MEMS device and preparation method thereof, and electronic device

Abstract

The invention provides an MEMS device and a preparation method thereof, and an electronic device, and the MEMS device comprises a substrate which is provided with a back cavity; the sensitive layer is suspended on the back cavity, and the edge of the sensitive layer is lapped on the substrate; the sacrificial layer is arranged on the sensitive layer, a cavity is formed in the sacrificial layer, a part of area of the sensitive layer is exposed out of the cavity, and at least part of the cavity is opposite to the back cavity; the back polar plate is arranged on the cavity in a suspended mode, the edge of the back polar plate is in lap joint with the sacrificial layer, a plurality of release holes penetrating through the back polar plate are formed in the back polar plate, and the release holes are communicated with the cavity; the total area of the openings, located in the first surface of the back pole plate, of the release holes accounts for 10-40% of the area of the first surface, so that the capacitance change of the MEMS device during application is improved, and the ASIC recognition threshold value is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a MEMS device and a preparation method thereof, and an electronic device. Background Art

[0002] Electronic cigarettes are a type of cigarette-like product that heats the liquid oil in the oil tank to produce "vapor" for users to inhale. They have a similar appearance, smoke, taste and feel to cigarettes. Since electronic cigarettes do not contain major harmful substances such as carbon monoxide and tar, they are far less harmful than real cigarettes, so they are increasingly used by smokers who want to quit smoking and are loved by young people.

[0003] At present, the pressure sensors in electronic cigarettes are basically electret capacitive sensors and MEMS capacitive pressure sensors. The relatively primitive capacitive sensors based on the electret principle have poor consistency, resulting in poor smoking taste, and are not resistant to high temperatures, resulting in difficulties in batch patching. The mainstream capacitive pressure sensors currently used in MEMS mainly control the smoke output of electronic cigarettes by detecting a certain change in capacitance (delta C) through a dedicated integrated circuit (Application Specific Integrated Circuit, referred to as ASIC). Although it is suitable for packaging and low cost, the delta C of this type of sensor is generally small. On the one hand, it is not easy to detect, and the ASIC is relatively high. In addition, a very small delta C can easily cause false triggering of electronic cigarettes. On the other hand, it is easy to cause the smoke oil to be sucked back, which may cause the device to fail. Therefore, there is an urgent need for a MEMS device that meets the requirements to solve at least one of the above problems. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] In view of the existing problems, the first aspect of the present invention provides a MEMS device, the MEMS device comprising:

[0006] a substrate having a back cavity;

[0007] A sensitive layer is suspended on the back cavity, and its edge is overlapped on the substrate;

[0008] A sacrificial layer, disposed on the sensitive layer, wherein a cavity is formed in the sacrificial layer, wherein the cavity exposes a portion of the sensitive layer, and the cavity is at least partially opposite to the back cavity;

[0009] A back pole plate is suspended on the cavity, and its edge overlaps the sacrificial layer, wherein a plurality of release holes penetrating the back pole plate are provided in the back pole plate, the plurality of release holes are connected to the cavity, and the total area of ​​the openings of the plurality of release holes on the first surface of the back pole plate accounts for 10 to 40% of the area of ​​the first surface.

[0010] A first aspect of the present invention provides a MEMS device, the MEMS device comprising:

[0011] a substrate having a back cavity;

[0012] A sensitive layer is suspended on the back cavity, and its edge is overlapped on the substrate;

[0013] A sacrificial layer, disposed on the sensitive layer, wherein a cavity is formed in the sacrificial layer, wherein the cavity exposes a portion of the sensitive layer, and the cavity is at least partially opposite to the back cavity;

[0014] A back plate is suspended on the cavity, and its edge is overlapped on the sacrificial layer, wherein a plurality of release holes penetrating the back plate are provided in the back plate, and the plurality of release holes are connected to the cavity;

[0015] The epitaxial layer covers the back plate and closes at least part of the release holes.

[0016] Exemplarily, the epitaxial layer covers the entire surface of the back plate.

[0017] Exemplarily, the epitaxial layer and the back plate include semiconductor materials of the same material.

[0018] Exemplarily, the base includes a substrate and an isolation layer located on the substrate, the back cavity runs through the substrate and the isolation layer, and an edge of the sensitive layer overlaps the isolation layer.

