Manufacturing method of MEMS loudspeaker

Abstract

The invention relates to the field of semiconductor devices and provides a manufacturing method of an MEMS loudspeaker. The manufacturing method comprises the following steps: etching operation: etching a piezoelectric structure deposited on a silicon wafer to form a slit penetrating through the piezoelectric structure; performing back etching protection operation; performing back etching operation; the manufacturing method comprises an etching operation, a back etching protection operation, a back etching protection removal operation and a scribing operation, the manufacturing method further comprises a stretchable film setting operation, and the stretchable film setting operation is between the etching operation and the back etching protection operation, or the stretchable film setting operation is between the back etching protection removal operation and the scribing operation. A stretchable film covering the slit is provided on the electrode layer side of the piezoelectric structure by a stretchable film setting operation, whereby the stretchable film can be integrated into the MEMS speaker.

Description

Technical Field

[0001] The present application relates to the field of semiconductor devices, and particularly to a manufacturing method of a MEMS speaker. Background Art

[0002] Currently, MEMS (Microelectromechanical Systems) has been widely applied, such as MEMS speakers.

[0003] The inventors of the present application found that due to the slits in traditional MEMS speakers, the low-frequency response is poor. In addition, in some existing technologies, a structure with a non-stretchable film is configured, but such a structure will lead to the deterioration of the mid-high frequency response.

[0004] This section aims to provide the background or context for the embodiments of the present application stated in the claims. The description herein is not admitted to be prior art merely because it is included in this section. Summary of the Invention

[0005] The inventors of the present application found that by disposing a stretchable film on the surface of the diaphragm of a MEMS speaker, using the stretchable film to fill or cover the vibration space, blocking the leakage channels of sound waves, reducing the sound leakage caused by the vibration space, weakening the acoustic short-circuit effect, and improving the low-frequency response of the speaker. At the same time, using the stretchable characteristics of the stretchable film to weaken the inhibitory effect of the stretchable film on the vibration of the diaphragm, ensuring that the mid-high frequency characteristics of the speaker are less affected. Thus, it is possible to improve the low-frequency response without substantially affecting the mid-high frequency characteristics of the speaker.

[0006] However, currently, the stretchable film is usually configured in a simple way of using patches, and its thickness is generally above 15 micrometers. For piezoelectric MEMS speakers, a stretchable film with a thinner thickness needs to be configured to ensure that the mid-high frequency performance is not affected while improving the low-frequency performance. To achieve the configuration of a thinner stretchable film, a new solution is needed.

[0007] To solve at least one of the above problems or other similar problems, an embodiment of the present application provides a manufacturing method of a MEMS speaker.

[0008] According to an embodiment of the present application, there is provided a manufacturing method of a MEMS speaker, the method comprising:

[0009] An etching operation of etching a piezoelectric structure deposited on a silicon wafer, the piezoelectric structure comprising at least one piezoelectric layer and at least one electrode layer, to form slits penetrating the piezoelectric structure;

[0010] A back-etching protection operation of forming a back-etching protection structure on the side opposite to the side where the silicon wafer is disposed of the piezoelectric structure;

[0011] Back-etching operation: perform back-etching from the side of the silicon wafer where the piezoelectric structure is provided to form a cavity;

[0012] Back-etching protection removal operation: remove the back-etching protection structure;

[0013] Dicing operation: dice along the part between the cavities of the silicon wafer to obtain MEMS speaker chips,

[0014] The method further includes a stretchable film setting operation: set a stretchable film covering the slit on the side of the piezoelectric structure close to the electrode layer. The stretchable film setting operation is between the etching operation and the back-etching protection operation, or the stretchable film setting operation is between the back-etching protection removal operation and the dicing operation.

[0015] One of the beneficial effects of the embodiments of the present application is that through the stretchable film setting operation, a stretchable film covering the slit is set on the side of the piezoelectric structure close to the electrode layer, so that the stretchable film can be integrated into the MEMS speaker. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 is a schematic diagram of a manufacturing method of a MEMS speaker according to an embodiment of the present application;

[0018] Figures 2 to 9 is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 1;

[0019] Figures 10 to 22 is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 2;

[0020] Figures 23 to 34 is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 3;

[0021] Figures 35 to 46 is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 4;

[0022] Figures 47 to 58 is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 5;

[0023] Figures 59 to 69It is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 6. Detailed implementation manners

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer and more understandable, the following further describes the embodiments of this application in detail with reference to the accompanying drawings. Herein, the illustrative embodiments of this application and their descriptions are used to explain this application, but do not limit this application.

[0025] In the embodiments of this application, terms such as "first", "second", "upper", and "lower" are used to distinguish different elements in terms of appellation, but do not represent the spatial arrangement or time sequence of these elements, and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the related listed terms. Terms such as "include", "comprise", and "have" mean the existence of the stated features, elements, components, or assemblies, but do not exclude the existence or addition of one or more other features, elements, components, or assemblies.

