Vibration frequency test structure and test method

Abstract

The invention provides a vibration frequency test structure and test method, and relates to the technical field of semiconductor test. The vibration frequency testing structure comprises a first supporting body and a first vibration unit arranged on the first supporting body, the first supporting body is completely the same as a second supporting body of an acoustic chip, the first vibration unit is completely the same as a second vibration unit of the acoustic chip, the first supporting body is provided with a first back cavity, and the second supporting body is provided with a second back cavity. The first back cavity is completely the same as the second back cavity on the second support body; the two opposite sides of the first vibration unit are respectively provided with a first through area, the first through areas are communicated with the first back cavity, and the cross sectional area of the first through areas is larger than that of the second through areas on the two sides of the second vibration unit. The vibration frequency test structure can replace an acoustic chip to carry out vibration frequency test, and the measured result is more accurate and can better represent the inherent frequency of the acoustic chip.

Description

Technical Field

[0001] This application relates to the field of semiconductor testing technologies, and more particularly, to a vibration frequency testing structure and a testing method. Background Art

[0002] In the design of acoustic chips, especially in the design of vibration sensing components, the natural frequency is surely one of the most important design parameters. The natural frequency of the vibration unit determines key parameters such as the frequency bandwidth range, operating frequency band, and amplitude of the acoustic chip. Therefore, before the acoustic chip leaves the factory, it is necessary to detect the natural frequency of its vibration unit. Differences in the natural frequency will be directly reflected in the sensitivity and frequency response of the acoustic chip.

[0003] The prior art usually uses an impedance analyzer to measure the natural frequency of the vibration unit. However, since the actual measurement is carried out in air and the acoustic chip adopts a particularly small slit-through design, especially for MEMS microphone chips with a cantilever beam as the vibration unit, the slit needs to be small to ensure the low-frequency performance of the system. Therefore, the natural frequency measured by the impedance analyzer is actually the frequency after the vibration unit is coupled with the surrounding air. Moreover, the measured natural frequency also depends on the shape of the vibration unit itself, such as surface flatness, deflection distribution of the vibration unit, and the state presented by the vibration units relative to each other. These will all cause differences in the acoustic states of the entire acoustic chip, and such differences will lead to different natural frequencies measured by the impedance analyzer. Therefore, the prior art cannot accurately measure the natural frequency of the vibration unit in the acoustic chip, resulting in the inability to accurately estimate the performance of the acoustic chip. Summary of the Invention

[0004] The purpose of this application is to provide, in view of the deficiencies in the above prior art, a vibration frequency testing structure and a testing method that can replace the acoustic chip for vibration frequency testing, and the measured results are more accurate and can better represent the natural frequency of the acoustic chip.

[0005] To achieve the above purpose, the technical solutions adopted in the embodiments of this application are as follows:

[0006] On the one hand, an embodiment of this application provides a vibration frequency testing structure for replacing the acoustic chip for vibration frequency testing. The vibration frequency testing structure includes: a first support body and a first vibration unit disposed on the first support body. The first support body is exactly the same as the second support body of the acoustic chip, and the first vibration unit is exactly the same as the second vibration unit of the acoustic chip. A first back cavity is provided on the first support body, and the first back cavity is exactly the same as the second back cavity on the second support body. First through areas are respectively provided on two opposite sides of the first vibration unit, the first through areas are communicated with the first back cavity, and the cross-sectional area of the first through areas is larger than the cross-sectional area of the second through areas on both sides of the second vibration unit.

[0007] Optionally, the cross-sectional area of the first through-hole area is three times or more that of the second through-hole area.

[0008] Optionally, the number of the first vibration units is at least two. At least two first vibration units are arranged on the first support body at the same layer and extend in different directions.

[0009] Optionally, a third vibration unit is further arranged on the first support body. The third vibration unit is located on the side of the first vibration unit, and a first through-hole area is arranged between the third vibration unit and the first vibration unit.

[0010] Optionally, the cross-sectional areas of the two first through-hole areas on both sides of the first vibration unit are equal.