[0019] Exemplarily, a support layer is further provided on the surface of the back plate adjacent to the sacrificial layer, and the release hole penetrates the back plate and the support layer.

[0020] A third aspect of the present application provides a method for preparing a MEMS device, the method comprising:

[0021] providing a substrate;

[0022] forming a sensitive layer, a sacrificial layer and a back plate in sequence on the substrate;

[0023] Forming a plurality of release holes penetrating the back plate in the back plate to expose a portion of the sacrificial layer, wherein the total area of ​​the openings of the plurality of release holes located on the first surface of the back plate accounts for 10 to 40% of the area of ​​the first surface;

[0024] Etching the sacrificial layer through a plurality of release holes to remove a portion of the sacrificial layer to form a cavity, wherein the cavity exposes a portion of the surface of the sensitive layer;

[0025] A back cavity is formed in the substrate and penetrates the substrate, exposing a portion of the surface of the sensitive layer, wherein the back cavity and the cavity are at least partially opposite to each other.

[0026] A fourth aspect of the present application provides a method for preparing a MEMS device, the method comprising:

[0027] providing a substrate;

[0028] forming a sensitive layer, a sacrificial layer and a back plate in sequence on the substrate;

[0029] forming a plurality of release holes penetrating the back plate in the back plate to expose a portion of the sacrificial layer;

[0030] Etching the sacrificial layer through a plurality of release holes to remove a portion of the sacrificial layer to form a cavity, wherein the cavity exposes a portion of the surface of the sensitive layer;

[0031] forming an epitaxial layer covering the back plate, wherein the epitaxial layer closes at least part of the plurality of release holes;

[0032] A back cavity is formed in the substrate and penetrates the substrate, exposing a portion of the surface of the sensitive layer, wherein the back cavity and the cavity are at least partially opposite to each other.

[0033] Exemplarily, the epitaxial layer covers the entire surface of the back plate.

[0034] Another aspect of the present invention provides an electronic device, comprising the aforementioned MEMS device.

[0035] The MEMS device and its preparation method in one aspect of the present invention, by reducing the area ratio of the release hole on the back plate surface, improves the capacitance change when the MEMS device is used, improves the ASIC recognition threshold, and thus reduces the complexity of the ASIC. The reduction of the release holes can also reduce the risk of the back plate becoming soft; the increase in capacitance change and the reduction in the risk of the back plate becoming soft effectively prevent the problem of accidental touch of the electronic cigarette when the MEMS device is used in the electronic cigarette. In addition, the reduction of the release holes can also effectively reduce or even prevent the back-inhalation of the smoke oil.

[0036] The MEMS device and its preparation method in another aspect of the present invention can improve the capacitance change of the MEMS device when it is used by covering the epitaxial layer on the back plate so that the epitaxial layer closes at least part of the release holes, thereby improving the ASIC recognition threshold and reducing the complexity of the ASIC. Due to the reduction of the release holes and the coverage of the epitaxial layer, the rigidity of the back plate can be increased and the risk of the back plate becoming soft can be reduced. The increase in capacitance change and the reduction in the risk of the back plate becoming soft effectively prevent the problem of accidental touch of the electronic cigarette when the MEMS device is applied to the electronic cigarette. In addition, due to the presence of the epitaxial layer, the back-inhalation of the smoke oil can be effectively reduced or even prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The following drawings of the present invention are used to understand the present invention as part of the present invention. The embodiments of the present invention are shown in the drawings and the description thereof is used to explain the principle of the present invention.

[0038] In the attached figure:

[0039] Figure 1A A cross-sectional schematic diagram of a MEMS device according to a specific embodiment of the present invention is shown;

[0040] Figure 1B shows a distribution diagram of release holes in a conventional back plate;

[0041] Figure 1C A distribution diagram of release holes in a back plate according to a specific embodiment of the present invention is shown;

[0042] Figure 2 A cross-sectional schematic diagram of a MEMS device according to another specific embodiment of the present invention is shown;

[0043] FIG. 3A to FIG. 3E A cross-sectional schematic diagram of a device obtained by sequentially implementing a method for preparing a MEMS device according to a specific embodiment of the present invention is shown;

[0044] Figure 4 A flow chart showing a method for preparing a MEMS device according to a specific embodiment of the present invention;