[0026] In the embodiments of this application, the singular forms "a", "the", etc. include the plural forms and should be broadly understood as "a kind" or "a class" rather than being limited to the meaning of "one"; in addition, the term "the" should be understood to include both the singular form and the plural form unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least partially according to...", and the term "based on" should be understood as "at least partially based on...", unless the context clearly indicates otherwise.

[0027] The embodiments of this application provide a manufacturing method of a MEMS speaker, and the package structure of the bulk acoustic wave resonator can be applied to a chip package structure. Figure 1 It is a schematic diagram of the manufacturing method of the MEMS speaker according to the embodiments of this application.

[0028] As Figure 1 shown, the manufacturing method of the MEMS speaker includes:

[0029] 102: An etching operation, etching the piezoelectric structure deposited on the silicon wafer, where the piezoelectric structure includes at least one piezoelectric layer and at least one electrode layer, to form a slit penetrating the piezoelectric structure;

[0030] 104: A back-etching protection operation, forming a back-etching protection structure on the side opposite to the side of the piezoelectric structure where the silicon wafer is disposed;

[0031] 106: A back-etching operation, back-etching from the side of the silicon wafer where the piezoelectric structure is disposed to form a cavity;

[0032] 108: A back-etching protection removal operation, removing the back-etching protection structure;

[0033] 110: Dicing operation, dicing along the portion between the cavities of the silicon wafer to obtain a MEMS speaker chip.

[0034] 112: Stretchable film setting operation, setting a stretchable film covering the slit on the side of the piezoelectric structure close to the electrode layer. The stretchable film setting operation is between the etching operation and the back-etching protection operation, or the stretchable film setting operation is between the back-etching protection removal operation and the dicing operation.

[0035] According to the above embodiments, through the stretchable film setting operation, a stretchable film covering the slit is set on the side of the piezoelectric structure close to the electrode layer. Thus, the stretchable film can be integrated into the MEMS speaker. Therefore, the low-frequency sound pressure level response can be improved by configuring the stretchable film, and at the same time, the deterioration of the mid-high frequency response caused by other types of films (non-stretchable films) can be avoided, optimizing the response curve of the MEMS speaker.

[0036] In the embodiments of the present application, the piezoelectric structure of the MEMS speaker can also be called a diaphragm, which is suitable for driving air vibration through its own vibration to emit sound.

[0037] In the embodiments of the present application, the stretchable film is a thin film with stretchable characteristics, and the stretchable film is stretched when the diaphragm vibrates. In the embodiments of the present application, the stretchable characteristics of the stretchable film can be ensured by setting the Young's modulus and thickness of the stretchable film to meet specific conditions, reducing its influence on the vibration of the diaphragm, and ensuring the mid-high frequency (especially the mid-frequency) characteristics of the MEMS speaker.

[0038] In the embodiments of the present application, the stretchable film is a thin film with the Young's modulus and thickness meeting specific conditions. For example, it can be polydimethylsiloxane (PDMS), but the present application is not limited thereto. It can also be a stretchable film based on other materials, such as rubber and other polymer materials, such as silicone rubber or RTV (room-temperature-vulcanizing silicone) rubber.

[0039] In the embodiments of the present application, the piezoelectric structure includes at least one piezoelectric layer and at least one electrode layer. For example, as Figure 1 shown, the piezoelectric structure includes a seed layer, a first electrode layer, a first piezoelectric layer, a second electrode layer, a second piezoelectric layer, and a third electrode layer sequentially deposited on the silicon wafer. However, the present application does not limit this, and the piezoelectric structure can also be other structures.

[0040] In the embodiments of the present application, the seed layer can be grown on a silicon wafer. The material of the seed layer can be, but is not limited to, aluminum nitride, zirconium dioxide, etc. The first electrode layer can be deposited on the seed layer. The material of the first electrode layer can be, but is not limited to, metal materials such as molybdenum, platinum, aluminum, copper, silver, gold, etc. The first piezoelectric layer can be deposited on the first electrode layer. The material of the first piezoelectric layer can be, but is not limited to, aluminum nitride, zinc oxide, polyvinylidene fluoride, lead zirconate titanate, etc. The second electrode layer can be deposited on the first piezoelectric layer. The second piezoelectric layer can be deposited on the second electrode layer. The third electrode layer can be deposited on the second piezoelectric layer. The materials of the second electrode layer and the third electrode layer can also be, but are not limited to, metal materials such as molybdenum, platinum, aluminum, copper, silver, gold, etc. The materials of the second piezoelectric layer and the third piezoelectric layer can also be, but are not limited to, aluminum nitride, zinc oxide, polyvinylidene fluoride, lead zirconate titanate, etc.

[0041] In the embodiments of the present application, in the etching operation, the seed layer, the first electrode layer, the first piezoelectric layer, the second electrode layer, the second piezoelectric layer, and the third electrode layer are all etched to form slits 310 by dry etching and / or wet etching. Among them, this etching process can be carried out after single-layer deposition or after multi-layer deposition. The present application does not limit this.

[0042] In the embodiments of the present application, a back-etch protection operation needs to be carried out before back-etching, that is, front protection is carried out before back-etching. The material of the protective substance can be, but is not limited to, silicon dioxide, etc. In addition, the protection methods include, but are not limited to, temporary wafer bonding, polymer protection such as photoresist or polyimide (abbreviated as PI), UV film or E-CHUCK film protection, etc.

