

[0132] [Actions and Effects of the Sound Converter 200B According to the Ninth Embodiment] The sound transducer 200B according to the ninth embodiment also provides the same effects as the sound transducer 200 according to the eighth embodiment.

[0133] In acoustic transducer 200B, the multiple detection regions include first detection regions 323B and 423B, which are inner detection regions located near center C11 of diaphragm 220B in the radial direction of diaphragm 220B, and second detection regions 325B and 425B, which are outer detection regions located far from center C11 of diaphragm 220B in the radial direction of diaphragm 220B. Non-detection regions 324, 424 include electrode-free regions 381, 382 formed between the inner and outer detection regions in the circumferential direction of diaphragm 220, and multiple electrode-free regions 385, 386 extending in the radial direction of the diaphragm and formed at intervals in the circumferential direction of the diaphragm.

[0134] According to such an acoustic transducer 200B, by having the electrode-free areas 385 and 386 extending in the radial direction, the electrodes in the detection area can be divided into a plurality of areas.

[0135] [Modification of the acoustic transducer 200B according to the ninth embodiment] In acoustic transducer 200B, diaphragm (piezoelectric element) 220B has a piezoelectric film, and the piezoelectric film includes lower electrode layer 440B, lower piezoelectric layer 460 formed on lower electrode layer 440B, intermediate electrode layer 250 formed on lower piezoelectric layer 460, upper piezoelectric layer 360 formed on intermediate electrode layer 250B, and upper electrode layer 330 formed on upper piezoelectric layer 360. Between a plurality of detection regions (first detection regions 323B, 423B and second detection regions 325B, 425B), there is provided an electrode-free region (first electrode-free region) where the upper electrode and lower electrode are not formed, or an electrode-free region (second electrode-free region) where the intermediate electrode is not formed.

[0136] In acoustic transducer 200B, when an electrode no-formation region (first electrode no-formation region) is formed in the upper electrode and the lower electrode, an electrode no-formation region (second electrode no-formation region) may not be formed in the intermediate electrode. In acoustic transducer 200B, when an electrode no-formation region (second electrode no-formation region) is formed in the intermediate electrode, an electrode no-formation region (first electrode no-formation region) 381, 382, ​​483, 484 may not be formed in the upper electrode and the lower electrode.

[0137] Furthermore, in the detection region, the upper electrode, intermediate electrode, and lower electrode may be divided in the circumferential direction. In the circumferential direction, the division position (electrode-free region) of the upper electrode and the division position of the intermediate electrode may be different. Similarly, in the circumferential direction, the division position of the lower electrode and the division position of the intermediate electrode may be different.

[0138] [Circuit diagram of the acoustic transducer 200B according to the ninth embodiment] Next, a circuit diagram of the sound transducer 200B according to the ninth embodiment will be described below. Fig. 20 is a circuit diagram of the sound transducer 200B according to the ninth embodiment.

[0139] 20, the acoustic transducer 200B has a MEMS microphone chip 201. A diaphragm 220B is mounted on the MEMS microphone chip 201. The diaphragm 220B has a plurality of first detection areas 323B, 423B and second detection areas 325B, 425B.

[0140] The multiple first detection regions 323B, 423B include an upper electrode 331B, an intermediate electrode 251B, and a lower electrode 441B. The multiple second detection regions 325B, 425B include an upper electrode 333B, an intermediate electrode 253B, and a lower electrode 443B. The upper electrode 331B includes upper electrodes 331B-1, 331B-2, ..., 331B-n that are divided into n pieces in the circumferential direction, where n is a natural number. The same applies to the other upper electrodes, intermediate electrodes, and lower electrodes.

[0141] In the first detection areas 323B and 423B of the acoustic transducer 200B, the piezoelectric output charge between the upper electrode 331B and the intermediate electrode 251B, and the piezoelectric output charge between the intermediate electrode 251B and the lower electrode 441B can be detected. The multiple piezoelectric elements arranged in the circumferential direction are connected in series.

[0142] In the second detection areas 325B and 425B of the acoustic transducer 200B, the piezoelectric output charge between the upper electrode 333B and the intermediate electrode 253B, and the piezoelectric output charge between the intermediate electrode 253B and the lower electrode 443B can be detected. The multiple piezoelectric elements arranged in the circumferential direction are connected in series.