[0045] Figure 5 A flow chart of a method for preparing a MEMS device according to another specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0046] Next, the present invention will be more fully described in conjunction with the accompanying drawings, in which embodiments of the present invention are shown. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0047] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0048] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0049] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "a", "an", and "said / the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0050] Embodiments of the invention are described herein with reference to cross-sectional views that are schematic diagrams of ideal embodiments (and intermediate structures) of the invention. Thus, variations from the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the invention should not be limited to the specific shapes of the zones shown herein, but include shape deviations due to, for example, manufacturing. For example, an implanted region shown as a rectangle typically has rounded or curved features and / or an implant concentration gradient at its edges, rather than a binary change from an implanted region to a non-implanted region. Similarly, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the actual shape of the region of the device and are not intended to limit the scope of the invention.

[0051] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art in the field of the present invention. It will also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an ideal or overly formal sense unless expressly defined as such herein.

[0052] In order to thoroughly understand the present invention, detailed steps and structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementations, and the technical features of the various embodiments of the present application may be combined with each other without contradiction.

[0053] Embodiment 1

[0054] Reference below Figures 1A to 1C A MEMS device in an embodiment of the present application is explained and illustrated, wherein: Figure 1A A cross-sectional schematic diagram of a MEMS device according to a specific embodiment of the present invention is shown; Figure 1B shows a distribution diagram of release holes in a conventional back plate; Figure 1CA distribution diagram of release holes in a back plate according to a specific embodiment of the present invention is shown.

[0055] First, if Figure 1A As shown, the MEMS device of the present application includes a substrate, the substrate has a back cavity, and the back cavity runs through the substrate; the substrate may include a substrate 111, and the substrate 111 may be a silicon substrate. However, it is not limited thereto, and the substrate may also be a germanium substrate, a silicon germanium substrate, a silicon on insulator (SOI) or a germanium on insulator (GOI), etc., and certain doping particles may be injected into the substrate according to design requirements to change electrical parameters.

[0056] Optionally, the base further includes an isolation layer 112 formed on the substrate. The material of the isolation layer 112 may include silicon oxide or other suitable insulating materials to isolate the substrate 111 from the sensitive layer 120 .

[0057] Further, continue as Figure 1A As shown, the MEMS device of the present application includes a sensitive layer 120, which is suspended on the back cavity 1111 and has its edges overlapped on the substrate. For example, the middle area of ​​the sensitive layer 120 is suspended on the back cavity 1111 and its edges overlap on the isolation layer 112.

[0058] The material of the sensitive layer 120 may include doped polysilicon, silicon germanium, germanium, or other suitable metal or semiconductor materials to ensure that the subsequently released portion of the sensitive layer 120 can vibrate and deform and return to its original shape when subjected to sound or inertial force, etc., and to ensure that the sensitive layer 120 has good conductivity.

[0059] The thickness of the sensitive layer 120 affects the range of the MEMS pressure sensor. Generally speaking, the thinner the sensitive layer 120 is, the smaller the range of pressure measurement is; the thicker the sensitive layer 120 is, the larger the range of pressure measurement is. In this embodiment, those skilled in the art should understand that the thickness of the sensitive layer 120 should be selected appropriately according to actual needs.

[0060] Further, continue as Figure 1A As shown, the MEMS device of the present application further includes a sacrificial layer 130, which is disposed on the sensitive layer 120, and a cavity 131 is formed in the sacrificial layer 130, the cavity 131 exposes a partial area of ​​the sensitive layer 120, such as a middle area, and the cavity 131 is at least partially opposite to the back cavity 1111, for example, the cavity 131 and the back cavity 1111 are arranged opposite to each other. The material of the sacrificial layer 130 may include any suitable insulating material, for example, the material of the sacrificial layer 130 includes one or more of silicon oxide, silicon nitride, and silicon oxynitride.

[0061] In this embodiment, the back cavity 1111 and the cavity 131 release the lower surface and the upper surface of the middle area of ​​the sensitive layer 120, so that the released middle area of ​​the sensitive layer 120 can vibrate up and down, thereby forming a change in capacitance between it and the corresponding back plate when used.

[0062] Further, continue as Figure 1A As shown, the MEMS device of the present application also includes a back plate, which is suspended on the cavity 131 and has its edges overlapped on the sacrificial layer 130, wherein the back plate is provided with a plurality of release holes 151 (also referred to as acoustic holes) penetrating the back plate, and the plurality of release holes 151 are connected to the cavity 131.