[0043] In one or more embodiments, the method may further include before the etching operation:

[0044] A filling operation, forming a groove on one side of the silicon wafer for setting the piezoelectric structure, and setting a filling substance in the groove.

[0045] Thus, by setting the filling substance, it is possible to avoid contacting the stretchable film during back-etching, thereby preventing the stretchable film from being etched and contaminating the cavity for the back-etching process, and further avoiding affecting the normal operation of the back-etching machine.

[0046] In the embodiments of the present application, there is no limitation on the specific material of the filling substance. For example, it can be SiO2 or phospho-silicate glass (PSG). In addition, the filling substance can also be made of other materials.

[0047] In one or more embodiments, the method may further include:

[0048] A filling material removal operation that removes the filling material filled in the groove after the back-etch protection removal operation.

[0049] In one or more embodiments, in the above 112, the stretchable film setting operation includes setting the stretchable film by spin coating or setting the stretchable film by adhesion.

[0050] In the embodiments of the present application, in the case of using the spin coating method, the solution ratio can be adjusted according to the target thickness, and there is no need to etch and thin the stretchable film, with fewer processing steps. In the case of using the adhesion method, the stretchable film can be processed in a batch production manner and then adhered, which can save processing time and does not require processing with one formula corresponding to one thickness. In addition, different thinning processes can be carried out according to the different thickness requirements of the stretchable film for different speakers.

[0051] In the embodiments of the present application, in the case of thinning the stretchable film before the back-etch operation, the speaker diaphragm is not released, and vacuum suction can be used for thinning without affecting the speaker diaphragm. However, the present application is not limited to this, and the thinning operation of the stretchable film can also be carried out in other processes, such as after the back-etch operation or after the dicing operation.

[0052] In one or more embodiments, the spin coating method in the stretchable film setting operation includes spin coating the solution on the side of the piezoelectric structure adjacent to the third electrode layer. The solution includes a stock solution and a curing solution mixed in a predetermined ratio. Among them, the predetermined ratio of the stock solution and the curing solution is set according to the required thickness of the stretchable film. Thus, the solution ratio can be adjusted according to the target thickness, and there is no need to etch and thin the stretchable film, with fewer processing steps.

[0053] In the embodiments of the present application, the solution can be, for example, a PDMS solution. Among them, the stock solution can be, for example, a PDMS stock solution, and the curing solution includes but is not limited to methyltriethoxysilane (MTEOS), methyltripropoxysilane (MTPS), etc. The ratio of the stock solution to the curing solution can be 3:1 or 5:1 or 10:1 or 15:1, etc., which can be determined according to actual needs.

[0054] In the embodiments of the present application, in the case of setting the stretchable film by spin coating, a heat curing operation can be included to accelerate the formation of the stretchable film.

[0055] In one or more embodiments, in the spin coating method, the thickness of the stretchable film can be changed according to at least one of the following three: spin coating speed, spin coating time, and adding a diluent to the solution. That is, the thickness of the set stretchable film can also be achieved by methods such as changing the rotation speed of the spin coater, changing the spin coating time, and adding a diluent.

[0056] However, the present application is not limited thereto. For example, after the stretchable film is disposed by spin coating, the stretchable film layer can be etched through a stretchable film layer thinning operation so that the thickness of the stretchable film layer is an expected value. Thereby, the accuracy of the thickness of the stretchable film can be improved.

[0057] In the embodiments of the present application, the specific type of the diluent is not limited. For example, it may include but is not limited to benzene, toluene, chloroform, n-hexane, ethyl acetate, etc.

[0058] In one or more embodiments, the bonding method in the stretchable film setting operation includes bonding the stretchable film layer to the side of the piezoelectric structure adjacent to the third electrode layer.

[0059] Thus, the stretchable film can be processed and produced by mass-producing the stretchable film and then bonding it to the piezoelectric mechanism, thereby saving processing time. In addition, different thinning processes can be performed according to the different thickness requirements of different speakers, so as to easily adapt to different thickness requirements.

[0060] In one or more embodiments, the bonding includes bonding the stretchable film layer pasted on the substrate to the side of the piezoelectric structure adjacent to the third electrode layer, and then separating the substrate and the stretchable film layer. Thus, the setting of the stretchable film layer is achieved. Wherein, the substrate can be made of polyethylene terephthalate (PET) material, but the present application is not limited thereto, and substrates made of other materials can also be used.

[0061] However, the present application is not limited thereto. For example, the stretchable film layer can also be directly bonded to the piezoelectric structure itself. Thus, the process of peeling the stretchable film layer from the substrate can be avoided, and the situation of diaphragm breakage caused during the peeling process of the stretchable film layer from the substrate can be avoided.

[0062] In one or more embodiments, the method may further include a stretchable film layer thinning operation that etches the stretchable film layer so that the thickness of the stretchable film layer is an expected value.

[0063] Thus, even if the thickness of the stretchable film layer is not the thickness of the expected stretchable film, a stretchable film with an expected thickness can be obtained.

