MEMS resonator and preparation method thereof
By setting flat surfaces and recesses in the MEMS resonator and designing channels on the resonator, the problem of poor performance in the array structure is solved, and the inheritance and frequency adjustment of high Q value and low impedance are achieved, which improves MEMS Overall performance of the resonator.
Patent Information
- Application Number
- CN202411282271.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-13
- Publication Date
- 2024-12-10
AI Technical Summary
The existing MEMS resonators cannot effectively inherit the high Q value and low impedance performance of single-mode resonators in the array structure, resulting in poor performance of the array structure.
A MEMS resonator is designed, by connecting to the coupling beam on the side of the middle area of the resonant body, setting a flat surface, and setting a recess on the outermost resonant body facing away from the side of the coupling beam, the anchor point extends into the recess to connect the resonant body With the substrate, a channel is provided on the resonant body to adjust the frequency.
The performance of single-mode MEMS resonator is inherited into the array structure, which improves the Q value of the resonator and reduces the impedance, while enhancing the vibration of the resonator, filling the shortcomings of the frequency adjustment range.
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Figure CN119109434A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of micro-electromechanical systems, and in particular to a MEMS resonator and a method for preparing the same. Background Art
[0002] Micro-Electro-Mechanical System (MEMS) is a high-tech field based on microelectronics and micromachining technology. MEMS technology can integrate mechanical components, drive components, electronic control systems, digital processing systems, etc. into an integrated micro unit. MEMS devices have many advantages such as being small, intelligent, executable, integrable, having good process compatibility, and low cost. The development of MEMS technology has opened up a new technological field and industry. Micro sensors, micro actuators, micro components, micromechanical optical devices, vacuum microelectronic devices, power electronic devices, etc. made using MEMS technology have very broad application prospects in the fields of aviation, aerospace, automobiles, biomedicine, environmental monitoring, military, and the Internet of Things.
[0003] At present, in order to make the MEMS resonator have a higher Q value (quality factor), the commonly used method is to combine two single resonators of basic modes through a coupling beam to form an array structure design. However, there are defects in the specific connection design between the existing coupling beam and the two single resonators of basic modes, resulting in the performance of the single resonator of the basic mode cannot be inherited to the MEMS resonator of the array structure, such as the high Q value and low impedance of the single resonator cannot be inherited to the MEMS resonator of the array structure, which in turn leads to poor performance of the MEMS resonator of the array structure. Summary of the invention
[0004] In view of this, the present application provides a MEMS resonator and a method for preparing the same, so that the performance of a single-mode MEMS resonator can be inherited by a MEMS resonator with an array structure.
[0005] The present application provides a MEMS resonator, comprising a substrate, at least two resonators and two anchor points, wherein each of the resonators extends along a first direction and is arranged along a second direction perpendicular to the first direction, and each two adjacent resonators are connected by a coupling beam; in the second direction, the coupling beam is connected to the side surface of the middle region of the resonator, and the side surface of the middle region connected to the coupling beam is a flat surface; the side surfaces of the middle region of the two resonators located at the outermost sides and facing away from the coupling beam have a recessed portion recessed toward the inside of the resonator, and the two anchor points are connected to the substrate by respectively extending into the recessed portions.
[0006] In some embodiments, at least one side surface of the coupling beam that is not connected to the resonator is an arc-shaped surface that protrudes toward the outside of the coupling beam.
[0007] In some embodiments, the length of the coupling beam is 1 / 2 of the wavelength of the sound wave generated by the vibration of the resonator.
[0008] In some embodiments, each of the resonators has a channel that penetrates the resonator and connects the bottom surface and the top surface of the resonator, the opposite sides of the middle area are connected to the edge area, and the channel is located on the edge area.
[0009] In some embodiments, the channel includes a first channel, the first channel is located on a side of the edge region close to the recessed portion, and the first channel extends along the first direction and is arranged along the second direction.
[0010] In some embodiments, the channel further includes a second channel, the second channel extends along the first direction and is arranged along the second direction, and the second channel is located on a side of the first channel away from the recessed portion.
[0011] In some embodiments, the channel further includes a third channel, the third channel extends along the first direction and is arranged along the first direction, and the third channel is located between the first channel and the second channel.
[0012] In some embodiments, two opposite sides of the middle region are connected to the edge region, and at least one side surface of the resonator located in the edge region is an arc-shaped surface convexly disposed toward the outside of the resonator.
[0013] In some embodiments, the MEMS resonator further includes a driving electrode, a piezoelectric layer, and a sensing electrode stacked in sequence on the resonator, and the MEMS resonator is a piezoelectric resonator; alternatively, the MEMS resonator further includes a driving electrode and a sensing electrode disposed on the substrate, and the MEMS resonator is an electrostatic resonator.
[0014] The present application also provides a method for preparing a MEMS resonator, which is used to prepare the MEMS resonator as described above, comprising:
[0015] Providing an SOI wafer, the SOI wafer comprising a first insulating layer, a substrate, a second insulating material layer and a device material layer stacked in sequence from bottom to top;
[0016] Etching the device material layer to form a release port;
[0017] A portion of the second insulating material layer is removed through the release port so that the device material layer forms a device layer, wherein the device layer includes at least two resonators and two anchor points, each of which has a cavity between it and the substrate, each of which extends along a first direction and is arranged along a second direction perpendicular to the first direction, and each two adjacent resonators are connected by a coupling beam; in the second direction, the coupling beam is connected to the side of the middle area of the resonator, and the side of the middle area connected to the coupling beam is a flat surface; the side of the middle area of the two outermost resonators facing away from the coupling beam has a recessed portion recessed toward the inside of the resonator, and the two anchor points extend into the recessed portions respectively to connect the resonator to the substrate.