[0063] The principle of this application is similar to that of the MEMS capacitive pressure sensor currently used in electronic cigarettes. Both use an ASIC circuit to detect a certain change in capacitance value to determine whether the start-up condition is met, so that the electronic cigarette emits smoke. However, current MEMS devices such as MEMS pressure sensors require the release of the middle sacrificial layer 130, and there are a large number of voids on the back plate. Figure 1B As shown, in order to reduce the equivalent resistance and equalize the pressure, the conventional pressure sensor has a relatively large ratio of the acoustic hole area (that is, the ratio of the area of ​​the release hole 151 to the area of ​​the back plate), which is between 45% and 75%, which is conducive to obtaining high sensitivity. However, for the electronic cigarette pressure switch, it only needs to reach the threshold capacitance. Therefore, the greater the delta C change when smoking an electronic cigarette, the better, and the easier it is for the ASIC to detect. In addition, the operating frequency range of smoking an electronic cigarette belongs to low frequency, and there is no pressure release problem. Therefore, in this application, if Figure 1C As shown, the total area of ​​the openings of the plurality of release holes 151 located on the first surface of the back plate accounts for 10 to 40% of the area of ​​the first surface, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc., as long as the area can achieve the release of the sacrificial layer 130. By reducing the area ratio of the release holes 151 on the back plate surface, the capacitance change when the MEMS device is applied is increased, the ASIC recognition threshold is increased, thereby reducing the complexity of the ASIC, and the risk of the back plate becoming soft can also be reduced due to the reduction of the release holes 151; the increase in capacitance change and the reduction in the risk of the back plate becoming soft effectively prevent the problem of accidental touch of the electronic cigarette when the MEMS device is applied to the electronic cigarette. In addition, due to the reduction of the release holes 151, the sealing of the back plate is improved, and the back-inhalation of the smoke oil can be effectively reduced or even prevented.

[0064] It is worth mentioning that the way to reduce the release holes 151 includes but is not limited to reducing the diameter or number of the release holes 151. Due to the reduction of the release holes 151, the film thickness can be effectively reduced, and the stress and other problems can be reduced.

[0065] Optionally, a support layer 140 is further provided on the surface of the back plate adjacent to the sacrificial layer 130, and the release hole 151 penetrates the back plate and the support layer 140, that is, the support layer 140 also partially covers the sacrificial layer 130 outside the cavity 131, wherein the support layer 140 can be beneficial to enhance the connection reliability between the sacrificial layer 130 and the back plate, and play a supporting role for the back plate, thereby improving the reliability of the MEMS device. The material of the support layer 140 can be silicon nitride, or other suitable materials, which can use a material different from the sacrificial layer 130, so that when the sacrificial layer 130 is etched, the support layer 140 and the sacrificial layer 130 have a larger etching selectivity.

[0066] Further, if Figure 1A As shown, the MEMS device of the present application also includes a first conductive structure 160 and a second conductive structure 170, wherein the first conductive structure 160 is electrically connected to the sensitive film, and the second conductive structure 170 is electrically connected to the back plate. The first conductive structure 160 can be a metal interconnect structure, or a plug, etc., and the second conductive structure 170 can be a pad, or other suitable structures.

[0067] A complete MEMS device, such as a MEMS capacitive pressure sensor, may also include other structures, which are not described here one by one.

[0068] Embodiment 2

[0069] In order to solve at least one of the aforementioned technical problems, the present application also provides a MEMS device. Figure 2 A MEMS device in another embodiment of the present application is described.

[0070] First, if Figure 2 As shown, the MEMS device of the present application includes a substrate, the substrate has a back cavity 2111, and the back cavity 2111 runs through the substrate; the substrate may include a substrate 211, and the substrate 211 may be a silicon substrate. However, it is not limited thereto, the substrate 211 may also be a germanium substrate, a silicon germanium substrate, a silicon on insulator (SOI) or a germanium on insulator (GOI), etc., and certain doping particles may be injected into the substrate 211 according to design requirements to change electrical parameters.

[0071] Optionally, the base further includes an isolation layer 212 formed on the substrate 211 . The isolation layer 212 may be made of silicon oxide or other suitable insulating materials to isolate the substrate 211 from the sensitive layer 220 .