[0064] In one or more embodiments, the bonding can be performed between the etching operation and the back-etch protection operation. The stretchable film layer thinning operation can be before the back-etch protection operation, or the stretchable film layer thinning operation can be between the back-etch protection removal operation and the dicing operation, or the stretchable film layer thinning operation can be after the dicing operation.

[0065] Thus, by using the method of bonding the PDMS film layer, stretchable films can be mass-produced, saving processing time and eliminating the need to process each thickness with a corresponding formula. Moreover, different thinning processes can be carried out according to the different thickness requirements of stretchable films for different speakers. In addition, thinning the stretchable film before back-etching, with the speaker diaphragm not released, allows for vacuum suction during thinning without affecting the speaker diaphragm. Additionally, thinning the stretchable film after back-etching and before dicing has the advantage that the diaphragm structure stress can be released to a certain extent before bonding with the stretchable film. Furthermore, thinning the stretchable film after dicing offers the benefits of flexible processing and the ability to select some speaker devices for processing, enabling devices on the same wafer to be combined with stretchable films of different thicknesses.

[0066] In the embodiments of the present application, vibration spaces such as slits and the stretchable film can produce a synergistic effect on the MEMS speaker diaphragm: vibration spaces such as slits increase the vibration displacement by reducing the diaphragm modulus, enhancing the mid-frequency response, but causing a problem of low-frequency deterioration; after adding the stretchable film, the low-frequency response improves while the mid-frequency response remains basically unchanged. In contrast, non-stretchable films (i.e., films with Young's modulus and / or thickness not meeting specific conditions) cannot produce a synergistic effect with vibration spaces such as slits: vibration spaces such as slits increase the vibration displacement by reducing the diaphragm modulus, enhancing the mid-frequency response, but causing a problem of low-frequency deterioration; after adding the non-stretchable film, the mid-frequency response deteriorates severely, offsetting the improvement in mid-frequency response brought by vibration spaces such as slits.

[0067] However, the present application is not limited to this. In one or more embodiments, the bonding can also be performed between the back-etching protection removal operation and the dicing operation. The stretchable film layer thinning operation can be performed before the dicing operation, or the stretchable film layer thinning operation can be performed after the dicing operation. Thus, attaching and thinning the stretchable film after back-etching and before dicing has the advantage of completely releasing the diaphragm structure stress. Additionally, thinning the stretchable film after dicing offers the benefits of flexible processing and the ability to select some speaker devices for processing, enabling devices on the same wafer to be combined with stretchable films of different thicknesses.

[0068] In the existing method of configuring the stretchable film by pasting, the thickness of the configured stretchable film generally needs to be above 15 microns. In the embodiments of the present application, through the above method, a stretchable diaphragm with a thickness not exceeding 15 microns can be set. For example, by means of spin coating, or by means of etching thinning, or a combination of spin coating and etching thinning, a stretchable film with an expected thickness not exceeding 15 microns can be set on the MEMS speaker.

[0069] In one or more embodiments, the thickness of the stretchable film can not exceed 10 microns, and further, the thickness of the stretchable diaphragm can not exceed 1 micron.

[0070] In one or more embodiments, the Young's modulus of the stretchable film does not exceed 100 MPa. For example, the Young's modulus of the stretchable film does not exceed 10 MPa. Further, the Young's modulus of the stretchable film can be not more than 1 MPa. Thus, an MEMS speaker with good performance can be obtained. For example, by controlling the Young's modulus of the stretchable film not to exceed 100 MPa, it can be ensured that the decrease in the mid-frequency sound pressure level does not exceed 2 dB. Further still, by controlling the Young's modulus of the stretchable film not to exceed 10 MPa, it can be ensured that the mid-frequency sound pressure level basically does not decrease.

[0071] For example, through the simulation tests of the inventors, it is found that by controlling the Young's modulus of the stretchable film not to exceed 100 MPa, the decrease in the mid-frequency sound pressure level is ensured not to exceed 2 dB. Further still, by controlling the Young's modulus of the stretchable film not to exceed 10 MPa, the mid-frequency sound pressure level can be ensured to basically not decrease. In addition, when the stretchable film uses polymer materials such as rubber, for example, silicone rubber or RTV rubber, or PDMS, etc., the Young's modulus of the above materials does not exceed 10 MPa. Thus, it can be ensured that the mid-frequency sound pressure level basically does not decrease, ensuring a good improvement effect on the acoustic performance.

[0072] Thus, by making the Young's modulus and thickness of the stretchable film satisfy specific conditions, the stretchable characteristics of the stretchable film can be ensured, the influence on the vibration of the speaker diaphragm can be reduced, and the mid-high frequency (especially mid-frequency) characteristics of the MEMS speaker can be ensured. Regarding the specific set values of the thickness and Young's modulus of the stretchable film, any combination of the above examples can be used. For example, through simulation tests, the inventors found that for the same decrease in the sound pressure level, the smaller the Young's modulus of the stretchable film, the thicker the stretchable film can be correspondingly; similarly, for the same decrease in the sound pressure level, the thinner the stretchable film, the larger the Young's modulus of the stretchable film can be correspondingly. The Young's modulus and thickness of the stretchable film can cooperate with each other according to the above rules to ensure the stretchability of the stretchable film.