[0018] The present application provides a MEMS resonator and a preparation method thereof, comprising a substrate, at least two resonators and two anchor points, each resonator extending along a first direction and arranged along a second direction perpendicular to the first direction, and each two adjacent resonators are connected by a coupling beam; in the second direction, the coupling beam is connected to the side of the middle region of the resonator, and the side of the middle region connected to the coupling beam is a flat surface; the sides of the middle regions of the two resonators located at the outermost sides and away from the coupling beam have a recessed portion recessed toward the inside of the resonator, and the two anchor points are respectively extended into the recessed portions to connect the resonator to the substrate. In the present application, by setting the side of the middle region connected to the coupling beam as a flat surface, energy can be released, and the array-arranged resonators vibrate simultaneously, so that the performance of the single-mode MEMS resonator can be inherited to the array-structured MEMS resonator. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.
[0020] Figure 1 This is a schematic diagram of the first structure of the MEMS resonator provided by the present application;
[0021] Figure 2 is a second structural schematic diagram of the MEMS resonator provided by the present application;
[0022] Figure 3 yes Figure 1 and Figure 2 Schematic diagram of the planar structure of the MEMS resonator;
[0023] Figure 4is a simulation diagram of a MEMS resonator with an array structure provided by the present application;
[0024] Figure 5 This is a simulation diagram of a single-mode MEMS resonator;
[0025] Figure 6 It is a schematic diagram of the process of preparing a MEMS resonator provided by the present application;
[0026] Figure 7-Figure 14 This is a schematic diagram of the first process structure of the method for preparing a MEMS resonator provided by the present application;
[0027] Figure 15-18 This is a schematic diagram of the second process structure of the method for preparing a MEMS resonator provided in the present application.
[0028] Reference numerals:
[0029] 10. MEMS resonator; 100. substrate; 200. resonator; 210. recess; 220. channel; 221. first channel; 222. second channel; 223. third channel; 300. anchor point; 400. coupling beam; 500. first insulating layer; 600. second insulating layer; 601. second insulating material layer; 700. driving electrode; 701. first electrode layer; 800. piezoelectric layer; 801. piezoelectric material layer; 900. sensing electrode; 901. second electrode layer; 902. release port; 903. device layer; 904. device material layer; 905. PSG doping layer; 906. first electrical connection point; 907. second electrical connection point. DETAILED DESCRIPTION
[0030] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.
[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.
[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which this application belongs. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items. The terms "connection", "electrical connection", and "electrical connection" used herein include any direct and indirect electrical or structural connection means. Therefore, if the text describes a first device coupled / connected / electrically connected to a second device, it means that the first device can be directly electrically / structurally connected to the second device, or indirectly electrically / structurally connected to the second device through other devices or connection means.
[0033] The present application provides a MEMS resonator and a preparation method thereof, comprising a substrate, at least two resonators and two anchor points, each resonator extending along a first direction and arranged along a second direction perpendicular to the first direction, and every two adjacent resonators being connected by a coupling beam; in the second direction, the coupling beam is connected to the side surface of the middle region of the resonator, and the side surface of the middle region connected to the coupling beam is a flat surface; the side surfaces of the middle regions of the two outermost resonators away from the coupling beam have a recessed portion recessed toward the inside of the resonator, and the two anchor points are connected to the substrate by respectively extending into the recessed portions.
[0034] In the present application, the side of the middle area connected to the coupling beam is set as a flat surface to release energy, and the array-arranged resonators are made to vibrate simultaneously, so that the performance of the single-mode MEMS resonator can be inherited by the MEMS resonator of the array structure; in addition, a recessed portion recessed toward the inside of the resonator is set on the side of the middle area of the two outermost resonators away from the coupling beam, so that the outer edge of the resonator located in the middle area forms an angle with the lateral extension direction of the resonator, thereby blocking the sound waves generated by the vibration of the resonator, reducing energy loss, and planning the transmission path of the sound waves so that they interfere with each other in the resonator after rebounding, thereby enhancing the vibration of the resonator, thereby improving the Q value of the MEMS resonator, and reducing the impedance at the same time.
[0035] See also Figure 1 and Figure 3-Figure 5 , Figure 1 This is a schematic diagram of the first structure of the MEMS resonator provided by the present application; Figure 3 yes Figure 1 and Figure 2 Schematic diagram of the planar structure of the MEMS resonator, Figure 4 is a simulation diagram of the MEMS resonator array structure provided by this application, Figure 5 This is a simulation diagram of a single-mode MEMS resonator.
[0036] The present application provides a MEMS resonator 10, including a substrate 100, at least two resonators 200 and two anchor points 300. The material of the substrate 100 can be single crystal silicon. Each resonator 200 extends along a first direction X and is arranged along a second direction Y perpendicular to the first direction X. Every two adjacent resonators 200 are connected by a coupling beam 400. In the second direction Y, the coupling beam 400 is connected to the side of the middle area of the resonator 200, and the side of the middle area connected to the coupling beam 400 is a flat surface. The side of the middle area of the two outermost resonators 200 away from the coupling beam 400 has a recessed portion 210 recessed toward the inside of the resonator 200. The two anchor points 300 extend into the recessed portions 210 respectively to connect the resonator 200 to the substrate 100. Further, the anchor point 300 includes a first anchor, a second anchor, and a third anchor. The first anchor is connected to the resonator 200 through a recessed portion 210, the second anchor is connected to two opposite sides of one end of the first anchor away from the resonator 200, and the third anchor is connected to one side of the second anchor away from the first anchor. The plane width of the recessed portion 210 close to the first anchor may be greater than, equal to, or less than the plane width of the recessed portion 210 away from the first anchor. The first anchor has an embedded portion, which extends into the recessed portion 210 and is connected to the resonator 200. The plane width of the embedded portion close to the resonator 200 may be greater than, equal to, or less than the plane width of the embedded portion away from the resonator 200. In this embodiment, the plane width of the recessed portion 210 close to the first anchor may be greater than the plane width of the recessed portion 210 away from the first anchor, and the plane width of the embedded portion close to the resonator 200 may be less than the plane width of the embedded portion away from the resonator 200.