[0072] Further, continue as Figure 2As shown, the MEMS device of the present application includes a sensitive layer 220, which is suspended on the back cavity 2111 and has its edges overlapped on the substrate. For example, the middle area of ​​the sensitive layer 220 is suspended on the back cavity 2111 and its edges overlap on the isolation layer 212.

[0073] The material of the sensitive layer 220 may include doped polysilicon, silicon germanium, germanium, or other suitable metal or semiconductor materials to ensure that the subsequently released portion of the sensitive layer 220 can vibrate and deform and return to its original shape when subjected to sound or inertial force, etc., and to ensure that the sensitive layer 220 has good conductivity.

[0074] The thickness of the sensitive layer 220 affects the range of the MEMS pressure sensor. Generally speaking, the thinner the sensitive layer 220 is, the smaller the range of pressure measurement is; the thicker the sensitive layer 220 is, the larger the range of pressure measurement is. In this embodiment, those skilled in the art should understand that the thickness of the sensitive layer 220 should be selected appropriately according to actual needs.

[0075] Further, continue as Figure 2 As shown, the MEMS device of the present application further includes a sacrificial layer 230, which is disposed on the sensitive layer 220, and a cavity 231 is formed in the sacrificial layer 230, the cavity 231 exposes a partial area of ​​the sensitive layer 220, such as a middle area, and the cavity 231 is at least partially opposite to the back cavity 2111, for example, the cavity 231 and the back cavity 2111 are arranged opposite to each other. The material of the sacrificial layer 230 may include any suitable insulating material, for example, the material of the sacrificial layer 230 includes one or more of silicon oxide, silicon nitride, and silicon oxynitride.

[0076] In this embodiment, the back cavity 2111 and the cavity 231 release the lower surface and the upper surface of the middle area of ​​the sensitive layer 220, so that the released middle area of ​​the sensitive layer 220 can vibrate up and down, thereby forming a change in capacitance between it and the corresponding back plate 250 when used.

[0077] Further, continue as Figure 2 As shown, the MEMS device of the present application further includes a back plate 250, which is suspended on the cavity 231 and has its edge overlapped on the sacrificial layer 230, wherein the back plate 250 is provided with a plurality of release holes 251 (also referred to as acoustic holes) penetrating the back plate 250, and the plurality of release holes 251 are connected to the cavity 231. The material of the back plate 250 may include doped polysilicon, germanium silicon, germanium, or other suitable metal or semiconductor materials.

[0078] Optionally, a support layer 240 is further provided on the surface of the back plate 250 adjacent to the sacrificial layer 230, and the release hole 251 penetrates the back plate 250 and the support layer 240, that is, the support layer 240 also partially covers the sacrificial layer 230 outside the cavity 231, wherein the support layer 240 can be beneficial to enhance the connection reliability between the sacrificial layer 230 and the back plate 250, and play a supporting role for the back plate 250, thereby improving the reliability of the MEMS device. The material of the support layer 240 can be silicon nitride, or other suitable materials, which can use a material different from the sacrificial layer 230, so that the support layer 240 and the sacrificial layer 230 have a larger etching selectivity when etching the sacrificial layer 230.

[0079] Further, if Figure 2 As shown, the MEMS device of the present application also includes an epitaxial layer 260 , which covers the back plate 250 and closes at least part of the multiple release holes 251 . For example, the epitaxial layer 260 covers the entire surface of the back plate 250 and closes all the release holes 251 .

[0080] Optionally, the epitaxial layer 260 and the back plate 250 include the same semiconductor material, such as doped polysilicon, or germanium silicon, germanium, or other suitable metal or semiconductor materials. Optionally, the epitaxial layer 260 and the back plate 250 may also be different materials.

[0081] The common thickness of the epitaxial layer 260 and the back electrode plate 250 may be substantially the same as that of the conventional back electrode plate 150 , or thinner than that of the conventional back electrode plate 150 . Optionally, the thickness of the epitaxial layer 260 is in the range of 0.5 to 5 μm, and the thickness of the back electrode plate 250 is in the range of 0.2 to 1 μm.

[0082] The epitaxial layer 260 and the back plate 250 are used together as fixed plates of the MEMS device, and the deformation of the sensitive layer 220 causes the capacitance of the MEMS device to change.

