MEMS elements

Abstract

Provided is a MEMS element. A backplate (7) that includes a fixed electrode (5) and a vibrating membrane (3) which includes a movable electrode are disposed on a substrate (1) provided with a back chamber (9) so as to face one another with a spacer (5) interposed therebetween. The vibrating film (3) is comprises: column (11) that is connected to the backplate (7); column-side slits (12); and peripheral-side slits (13). A plurality of vibrating sections (14) are formed in the vibrating membrane (3). A central section of the vibrating membrane (3) is connected to the backplate (7) by the column (11), so that the amplitude of the central section of the vibrating membrane (3) can be restricted. Each of the plurality of vibrating sections is provided with the column-side slit (12) on the side facing a joint between the column (11) and the vibrating membrane (3), and is provided with the peripheral-side slit (13) in a peripheral section, which makes the difference between the amplitudes of the central section and the peripheral section of the vibrating membrane (3) small.

Description

[Technical field]

[0001] The present disclosure relates to a capacitive MEMS element used as a microphone, various sensors, and the like. [Background technology]

[0002] A known example of a MEMS (Micro Electro Mechanical Systems) element that uses semiconductor processes is a capacitive MEMS element in which a backplate including a fixed electrode with multiple acoustic holes and a vibrating membrane including a movable electrode are arranged on a substrate with an insulating film sandwiched between them as a spacer.

[0003] A capacitive MEMS element detects the displacement of a movable electrode caused by the vibration of a vibrating membrane as a change in capacitance between the movable electrode and a fixed electrode, and outputs a detection signal. This type of MEMS element is described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-55087 A Summary of the Invention [Problem to be solved by the invention]

[0005] For example, FIG. 11 shows a schematic cross-sectional view for explaining a conventional capacitive MEMS element. As shown in FIG. 11, in the conventional capacitive MEMS element, an insulating film 52 is formed on a substrate 51 serving as a support substrate, and a vibrating film 53 including a conductive movable electrode is formed on the insulating film 52. Furthermore, a spacer 54 made of an insulating film and a back plate 57 composed of a conductive fixed electrode 55 and an insulating film 56 are laminated to form an air gap structure. 58 is an acoustic hole formed in the back plate 57, 59 is a back chamber formed in the substrate 51, and 60 is a slit formed in the peripheral portion of the vibrating film 53. When sound pressure or the like is applied to such a capacitive MEMS element, the center portion of the vibrating film 53 vibrates greatly. At this time, the peripheral portion of the vibrating film 53 bonded to the substrate 51 and the spacer 54 is made to vibrate easily by forming the slit 60, but the amplitude of the peripheral portion is smaller than that of the central portion.

[0006] Generally, in a capacitive MEMS element, if the spring constant of the diaphragm 53 is reduced to increase the sensitivity, the displacement becomes too large, causing contact between the diaphragm 53 and the back plate 57, or causing a difference in the amplitude between the center of the diaphragm 53, which has a large displacement, and the peripheral portion, which has a small displacement. As a result, the area of ​​the diaphragm 53 that displaces parallel to the back plate 57 becomes smaller, causing a problem of deterioration of the AOP (Acoustic overload point).

[0007] However, when using this capacitive MEMS element as a microphone, it is necessary to improve the AOP while minimizing the decrease in sensitivity.

[0008] Therefore, an object of the present disclosure is to provide a MEMS device having good sensitivity and an improved AOP. [Means for solving the problem]

[0009] One embodiment of a MEMS element of the present disclosure comprises a substrate having a back chamber, a vibration membrane including a movable electrode bonded onto the substrate, and a back plate including a fixed electrode arranged opposite the movable electrode, wherein the vibration membrane has a pillar in its center connecting the back plate and the vibration membrane, and has a plurality of vibration parts in a region between a joint between the pillar and the vibration membrane and a peripheral portion of the vibration membrane, each of the plurality of vibration parts being formed from a region surrounded by a pillar-side slit joined to a first slit part and a second slit part extending in mutually different directions from the joint side between the pillar and the vibration membrane toward the peripheral portion, and a peripheral-side slit arranged on the peripheral portion between an extension line from the first slit part toward the peripheral portion and an extension line from the second slit part toward the peripheral portion. Effect of the Invention