[0073] In one example, when both the Young's modulus and thickness of the stretchable film take smaller values, better stretchability can be achieved, and thus better acoustic performance can be achieved.

[0074] In some embodiments, the influence of the stretchable film on the vibration of the diaphragm can also be ensured to be small by defining the relationship between the thickness of the stretchable film and the diaphragm. In one example, the thickness of the stretchable film does not exceed 50 times the thickness of the diaphragm. In a further example, the thickness of the stretchable film does not exceed 10 times the thickness of the diaphragm.

[0075] In one or more embodiments, the density of the stretchable film does not exceed 10 g / cm³. For example, the density of the stretchable film can not exceed 1 g / cm³. Further, the density of the stretchable film does not exceed 0.1 g / cm³.

[0076] Above, in combination with Figure 1 , the manufacturing method of the MEMS speaker of the present application has been described. Next, with reference to specific embodiments and device cross-sectional views, the process of this manufacturing method will be exemplarily described. For the description of each layer of material, reference can be made to the corresponding description content above.

[0077] Embodiment 1

[0078] Figures 2 to 9 FIG. is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 1.

[0079] The manufacturing method of Embodiment 1 is as follows:

[0080] As Figure 2 and Figure 3 shown, a piezoelectric structure including a seed layer 110, a first electrode layer 120, a first piezoelectric layer 130, a second electrode layer 140, a second piezoelectric layer 150, and a third electrode layer 160 deposited on a silicon wafer 100 is etched by dry etching and / or wet etching to form a slit 310.

[0081] As Figure 4 shown, a PDMS solution is spin-coated on the speaker wafer to form a stretchable film 170, which may include a heating and curing operation. As Figure 4 shown, the PDMS solution can enter the slit 310, so that the stretchable film is also provided in the slit.

[0082] As Figure 5 shown, a protective object 180 is provided to protect the front side before back etching.

[0083] As Figure 6 shown, a cavity 320 is formed by back etching.

[0084] As Figure 7 shown, the protective object 180 as the front protective layer is removed.

[0085] As Figure 8 and Figure 9 shown, scribing is performed along the dotted line to obtain a MEMS speaker device integrated with the stretchable film 170.

[0086] Thus, according to the manufacturing method of Embodiment 1, by using the PDMS spin-coating method, the solution ratio can be adjusted according to the target thickness, and there is no need to etch and thin the stretchable film, and the processing steps are few.

[0087] Embodiment 2

[0088] Figures 10 to 22 FIG. is a device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 2.

[0089] The manufacturing method of Example 2 is as follows:

[0090] As Figure 10 and 11 shown, a groove 340 is formed by grooving on the silicon wafer 100.

[0091] As Figure 12 shown, a filling material 190 is disposed in the groove 340, and the filling material may be SiO2 or phosphosilicate glass PSG.

[0092] As Figure 13 shown, it may include planarizing the filling material 190, that is, making the surface of the filling material 190 flush with the surface of the silicon wafer 100.

[0093] As Figure 14 and Figure 15 shown, the piezoelectric structure including the seed layer 110, the first electrode layer 120, the first piezoelectric layer 130, the second electrode layer 140, the second piezoelectric layer 150, and the third electrode layer 160 deposited on the silicon wafer 100 is etched by dry etching and / or wet etching to form slits 310.

[0094] As Figure 16 shown, a PDMS solution is spin-coated on the speaker wafer to form a stretchable film 170, and a heat curing operation may be included. As Figure 16 shown, the PDMS solution can enter the slits 310, so that the stretchable film is also disposed in the slits.

[0095] As Figure 17 shown, a protective layer 180 is provided to protect the front side before back etching.

[0096] As Figure 18 shown, a cavity 320 is formed by back etching.

[0097] As Figure 19 shown, the protective layer 180 serving as the front protective layer is removed.

[0098] As Figure 20 shown, the filling material 190 in the groove is removed.

[0099] As Figure 21 and Figure 22 shown, scribing is performed along the dotted line to obtain a MEMS speaker device integrated with the stretchable film 170.

[0100] Thus, according to the manufacturing method of Embodiment 2, on the one hand, the spin coating scheme is adopted, and the solution ratio can be adjusted according to the target thickness without etching and thinning the stretchable film. On the other hand, by setting the filling material, it is possible to avoid contacting the stretchable film during back etching, preventing the contamination of the cavity where the back etching process is carried out due to the etching of the stretchable film, and thus avoiding affecting the normal operation of the back etching machine.

[0101] Embodiment 3

[0102] Figures 23 to 34 It is the device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 3.

[0103] The manufacturing method of Embodiment 3 is as follows:

[0104] As Figure 23 and Figure 24 shown, a slit 310 is etched in the piezoelectric structure including a seed layer 110, a first electrode layer 120, a first piezoelectric layer 130, a second electrode layer 140, a second piezoelectric layer 150, and a third electrode layer 160 deposited on a silicon wafer 100 through dry etching and / or wet etching.