[0011] On the other hand, an embodiment of the present application provides a vibration frequency testing method, including: providing a wafer and dividing at least one detection area on the surface of the wafer; processing at least one vibration frequency testing structure and a plurality of acoustic chips in the detection area, wherein the vibration frequency testing structure includes: a first support body and a first vibration unit arranged on the first support body. A first back cavity is arranged on the first support body. First through-hole areas are respectively arranged on the two opposite sides of the first vibration unit. The first through-hole areas communicate with the first back cavity. The acoustic chip includes a second support body and a second vibration unit arranged on the second support body. A second back cavity is arranged on the second support body. Second through-hole areas are respectively arranged on the two opposite sides of the second vibration unit. The second through-hole areas communicate with the second back cavity. The first support body and the second support body are completely the same. The first vibration unit and the second vibration unit are completely the same. The first back cavity and the second back cavity are completely the same. The cross-sectional area of the first through-hole area is larger than that of the second through-hole areas on both sides of the second vibration unit; testing the vibration frequency of the first vibration unit to obtain the natural frequency of the first vibration unit, and the natural frequency of the first vibration unit is the natural frequency of the second vibration unit.

[0012] Optionally, the number of the detection areas is multiple, adjacent detection areas are connected to each other, and the multiple detection areas are distributed in a rectangular array.

[0013] Optionally, in each detection area, the vibration frequency testing structure and the plurality of acoustic chips are distributed in a rectangular array.

[0014] Optionally, before or after testing the vibration frequency of the first vibration unit, the vibration frequency testing method further includes: cutting the wafer to obtain independent vibration frequency testing structures and a plurality of acoustic chips.

[0015] Optionally, performing a vibration frequency test on the first vibration unit to obtain the vibration frequency of the first vibration unit includes: placing the vibration frequency test structure on a test bench; applying an alternating voltage within a preset frequency range to both electrical ends of the first vibration unit using an impedance analyzer to cause the first vibration unit to vibrate, where the preset frequency range includes the natural frequency of the first vibration unit; obtaining the frequency reading corresponding to the first peak of the impedance angle of the first vibration unit within the preset frequency range, and the frequency reading is the natural frequency of the first vibration unit.

[0016] The beneficial effects of this application include:

[0017] This application provides a vibration frequency test structure for replacing an acoustic chip to perform a vibration frequency test. The vibration frequency test structure includes: a first support body and a first vibration unit disposed on the first support body. The first support body is exactly the same as the second support body of the acoustic chip, the first vibration unit is exactly the same as the second vibration unit of the acoustic chip, a first back cavity is provided on the first support body, and the first back cavity is exactly the same as the second back cavity on the second support body; first through areas are respectively provided on two opposite sides of the first vibration unit, the first through areas communicate with the first back cavity, and the cross-sectional area of the first through areas is larger than the cross-sectional area of the second through areas on both sides of the second vibration unit. For the above vibration frequency test structure, by setting its first vibration unit to be exactly the same as the second vibration unit of the acoustic chip, setting its first support body to be exactly the same as the second support body of the acoustic chip, and setting its first back cavity to be exactly the same as the second back cavity of the acoustic chip, it replaces the acoustic chip to perform a vibration frequency test. However, since the cross-sectional area of the first through areas of the vibration frequency test structure is larger than the cross-sectional area of the second through areas of the acoustic chip, the first back cavity communicates with the infinitely large air area above the first vibration unit, and the equivalent acoustic compliance of the first back cavity during the test can be considered to be infinitely large, so that the first vibration unit is not affected by the air acoustic environment in which it is located during the test, and the measured vibration frequency is the natural frequency of the first vibration unit itself. Compared with directly testing the acoustic chip, the obtained vibration frequency test result is more accurate and can better represent the natural frequency of the second vibration unit in the acoustic chip itself. Description of the Drawings

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of this application, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0019] Figure 1 Schematic diagram of the acoustic chip placed on the test bench;

[0020] Figure 2 Schematic structural diagram of an acoustic chip;

[0021] Figure 3 Schematic diagram of the vibration frequency test structure provided by an embodiment of the present application placed on a test bench;

[0022] Figure 4 One of the schematic diagrams of the vibration frequency test structure provided by an embodiment of the present application;

[0023] Figure 5 Another schematic diagram of the vibration frequency test structure provided by an embodiment of the present application;

[0024] Figure 6 One of the flowcharts of the vibration frequency test method provided by an embodiment of the present application;

[0025] Figure 7 Schematic diagram of forming a vibration frequency test structure and an acoustic chip on a wafer;

[0026] Figure 8 Another flowchart of the vibration frequency test method provided by an embodiment of the present application.