[0010] According to the MEMS element of the present disclosure, since the center part of the diaphragm is joined to the back plate by a pillar, the amplitude of the center part of the diaphragm is suppressed, and further, by providing a slit in the diaphragm, a vibration part with a small difference in the amplitude between the center part and the peripheral part of the diaphragm can be formed. A plurality of such vibration parts are formed on the diaphragm, and a large detection signal can be obtained as a whole. Furthermore, by dividing the diaphragm into a plurality of vibration parts with small areas, the force applied to each vibration part is reduced when a bias voltage is applied between the fixed electrode and the movable electrode, and the distortion of the detection signal is reduced. Thus, according to the present disclosure, it is possible to provide a MEMS element that can improve the AOP without reducing the sensitivity. As a result, a high-performance MEMS element for microphones can be obtained. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of a MEMS element (embodiment 1) according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic plan view illustrating a vibrating membrane portion in the first embodiment. [Diagram 3] 5A to 5C are diagrams illustrating vibration characteristics of a vibration section in the first embodiment. [Figure 4] 5A to 5C are diagrams illustrating vibration characteristics of a vibration section in the first embodiment. [Diagram 5] 5A to 5C are diagrams illustrating vibration characteristics of a vibration section in the first embodiment. [Figure 6] 5A to 5C are diagrams illustrating vibration characteristics of a vibration section in the first embodiment. [Figure 7] FIG. 11 is a schematic plan view illustrating a vibrating membrane portion in a MEMS element (embodiment 2) according to another embodiment of the present disclosure. [Figure 8] FIG. 13 is a schematic plan view illustrating a vibrating membrane portion in a MEMS element (embodiment 3) according to still another embodiment of the present disclosure. [Figure 9] FIG. 11 is a schematic cross-sectional view of a MEMS element (embodiment 4) according to still another embodiment of the present disclosure. [Figure 10] 13 is a schematic plan view illustrating a vibrating membrane portion in embodiment 4. FIG. [Figure 11] 1 is a schematic cross-sectional view of a conventional capacitive MEMS element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, embodiments of the MEMS element of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to these embodiments. For the purpose of explanation, some dimensions in Figures 1 and 2 and 7 to 11 are exaggerated, and the dimensional ratios of each member and part are not accurately shown.

[0013] (Embodiment 1) Fig. 1 is a schematic cross-sectional view for explaining a first embodiment of a MEMS element of the present disclosure. As shown in Fig. 1, in one embodiment of a MEMS element 100 of the present disclosure, an insulating film 2 made of, for example, a thermal oxide film is formed on a substrate 1 made of, for example, a silicon substrate as a support substrate, and a vibrating film 3 including a conductive movable electrode made of, for example, polysilicon is formed on the insulating film 2. Furthermore, an insulating spacer 4 made of, for example, a USG (Undoped Silicate Glass) film, and a back plate 7 including a conductive fixed electrode 5 made of, for example, polysilicon, and an insulating film 6 made of, for example, silicon nitride are laminated.

[0014] In the MEMS element of this embodiment, the vibration membrane 3 and the back plate 7 are each joined and connected to a pillar 11, and are provided with pillar-side slits 12A to 12D and peripheral-side slits 13A to 13D.

[0015] Fig. 2 is a plan view schematic diagram illustrating the vibration membrane portion of the MEMS element shown in Fig. 1, and is a diagram illustrating the arrangement of pillar 11, pillar-side slits 12A-12D, and peripheral edge side slits 13A-13D. In Fig. 1, back chamber 9 formed in substrate 1 is circular, and the outer periphery in Fig. 2 corresponds to the outer periphery of back chamber 9 of substrate 1. The cross-sectional schematic diagram shown in Fig. 1 is a cross-sectional diagram passing through the center of pillar 11 and two pillar-side slits 12A and 12C, or 12B and 12D, which face each other with respect to pillar 11 as the center, in Fig. 2.

[0016] 2, when the portion of the diaphragm 3 corresponding to the back chamber 9 is circular, the pillar 11 is disposed on the diaphragm 3 so that the center of the diaphragm 3 coincides with the center of the circular pillar 11. A plurality of vibrating sections 14A to 14D are formed in the region between the joint of the diaphragm 3 with the pillar 11 and the peripheral portion of the diaphragm 3. Therefore, the pillar-side slits 12A to 12D and the peripheral portion-side slits 13A to 13D are disposed around the pillar 11. In the present embodiment shown in FIG. 2, an example in which four vibrating sections 14A to 14D are formed is shown.

[0017] A detailed description will be given by taking one vibrating part as an example. In the vibrating part 14A formed in the upper right region of the pillar 11 of the vibrating membrane 3 shown in Fig. 2, a pillar-side slit 12A is formed by a first slit part 12a extending from the pillar 11 side in parallel to the radial direction of the vibrating membrane 3 and in the upward direction in the drawing, and a second slit part 12b extending from the pillar 11 side in parallel to the radial direction of the vibrating membrane 3 and in the right direction in the drawing, and joining to the first slit part 12a at a joining angle of 90 degrees.

[0018] By forming the pillar-side slit 12A, a part of the diaphragm 3 on the pillar 11 side, the vibration of which is restricted by the pillar 11, becomes more likely to vibrate.

[0019] Furthermore, by forming peripheral slits 13A in the peripheral portion of the vibrating membrane 3 that is bonded to the substrate 1, the insulating film 2, and the spacer 4, the peripheral portion of the vibrating membrane 3, whose vibration is restricted by bonding to the substrate 1, etc., becomes more likely to vibrate. These peripheral slits 13A have the same effect as the slits 60 formed in the general MEMS element described in Fig. 11, but in particular, the peripheral slits 13A in this embodiment are formed to open to the positions intersecting with the extension lines in the extension direction of the first slit portion 12a and the extension line in the extension direction of the second slit portion 12b, each shown by a two-dot chain line in Fig. 2, or to the vicinity thereof, in order to make the area surrounded by these extension lines into one vibrating portion.