[0105] As Figure 25 shown, before the transfer of the PDMS film layer 170, the PDMS film layer 170 can be adhered to a PET substrate 210, and the speaker wafer is below the PDMS film layer 170.

[0106] As Figure 26 shown, the situation during the transfer of the PDMS film layer 170 is presented. One side of the PDMS film layer 170 is adhered to the PET substrate 210 and bonded to the third electrode layer 160 of the speaker wafer.

[0107] As Figure 27 shown, the situation after the transfer of the PDMS film layer 170 is presented. The PET substrate 210 is separated from the PDMS film layer 170, leaving the PDMS film layer 170 tightly bonded to the speaker wafer.

[0108] As Figure 28 shown, a stretchable film layer thinning operation is performed. The part indicated by the dashed line is the removed part of the PDMS film layer, leaving a PDMS film layer with the expected thickness as the stretchable film. Among them, methods such as etching can be selected to remove the PDMS film, but it is not limited to this.

[0109] As Figure 29 shown, the situation after the final etching of the PDMS film is presented.

[0110] As Figure 30 shown, a protective object 180 is set for front protection before back etching.

[0111] As Figure 31As shown, a cavity 320 is formed by back-etching.

[0112] As Figure 32 shown, the protective layer 180 as the front protective layer is removed.

[0113] As Figure 33 and Figure 34 shown, scribing is performed along the dotted line to obtain a MEMS speaker device integrated with the stretchable film 170.

[0114] Thus, according to the manufacturing method of Embodiment 3, by using the method of bonding PDMS film layers, stretchable films can be mass-produced, saving processing time, and there is no need to process one thickness corresponding to one formula. Different thinning processes can also be performed according to the different thickness requirements of the stretchable film for different speakers. In addition, before back-etching, the stretchable film is thinned. Since the speaker diaphragm is not released, vacuum can be sucked during thinning, and it will not affect the speaker diaphragm.

[0115] Embodiment 4

[0116] Figures 35 to 46 is the device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 4.

[0117] The manufacturing method of Embodiment 4 is as follows:

[0118] As Figure 35 and Figure 36 shown, a piezoelectric structure including a seed layer 110, a first electrode layer 120, a first piezoelectric layer 130, a second electrode layer 140, a second piezoelectric layer 150, and a third electrode layer 160 deposited on a silicon wafer 100 is etched by dry etching and / or wet etching to form slits 310.

[0119] As Figure 37 shown, before the transfer of the PDMS film layer 170, the PDMS film layer 170 can be adhered to the PET substrate 210, and the speaker wafer is below the PDMS film layer 170.

[0120] As Figure 38 shown, the situation during the transfer of the PDMS film layer 170 is shown. One side of the PDMS film layer 170 is adhered to the PET substrate 210 and bonded to the third electrode layer 160 of the speaker wafer.

[0121] As Figure 39 shown, the situation after the transfer of the PDMS film layer 170 is shown. The PET substrate 210 is separated from the PDMS film layer 170, leaving the PDMS film layer 170 tightly bonded to the speaker wafer.

[0122] As Figure 40 shown, a protective layer 180 is set for front protection before back-etching.

[0123] As shown Figure 41 A cavity 320 is formed by back-etching.

[0124] As shown Figure 42 The protective layer 180 as the front protective layer is removed.

[0125] As shown Figure 43 A stretchable film layer thinning operation is performed. The part shown by the dotted line is the removed part of the PDMS film layer, and the PDMS film layer with the expected thickness is left as the stretchable film. Among them, methods such as etching can be selected to remove the PDMS film, but it is not limited to this.

[0126] As shown Figure 44 The situation after the final etching of the PDMS film is shown.

[0127] As shown Figure 45 and Figure 46 Scribing is performed along the dotted line to obtain a MEMS speaker device integrated with the stretchable film 170.

[0128] Thus, according to the manufacturing method of Embodiment 4, by using the method of bonding the PDMS film layer, stretchable films can be mass-produced, saving processing time, and there is no need to process one thickness corresponding to one formula. Different thinning processes can also be performed according to the different thickness requirements of the stretchable film for different speakers. In addition, thinning the stretchable film after back-etching and before scribing has the advantage that the stress of the diaphragm structure can be released to a certain extent before combining with the stretchable film.

[0129] Embodiment 5

[0130] Figures 47 to 58 It is the device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 5.

[0131] The manufacturing method of Embodiment 5 is as follows:

[0132] As shown Figure 47 and Figure 48 The piezoelectric structure including the seed layer 110, the first electrode layer 120, the first piezoelectric layer 130, the second electrode layer 140, the second piezoelectric layer 150, and the third electrode layer 160 deposited on the silicon wafer 100 is etched to form slits 310 by dry etching and / or wet etching.

[0133] As shown Figure 49 Before the transfer of the PDMS film layer 170, the PDMS film layer 170 can be adhered to the PET substrate 210, and the speaker wafer is below the PDMS film layer 170.