[0027] Icons: 10 - Acoustic chip; 11 - Second support; 12 - Second vibration unit; 13 - Second through area; 14 - Second back cavity; 20 - Test bench; 30 - Vibration frequency test structure; 31 - First support; 32 - First vibration unit; 33 - First back cavity; 34 - First through area; 35 - Third vibration unit; 40 - Wafer; 41 - Detection area; Detailed implementation manners

[0028] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. It should be noted that, without conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the protection scope of the present application.

[0030] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0031] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present application, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "linked" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0033] Please refer to Figure 1 and Figure 2 , the acoustic chip 10 includes a second support body 11 and at least two second vibration units 12 arranged on the second support body 11 on the same layer. A second through area 13 is provided between two adjacent second vibration units 12. A second back cavity 14 that penetrates the second support body 11 and communicates with the second through area 13 is provided on the second support body 11, so that the area on the second vibration unit 12 corresponding to the second back cavity 14 can achieve vibration. The natural frequency of the second vibration unit 12 determines key parameters such as the frequency bandwidth range, working frequency band, amplitude, etc. of the acoustic chip 10. Therefore, before the acoustic chip 10 leaves the factory, it is necessary to detect the natural frequency of the second vibration unit 12. The difference in the natural frequency will be directly reflected in the sensitivity of the acoustic chip 10 and the system frequency response after the chip is packaged.

[0034] In the prior art, an impedance analyzer is generally used to measure the natural frequency of the second vibration unit 12. The general measurement steps are as follows: Place the side of the second support body 11 of the acoustic chip 10 facing away from the second vibration unit 12 on the test bench 20, and then use an impedance analyzer to perform a voltage sweep on the second vibration unit 12 at a preset voltage. Obviously, when sweeping the second vibration unit 12 at the preset voltage, if the vibration frequency of the second vibration unit 12 is close to the frequency of the sweep voltage, the vibration amplitude will reach resonance. At this time, the impedance angle of the second vibration unit 12 will obtain a peak value (i.e., reach the maximum value periodically). The frequency at which the impedance angle first obtains a peak value is considered to be the natural frequency of the tested second vibration unit 12.

[0035] From the above analysis, it can be seen that when measuring the natural frequency of the acoustic chip 10, the method of forced vibration is adopted, that is, an AC voltage with a preset frequency band width is applied to the electrical terminals of the second vibration unit 12 to cause its vibration and observe the frequency position of its resonance. However, the test results of the electrical lumped parameters of the second vibration unit 12 itself depend on the coupling results of the structure body of the second vibration unit 12 and the acoustic domains around its vibration. These acoustic domains include the thermo-viscous acoustic domain of the second through-hole area 13, the pressure acoustic domain of the second back cavity 14, and the infinite pressure acoustic domain where the second vibration unit 12 vibrates upward. Therefore, the vibration frequency obtained by observing the impedance angle using an impedance analyzer is the resonance frequency of the forced vibration system in which the second vibration unit 12 is coupled with the surrounding acoustic domains, and this resonance frequency may be significantly higher than the natural frequency of the second vibration unit 12 itself.

[0036] The above analysis shows that when using the acoustic chip 10 as the sensing chip, the second through-hole area 13 of the acoustic chip 10 needs to be very small and the acoustic resistance needs to be very large to improve the low-frequency response. However, during the test, if the second through-hole area 13 is too small, the measured vibration frequency may be significantly higher than the natural frequency of the second vibration unit 12 itself. Therefore, the prior art cannot accurately measure the natural frequency of the second vibration unit 12 in the acoustic chip 10, resulting in the inability to accurately estimate the performance of the acoustic chip 10.

[0037] To solve the above technical problems, on the one hand of the embodiments of the present application, please refer to Figure 1 and Figure 3 , a vibration frequency test structure 30 is provided to replace the acoustic chip 10 for vibration frequency testing. That is to say, place the vibration frequency test structure 30 on the test bench 20 and perform vibration frequency testing on it. The measured vibration frequency is the natural frequency of the acoustic chip 10.