[0020] In this way, the area surrounded by the pillar-side slits 12A and the peripheral-side slits 13A becomes one vibrating part 14A. Similarly, the area surrounded by the pillar-side slits 12B and the peripheral-side slits 13B becomes one vibrating part 14B, the area surrounded by the pillar-side slits 12C and the peripheral-side slits 13C becomes one vibrating part 14C, and the area surrounded by the pillar-side slits 12D and the peripheral-side slits 13D becomes one vibrating part 14D. The multiple vibrating parts 14A to 14D are evenly arranged around the center of the pillar 11 (the center of the vibrating membrane 3), thereby forming four vibrating parts with uniform characteristics.

[0021] Next, the vibration characteristics of the vibrating parts will be described using the vibration characteristics of vibrating part 14A as an example. The vibration characteristics of vibrating part 14A vary depending on the material and thickness of vibrating membrane 3 and its size. Furthermore, the vibration characteristics can be changed by the shapes of pillar side slits 12A and periphery side slits 13A. Note that if the shapes of vibrating parts 14B to 14D are the same as those of vibrating part 14A, the vibration characteristics will be the same as those of vibrating part 14A, so description thereof will be omitted.

[0022] 3 to 6 are diagrams for explaining the vibration characteristics of the vibration part 14A of the MEMS element of this embodiment. The vertical axis of FIG. 3 is the amplitude amount, which is expressed as a relative amount with the largest amplitude being 1.00. The horizontal axis of FIG. 3 is the distance from the center of the vibration membrane 3, and its direction is the radial direction of the vibration membrane 3 from the center of the pillar 11 through the joint between the first slit part 12a and the second slit part 12b of the pillar side slit 12A, and represents the relative distance with the center of the pillar 11 being 0.00 and the outer periphery shown in FIG. 2 being 1.00. In FIG. 3, the amplitude amount of the vibration part 14A is compared when the length of the pillar side slit 12A in the extension direction is changed to 19% (vibration membrane A), 38% (vibration membrane B), and 56% (vibration membrane C), and here, the length of the pillar side slit 12A in the extension direction is expressed as a ratio with the length from the center of the pillar 11 to the outer periphery shown in FIG. 2 being 100. The conditions other than the length of the pillar side slit 12A in the extension direction are the same.

[0023] As shown in Fig. 3, it can be seen that both vibrate between the pillar-side slit 12A and the peripheral-side slit 13A. It can also be seen that the longer the pillar-side slit 12A is (slit length: diaphragm A < diaphragm B < diaphragm C), the larger the amplitude in the vicinity of the pillar-side slit 12A is (amplitude: diaphragm A < diaphragm B < diaphragm C). It can also be seen that the amplitude in the vicinity of the peripheral-side slit 13A changes.

[0024] In particular, in the case of diaphragm B, it can be seen that vibrations with an almost uniform amplitude occur in the entire vibrating part 14A between the pillar-side slit 12A and the periphery-side slit 13A. This indicates that the movable electrode (diaphragm 3) of vibrating part 14A is displaced almost parallel to the opposing fixed electrode 5. Therefore, in terms of improving the AOP, in this embodiment, it is preferable to use diaphragm B as the slit length of pillar-side slit 12A among diaphragms A to C.

[0025] The adjustment of the vibration characteristics of the vibration part 14A is not limited to the adjustment by the length of the column side slit 12A described in FIG. 3. The adjustment of the vibration characteristics of the vibration part 14A can also be made by changing the arrangement of the column side slit 12A. FIG. 4 compares the amplitude of the vibration part 14A when the vibration film B shown in FIG. 3 and the vibration film D are the same conditions such as the slit length, and the column side slit 12A is moved in the peripheral side direction by several percent, with the position from the column 11 to the position corresponding to the outer periphery shown in FIG. 2 being taken as 100. As shown in FIG. 4, when the column side slit 12A is moved to the peripheral side, it can be seen that the column side end of the vibration area moves from the center of the vibration film to the peripheral side. Therefore, the shape of the vibration part 14A changes and the vibration characteristics change. In this case, the area of ​​the vibration part 14A becomes smaller, and the relative amplitude becomes smaller. Therefore, it is preferable to determine the arrangement of the column side slit 12A in order to obtain the desired vibration characteristics. Naturally, moving the pillar-side slit 12A toward the center of the diaphragm 3 also changes the shape of the vibrating part 14A, and the vibration characteristics change. Furthermore, changing the arrangement of the peripheral-side slit 13A also changes the shape of the vibrating part 14A, and therefore the vibration characteristics change. Therefore, the shape and arrangement are changed to achieve the desired vibration characteristics. The following describes the case of the diaphragm B.

[0026] Fig. 5 is a diagram for explaining the vibration characteristics of the vibrating part 14A of the MEMS element of this embodiment having the vibrating membrane B in comparison with the vibration characteristics of a conventional example. The conventional example uses a vibrating membrane 53 of a general conventional MEMS element having the structure shown in Fig. 11. In Fig. 5, each amplitude amount is expressed as a relative amount with the largest amplitude being 1.00. The distance from the center of the vibrating membrane is expressed as a relative distance with the center of the vibrating membrane being 0.00 and the position corresponding to the outer periphery shown in Fig. 2 being 1.00.