[0134] As shown Figure 50As shown, the situation during the transfer of the PDMS film layer 170 is presented. One side of the PDMS film layer 170 adheres to the PET substrate 210 and is bonded to the third electrode layer 160 of the speaker wafer.

[0135] As Figure 51 shown, the situation after the transfer of the PDMS film layer 170 is presented. The PET substrate 210 is separated from the PDMS film layer 170, leaving the PDMS film layer 170 tightly bonded to the speaker wafer.

[0136] As Figure 52 shown, a protector 180 is set up for front protection before back-etching.

[0137] As Figure 53 shown, a cavity 320 is formed by back-etching.

[0138] As Figure 54 shown, the protector 180 serving as the front protective layer is removed.

[0139] As Figure 55 and Figure 56 shown, scribing is performed along the dashed line to obtain the scribed chips.

[0140] As Figure 57 shown, a stretching film layer thinning operation is carried out. The part indicated by the dashed line is the removed part of the PDMS film layer, leaving the PDMS film layer with the desired thickness as the stretchable film. Among them, methods such as etching can be selected to remove the PDMS film, but it is not limited to this.

[0141] As Figure 58 shown, the situation after the final etching of the PDMS film is presented, obtaining a MEMS speaker device integrated with the stretchable film 170.

[0142] Thus, according to the manufacturing method of Embodiment 5, by using the method of bonding the PDMS film layer, stretchable films can be mass-produced, saving processing time, and there is no need to process according to one formula for one thickness. Different thinning processes can also be carried out according to the different thickness requirements of the stretchable film for different speakers. In addition, thinning the stretchable film after scribing has the advantages of flexible processing, and some speaker devices can be selected for processing, enabling devices on the same wafer to be combined with stretchable films of different thicknesses.

[0143] Embodiment 6

[0144] Figures 59 to 69 is the device cross-sectional view corresponding to each step in the manufacturing method of Embodiment 6.

[0145] The manufacturing method of Embodiment 6 is as follows:

[0146] As Figure 59 and Figure 60As shown, a piezoelectric structure including a seed layer 110, a first electrode layer 120, a first piezoelectric layer 130, a second electrode layer 140, a second piezoelectric layer 150, and a third electrode layer 160 deposited on a silicon wafer 100 is etched by dry etching and / or wet etching to form a slit 310.

[0147] As Figure 61 shown, a protector 180 is provided for front protection before back etching. The protector can be, for example, silicon dioxide. By providing silicon dioxide, the stress can be controlled, and by providing silicon dioxide with a certain thickness, breakage after back etching can be avoided. Among them, as Figure 61 shown, the protector 180 can enter the speaker slit 310.

[0148] As Figure 62 shown, a cavity 320 is formed by back etching.

[0149] As Figure 63 shown, the protector 180 serving as the front protective layer is removed. For example, a silicon dioxide layer. Among them, not only can the traditional wet method be used, but also gaseous hydrofluoric acid can be used. This application does not limit this.

[0150] As Figure 64 shown, the PDMS film layer 170 is gradually brought closer to and finally contacted with the speaker wafer.

[0151] As Figure 65 shown, the situation where the PDMS film layer 170 is tightly bonded to the speaker wafer is shown.

[0152] As Figure 66 shown, a stretchable film layer thinning operation is performed. The part indicated by the dotted line is the part 330 of the PDMS film layer that is etched away, leaving a PDMS film with the expected thickness.

[0153] As Figure 67 shown, the situation where the PDMS film layer is finally etched is shown.

[0154] As Figure 68 and 69 shown, scribing is performed along the dotted line to obtain a MEMS speaker device integrated with the stretchable film 170.

[0155] Thus, according to the manufacturing method of Embodiment 6, by using the method of bonding the PDMS film layer, stretchable films can be mass-produced, saving processing time, and there is no need to process one thickness corresponding to one formula. Different thinning processes can also be performed according to the different thickness requirements of the stretchable film for different speakers. In addition, this solution does not include the process of peeling PDMS from the substrate (such as PET), and the situation where the diaphragm is damaged during the peeling process of PDMS from the substrate can be avoided.

[0156] In addition, as Figures 61 to 69 shown, after back-etching and before dicing, a thinning stretchable film can be attached. The advantage is that the stress of the diaphragm structure can be completely released. However, the present application is not limited thereto. For example, as shown in the method of Solution 5, etching the PDMS film layer can also be performed after dicing.

[0157] The embodiment of the present application also provides a computer-readable program. When the program is executed, the program causes a processor in the computer to execute the manufacturing method of the MEMS speaker described in the foregoing embodiment.

[0158] The embodiment of the present application also provides a non-transitory computer-readable storage medium for storing a computer program. When the computer program is executed by a computer, the computer is caused to execute the manufacturing method of the MEMS speaker described in the foregoing embodiment.

[0159] Each of the above embodiments only exemplarily illustrates the embodiments of the present application. However, the present application is not limited thereto, and appropriate modifications can also be made on the basis of each of the above embodiments. For example, each of the above embodiments can be used alone, or one or more of the above embodiments can be combined.