[0037] In the present application, by setting the side of the middle area connected to the coupling beam 400 as a flat surface, that is, the coupling beam 400 is not embedded in the coupling resonator 200, that is, the coupling beam 400 is flatly coupled with the resonator 200, so that energy can be released, and the array-arranged resonators 200 vibrate at the same time, so that the performance of the single-mode MEMS resonator 10 can be inherited to the array-structured MEMS resonator 10, and the frequency is almost unchanged, and the impedance is reduced to 1 / 3 of the single-mode MEMS resonator 10, please refer to Figure 4 and Figure 5The impedance of a single-mode MEMS resonator is about 300Ω, and the impedance of the MEMS resonator 10 with an array structure is only about 90Ω; in addition, a recessed portion 210 recessed toward the inside of the resonator 200 is provided on the side of the middle area of the two outermost resonators 200 and away from the coupling beam 400, so that the outer edge of the resonator 200 located in the middle area forms an angle with the lateral extension direction of the resonator 200, thereby blocking the sound waves generated by the vibration of the resonator 200, reducing the loss of energy, and planning the transmission of the sound waves. The path is formed so that it interferes in the resonator 200 after rebounding, thereby enhancing the vibration of the resonator 200, thereby improving the Q value of the MEMS resonator 10 and reducing the impedance at the same time; in addition, because the recessed portion 210 is arranged in the middle area of the resonator 200 and the anchor point 300 is connected to the recessed portion 210, the recessed portion 210 can suppress the stray mode; in addition, the recessed portion 210 is arranged on the resonator 200, which can reduce the stiffness of the resonator 200, thereby increasing the vibration displacement of the resonator 200, and thereby improving the performance of the MEMS resonator 10.
[0038] In one embodiment, at least one side surface of the coupling beam 400 that is not connected to the resonator 200 is an arc-shaped surface that is convexly disposed toward the outside of the coupling beam 400. Specifically, at least one of the two side surfaces of the coupling beam 400 in the second direction Y is an arc-shaped surface that is convexly disposed toward the outside of the coupling beam 400, rather than a flat surface, so that the outer edge of the coupling beam 400 is uneven, thereby blocking the sound waves generated by the vibration of the resonator 200, reducing energy loss, and thus improving the performance of the MEMS resonator 10.
[0039] In one embodiment, the arc surface of the coupling beam 400 may be composed of a plurality of small arc surfaces, such as an arc shape similar to fish scales, so as to further block the sound waves generated by the vibration of the resonator 200 and reduce energy loss.
[0040] In one embodiment, the length of the coupling beam 400 is 1 / 2 of the wavelength of the sound wave generated by the vibration of the resonator 200, and the length direction of the coupling beam 400 is the same as the second direction Y, so that after the sound wave is transmitted to the resonator 200 through the coupling beam 400, it overlaps with the sound wave of the resonator 200, thereby improving the performance of the MEMS resonator 10.
[0041] In one embodiment, the depth and width of the anchor point 300 extending into the recess 210 may be designed to further increase the Q value and reduce the impedance. The specific parameters are determined according to the structure, size, and vibration mode design of the resonator 200 .
[0042] In one embodiment, a gap is provided between the side surface of the anchor point 300 extending into the recessed portion 210 and the side wall of the recessed portion 210 to further block the sound waves generated by the vibration of the resonator 200, reduce energy loss, and plan the transmission path of the sound waves so that they interfere in the resonator 200 after rebounding, thereby enhancing the vibration of the resonator 200, thereby improving the Q value of the MEMS resonator 10, and reducing the impedance at the same time.
[0043] In one embodiment, the resonator 200 has a channel 220 that penetrates the resonator 200 and connects the bottom surface and the top surface of the resonator 200. The opposite sides of the region in the middle region that is not connected to the anchor point 300 are connected to the edge region. The channel 220 is located on the edge region, and the length direction of the channel 220 is the same as the lateral extension direction of the resonator 200. In the present application, by providing the channel 220 that penetrates the resonator 200 on the edge region, it is possible to avoid the reduction of the Q value of the MEMS resonator 10 and the increase of the impedance, and the frequency adjustment of the MEMS resonator 10 of 0.01-5MHz can be achieved by adjusting the length of the channel 220. Even if the Q value is reduced, the change in the Q value is less than 5%, which is almost negligible.