[0027] As shown in Fig. 5, in a typical MEMS element shown as a conventional example, the amplitude is greatest at the center of the vibrating membrane 3, and decreases toward the periphery. In other words, the area that can be expressed as a vibrating portion is up to a certain distance from the center, and the area around the periphery does not function as a vibrating portion. In contrast, in the MEMS element of this embodiment, it can be seen that the entire vibrating membrane in the area between the pillar-side slit 12A and the periphery-side slit 13A vibrates relatively uniformly and functions as a vibrating portion (vibrating portion 14A).

[0028] In this embodiment, since it is divided into four vibration parts 14A to 14D as shown in Fig. 2, the signal output from each vibration part is small. However, since it has multiple vibration parts and the area of ​​the vibration parts that displace in the radial direction of the vibration membrane 3 almost parallel to the fixed electrode 5 as shown in Fig. 5 increases, it is possible to obtain sufficiently high sensitivity.

[0029] FIG. 6 shows the change in the amplitude when a sound pressure of 130 dB is applied to the diaphragm 3. There is no significant difference in the amplitude of the diaphragm B of this embodiment and that of the conventional diaphragm. However, when comparing the change in the amplitude, it is found that the diaphragm B of this embodiment has a symmetrical amplitude. In this way, the MEMS element of this embodiment in which the diaphragm 3 including the movable electrode is displaced almost parallel to the fixed electrode 5 improves the AOP. Furthermore, if the diaphragm 3 is made of a material that is easy to vibrate and has a small spring constant, the force applied to each vibrating part is reduced when a bias voltage is applied between the fixed electrode 5 and the movable electrode, so that the distortion of the detection signal is reduced, and the AOP can be improved. In this embodiment, by providing the pillars 11, even if the diaphragm 3 has a small spring constant, problems such as the diaphragm 3 vibrating too much do not occur.

[0030] As shown in Fig. 3 and other figures, the vibration characteristics of the vibrating membrane 3 can be changed as appropriate to desired vibration characteristics. Therefore, the vibrating membrane 3 of the MEMS element of the present disclosure can be configured to include a plurality of vibrating parts with the same vibration characteristics, or to be configured to combine vibrating parts with different vibration characteristics to complement each other. In the latter case, for example, it is possible to configure the detection signal by combining a vibrating part having vibration characteristics in which the amplitude amount on the pillar side is relatively large and the amplitude amount on the periphery side is relatively small with a vibrating part having vibration characteristics in which the amplitude amount on the pillar side is relatively small and the amplitude amount on the periphery side is relatively large.

[0031] (Embodiment 2) Next, a second embodiment of the MEMS element of the present disclosure will be described. Fig. 7 is a plan view schematic diagram illustrating the vibration membrane portion of the MEMS element shown in Fig. 1, and is a diagram illustrating the arrangement of pillar 11, pillar-side slits 12E-12J, and peripheral-side slits 13E-13J. In Fig. 1, back chamber 9 formed in substrate 1 is circular, and the outer periphery in Fig. 7 corresponds to the outer periphery of back chamber 9 of substrate 1.

[0032] As shown in Fig. 7, when the portion of the diaphragm 3 corresponding to the back chamber 9 is circular, the pillar 11 is arranged on the diaphragm 3 so that the center of the diaphragm 3 coincides with the center of the circular pillar 11. A plurality of vibrating portions 14E to 14J are formed in the region between the joint of the diaphragm 3 with the pillar 11 and the peripheral portion of the diaphragm 3. For this purpose, pillar-side slits 12E to 12J and peripheral-side slits 13E to 13J are arranged around the pillar 11. In the present embodiment shown in Fig. 7, an example in which six vibrating portions 14E to 14J are formed is shown.

[0033] A detailed description will be given by taking one vibrating part as an example. In vibrating part 14E formed in the upper right region of pillar 11 of vibrating membrane 3 shown in Fig. 7, pillar side slit 12E is formed by first slit part 12a extending from pillar 11 side in parallel to the radial direction of vibrating membrane 3 in the upward direction in the drawing, and second slit part 12b extending from pillar 11 side in parallel to the radial direction of vibrating membrane 3 in the upper right direction in the drawing and joining to first slit part 12a at a joining angle of 60 degrees.

[0034] By forming the pillar-side slit 12E, a part of the diaphragm 3 on the pillar 11 side, the vibration of which is restricted by the pillar 11, becomes more likely to vibrate.

[0035] Furthermore, by forming peripheral slits 13E in the peripheral portion where vibrating membrane 3 is bonded to substrate 1, insulating film 2, and spacer 4, the peripheral portion of vibrating membrane 3, whose vibration is restricted by bonding to substrate 1, etc., becomes more likely to vibrate. These peripheral slits 13E are formed to open to the position where they intersect with the extension lines in the extension direction of first slit portion 12a and the extension line in the extension direction of second slit portion 12b, both shown by two-dot chain lines in Fig. 7, or to the vicinity thereof, in order to form an area surrounded by these extension lines into one vibrating portion.

[0036] In this way, the area surrounded by the pillar-side slits 12E and the periphery-side slits 13E becomes one vibrating part 14E. Vibrating parts 14F-14J are formed in the same manner. The multiple vibrating parts 14E-14J are evenly arranged around the center of pillar 11 (the center of vibrating membrane 3), resulting in six vibrating parts with uniform characteristics.