[0160] The present application has been described in combination with specific embodiments. However, those skilled in the art should understand that these descriptions are exemplary and not a limitation on the protection scope of the present application. Those skilled in the art can make various modifications and changes to the present application according to the spirit and principle of the present application, and these modifications and changes are also within the scope of the present application.

[0161] The preferred embodiments of the present application have been described above with reference to the drawings. Many features and advantages of these embodiments are clear from this detailed description. Therefore, the appended claims are intended to cover all such features and advantages that fall within the true spirit and scope of these embodiments. In addition, since many modifications and variations are readily conceivable by those skilled in the art, the embodiments of the present application are not to be limited to the exact structures and operations illustrated and described, but may cover all suitable modifications, variations, and equivalents that fall within their scope.

Claims

1. A manufacturing method of a MEMS speaker, characterized in that, the method comprises: an etching operation, etching a piezoelectric structure deposited on a silicon wafer, the piezoelectric structure comprising at least one piezoelectric layer and at least one electrode layer, to form slits penetrating through the piezoelectric structure; a back-etch protection operation, forming a back-etch protection structure on the side opposite to the side of the piezoelectric structure where the silicon wafer is disposed; a back-etch operation, back-etching from the side of the silicon wafer where the piezoelectric structure is disposed to form a cavity; a back-etch protection removal operation, removing the back-etch protection structure; a dicing operation, dicing along the portion between the cavities of the silicon wafer to obtain a MEMS speaker chip, the method further comprises a stretchable film setting operation, setting a stretchable film covering the slits on the side of the piezoelectric structure close to the electrode layer, and the stretchable film setting operation is between the etching operation and the back-etch protection operation, or, the stretchable film setting operation is between the back-etch protection removal operation and the dicing operation.

2. The method according to claim 1, characterized in that, before the etching operation, the method further comprises: a filling operation, forming a groove on the surface of the silicon wafer for disposing the piezoelectric structure and filling a filling material in the groove.

3. The method according to claim 2, characterized in that, the method further comprises: a filling material removal operation, removing the filling material filled in the groove after the back-etch protection removal operation.

4. The method according to claim 1, characterized in that, the stretchable film setting operation comprises setting the stretchable film by spin coating or by bonding.

5. The method according to claim 4, characterized in that, the spin coating comprises spin coating a solution on the side of the piezoelectric structure close to the electrode layer, and the solution comprises a stock solution and a curing solution mixed in a predetermined ratio.

6. The method according to claim 5, characterized in that, in the spin coating method, the thickness of the stretchable film is changed according to at least one of the following three: spin coating speed, spin coating time, adding a diluent to the solution.

7. The method according to claim 6, characterized in that, the method further comprises: a stretchable film layer thinning operation, etching the stretchable film layer so that the thickness of the stretchable film layer is an expected value.

8. The method according to claim 4, characterized in that, the bonding comprises bonding a stretchable film layer to the side of the piezoelectric structure close to the electrode layer.

9. The method according to claim 8, characterized in that, the bonding comprises bonding the stretchable film layer pasted on a substrate to the side of the piezoelectric structure close to the electrode layer, and then separating the substrate and the stretchable film layer.

10. The method according to claim 9, characterized in that, the method further comprises: a stretchable film layer thinning operation, etching the stretchable film layer so that the thickness of the stretchable film layer is an expected value.

11. The method according to claim 10, characterized in that, the bonding is performed between the etching operation and the back-etch protection operation, The stretchable film layer thinning operation is performed before the back-etch protection operation, or the stretchable film layer thinning operation is performed between the back-etch protection removal operation and the dicing operation, or the stretchable film layer thinning operation is performed after the dicing operation.

12. The method according to claim 10, wherein, the bonding is performed between the back-etch protection removal operation and the dicing operation, the stretchable film layer thinning operation is performed before the dicing operation, or the stretchable film layer thinning operation is performed after the dicing operation.

13. The method according to any one of claims 1 to 12, wherein, the piezoelectric structure includes a seed layer, a first electrode layer, a first piezoelectric layer, a second electrode layer, a second piezoelectric layer, and a third electrode layer sequentially deposited on the silicon wafer.

14. The method according to any one of claims 1 to 12, wherein, the thickness of the stretchable film does not exceed 15 micrometers.

15. The method according to claim 14, wherein, the thickness of the stretchable film does not exceed 10 micrometers.

16. The method according to claim 15, wherein, the thickness of the stretchable film does not exceed 1 micrometer.

17. The method according to any one of claims 1 to 12, wherein, the Young's modulus of the stretchable film does not exceed 100 MPa.

18. The method according to claim 17, wherein, the Young's modulus of the stretchable film does not exceed 10 MPa.

19. The method according to claim 18, wherein, the Young's modulus of the stretchable film does not exceed 1 MPa.

20. The method according to any one of claims 1 to 12, wherein, the density of the stretchable film does not exceed 10 g / cm³.

21. The method according to claim 20, wherein, the density of the stretchable film does not exceed 1 g / cm³.

22. The method according to claim 21, wherein, the density of the stretchable film does not exceed 0.1 g / cm³.

23. The method according to any one of claims 1 to 12, wherein, the stretchable film can be polydimethylsiloxane.

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