[0044] In one embodiment, the channel 220 includes a first channel 221, the first channel 221 is located on a side of the edge region close to the recessed portion 210, and the first channel 221 extends along the first direction X and is arranged along the second direction Y. Specifically, the number of the first channels 221 may be multiple, such as the number of the first channels 221 may be 2, 3, 6, 10 or 13, etc. In this embodiment, the number of the first channels 221 is taken as an example for description; the resonator 200 extends transversely along the first direction X, the two first channels 221 extend along the first direction X and are arranged along the second direction Y, and the first channel 221 is located on a side of the edge region close to the middle region; the length direction of the first channel 221 is the same as the extension direction of the first channel 221, and the width direction of the first channel 221 is the same as the arrangement direction of the first channel 221, wherein the length of the first channel 221 is 8-12 μm, and the width of the first channel 221 is 0.9-1.2 μm. Optionally, the length of the first channel 221 may be 8 μm, 8.9 μm, 9.4 μm, 11.5 μm or 12 μm, etc., and the width of the first channel 221 may be 0.9 μm, 0.95 μm, 1 μm, 1.13 μm or 1.2 μm, etc. In the present application, by arranging the first channel 221 on one side of the edge region close to the anchor point 300, that is, the first channel 221 is in the stress concentration region, the frequency of the MEMS resonator 10 can be adjusted by adjusting the length of the first channel 221, and at the same time, the Q value and impedance of the MEMS resonator 10 are not affected, thereby improving the performance of the MEMS resonator 10; in addition, by only adjusting the length of the first channel 221, the frequency of the MEMS resonator 10 can be adjusted at a ratio of 5000 ppm / um.
[0045] In one embodiment, the channel 220 further includes a second channel 222 . The second channel 222 extends along the first direction X and is arranged along the second direction Y. The second channel 222 is located on a side of the first channel 221 away from the recess 210 . Specifically, the number of the second channels 222 may be multiple, such as the number of the second channels 222 may be 2, 3, 6, 10 or 13, etc. In the present embodiment, the number of the second channels 222 is 2 as an example for description; the two second channels 222 extend along the first direction X and are arranged along the second direction Y, and the second channel 222 is located on the side of the second channel 222 away from the recess 210, that is, the second channel 222 is located on the side of the edge area away from the middle area; the length direction of the second channel 222 is the same as the extension direction of the second channel 222, and the width direction of the second channel 222 is the same as the arrangement direction of the second channel 222, wherein the length of the second channel 222 is 8-12 μm, and the width of the second channel 222 is 0.9-1.2 μm. Optionally, the length of the second channel 222 may be 8 μm, 8.9 μm, 9.4 μm, 11.5 μm or 12 μm, etc., and the width of the second channel 222 may be 0.9 μm, 0.95 μm, 1 μm, 1.13 μm or 1.2 μm, etc. In the present application, by arranging the second channel 222 on the side of the edge region away from the anchor point 300, that is, the second channel 222 is in a non-stress concentration region, the stiffness of the resonator 200 can be reduced, thereby increasing the vibration displacement of the resonator 200, and the second channel 222 arranged here has little effect on the frequency.
[0046] In one embodiment, the channel 220 further includes a third channel 223, the third channel 223 extends along the first direction X and is arranged along the first direction X, and the third channel 223 is located between the first channel 221 and the second channel 222. Specifically, the number of the third channels 223 may be multiple, such as the number of the third channels 223 may be 2, 3, 6, 10 or 13, etc. In this embodiment, the number of the third channels 223 is 2 as an example for description; the two third channels 223 extend along the first direction X and are arranged along the first direction X; the length direction of the third channel 223 is the same as the extension direction of the third channel 223, and the width direction of the third channel 223 is perpendicular to the arrangement direction of the third channel 223, wherein the length of the third channel 223 is 8-12 μm, and the width of the third channel 223 is 0.9-1.2 μm. Optionally, the length of the third channel 223 may be 8 μm, 8.9 μm, 9.4 μm, 11.5 μm or 12 μm, etc., and the width of the third channel 223 may be 0.9 μm, 0.95 μm, 1 μm, 1.13 μm or 1.2 μm, etc. Optionally, the extension directions of the first channel 221, the second channel 222 and the third channel 223 are not on the same straight line. In the present application, by arranging the third channel 223 on one side of the edge region close to the anchor point 300, that is, the third channel 223 is in the stress concentration region, the frequency of the MEMS resonator 10 can be adjusted by adjusting the length of the third channel 223, while the Q value and impedance of the MEMS resonator 10 are not affected, thereby improving the performance of the MEMS resonator 10; in addition, by only adjusting the length of the third channel 223, the frequency of the MEMS resonator 10 can be adjusted at a ratio of ~1000 ppm / um.
[0047] For example, taking the frequency adjustment of a length of 1 μm as an example, when the length of the first channel 221 is 9 μm, the frequency of the MEMS resonator 10 is 27.009 MHz; when the length of the first channel 221 is 10 μm, the frequency of the MEMS resonator 10 is 26.951 MHz; when the length of the first channel 221 is 11 μm, the frequency of the MEMS resonator 10 is 26.911 MHz. When the length of the third channel 223 is 9 μm, the frequency of the MEMS resonator 10 is 26.951 MHz; when the length of the third channel 223 is 10 μm, the resonator frequency is 26.963 MHz. At this time, after adjusting the length of the first channel 221 and / or the third channel 223, the Q value of the device remains basically unchanged. Even if there is a change, the change in the Q value is less than 5%, which is almost negligible.
[0048] In one embodiment, the MEMS resonator 10 can operate in any in-plane mode, including SE (square-extensional) mode, LE (length-extensional) mode, breathing mode, Wine glass mode, WE (width-extensional) mode or Lame mode.
[0049] In one embodiment, at least one side surface of the resonator 200 located in the edge area is an arc-shaped surface protruding toward the outside of the resonator 200, that is, in a plan view, at least one side surface of the side surface of the resonator 200 located in the edge area is not a flat surface, thereby further blocking the sound waves generated by the vibration of the resonator 200, reducing energy loss, and planning the transmission path of the sound waves so that they interfere in the resonator 200 after rebounding, thereby enhancing the vibration of the resonator 200, further improving the Q value, and reducing the impedance.