[0037] The vibration characteristics of the vibrating parts 14E to 14J of this embodiment show the same tendency as those of the vibrating parts 14A to 14D of the above-mentioned embodiment 1. Specifically, the vibration characteristics of the vibrating parts 14E to 14J change depending on the material, thickness and size of the vibrating membrane 3. Furthermore, the vibration characteristics change depending on the shapes and arrangements of the pillar side slits 12E to 12J and the periphery side slits 13E to 13J.

[0038] Therefore, the vibration parts 14E to 14J of the MEMS element of this embodiment will also exhibit vibration characteristics similar to those shown in Figs. 3 to 6, similar to the vibration part of the first embodiment. In addition, when comparing the vibration part of this embodiment with the vibration part of the first embodiment, the angle (joint angle) at which the first slit part 12a and the second slit part 12b of the column side slit intersect in this embodiment is smaller. Here, when the extension lengths of the first slit part 12a and the second slit part 12b are the same, if the joint angle is small, the amplitude of the column side will be small. Also, if the joint angle is small, the length of the periphery side slit will be short, and the amplitude of the periphery side will be small. Therefore, as explained in Fig. 4, it is preferable to obtain desired vibration characteristics by appropriately setting the length of the column side slits 12E to 12J.

[0039] In this manner, also in this embodiment, the amplitude of the vibration membrane 3 can be made substantially uniform in the regions between the pillar-side slits 12E-12J and the corresponding periphery-side slits 13E-13J. This is because the vibration membrane 3 including the movable electrodes of the vibration portions 14E-14J is displaced substantially parallel to the fixed electrode 5 facing it.

[0040] In this embodiment, since it is divided into six vibration parts 14E to 14J as shown in Fig. 7, the signal output from each vibration part is small. However, since it has multiple vibration parts and the area of ​​the vibration parts that can be displaced in the radial direction of the vibrating membrane 3 almost parallel to the fixed electrode 5 increases, it is possible to obtain sufficiently high sensitivity.

[0041] Furthermore, the AOP is improved because the vibrating membrane 3 including the movable electrode is displaced almost parallel to the fixed electrode 5. Furthermore, by using a vibrating membrane 3 that has a small spring constant and is easy to vibrate, the force applied to each vibrating part can be reduced when a bias voltage is applied between the fixed electrode 5 and the movable electrode of the vibrating part, and the distortion of the detection signal is reduced, thereby improving the AOP. In this embodiment, by providing the pillars 11, problems such as excessive vibration of the vibrating membrane 3 do not occur even when the vibrating membrane 3 has a small spring constant.

[0042] Furthermore, it is also possible to use a configuration including a plurality of vibration sections having the same vibration characteristics, or a configuration in which vibration sections having different vibration characteristics are combined to complement each other.

[0043] (Embodiment 3) Next, a third embodiment of the MEMS element of the present disclosure will be described. Fig. 8 is a schematic plan view illustrating the vibration membrane portion of the MEMS element shown in Fig. 1, and is a diagram illustrating the arrangement of the pillar 11, the pillar-side slits 12K-12N, and the peripheral portion-side slits 13K-13N. In Fig. 1, the back chamber 9 formed in the substrate 1 is circular, and the outer periphery in Fig. 8 corresponds to the outer periphery of the back chamber 9 of the substrate 1. In the MEMS element of this embodiment shown in Fig. 8, the shape of the peripheral portion-side slits 13K-13N is different from that of the MEMS element described in the first embodiment shown in Fig. 2.

[0044] A detailed description will be given by taking one vibrating part as an example. A column-side slit 12K consisting of a first slit part 12a and a second slit part 12b is formed in a vibrating part 14K formed in the upper right region of a column 11 of a vibrating membrane 3 shown in FIG. 8. The column-side slit 12K corresponds to the column-side slit 12A shown in FIG. 2. A peripheral-side slit 13K consisting of a third slit part 13a and a fourth slit part 13b is also formed. The third slit part 13a corresponds to the peripheral-side slit 13A shown in FIG. 2. In this embodiment, the fourth slit part 13b is disposed on the column 11 side of the third slit part 13a, and the third slit part 13a and the fourth slit part 13b constitute the peripheral-side slit 13K.

[0045] The peripheral side slit 13K, which is composed of the third slit portion 13a and the fourth slit portion 13b, is formed to open to the position where it intersects with the extension line in the extension direction of the first slit portion 12a and the extension line in the extension direction of the second slit portion 12b, which are respectively shown by the two-dot chain lines in Fig. 8, or to the vicinity thereof, in order to make one vibration portion out of the area surrounded by the extension line. By adding this fourth slit portion 13b, the peripheral portion of the vibrating membrane 3 is more likely to vibrate than when the peripheral side slits 13A to 13D, which are composed only of the third slit portion 13a shown in Fig. 2, are provided.

[0046] In this way, the area surrounded by the pillar-side slits 12K and the periphery-side slits 13K becomes one vibrating part 14K. The vibrating parts 14L to 14N are each formed in the same manner. The multiple vibrating parts 14K to 14N are evenly arranged around the center of the pillar 11 (the center of the vibrating membrane 3), resulting in four vibrating parts 14K to 14N with uniform characteristics.