[0038] Specifically, the vibration frequency test structure 30 includes: a first support body 31 and a first vibration unit 32 disposed on the first support body 31. The first support body 31 is exactly the same as the second support body 11 of the acoustic chip 10, and the first vibration unit 32 is exactly the same as the second vibration unit 12 of the acoustic chip 10. The so-called exactly the same here means that the dimensions, shapes, and materials are exactly the same. If it is mentioned again as exactly the same in the following description, it also has the same meaning. The number of the first vibration units 32 is at least one. When the number of the first vibration units 32 is two or more, two or more first vibration units 32 are simultaneously connected to the first support body 31. If there are different second vibration units 12 in the acoustic chip 10 (for example, the dimensions of two second vibration units 12 are different, or the shapes of two second vibration units 12 are different), then at least one first vibration unit 32 needs to be provided on the vibration frequency test structure 30 for each type of second vibration unit 12.

[0039] A first back cavity 33 is provided on the first support body 31. The first back cavity 33 penetrates the upper surface and the lower surface of the first support body 31, so that the area of the first vibration unit 32 corresponding to the first back cavity 33 can be suspended, thereby realizing vibration. The first back cavity 33 is exactly the same as the second back cavity 14 on the second support body 11.

[0040] Please refer to Figure 4 , first through areas 34 are respectively provided on two opposite sides of the first vibration unit 32. If there are other vibration units on the side surface of the first vibration unit 32 (such as another first vibration unit 32, or another vibration unit different from the first vibration unit 32), then the first through area 34 refers to the area between the first vibration unit 32 and other vibration units; if there are no other vibration units on the side surface of the first vibration unit 32, then the first through area 34 refers to the area of the side surface of the first vibration unit 32. At this time, the cross-sectional area of the first through area 34 is very large. The first through area 34 communicates with the first back cavity 33. The difference between the vibration frequency test structure 30 and the acoustic chip 10 is that the cross-sectional area of the first through area 34 is larger than the cross-sectional area of the second through areas 13 on both sides of the second vibration unit 12, thereby weakening the coupling between the structure body of the first vibration unit 32 and the acoustic domain around its vibration. Exemplarily, the cross-sectional area of the first through area 34 is three times or more than three times the cross-sectional area of the second through area 13. Here, the cross-sectional area of the through area refers to the area of the cross-section of the through area parallel to the surface of the test bench 20. Generally speaking, it meets the requirements that no thermo-viscous region with obvious acoustic resistance is generated in the first through area 34.

[0041] The size of the second through-hole area 13 in the acoustic chip 10 is very small. After being placed on the test bench 20, its second back cavity 14 can be approximately considered to be in a closed state. Therefore, when directly testing the acoustic chip 10, the measured vibration frequency is affected by the coupling between the structural body of the second vibration unit 12 and the acoustic domain around its vibration, and the result is not accurate. However, for the vibration frequency test structure 30 provided in the embodiment of the present application, the size of its first through-hole area 34 is relatively large. After being placed on the test bench 20, the upper part of the first vibration unit 32 and the first back cavity 33 can be interconnected through the first through-hole area 34. During the test, the equivalent acoustic compliance of the first back cavity 33 can be considered to be infinite, so that the first vibration unit 32 is not affected by the air acoustic environment in which it is located during the test, and the measured vibration frequency is the natural frequency of the first vibration unit 32 itself. Moreover, the first vibration unit 32 is exactly the same as the second vibration unit 12, and the first support body 31 and the first back cavity 33 below the first vibration unit 32 are also exactly the same as the second support body 11 and the second back cavity 14 below the second vibration unit 12 respectively. Therefore, the natural frequency of the first vibration unit 32 measured is the natural frequency of the second vibration unit 12 itself on the acoustic chip 10.

[0042] It should be noted that in order to ensure that the test result of the first vibration unit 32 can represent the second vibration unit 12, preferably, the vibration frequency test structure 30 and the acoustic chip 10 are formed in a preset area on the same wafer 40. The preset area is a small area divided on the wafer 40. In this area, the natural frequencies of the first vibration unit 32 and the second vibration unit 12 processed are the same or the difference is within a preset range, and the preset range is an acceptable error range.