[0050] Optionally, the side of the resonator 200 located in the edge area facing away from the resonator 200 located in the middle area and the upper and lower side surfaces of the resonator 200 located in the edge area are all curved surfaces, that is, the three side surfaces of the resonator 200 located in the edge area are not flat surfaces. In this embodiment, the three side surfaces of the resonator 200 located in the edge area are taken as an example to illustrate, so that the sound waves generated by the vibration of the resonator 200 can be further blocked, the energy loss can be reduced, and the transmission path of the sound waves can be planned so that they interfere in the resonator 200 after rebounding, thereby enhancing the vibration of the resonator 200, thereby improving the Q value and reducing the impedance.
[0051] In one embodiment, the arc surface of the resonator 200 can be composed of multiple small arc surfaces, such as an arc shape similar to fish scales, so as to further block the sound waves generated by the vibration of the resonator 200, reduce energy loss, and plan the transmission path of the sound waves so that they interfere in the resonator 200 after rebounding, thereby enhancing the vibration of the resonator 200, thereby improving the Q value and reducing the impedance.
[0052] In one embodiment, the curvature of the arc-shaped surface may be designed to further increase the Q value and reduce the impedance. The specific parameters are determined according to the structure, size, and vibration mode design of the resonator 200 .
[0053] In one embodiment, the MEMS resonator 10 further includes a driving electrode 700, a piezoelectric layer 800, and a sensing electrode 900 stacked in sequence on the resonator 200, and the MEMS resonator 10 is a piezoelectric resonator. Specifically, the material of the piezoelectric layer 800 includes at least one of aluminum nitride, zinc oxide, and PZT; the materials of the driving electrode 700 and the sensing electrode 900 include molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.
[0054] In one embodiment, the MEMS resonator 10 further includes a first insulating layer 500 and a second insulating layer 600, the resonator 200 and the anchor point 300 are composed of a device layer 903, the first insulating layer 500, the substrate 100, the second insulating layer 600 and the device layer 903 are stacked in sequence from bottom to top, wherein a cavity is provided between the resonator 200 and the substrate 100, the channel 220 penetrates the sensing electrode 900, the piezoelectric layer 800, the driving electrode 700 and the device layer 903 to expose the cavity, the side surface of the resonator 200 has a release port 902 penetrating the sensing electrode 900, the piezoelectric layer 800, the driving electrode 700 and the device layer 903 to expose the cavity, and the MEMS resonator 10 is further provided with a first electrical connection point 906 electrically connected to the driving electrode 700 and a second electrical connection point 907 electrically connected to the sensing electrode 900.
[0055] See also Figure 2 , Figure 2 is a schematic diagram of the second structure of the MEMS resonator provided in this application. It should be noted that: Figure 2 and Figure 1 The difference is that: the MEMS resonator 10 also includes a driving electrode 700 and a sensing electrode 900 disposed on the substrate 100, and the MEMS resonator 10 is an electrostatic resonator. Further, the sensing electrode 900 and the driving electrode 700 are connected to the substrate 100 through the second insulating layer 600, the MEMS resonator 10 is not provided with a piezoelectric layer 800, the release port 902 is provided between the resonator 200 and the sensing electrode 900 or the driving electrode 700, and the electrodes are located on both sides of the resonator 200, and the other Figure 1 The same as in, no further description is given here.
[0056] The present application provides a MEMS resonator 10, which is configured such that the side of the middle area connected to the coupling beam 400 is set as a flat surface, that is, the coupling beam 400 is not embedded in the coupling resonator 200, that is, the coupling beam 400 is flatly coupled with the resonator 200, so that energy can be released, and the resonators 200 arranged in an array vibrate at the same time, so that the performance of the single-mode MEMS resonator 10 can be inherited by the MEMS resonator 10 of the array structure, and the frequency is almost unchanged, and the impedance is reduced to 1 / 3 of the single-mode MEMS resonator 10, the impedance of the single-mode MEMS resonator 10 is about 300Ω, and the impedance of the MEMS resonator 10 of the array structure is only about 90Ω; in addition, a recessed portion 210 recessed toward the inside of the resonator 200 is provided on the side of the middle area of the two outermost resonators 200 and away from the coupling beam 400, so that the outer edge of the resonator 200 located in the middle area forms an angle with the direction in which the resonator 200 extends laterally, thereby blocking the resonator 200 vibration, reduce energy loss, and plan the transmission path of the sound wave so that it interferes in the resonator 200 after rebounding, enhances the vibration of the resonator 200, and thus improves the Q value of the MEMS resonator 10, while reducing impedance; in addition, because the recessed portion 210 is arranged in the middle area of the resonator 200, and the anchor point 300 is connected to the recessed portion 210, the recessed portion 210 can suppress the stray mode; in addition, the recessed portion 210 is arranged on the resonator 200, which can reduce the stiffness of the resonator 200, thereby increasing the vibration displacement of the resonator 200, and thereby improving the performance of the MEMS resonator 10; in addition, by arranging the channel 220 on the resonator 200, the frequency adjustment of the MEMS resonator 10 of 0.01-5MHz can be achieved by adjusting the length of the channel 220, which effectively fills the deficiency of the trimming frequency modulation coverage range, and the adjustment for different frequencies will not have a significant impact on the performance of the MEMS resonator 10 itself, such as Q value, impedance, etc.