[0047] In this embodiment as well, the material and thickness constituting the vibrating membrane 3, its size, the shape and arrangement of the pillar-side slits 12K to 12N and the peripheral-side slits 13K to 13N may be appropriately set so that the vibrating portions 14K to 14N have the desired vibration characteristics.

[0048] Although the present embodiment has been described taking as an example a MEMS element having four vibrating parts 14K to 14N, it is also possible to apply the present embodiment to a MEMS element having six vibrating parts as shown in the above embodiment 2. As the number of vibrating parts increases, the length of the peripheral side slit becomes shorter and the amplitude of vibration of the peripheral part of the vibrating membrane 3 becomes smaller. Therefore, in order to increase the amplitude of the peripheral part, it is preferable to change the amplitude of the peripheral part to achieve desired vibration characteristics by using a configuration including a fourth slit part.

[0049] In this manner, also in this embodiment, the amplitude of the vibration membrane 3 can be made substantially uniform in the regions between the pillar-side slits 12K to 12N and the corresponding periphery-side slits 13K to 13N.

[0050] In this embodiment, the signal output from each of the vibration parts 14K-14N is small because the vibration part is divided into a plurality of vibration parts. However, the area of ​​the vibration parts that are provided with the plurality of vibration parts 14K-14N and displaced in the radial direction of the vibration membrane 3 substantially parallel to the fixed electrode 5 increases, so that a sufficiently high sensitivity can be obtained. In particular, in this embodiment, the amplitude of the peripheral part of the vibration membrane 3 increases, so that a higher sensitivity can be obtained than that of the MEMS element described in the first embodiment.

[0051] Furthermore, the AOP is improved because the vibrating membrane 3 including the movable electrode is displaced almost parallel to the fixed electrode 5. Furthermore, by using a vibrating membrane 3 that has a small spring constant and is easy to vibrate, the force applied to each vibrating part when a bias voltage is applied between the fixed electrode 5 and the movable electrode of the vibrating part can be reduced, and the distortion of the detection signal can be reduced, thereby improving the AOP. In this embodiment, too, by providing the pillars 11, problems such as excessive vibration of the vibrating membrane 3 do not occur even when a vibrating membrane 3 with a small spring constant is used.

[0052] Furthermore, it is also possible to adopt a configuration including vibrating parts with the same vibration characteristics, or a configuration in which vibrating parts with different vibration characteristics are combined to complement each other.

[0053] (Embodiment 4) Next, a fourth embodiment of the MEMS element of the present disclosure will be described. In the first to third embodiments, the peripheral slits 13 are through holes in the diaphragm 3. In contrast, the peripheral slits 13P to 13S of the present embodiment are openings formed at the open end of the diaphragm 3 and the opposing surface of the open end, as shown in FIG. 9. FIG. 9 is a schematic cross-sectional view for explaining the fourth embodiment of the MEMS element of the present disclosure. FIG. 10 is a schematic plan view for explaining the diaphragm portion of the MEMS element shown in FIG. 9, and is a schematic plan view seen from the back plate 7 side excluding the back plate 7. The MEMS element 200 according to the present embodiment is different from the MEMS element 100 shown in FIG. 1 described in the first embodiment in the support structure of the diaphragm 3 including the movable electrode, and some ends of the diaphragm 3 are open ends.

[0054] In the MEMS element of this embodiment, the end of a part of the vibrating membrane 3 facing the substrate 1, the insulating film 2, or the spacer 4 is an open end, and the part of the vibrating membrane 3 that is not an open end is a support part 15. The schematic cross-sectional view shown in Fig. 9 is a cross-sectional view passing through the center of the pillar 11 and two pillar-side slits 12P and 12R, or 12Q and 12S, which face each other with the pillar 11 as the center, in Fig. 10. Therefore, the support part 15 of the vibrating membrane 3 is not shown in Fig. 9, and the structure is such that the support part 15 of the vibrating membrane 3 is laminated on the insulating film 2 in an area not shown, and the spacer 4 is laminated on this support part 15.

[0055] In the MEMS element of this embodiment, the end of the vibration membrane 3 becomes an open end, and the surface facing this open end, specifically the gap between the spacer 4, becomes the peripheral edge side slits 13P to 13S.

[0056] The peripheral side slits 13P to 13S correspond to the peripheral side slits 13A to 13N described in the above embodiments 1 to 3. Therefore, as shown in FIG. 10, when the portion of the diaphragm 3 corresponding to the back chamber 9 is circular, the pillar 11 is arranged on the diaphragm 3 so that the center of the diaphragm 3 and the center of the circular pillar 11 coincide with each other. A plurality of vibration parts 14P to 14S are formed in the region between the joint part of the diaphragm 3 with the pillar 11 and the open end of the diaphragm 3. For this purpose, the pillar side slits 12P to 12S and the peripheral side slits 13P to 13S are arranged around the pillar 11. In the present embodiment shown in FIG. 10, an example in which four vibration parts 14P to 14S are formed is shown.