[0043] For the above-mentioned vibration frequency test structure 30, by setting its first vibration unit 32 to be exactly the same as the second vibration unit 12 of the acoustic chip 10, setting its first support body 31 to be exactly the same as the second support body 11 of the acoustic chip 10, and setting its first back cavity 33 to be exactly the same as the second back cavity 14 of the acoustic chip 10, the vibration frequency test is carried out instead of the acoustic chip 10. However, since the cross-sectional area of the first through-hole area 34 of the vibration frequency test structure 30 is larger than the cross-sectional area of the second through-hole area 13 of the acoustic chip 10, the first back cavity 33 is connected to the infinite air area above the first vibration unit 32. During the test, the equivalent acoustic compliance of the first back cavity 33 can be considered to be infinite, so that the first vibration unit 32 is not affected by the air acoustic environment in which it is located during the test, and the measured vibration frequency is the natural frequency of the first vibration unit 32 itself. Compared with directly testing the acoustic chip 10, the obtained vibration frequency test result is more accurate and can better represent the natural frequency of the second vibration unit 12 itself in the acoustic chip 10.

[0044] Optionally, the cross-sectional areas of the two first through areas 34 on both sides of the first vibration unit 32 are equal.

[0045] With such a setting, during testing, abnormal situations such as the deflection of the first-order vibration mode will not occur due to different acoustic resistances on both sides of the first vibration unit 32, and the test results will be more accurate. Of course, if the area of the first through area 34 is large enough, it is not necessary for the cross-sectional areas of the two first through areas 34 on both sides of the same first vibration unit 32 to be equal.

[0046] Optionally, the number of the first vibration units 32 is at least two. At least two first vibration units 32 are arranged on the first support 31 in the same layer and extend in different directions.

[0047] It should be noted that at least two first vibration units 32 extending in different directions means that at least two first vibration units 32 extend in different directions on the horizontal plane.

[0048] When the number of the first vibration units 32 is two or more, one of the first vibration units 32 is used to test the natural frequency, and the other first vibration units 32 can be used for other tests. For example, testing the natural frequency difference of the first vibration units 32 in different extending directions to characterize the natural frequency difference of the second vibration units 12 in different extending directions.

[0049] Optionally, please refer to Figure 4 and Figure 5 , there is also a third vibration unit 35 on the first support 31. The third vibration unit 35 is located on the side of the first vibration unit 32, and there is a first through area 34 between the third vibration unit 35 and the first vibration unit 32.

[0050] The first vibration unit 32 is obtained by etching a first through area 34 on the entire surface vibration film layer. During the etching process, the remaining part of the vibration film layer is retained to obtain the third vibration unit 35. Therefore, allowing the existence of the third vibration unit 35 can simplify the processing process of the vibration frequency test structure 30.

[0051] This embodiment also provides a vibration frequency test method. Please refer to Figure 6 , including:

[0052] S100: Provide a wafer and divide at least one detection area on the surface of the wafer.

[0053] Please refer to Figure 7 , the number of the detection areas 41 can be appropriately adjusted according to the size of the wafer 40. The larger the wafer 40, in principle, the more the number of the divided detection areas 41. Please refer to Figure 2 and Figure 4, so as to ensure that the natural frequency of the first vibration unit 32 of the vibration frequency test structure 30 processed within a detection area 41 is the same as or the difference from the natural frequency of the second vibration unit 12 of the acoustic chip 10 within a preset range.

[0054] S200: Process at least one vibration frequency test structure and multiple acoustic chips within a detection area. Among them, the vibration frequency test structure includes: a first support body and a first vibration unit provided on the first support body. A first back cavity is provided on the first support body. First through areas are respectively provided on two opposite sides of the first vibration unit, and the first through areas communicate with the first back cavity. The acoustic chip includes a second support body and a second vibration unit provided on the second support body. A second back cavity is provided on the second support body. Second through areas are respectively provided on two opposite sides of the second vibration unit, and the second through areas communicate with the second back cavity. The first support body and the second support body are completely the same, the first vibration unit and the second vibration unit are completely the same, the first back cavity and the second back cavity are completely the same, and the cross-sectional area of the first through area is larger than the cross-sectional area of the second through areas on both sides of the second vibration unit.

[0055] At least one vibration frequency test structure 30 and multiple acoustic chips 10 are processed within each detection area 41. The vibration frequency test structure 30 can be used to test the vibration frequency instead of the acoustic chip 10 within the same detection area 41, and the test result can characterize the natural frequency of the acoustic chip 10 within the same detection area 41. Generally speaking, the number of vibration frequency test structures 30 within a detection area is one, and the vibration frequency test structure 30 is arranged at a corner of the detection area 41 or at the middle position of the detection area 41.

[0056] The structures of the vibration frequency test structure 30 and the acoustic chip 10 have been described in detail in the foregoing embodiments, and will not be elaborated herein.