[0057] See also Figure 6-Figure 14 , Figure 6 It is a schematic diagram of the process of preparing a MEMS resonator provided by the present application; Figure 7-Figure 14 This is a schematic diagram of the first process structure of the method for preparing a MEMS resonator provided by the present application. The present application also provides a method for preparing a MEMS resonator, which is used to prepare the MEMS resonator 10 provided by the present application, comprising:
[0058] S11. Provide an SOI wafer, wherein the SOI wafer includes a first insulating layer, a substrate, a second insulating material layer, and a device material layer stacked in sequence from bottom to top.
[0059] See also Figure 7Specifically, the materials of the first insulating layer 500 and the second insulating material layer 601 may be silicon oxide, aluminum nitride, aluminum oxide, etc. The material of the substrate 100 may be single crystal silicon.
[0060] See also Figure 8 In one embodiment, after step S11, the method further includes: disposing a PSG doping layer 905 on the device material layer 904, and performing an annealing process.
[0061] See also Fig. 9 In one embodiment, after the steps of forming a PSG doping layer 905 on the device material layer 904 and annealing, the method further includes: depositing a first electrode layer 701, a piezoelectric material layer 801 and a second electrode layer 901 on the device material layer 904 in sequence, and etching the second electrode layer 901 to expose a portion of the piezoelectric material layer 801, wherein the first electrode layer 701 and the second electrode layer 901 can be prepared by sputtering or electron beam evaporation; the piezoelectric material layer 801 can be prepared by low pressure chemical vapor deposition (LPCVD) or molecular beam epitaxy (MBE); wherein the materials of the first electrode layer 701 and the second electrode layer 901 can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof; the material of the piezoelectric material layer 801 can be aluminum nitride, zinc oxide, lead zirconate titanate (PZT), etc.
[0062] Specifically, a first electrode layer 701, a piezoelectric material layer 801 and a second electrode layer 901 can be formed in sequence from bottom to top on the device material layer 904; then, a patterned first photoresist layer is formed on the second electrode layer 901 through a photolithography process, and then ion beam etching (IBE, lon Beam Etching) is used to etch part of the second electrode layer 901 and expose part of the piezoelectric material layer 801; finally, the first photoresist layer is removed.
[0063] See also Fig.10 In one embodiment, after the steps of depositing the first electrode layer 701 , the piezoelectric material layer 801 and the second electrode layer 901 sequentially formed on the device material layer 904 , and etching the second electrode layer 901 to expose a portion of the piezoelectric material layer 801 , the method further includes: etching the piezoelectric material layer 801 to expose the first electrode layer 701 .
[0064] Specifically, a patterned second photoresist layer is formed on the surface of the piezoelectric material layer 801 by a photolithography process, and a portion of the piezoelectric material layer 801 is etched by ion beam etching (IBE) to form a through hole that penetrates the piezoelectric material layer 801 and exposes a portion of the first electrode layer 701; then, the second photoresist layer is removed.
[0065] See also Fig.11In one embodiment, after the step of etching the piezoelectric material layer 801 to expose the first electrode layer 701, the process further includes: forming a first electrical connection point 906 that passes through the piezoelectric material layer 801 and connects to the first electrode layer 701, and a second electrical connection point 907 that covers a portion of the second electrode layer 901, wherein the first electrical connection point 906 is located in the through hole. The material of the first electrical connection point 906 and the second electrical connection point 907 can be gold or aluminum. The first electrical connection point 906 and the second electrical connection point 907 are formed by sputtering or electron beam evaporation.
[0066] See also Fig.12 In one embodiment, after forming the first electrical connection point 906 penetrating the piezoelectric material layer 801 and connected to the first electrode layer 701 and the second electrical connection point 907 covering a portion of the second electrode, the process further includes: patterning the first electrode layer 701, the piezoelectric material layer 801 and the second electrode layer 901 to obtain the driving electrode 700, the piezoelectric layer 800 and the sensing electrode 900 respectively.
[0067] Specifically, a patterned third photoresist layer is formed on the surface of the piezoelectric material layer 801 and the second electrode layer 901 by a photolithography process, and ion beam etching (IBE) is used to etch a portion of the first electrode layer 701, the piezoelectric material layer 801 and the second electrode layer 901 to obtain the driving electrode 700, the piezoelectric layer 800, and the sensing electrode 900, and to form a pre-release port and a pre-channel, which penetrate the driving electrode 700, the piezoelectric layer 800 and the sensing electrode 900 to expose a portion of the device material layer 904, in preparation for etching the device layer 903. This step does not require the removal of the third photoresist layer.
[0068] S12, etching the device material layer to form a release port.
[0069] See also Fig.13 Specifically, the third photoresist layer can be used as a protective layer, and then the exposed device material layer 904 is etched by a deep reactive ion etching process, the pre-release port forms a release port 902 and the pre-channel forms a channel 220, the device material layer 904 forms a device layer 903, the release port 902 is located around the channel 220, the release port 902 and the channel 220 both penetrate the sensing electrode 900, the piezoelectric layer 800, the driving electrode 700 and the device layer 903 to expose the second insulating material layer 601, the channel 220 includes a first channel 221, a second channel 222 and a third channel 223, and this step does not require the removal of the third photoresist layer.
[0070] S13. Part of the second insulating material layer is removed through the release port so that the device material layer forms a device layer, wherein the device layer includes at least two resonators and two anchor points, each of which has a cavity between the resonator and the substrate, each of which extends along a first direction and is arranged along a second direction perpendicular to the first direction, and each two adjacent resonators are connected by a coupling beam; in the second direction, the coupling beam is connected to the side of the middle area of the resonator, and the side of the middle area connected to the coupling beam is a flat surface; the sides of the middle area of the two outermost resonators away from the coupling beam have a recessed portion recessed toward the inside of the resonator, and the two anchor points extend into the recessed portions respectively to connect the resonator to the substrate.