[0143] Furthermore, MEMS microphone chip 201 has pads 213 and 214. Electrodes of a plurality of piezoelectric elements are connected to pads 213 and 214. Acoustic transducer 200B includes IC 202 connected to pad 213. IC 202 is an amplifier that amplifies the output signal of the piezoelectric element of diaphragm 220B. Note that IC 202 may be provided with a function of amplifying the output signal of the piezoelectric element of diaphragm 220B and then performing AD (analog-to-digital) conversion.

[0144] The polarity of the charge generated in the second detection regions 325B, 425B is opposite to the polarity of the charge generated in the first detection regions 323B, 423B. Therefore, the second detection regions 325B, 425B and the first detection regions 323B, 423B are connected in series with the wiring reversed.

[0145] [Electrode connection] In the acoustic transducer 200B, the upper electrodes 331B and the intermediate electrodes 251B of the first detection areas 323B may be electrically connected in series. Similarly, the upper electrodes 333B and the intermediate electrodes 253B of the second detection areas 325B may be electrically connected in series.

[0146] In acoustic transducer 200B, lower electrodes 441B and intermediate electrodes 251B of multiple first detection areas 423B may be electrically connected in series. Similarly, lower electrodes 433B and intermediate electrodes 253B of multiple second detection areas 425B may be electrically connected in series.

[0147] In the sound transducer 200B, the upper electrodes and lower electrodes of each of the plurality of detection regions may be electrically connected in parallel.

[0148] [Relationship between sensing area diameter ratio and normalized SNR] Next, the relationship between the sensing area diameter ratio and the normalized SNR will be described. Fig. 21 is a graph showing the relationship between the sensing area diameter ratio and the normalized SNR. In Fig. 21, the horizontal axis represents the sensing area diameter ratio [%], and the vertical axis represents the normalized SNR [%]. The graph shown in Fig. 21 is a graph showing the relationship between the sensing area diameter ratio and the normalized SNR in the sound transducer 200 according to the eighth embodiment shown in Fig. 12.

[0149] The "sensing area ratio" can be expressed by the following formula (1). Sensing area ratio = (electrode separation radius / diaphragm radius) × 100 (1) The "electrode section separation section radius" may be the radius of inner detection area 323. The "diaphragm radius" may be the radius of diaphragm 220. In Figure 12, the diameter φ323 of inner detection area 323 and the diameter φ325 of diaphragm 220 are shown.

[0150] The inner diameter of opening 221 covered by diaphragm 220 was set as 100% of the sensing area diameter ratio. When 71% of the area is covered by an electrode-free area, the normalized SNR is set to 100%. In FIG. 12, "◯" indicates the position of the boundary between inner detection area 323 and non-detection area 324. In FIG. 12, "X" indicates the position of the boundary between outer detection area 325 and non-detection area 324.

[0151] The SNR normalized value of inner detection region 323 is a value obtained when the boundary between outer detection region 325 and non-detection region 324 is set to 71% and the outer diameter Φ323 of inner detection region 323 is changed.

[0152] The SNR normalized value of outer detection region 325 is a value obtained when the boundary between inner detection region 323 and non-detection region 324 is set to 71% and the inner diameter Φ324 of outer detection region 325 is changed.

[0153] 21, the SNR normalized value of the inner detection area 323 was maximum at point P21. The sensing area diameter ratio at point P21 was 59%.

[0154] 21, the SNR normalized value of the outer detection area 325 was maximum at point P22. The sensing area diameter ratio at point P22 was 81%.

[0155] When the sensing area diameter ratio of the inner detection area 323 was 44% or more and 71% or less, the normalized SNR value was 100% or more. When the sensing area diameter ratio of the inner detection area 323 was 49% or more and 67% or less, the normalized SNR value was 104% or more. When the sensing area diameter ratio of the inner detection area 323 was 51% or more and 65% or less, the normalized SNR value was 106% or more.

[0156] The sensing area diameter ratio of the inner detection area 323 is preferably 44% or more and 71% or less, more preferably 49% or more and 67% or less, and even more preferably 51% or more and 65% or less.