[0057] S300: Test the vibration frequency of the first vibration unit to obtain the natural frequency of the first vibration unit, and the natural frequency of the first vibration unit is the natural frequency of the second vibration unit.

[0058] Since the first vibration unit 32 is exactly the same as the second vibration unit 12, the first support 31 and the first back cavity 33 below the first vibration unit 32 are also exactly the same as the second support 11 and the second back cavity 14 below the second vibration unit 12 respectively. Therefore, the measured natural frequency of the first vibration unit 32 is the natural frequency of the second vibration unit 12 itself on the acoustic chip 10. In the above vibration frequency testing method, during the process of manufacturing the acoustic chip 10, at least one vibration frequency testing structure 30 is additionally manufactured in each detection area 41 of the wafer 40, and the vibration frequency testing structure 30 is used to replace the acoustic chip 10 in the same area for vibration frequency testing. Since the cross-sectional area of the first through area 34 of the vibration frequency testing structure 30 is larger than the cross-sectional area of the second through area 13 of the acoustic chip 10, during testing, the first vibration unit 32 of the vibration frequency testing structure 30 is not affected by the air acoustic environment where it is located, and the measured vibration frequency is the natural frequency of the first vibration unit 32 itself, that is, the natural frequency of the second vibration unit 12 itself on the acoustic chip 10. Compared with directly testing the acoustic chip 10, the obtained vibration frequency test result is more accurate and can better represent the natural frequency of the second vibration unit 12 itself in the acoustic chip 10.

[0059] Optionally, to further improve the accuracy of detection, the number of detection areas 41 is multiple, adjacent detection areas 41 are connected to each other, and the multiple detection areas 41 are arranged in a rectangular array.

[0060] The surface of the wafer 40 is divided into multiple detection areas 41, so that the area of each detection area 41 is small, thereby ensuring that the vibration frequency of the first vibration unit 32 in the same detection area 41 is the same as or the difference from the vibration frequency of the second vibration unit 12 is within a preset range, so as to improve the accuracy of detection. Adjacent detection areas 41 are connected to each other to avoid missed detection. And arranging the detection areas 41 in a rectangular array is convenient for dividing the wafer 40.

[0061] It can be understood that the surface of the wafer 40 is generally circular. Therefore, the detection areas 41 near the edge of the wafer 40 may not be rectangular.

[0062] Optionally, please refer to Figure 7 , in each detection area 41, the vibration frequency testing structure 30 and multiple acoustic chips 10 are arranged in a rectangular array.

[0063] Such an arrangement can facilitate the manufacturing of the vibration frequency testing structure 30 and the acoustic chips 10, as well as subsequent cutting of the wafer 40 to separate the vibration frequency testing structure 30 and the acoustic chips 10.

[0064] Optionally, before or after testing the vibration frequency of the first vibration unit, the vibration frequency testing method further includes:

[0065] The wafer is cut to obtain independent vibration frequency test structures and multiple acoustic chips.

[0066] Please refer to Figure 3 and Figure 7 For the foregoing vibration frequency test of the first vibration unit 32, it can be carried out before cutting the wafer 40. At this time, both the vibration frequency test structure 30 and the acoustic chip 10 are still on the same wafer 40. The foregoing vibration frequency test of the first vibration unit 32 can also be carried out after cutting the wafer 40. At this time, the vibration frequency test structure 30 and the acoustic chip 10 have been separated from each other.

[0067] Optionally, please refer to Figure 8 for the vibration frequency test of the first vibration unit to obtain the vibration frequency of the first vibration unit, including:

[0068] S310: Place the vibration frequency test structure on the test bench.

[0069] S320: Apply an alternating current voltage within a preset frequency range to both electrical ends of the first vibration unit by using an impedance analyzer to cause the vibration of the first vibration unit. The preset frequency range includes the natural frequency of the first vibration unit.

[0070] S330: Obtain the frequency reading corresponding to the first peak of the impedance angle within the preset frequency range of the first vibration unit. The frequency reading is the natural frequency of the first vibration unit.

[0071] It can be understood that, please refer to Figure 3 and Figure 7 together. At this time, if the wafer 40 has not been cut yet, then a whole wafer 40 formed with the vibration frequency test structure 30 is placed on the test bench 20.