[0071] See also Fig.14 Specifically, a patterned fourth photoresist layer can be formed on the side wall of the release port 902 away from the second electrical connection point 907 by a photolithography process to protect the second insulating material layer 601 on the non-etched side; then, a dry etching process or a wet etching process is used to etch part of the second insulating material layer 601 through the release port 902 to form a cavity between the substrate 100 and the device layer 903, so that the device layer 903 is suspended; finally, the third photoresist layer and the fourth photoresist layer are removed to form a MEMS resonator 10, wherein each resonator 200 extends along the first direction X and is perpendicular to the first direction X. The resonators 200 are arranged in a second direction Y in a straight arrangement, and every two adjacent resonators 200 are connected by a coupling beam 400, and a cavity is provided between the resonators 200 and the substrate 100; in the second direction Y, the coupling beam 400 is connected to the side of the middle area of the resonator 200, and the side of the middle area connected to the coupling beam 400 is a flat surface; the sides of the middle areas of the two outermost resonators 200 away from the coupling beam 400 have a recessed portion 210 recessed toward the inside of the resonator 200, and the two anchor points 300 are respectively extended into the recessed portions 210 to connect the resonator 200 to the substrate 100.
[0072] See also Figure 2 and Figure 15-18 , Figure 15-18 This is a second process structure diagram of the method for preparing a MEMS resonator provided in the present application. It should be noted that the difference between the second process structure diagram and the first process structure diagram is that:
[0073] See also Figure 15-17 , and please continue to see Figure 6After step S11 and the steps of forming a PSG doping layer 905 on the device material layer 904 and annealing, the steps of depositing the first electrode layer 701 , the piezoelectric material layer 801 and the second electrode layer 901 are not performed, and step S12 is directly performed to etch the device material layer 904 to form a release port 902 . Specifically, a patterned fifth photoresist layer is formed on the device material layer 904 by a photolithography process, and the device material layer 904 is etched by a deep reactive ion etching process (DRIE) to form a release port 902, a channel 220, a resonator 200, and an electrode. The release port 902 is disposed between the resonator 200 and the electrode, and the electrode is located on both sides of the resonator 200. The electrode includes a sensing electrode 900 and a driving electrode 700. The release port 902 and the channel 220 both expose the second insulating material layer 601. The channel 220 includes a first channel 221, a second channel 222, and a third channel 223. The fifth photoresist layer is not removed in this step.
[0074] See also Fig.18 In step S13, the second insulating material layer 601 is etched through the release port 902 by a dry or wet process, and all the second insulating material layer 601 below the resonator 200 is etched by controlling the etching process to form a cavity, so that the resonator 200 is suspended, and the second insulating material layer 601 below the driving electrode 700 and the sensing electrode 900 is etched to form a second insulating layer 600, and the driving electrode 700 and the sensing electrode 900 are connected to the substrate 100 through the second insulating layer 600; then, the fifth photoresist layer is removed. The rest is the same as the first process, and will not be repeated here.
[0075] In the present application, the MEMS resonator 10 prepared by the above-mentioned preparation method has a lower manufacturing cost than the MEMS resonator 10 formed by Cavity SOI. It can also avoid the further increase of SOI wafer warping due to the increase in the number of bonding times when making Cavity SOI, thereby avoiding the impact of multiple pairs of stacked structure MEMS resonators 10. At the same time, when using Cavity SOI, the overall thickness of the MEMS resonator 10 will inevitably increase, thereby avoiding the need to add multiple thinning steps in the process steps, thereby reducing the processing risk; in addition, by setting the side of the middle area connected to the coupling beam 400 to a flat surface, that is, the coupling beam 400 is not embedded in the coupling resonator 200, that is, the coupling beam 400 is flatly coupled with the resonator 200, so that energy can be released, and the array-arranged resonators 200 vibrate at the same time, so that the performance of the single-mode MEMS resonator 10 can be inherited. The MEMS resonator 10 of the array structure is connected to the MEMS resonator 10 of the array structure, and the frequency is almost unchanged, and the impedance is reduced to 1 / 3 of the single-mode MEMS resonator 10. The impedance of the single-mode MEMS resonator 10 is about 300Ω, and the impedance of the MEMS resonator 10 of the array structure is only about 90Ω; in addition, by providing a concave portion 210 concave toward the inside of the resonator 200 on the side of the middle area of the two outermost resonators 200 and away from the coupling beam 400, the outer edge of the resonator 200 located in the middle area is close to the resonator 200. 0 forms an angle in the direction of lateral extension, thereby blocking the sound waves generated by the vibration of the resonator 200, reducing energy loss, and planning the transmission path of the sound waves, so that they interfere in the resonator 200 after rebounding, enhancing the vibration of the resonator 200, thereby improving the Q value of the MEMS resonator 10, and reducing the impedance at the same time; in addition, because the recessed portion 210 is arranged in the middle area of the resonator 200, and the anchor point 300 is connected to the recessed portion 210, the recessed portion 210 can suppress stray modes; in addition, the recessed portion is arranged on the resonator 200 210, the stiffness of the resonator 200 can be reduced, thereby increasing the vibration displacement of the resonator 200, and thereby improving the performance of the MEMS resonator 10; in addition, by setting a channel 220 on the resonator 200, the frequency adjustment of the MEMS resonator 10 of 0.01-5MHz can be achieved by adjusting the length of the channel 220, which effectively fills the deficiency of the trimming frequency modulation coverage range, and the adjustment for different frequencies will not have a significant impact on the performance of the MEMS resonator 10 itself, such as Q value, impedance, etc.