[0057] A detailed description will be given by taking one vibrating part as an example. In the vibrating part 14P formed in the upper right region of the pillar 11 of the vibrating membrane 3 shown in Fig. 10, a pillar-side slit 12P is formed by a first slit part 12a extending from the pillar 11 side in parallel to the radial direction of the vibrating membrane 3 and in the upward direction in the drawing, and a second slit part 12b extending from the pillar 11 side in parallel to the radial direction of the vibrating membrane 3 and in the right direction in the drawing, and joining to the first slit part 12a at a joining angle of 90 degrees.

[0058] By forming the pillar-side slit 12P, a part of the diaphragm 3 on the pillar 11 side, the vibration of which is restricted by the pillar 11, becomes more likely to vibrate.

[0059] The peripheral side slit 13P formed by the open end of the vibrating membrane 3 is formed to open to the position where it intersects with or near the extension line, in order to make the area surrounded by the extension line of the first slit portion 12a in the extension direction and the extension line of the second slit portion 12b in the extension direction, each shown by a dotted line in Figure 10, into a single vibrating portion.

[0060] In this way, the area surrounded by the pillar-side slits 12P and the periphery-side slits 13P becomes one vibrating part 14P. Vibrating parts 14Q to 14S are formed in the same manner. The multiple vibrating parts 14P to 14S are evenly arranged around the center of pillar 11 (the center of vibrating membrane 3), resulting in four vibrating parts with uniform characteristics.

[0061] The vibration characteristics of the vibrating parts 14P to 14S of this embodiment show the same tendency as those of the vibrating parts 14A to 14D of the above-mentioned embodiment 1. Specifically, the vibration characteristics of the vibrating parts 14P to 14S change depending on the material, thickness, and size of the vibrating membrane 3. Furthermore, the vibration characteristics change depending on the shape and arrangement of the pillar-side slits 12P to 12S.

[0062] Therefore, the vibration parts 14P to 14S of the MEMS element of this embodiment also exhibit vibration characteristics similar to those shown in Figures 3 to 6, similar to the vibration parts of the above-mentioned embodiment 1. Note that, when the vibration part of this embodiment is compared with the vibration part of the above-mentioned embodiment 1, the vibration membrane 3 of this embodiment has a smaller area bonded to the substrate 1, etc., and is less susceptible to the effects of deformation of the substrate 1, etc.

[0063] In this manner, also in this embodiment, the amplitude of the vibration membrane 3 can be made substantially uniform in the regions between the pillar-side slits 12P-12S and the corresponding periphery-side slits 13P-13S. This is because the vibration membrane 3 including the movable electrodes of the vibration portions 14P-14S is displaced substantially parallel to the fixed electrode 5 facing it.

[0064] In this embodiment, as shown in Fig. 10, the signal output from each vibration part is small because it is divided into four vibration parts 14P to 14S. However, by providing a plurality of vibration parts, the area of ​​the vibration parts that can be displaced in the radial direction of the vibrating membrane 3 and approximately parallel to the fixed electrode 5 increases, so it is possible to obtain sufficiently high sensitivity.

[0065] Furthermore, the AOP is improved because the vibrating membrane 3 including the movable electrode is displaced almost parallel to the fixed electrode 5. Furthermore, by using a vibrating membrane 3 that has a small spring constant and is easy to vibrate, the force applied to each vibrating part can be reduced when a bias voltage is applied between the fixed electrode 5 and the movable electrode of the vibrating part, and the distortion of the detection signal is reduced, thereby improving the AOP. In this embodiment, by providing the pillars 11, problems such as excessive vibration of the vibrating membrane 3 do not occur even when the vibrating membrane 3 has a small spring constant.

[0066] Although the present embodiment has been described by taking as an example a MEMS element having four vibrating parts 14P-14S, it is also possible to apply the present embodiment to a MEMS element having six vibrating parts as in the above-mentioned second embodiment. In this case, the number of supporting parts 15 may be six. Also, in order to increase the amount of amplitude near the supporting parts 15, the peripheral side slits 13P-13S may each be configured to have a fourth slit part 13b as described in the above-mentioned third embodiment, and the amount of amplitude near the supporting parts 15 of the vibrating membrane 3 may be changed to obtain desired vibration characteristics.

[0067] Also, it is possible to adopt a configuration including vibrating parts with the same vibration characteristics, or a configuration in which vibrating parts with different vibration characteristics are combined to complement each other.

[0068] (summary) (1) One embodiment of a MEMS element of the present disclosure comprises a substrate having a back chamber, a vibration membrane including a movable electrode bonded onto the substrate, and a back plate including a fixed electrode arranged opposite the movable electrode, the vibration membrane having a pillar in its center connecting the back plate and the vibration membrane, and having a plurality of vibration parts in a region between a joint between the pillar and the vibration membrane and a peripheral portion of the vibration membrane, each of the plurality of vibration parts being formed from a region surrounded by a pillar-side slit joined to a first slit part and a second slit part extending in mutually different directions from the joint side between the pillar and the vibration membrane toward the peripheral portion, and a peripheral-side slit arranged on the peripheral portion between an extension line from the first slit part toward the peripheral portion and an extension line from the second slit part toward the peripheral portion.