[0157] When the sensing area diameter ratio of the outer detection area 325 was 71% or more and 89% or less, the normalized SNR value was 100% or more. When the sensing area diameter ratio of the outer detection area 325 was 75% or more and 87% or less, the normalized SNR value was 104% or more. When the sensing area diameter ratio of the outer detection area 325 was 78% or more and 84% or less, the normalized SNR value was 106% or more.

[0158] The sensing area diameter ratio of outer detection area 325 is preferably 71% or more and 89% or less, more preferably 75% or more and 87% or less, and even more preferably 78% or more and 84% or less.

[0159] When the sensing area diameter ratio of inner detection area 323 is 71% and the sensing area diameter ratio of outer detection area 325 is 71%, the electrode division position may be at the 71% position.

[0160] In the acoustic transducer 200, when the sensing area diameter ratio of the outer detection area 325 is 71% or more and 89% or less, the sensing area diameter ratio of the inner detection area 323 may be an outer value of the range of 44% or more and 71% or less. In such a case, the SNR normalized value may become high.

[0161] In the acoustic transducer 200, when the sensing area diameter ratio of the inner detection area 323 is 44% or more and 71% or less, the sensing area diameter ratio of the outer detection area 325 may be a value outside the range of 71% or more and 89% or less. In such a case, the SNR normalized value may become high.

[0162] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form.

[0163] In the above embodiment, the acoustic transducers 100, 100B to 100G are illustrated as having a cantilever 20 with a cantilever structure having a free end 21 and a fixed end 22, but the acoustic transducers 100, 100B to 100G are not limited to this. The acoustic transducers 100, 100B to 100G may also have a doubly supported beam structure in which both ends of the beam structure are connected to opposing portions of the fixed frame 10 as fixed ends 22. In the acoustic transducers 100, 100B to 100G of this structure, when sound pressure is applied, the central portion of the doubly supported beam bends in the thickness direction. The acoustic transducers 100, 100B to 100G may also have a doubly supported beam instead of the cantilever 20 (20A to 20D).

[0164] In the above embodiment, an example is given of a case where an upper electrode 30, a lower electrode 40, and an intermediate electrode 50 are formed in the non-detection region 24, but at least one of the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may not be formed in the non-detection region 24, or the upper electrode 30 and the lower electrode 40 may not be formed, or the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may not be formed. [Explanation of symbols]

[0165] 100, 100B, 100C, 100D, 100E, 100F, 100G, 200, 200B: acoustic transducer, 10: fixed frame, 20: cantilever, 20A: cantilever (first cantilever), 20B: cantilever (second cantilever), 20C: cantilever (first cantilever), 20D: cantilever (second cantilever), 20F: cantilever (second cantilever), 21: free end, 22: fixed end, 23: detection Region, 24: Non-detection region, 30: Upper electrode, 40: Lower electrode, 50, 50G: Intermediate electrode, 61: First piezoelectric layer, 62: Second piezoelectric layer, 81: Non-electrode region (region where upper electrode is not formed), 82: Non-electrode region (region where lower electrode is not formed), 83: Non-electrode region (region where intermediate electrode is not formed), W20: Width (width of first cantilever), W20F: Width (width of second cantilever), 220, 220B: Vibration plate ( Piezoelectric element, diaphragm), 222: outer periphery (fixed body), 323, 323B: first detection area (inner detection area), 324: non-detection area (first non-detection area), 325, 325B: second detection area (outer detection area), 331, 331B: upper electrode of detection area, 332: upper electrode of non-detection area, 333, 333B: upper electrode of detection area, 381, 382: non-electrode forming area, 385, 386: non-electrode forming area (second non-detection area), 423, 423B: first detection area (inner detection area), 424: non-detection area (first non-detection area), 425, 425B: second detection area (outer detection area), 431, 431B: upper electrode of detection area, 432: upper electrode of non-detection area, 433, 433B: upper electrode of detection area, 481, 482: electrode-free area, C11: center of diaphragm, X: X-axis direction (first direction), Y: Y-axis direction (direction intersecting with the first direction), Z: Z-axis direction (plate thickness direction).

Claims

1. A fixed frame and a piezoelectric element fixed to the fixed frame, The piezoelectric element is a detection area capable of detecting a physical quantity; and a non-detection region in which no physical quantity is detected.