[0083] In this embodiment, by making the epitaxial layer 260 close at least part of the release holes 251, the capacitance change of the MEMS device when it is used can be increased, and the ASIC recognition threshold (that is, the threshold switch capacitance) can be increased, thereby reducing the complexity of the ASIC. In addition, due to the reduction of the release holes 251 and the coverage of the epitaxial layer 260, the rigidity of the back plate 250 can be increased, and the risk of the back plate becoming soft can be reduced. The increase in capacitance change and the reduction in the risk of the back plate becoming soft effectively prevent the problem of accidental touch of the electronic cigarette when the MEMS device is applied to the electronic cigarette. In addition, due to the presence of the epitaxial layer 260, the back suction of the smoke oil can be effectively reduced or even prevented.

[0084] The following will refer to FIG. 3A to FIG. 3E ,as well as Figure 4 The preparation method of the MEMS device in Example 2 is described.

[0085] First, if Figure 4 As shown, the method for preparing a MEMS device of the present application includes the following steps S410 to S460:

[0086] First, in step S410, a substrate is provided.

[0087] like Figure 3A As shown, the base may include a substrate 211, and the substrate 211 may be a silicon substrate. However, the present invention is not limited thereto, and the substrate 211 may also be a germanium substrate, a silicon germanium substrate, a silicon on insulator (SOI) or a germanium on insulator (GOI), etc. Certain doping particles may be implanted into the substrate 211 according to design requirements to change electrical parameters.

[0088] Optionally, the base further includes an isolation layer 212 formed on the substrate 211 . The isolation layer 212 may be made of silicon oxide or other suitable insulating materials to isolate the substrate 211 from the sensitive layer 220 .

[0089] In step S420, a sensitive layer 220, a sacrificial layer 230 and a back electrode plate 250 are sequentially formed on the substrate.

[0090] For example, continue as Figure 3A As shown, first, a sensitive layer 220 is formed on a substrate, for example, by chemical vapor deposition or physical vapor deposition, and a patterned mask layer, for example, a photoresist layer, is formed on the sensitive layer 220. The patterned mask layer is used as a mask to etch the sensitive layer 220 and stop at the substrate, for example, at the isolation layer 212, thereby forming a through hole in the sensitive layer 220. The mask layer is then removed, and then a sacrificial layer 230, a supporting layer 240 and a back plate 250 are sequentially deposited on the sensitive layer 220.

[0091] The materials of the sensitive layer 220 and the back plate 250 may include doped polysilicon, silicon germanium, germanium, and other suitable metals or semiconductor materials to ensure that the subsequently released portion of the sensitive layer 220 can vibrate and deform and return to its original shape when subjected to sound or inertial forces, etc., and to ensure that the sensitive layer 220 has good conductivity.

[0092] The thickness of the sensitive layer 220 affects the range of the MEMS pressure sensor. Generally speaking, the thinner the sensitive layer 220 is, the smaller the range of pressure measurement is; the thicker the sensitive layer 220 is, the larger the range of pressure measurement is. In this embodiment, those skilled in the art should understand that the thickness of the sensitive layer 220 should be selected appropriately according to actual needs.

[0093] Next, in step S430 , a plurality of release holes 251 penetrating the back electrode plate 250 are formed in the back electrode plate 250 to expose a portion of the sacrificial layer 230 .

[0094] Specifically, Figure 3B As shown, the back plate 250 and the support layer 240 are etched to form a plurality of release holes 251, exposing the sacrificial layer 230. The etching method can be dry etching or wet etching or other suitable methods, which are not specifically limited here.

[0095] Specifically, the number of the release holes 251 can be reasonably set according to actual needs.

[0096] In step S440, if Figure 3C As shown, the sacrificial layer 230 is etched through a plurality of release holes 251 to remove a portion of the sacrificial layer 230 to form a cavity 231 , and the cavity 231 exposes a portion of the surface of the sensitive layer 220 .

[0097] Specifically, the etchant used to etch the sacrificial layer 230 may include a buffered oxide etchant (BOE), a hydrofluoric acid solution, or a hydrofluoric acid vapor (Vapor HF). The buffered oxide etchant may be a mixture of HF and NH4F in different proportions.

[0098] In this step, Figure 3B The formed structure is placed in a predetermined etching solution, and the etching solution etches the sacrificial layer 230 through the release holes 251 until the upper surface of the sensitive layer 220 is exposed.