[0069] According to the MEMS element of this embodiment, the amplitude of the center of the diaphragm is suppressed by arranging a pillar that is joined to the back plate in the center of the diaphragm, and further, by providing a pillar-side slit and a peripheral-side slit in the diaphragm, a vibration part with a small difference in amplitude between the center and peripheral parts of the diaphragm can be formed. A plurality of such vibration parts are formed, and a large detection signal can be obtained as a whole. Furthermore, by increasing the amplitude of the vibration part and dividing it into a plurality of vibration parts, the force applied to each vibration part can be reduced when a bias voltage is applied between the fixed electrode and the movable electrode of the vibration part, and the distortion of the detection signal is reduced.

[0070] (2) By making the pillar side slit an opening penetrating the vibration membrane and the peripheral side slit an opening penetrating the vibration membrane or an opening between the open end of the vibration membrane and the opposing surface of the open end, the vibration characteristics of the vibration membrane can be easily changed.

[0071] (3) The peripheral portion side slit may include a third slit portion formed along the inside of the peripheral portion of the vibrating membrane, and a fourth slit portion formed along the third slit portion on the pillar side of the third slit portion. By adding the fourth slit portion, the peripheral portion of the vibrating membrane can be made easier to vibrate.

[0072] (4) The plurality of vibration parts can each have the same vibration characteristics, making it possible to obtain a large detection signal.

[0073] (5) By configuring the multiple vibration parts to include at least two vibration parts having different vibration characteristics, the vibration characteristics of the central part or peripheral part of the vibration membrane can be changed, respectively, to form a vibration part with a small difference in amplitude between the central part and peripheral part of the vibration membrane, and an even larger detection signal can be obtained.

[0074] (6) By configuring all of the plurality of vibrating parts to have the column side slits of the same shape and the peripheral side slits of the same shape, a large detection signal can be obtained.

[0075] (7) By configuring the multiple vibration parts to include at least two vibration parts having at least one of the column side slits of different shapes or the peripheral side slits of different shapes, it is possible to change the vibration characteristics of the central part or the peripheral part of the vibration membrane, respectively, to form a vibration part with a small difference in amplitude between the central part and the peripheral part of the vibration membrane, and thereby obtain an even larger detection signal.

[0076] (8) The first slit portion and the second slit portion constituting the column side slit are configured to have a length and / or a joint angle that allows predetermined vibration characteristics to be obtained. This makes it possible to change the vibration characteristics of the central portion of the vibrating membrane and form a vibrating portion with less difference in amplitude between the central portion and the peripheral portion of the vibrating membrane, thereby obtaining an even larger detection signal. [Explanation of symbols]

[0077] 1 Board 2. Insulating film 3. Diaphragm 4 Spacer 5 Fixed electrode 6. Insulating film 7 Backplate 8. Acoustic Hall 9 Back Chamber 10 Slit 11 Pillars 12, 12A~12N, 12P~12S Pillar side slit 12a First slit section 12b Second slit section 13, 13A~13N, 13P~13S Peripheral slits 13a Third slit section 13b Fourth slit section 14, 14A~14N, 14P~14S Vibration part 15 Support part

Claims

1. A substrate having a back chamber; a vibrating membrane including a movable electrode bonded onto the substrate; a back plate including a fixed electrode arranged opposite the movable electrode; Equipped with The vibrating membrane is A pillar is provided at the center thereof for connecting the back plate and the diaphragm, and a plurality of vibration parts in a region between a joint between the pillar and the vibration membrane and a peripheral edge of the vibration membrane; Each of the plurality of vibration units is a column-side slit formed by joining a first slit portion and a second slit portion extending in different directions from each other from a joint side of the column and the vibration membrane toward the peripheral portion, and a peripheral portion-side slit disposed on the peripheral portion between an extension line from the first slit portion toward the peripheral portion and an extension line from the second slit portion toward the peripheral portion, MEMS element.

2. The pillar-side slit is an opening penetrating the vibration membrane, and the peripheral-side slit is an opening penetrating the vibration membrane or an opening between an open end of the vibration membrane and an opposing surface of the open end. The MEMS element according to claim 1 .

3. The peripheral portion side slit includes a third slit portion formed along the inner side of the peripheral portion of the vibration membrane, and a fourth slit portion formed along the third slit portion on the pillar side of the third slit portion. The MEMS element according to claim 1 or 2.

4. The plurality of vibration units each have the same vibration characteristics. The MEMS element according to any one of claims 1 to 3.

5. The plurality of vibration units include at least two vibration units having vibration characteristics different from each other. The MEMS element according to any one of claims 1 to 3.

6. All of the plurality of vibration parts have the column side slits of the same shape and the peripheral side slits of the same shape. The MEMS element according to any one of claims 1 to 4.

7. The plurality of vibration parts include at least two vibration parts having at least one of the column side slits having different shapes from each other or the peripheral side slits having different shapes from each other, The MEMS element according to any one of claims 1 to 3 and 5.

8. The first slit portion and the second slit portion constituting the column side slit are formed with a length and / or a joint angle that obtains predetermined vibration characteristics. The MEMS element according to any one of claims 1 to 7.

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