[0076] The present application provides a MEMS resonator 10 and a preparation method thereof, wherein the side of the middle area connected to the coupling beam 400 is set to a flat surface, that is, the coupling beam 400 is not embedded in the coupling resonator 200, that is, the coupling beam 400 is flatly coupled with the resonator 200, so that energy can be released, and the array-arranged resonators 200 vibrate at the same time, so that the performance of the single-mode MEMS resonator 10 can be inherited by the MEMS resonator 10 of the array structure, and the frequency is almost unchanged, and the impedance is reduced to 1 / 3 of the single-mode MEMS resonator 10, the impedance of the single-mode MEMS resonator 10 is about 300Ω, and the impedance of the MEMS resonator 10 of the array structure is only about 90Ω; in addition, a recessed portion 210 recessed toward the inside of the resonator 200 is provided on the side of the middle area of the two outermost resonators 200 and away from the coupling beam 400, so that the outer edge of the resonator 200 located in the middle area forms an angle with the lateral extension direction of the resonator 200, thereby blocking The sound waves generated by the vibration of the resonator 200 reduce the loss of energy, and plan the transmission path of the sound waves so that they interfere in the resonator 200 after rebounding, thereby enhancing the vibration of the resonator 200, thereby improving the Q value of the MEMS resonator 10 and reducing the impedance at the same time; in addition, because the recessed portion 210 is arranged in the middle area of the resonator 200, and the anchor point 300 is connected to the recessed portion 210, the recessed portion 210 can suppress the stray mode; in addition, the recessed portion 210 is arranged on the resonator 200, which can reduce the stiffness of the resonator 200, thereby increasing the vibration displacement of the resonator 200, thereby improving the performance of the MEMS resonator 10; in addition, by arranging the channel 220 on the resonator 200, the frequency adjustment of the MEMS resonator 10 of 0.01-5MHz can be achieved by adjusting the length of the channel 220, which effectively fills the deficiency of the trimming frequency modulation coverage range, and the adjustment for different frequencies will not have a significant impact on the performance of the MEMS resonator 10 itself, such as Q value, impedance, etc.
[0077] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the specification and drawings of the present application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A MEMS resonator, characterized in that: The invention comprises a substrate, at least two resonators and two anchor points, each of the resonators extends along a first direction and is arranged along a second direction perpendicular to the first direction, and each two adjacent resonators are connected by a coupling beam; in the second direction, the coupling beam is connected to the side surface of the middle area of the resonator, and the side surface of the middle area connected to the coupling beam is a flat surface; The sides of the middle region of the two outermost resonators facing away from the coupling beam have a recessed portion recessed toward the inside of the resonator, and the two anchor points respectively extend into the recessed portions to connect the resonator to the substrate.
2. The MEMS resonator according to claim 1, characterized in that: At least one side surface of the coupling beam that is not connected to the resonator is an arc-shaped surface that is convexly arranged toward the outside of the coupling beam.
3. The MEMS resonator according to claim 1, characterized in that: The length of the coupling beam is 1 / 2 of the wavelength of the sound wave generated by the vibration of the resonator.
4. The MEMS resonator according to claim 1, characterized in that: Each of the resonators has a channel that penetrates the resonator and connects the bottom surface and the top surface of the resonator. The opposite two sides of the middle area are connected to the edge area, and the channel is located on the edge area.
5. The MEMS resonator according to claim 4, characterized in that: The channel includes a first channel, the first channel is located on a side of the edge region close to the recessed portion, and the first channel extends along the first direction and is arranged along the second direction.
6. The MEMS resonator according to claim 5, characterized in that: The channel further includes a second channel extending along the first direction and arranged along the second direction, and the second channel is located on a side of the first channel away from the recessed portion.
7. The MEMS resonator according to claim 6, characterized in that: The channel further includes a third channel extending along the first direction and arranged along the first direction, and the third channel is located between the first channel and the second channel.
8. The MEMS resonator according to claim 1, characterized in that: The opposite sides of the middle area are connected to the edge area, and at least one side surface of the resonator located in the edge area is an arc-shaped surface convexly arranged toward the outside of the resonator.
9. The MEMS resonator according to any one of claims 1 to 8, characterized in that: The MEMS resonator further includes a driving electrode, a piezoelectric layer and a sensing electrode stacked in sequence on the resonator, and the MEMS resonator is a piezoelectric resonator. Alternatively, the MEMS resonator further includes a driving electrode and a sensing electrode arranged on the substrate, and the MEMS resonator is an electrostatic resonator.
10. A method for preparing a MEMS resonator, characterized in that: For preparing the MEMS resonator according to any one of claims 1 to 9, comprising: Providing an SOI wafer, the SOI wafer comprising a first insulating layer, a substrate, a second insulating material layer and a device material layer stacked in sequence from bottom to top; Etching the device material layer to form a release port; A portion of the second insulating material layer is removed through the release port so that the device material layer forms a device layer, wherein the device layer includes at least two resonators and two anchor points, each of which has a cavity between it and the substrate, each of which extends along a first direction and is arranged along a second direction perpendicular to the first direction, and each two adjacent resonators are connected by a coupling beam; in the second direction, the coupling beam is connected to the side of the middle area of the resonator, and the side of the middle area connected to the coupling beam is a flat surface; the side of the middle area of the two outermost resonators facing away from the coupling beam has a recessed portion recessed toward the inside of the resonator, and the two anchor points extend into the recessed portions respectively to connect the resonator to the substrate.