[0099] Next, in step S450 , an epitaxial layer 260 is formed to cover the back plate 250 , and the epitaxial layer 260 closes at least a portion of the release holes 251 .

[0100] like Figure 3D As shown, the epitaxial layer 260 covers the back plate 250 and closes at least part of the release holes 251 in the plurality of release holes 251. For example, the epitaxial layer 260 covers the entire surface of the back plate 250 and closes all the release holes 251. The epitaxial layer 260 can be formed by methods such as chemical vapor deposition or physical vapor deposition.

[0101] Optionally, the epitaxial layer 260 and the back plate 250 include the same semiconductor material, such as doped polysilicon, or germanium silicon, germanium, or other suitable metal or semiconductor materials. Optionally, the epitaxial layer 260 and the back plate 250 may also be different materials.

[0102] The combined thickness of the epitaxial layer 260 and the back electrode plate 250 may be substantially the same as the thickness of a conventional back electrode plate 150 , or thinner than the thickness of a conventional back electrode plate 150 .

[0103] The epitaxial layer 260 and the back plate 250 are used together as fixed plates of the MEMS device, and the deformation of the sensitive layer 220 causes the capacitance of the MEMS device to change.

[0104] In step S460, if Figure 3E As shown, a back cavity 2111 penetrating the substrate is formed in the substrate and exposes a portion of the surface of the sensitive layer 220 , wherein the back cavity 2111 and the cavity 231 are at least partially opposite to each other.

[0105] Specifically, the substrate can be etched by dry etching or wet etching to form the back cavity 2111. For example, a mask layer, such as a photoresist layer, which defines the shape and position of the back cavity 2111 is formed on the back side of the substrate (i.e., the side away from the sensitive layer 220). The substrate 211 and the isolation layer 212 of the substrate are etched (e.g., dry etching) using the mask layer as a mask until the lower surface of the sensitive layer 220 is exposed, thereby forming the back cavity 2111, and then the mask layer is removed.

[0106] By forming the back cavity 2111 and the cavity 231 , the middle area of ​​the sensitive film layer can vibrate up and down, thereby achieving a change in capacitance.

[0107] It is worth mentioning that the above preparation method is only used as an example, and the preparation method for a complete MEMS device may also include other necessary steps, or the order of the above steps may also be exchanged or performed in an alternating manner.

[0108] like Figure 5 As shown, the method for preparing the MEMS device of the first embodiment may include the following steps S510 to S550:

[0109] In step S510, a substrate is provided;

[0110] In step S520, a sensitive layer, a sacrificial layer and a back plate are sequentially formed on the substrate;

[0111] In step S530, a plurality of release holes are formed in the back plate, penetrating the back plate, to expose a portion of the sacrificial layer, wherein the total area of ​​the openings of the plurality of release holes located on the first surface of the back plate accounts for 10 to 40% of the area of ​​the first surface;

[0112] In step S540, the sacrificial layer is etched through a plurality of release holes to remove a portion of the sacrificial layer to form a cavity, wherein the cavity exposes a portion of the surface of the sensitive layer;

[0113] In step S550, a back cavity penetrating the substrate is formed in the substrate and a portion of the surface of the sensitive layer is exposed, wherein the back cavity and the cavity are at least partially opposite to each other.

[0114] Some details about step S510 and step S550 can be referred to the related steps S410 to S460 mentioned above, which will not be repeated here.

[0115] Embodiment 3

[0116] Another embodiment of the present invention provides an electronic device, including the MEMS device described in the first embodiment or the MEMS device described in the second embodiment.

[0117] The electronic device of this embodiment can be any electronic product or device such as a mobile phone, a tablet computer, a laptop computer, a netbook, a game console, a television, a VCD, a DVD, a navigator, a camera, a video camera, a voice recorder, an MP3, an MP4, a PSP, etc., or any intermediate product including the MEMS pressure sensor. The electronic device of the embodiment of the present invention has better performance due to the use of the above-mentioned MEMS pressure sensor.

[0118] The electronic device of the present application may be an electronic cigarette, in particular, which includes the aforementioned MEMS device, wherein the electronic cigarette further includes an ASIC, and the ASIC may be electrically connected to the MEMS device, so as to process the signal output by the MEMS.