[0072] Apply an alternating current voltage within a preset frequency range to both electrical ends of the first vibration unit 32 by using an impedance analyzer, thereby causing the vibration of the first vibration unit 32. When the frequency of the alternating current voltage approaches the natural frequency of the first vibration unit 32, the first vibration unit 32 will resonate. At this time, the impedance angle of the first vibration unit 32 will obtain a peak value. Read the frequency reading corresponding to the first peak of the impedance angle, which is considered to be the natural frequency of the tested first vibration unit 32.

[0073] It should be noted that during the entire test process, the impedance angle will show a changing trend of first increasing and then decreasing multiple times. Therefore, multiple peaks will be obtained for the impedance angle during the test. The multiple peaks may be equal or may not be equal. And the frequency reading corresponding to the first peak can be recognized as the natural frequency of the first vibration unit 32.

[0074] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and changes can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A vibration frequency test structure for replacing an acoustic chip to conduct vibration frequency tests, characterized in that The vibration frequency test structure includes: a first support body and a first vibration unit provided on the first support body. The first support body is exactly the same as the second support body of the acoustic chip, the first vibration unit is exactly the same as the second vibration unit of the acoustic chip, a first back cavity is provided on the first support body, and the first back cavity is exactly the same as the second back cavity on the second support body; first through areas are respectively provided on two opposite sides of the first vibration unit, the first through areas are communicated with the first back cavity, and the cross-sectional area of the first through areas is larger than the cross-sectional area of second through areas on two sides of the second vibration unit.

2. The vibration frequency test structure according to claim 1, wherein The cross-sectional area of the first through areas is three times or more that of the cross-sectional area of the second through areas.

3. The vibration frequency testing structure according to claim 1, wherein The number of the first vibration units is at least two. At least two first vibration units are arranged on the first support body in the same layer and extend in different directions.

4. The vibration frequency test structure according to claim 1, wherein A third vibration unit is further provided on the first support body. The third vibration unit is located on the side of the first vibration unit, and the first through area is provided between the third vibration unit and the first vibration unit.

5. The vibration frequency test structure according to claim 1, wherein The cross-sectional areas of the two first through areas on two sides of the first vibration unit are equal.

6. A vibration frequency testing method, characterized in that, including: Providing a wafer and dividing at least one detection area on the surface of the wafer; Processing at least one vibration frequency test structure and a plurality of acoustic chips in the detection area. The vibration frequency test structure includes: a first support body and a first vibration unit provided on the first support body. A first back cavity is provided on the first support body. First through areas are respectively provided on two opposite sides of the first vibration unit. The first through areas are communicated with the first back cavity. The acoustic chip includes a second support body and a second vibration unit provided on the second support body. A second back cavity is provided on the second support body. Second through areas are respectively provided on two opposite sides of the second vibration unit. The second through areas are communicated with the second back cavity. The first support body is exactly the same as the second support body, the first vibration unit is exactly the same as the second vibration unit, the first back cavity is exactly the same as the second back cavity, and the cross-sectional area of the first through areas is larger than the cross-sectional area of second through areas on two sides of the second vibration unit; Performing a vibration frequency test on the first vibration unit to obtain the natural frequency of the first vibration unit, and the natural frequency of the first vibration unit is the natural frequency of the second vibration unit.

7. The vibration frequency testing method according to claim 6, wherein The number of the detection areas is multiple, adjacent detection areas are connected to each other, and the multiple detection areas are distributed in a rectangular array.

8. The vibration frequency testing method according to claim 6, wherein In each detection area, the vibration frequency test structure and the plurality of acoustic chips are distributed in a rectangular array.

9. The vibration frequency testing method according to claim 6, characterized in that, Before or after performing the vibration frequency test on the first vibration unit, the vibration frequency test method further includes: Cutting the wafer to obtain independent vibration frequency test structures and a plurality of acoustic chips.

10. The vibration frequency test method according to claim 6, wherein, Performing the vibration frequency test on the first vibration unit to obtain the natural frequency of the first vibration unit includes: Place the vibration frequency test structure on the test bench; Apply an AC voltage within a preset frequency range to the electrical terminals of the first vibration unit using an impedance analyzer to induce vibration of the first vibration unit, where the preset frequency range includes the natural frequency of the first vibration unit; Obtain the frequency reading corresponding to the first peak of the impedance angle of the first vibration unit within the preset frequency range, and the frequency reading is the natural frequency of the first vibration unit.

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