2. the piezoelectric element has a piezoelectric film, The piezoelectric film is A lower electrode; a first piezoelectric layer formed on the lower electrode; an intermediate electrode formed on the first piezoelectric layer; a second piezoelectric layer formed on the intermediate electrode; an upper electrode formed on the second piezoelectric layer; The acoustic transducer according to claim 1 , further comprising an electrode-free region between the detection region and the non-detection region, in which at least one of the lower electrode, the intermediate electrode, and the upper electrode is not formed.

3. the piezoelectric element is a cantilever having one end fixed to the fixed frame and the other end free, the cantilever extending from the fixed frame to the inside of the fixed frame; The cantilever is 3. The acoustic transducer according to claim 1, further comprising a first cantilever and a second cantilever that face each other in a first direction in which the cantilevers extend.

4. The acoustic transducer according to claim 3 , wherein the detection region has a length from the fixed end in a first direction in which the cantilever extends, the length being 20% ​​to 75% of the total length of the cantilever.

5. The acoustic transducer according to claim 4 , wherein the detection region has a length in the first direction from the fixed end that is 30% to 60% of the total length of the cantilever.

6. The acoustic transducer according to claim 5 , wherein the detection region has a length in the first direction from the fixed end that is 40% to 45% of the total length of the cantilever.

7. In a first direction in which the cantilever extends, 4. The acoustic transducer according to claim 3, wherein the end of the detection region closer to the free end is formed at a position from the fixed end that is 20% to 75% of the total length of the cantilever.

8. In the first direction, 8. The acoustic transducer according to claim 7, wherein the end of the detection region closer to the free end is formed at a position from the fixed end that is 30% to 60% of the total length of the cantilever.

9. In the first direction, 9. The acoustic transducer according to claim 8, wherein the end of the detection region closer to the free end is formed at a position between 40% and 45% of the total length of the cantilever from the fixed end.

10. the piezoelectric element is a diaphragm, 3. The acoustic transducer according to claim 1, wherein the outer periphery of the diaphragm is a fixed end fixed to the fixed frame.

11. The plurality of detection regions include: an inner detection area disposed at a position close to the center of the diaphragm in the radial direction of the diaphragm; an outer detection region disposed at a position far from the center of the diaphragm in the radial direction of the diaphragm, The non-detection region is a first non-detection region provided in the circumferential direction of the diaphragm and formed between the inner detection region and the outer detection region; a plurality of second non-detection regions extending in a radial direction of the diaphragm and formed at intervals in a circumferential direction of the diaphragm; a radially outer end of the inner detection region is formed at a position that is 44% or more and 71% or less of a radius of the diaphragm from the center of the diaphragm, The radially inner end of the outer detection region is The acoustic transducer described in claim 10, wherein the diaphragm is positioned radially outward from the radially outer end of the inner detection area and is formed at a position that is 71% or more and 89% or less of the radius of the diaphragm from the center of the diaphragm.

12. a radially outer end of the inner detection region is formed at a position that is 49% or more and 67% or less of a radius of the diaphragm from the center of the diaphragm, The acoustic transducer according to claim 11 , wherein the radially inner end of the outer detection region is formed at a position that is 75% to 87% of the radius of the diaphragm from the center of the diaphragm.

13. a radially outer end of the inner detection region is formed at a position that is 51% or more and 65% or less of a radius of the diaphragm from the center of the diaphragm, The acoustic transducer according to claim 11 , wherein the radially inner end of the outer detection region is formed at a position that is 78% to 84% of the radius of the diaphragm from the center of the diaphragm.

14. The acoustic transducer according to claim 2 , wherein the electrode-free region is a region where the intermediate electrode is not formed.

15. The electrode-free region is a region where the lower electrode is not formed; The acoustic transducer according to claim 2 , further comprising: a region where the upper electrode is not formed.

16. The acoustic transducer according to claim 15, wherein the area where the lower electrode is not formed is located farther from the fixed end fixed to the fixed frame than the area where the upper electrode is not formed.

17. The acoustic transducer according to claim 3 , wherein a direction in which the cantilever protrudes is a first direction, and a width of the first cantilever is wider than a width of the second cantilever in a direction intersecting the first direction.

18. A fixed frame and a doubly supported beam, both ends of which are fixed to opposing portions of the fixed frame; The doubly supported beam is a detection area capable of detecting a physical quantity; and a non-detection region in which no physical quantity is detected.

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