[0119] Since the electronic cigarette of the present application has the aforementioned MEMS device, it also has the advantages of the aforementioned MEMS device.

[0120] Although multiple embodiments are described herein, it should be understood that a variety of other modifications and embodiments may be conceived by those skilled in the art, all of which will fall within the spirit and scope of the concepts disclosed in the present invention. More particularly, various modifications and changes may be made to the arrangements and / or components of the combined arrangements of the subject matter within the scope of the present disclosure, the drawings, and the appended claims. In addition to modifications and changes to the components and / or arrangements, the use of alternatives is also an obvious option for those skilled in the art.

Claims

1. A MEMS device, characterized in that: The MEMS device comprises: a substrate having a back cavity; A sensitive layer is suspended on the back cavity, and its edge is overlapped on the substrate; A sacrificial layer, disposed on the sensitive layer, wherein a cavity is formed in the sacrificial layer, wherein the cavity exposes a portion of the sensitive layer, and the cavity is at least partially opposite to the back cavity; A back pole plate is suspended on the cavity, and its edge overlaps the sacrificial layer, wherein a plurality of release holes penetrating the back pole plate are provided in the back pole plate, the plurality of release holes are connected to the cavity, and the total area of ​​the openings of the plurality of release holes on the first surface of the back pole plate accounts for 10 to 40% of the area of ​​the first surface.

2. A MEMS device, characterized in that: The MEMS device comprises: a substrate having a back cavity; A sensitive layer is suspended on the back cavity, and its edge is overlapped on the substrate; A sacrificial layer, disposed on the sensitive layer, wherein a cavity is formed in the sacrificial layer, wherein the cavity exposes a portion of the sensitive layer, and the cavity is at least partially opposite to the back cavity; A back plate is suspended on the cavity, and its edge is overlapped on the sacrificial layer, wherein a plurality of release holes penetrating the back plate are provided in the back plate, and the plurality of release holes are connected to the cavity; The epitaxial layer covers the back plate and closes at least part of the release holes.

3. The MEMS device according to claim 2, characterized in that: The epitaxial layer covers the entire surface of the back plate.

4. The MEMS device according to claim 2, characterized in that: The epitaxial layer and the back plate include semiconductor materials of the same material.

5. The MEMS device according to claim 1 or 2, characterized in that: The base comprises an isolation layer on which a substrate is located, the back cavity penetrates through the substrate and the isolation layer, and an edge of the sensitive layer overlaps the isolation layer.

6. The MEMS device according to claim 1 or 2, characterized in that: A support layer is further arranged on the surface of the back plate adjacent to the sacrificial layer, and the release hole penetrates the back plate and the support layer.

7. A method for preparing a MEMS device, characterized in that: The preparation method comprises: providing a substrate; forming a sensitive layer, a sacrificial layer and a back plate in sequence on the substrate; Forming a plurality of release holes penetrating the back plate in the back plate to expose a portion of the sacrificial layer, wherein the total area of ​​the openings of the plurality of release holes located on the first surface of the back plate accounts for 10 to 40% of the area of ​​the first surface; Etching the sacrificial layer through a plurality of release holes to remove a portion of the sacrificial layer to form a cavity, wherein the cavity exposes a portion of the surface of the sensitive layer; A back cavity is formed in the substrate and penetrates the substrate, exposing a portion of the surface of the sensitive layer, wherein the back cavity and the cavity are at least partially opposite to each other.

8. A method for preparing a MEMS device, characterized in that: The preparation method comprises: providing a substrate; forming a sensitive layer, a sacrificial layer and a back plate in sequence on the substrate; forming a plurality of release holes penetrating the back plate in the back plate to expose a portion of the sacrificial layer; Etching the sacrificial layer through a plurality of release holes to remove a portion of the sacrificial layer to form a cavity, wherein the cavity exposes a portion of the surface of the sensitive layer; forming an epitaxial layer covering the back plate, wherein the epitaxial layer closes at least part of the plurality of release holes; A back cavity is formed in the substrate and penetrates the substrate, exposing a portion of the surface of the sensitive layer, wherein the back cavity and the cavity are at least partially opposite to each other.

9. The preparation method according to claim 8, characterized in that: The epitaxial layer covers the entire surface of the back plate.

10. An electronic device, characterized in that: The electronic device comprises the MEMS device according to any one of claims 1 to 6.

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